Questions about gearing for solely dirt riding

[mattygritt]

Hi everyone! I have a 2020 Bashan Brozz with pretty much everything stock. I have put about 500 miles on it. I really only ride on dirt roads. Pretty soft sand. I only seem to ride in 2nd and 3rd going pretty slow down these roads.

I would love a little more power in my bottom end. It looks like my stock Brozz has 17T front sprocket and a 46T rear sprocket.

This is my first and only motorcycle. I am not too sure about gearing and if it'll make a huge difference. But I really only ride the bike going up to at most 40 mph (and even that's a stretch; most of the time I am going 20-25 cause thats the speed limit on these dirt roads). Would gearing down to a 16T front sprocket, and going up to maybe a 50T rear sprocket give me more what I am looking for? Some more power in the lower gears?

I used a sprocket calculator and I really just don't understand the gear ratio stuff. Any advice is appreciated! Thanks!

[XLsior]

not a huge change from a 17t front down to a 16t.


try a 15t front sprocket. Shouldn't require a chain length link taken out with rear wheel adjustment/chain tension.


Front sprockets are cheap...rear sprockets not so much.


After that you can work out if you want a smaller front or if the 16t would be the sweet spot for your riding preferences.


46rear sprocket is fine. 1 tooth change on the rear is minimal effect.



the saying goes 1 tooth change in the front is like 3 in the back.

[Megadan]

Is it a standard brozz with the 17 inch rear wheel, or a RECON with the 18 inch rear wheel?

I do agree completely with the 15 front. The original Hawk has a 15 front and a 50 rear with the 18 inch rear wheel and it's geared perfectly for what you want. With a 17 inch rear wheel the 15 front and 46 rear would be very close to the same.

[mattygritt]

Thanks guys! It is the Recon but in 2020 it came with a 19" front wheel and 17" rear. I'll end up going with the 15T front sprocket then and give it a shot!! Appreciate the advice.

Maybe a dumb question... but how do you know if you have to remove a link from the chain? I am still rocking the stock chain the Brozz came with.

[XLsior]

if the back wheel is fully adjusted out and there is still to much slack in the chain you will need to take out a link if you're dropping down teeth in the front.

[Thumper]

Yes! Dropping a couple of teeth on the front will drop the ratio on every gear by about 11%


You will definitely notice 2nd and 3rd have a little more torque, and going 11% slower at a given rpm. Of course it also means 11% slower at same rpm in 5th on pavement!

It is actually amazing that you are still using the original chain, a 428. If the new gearing works for you, you might consider an upgrade to a RK Takasago 428H chain. Just $23. It will be quieter and stronger, and mate well during breaking in period on the new front sprocket.

I upgraded to 520 chain with sprockets on my Brozz (Bashan) Storm, but probably would have been OK with the better 428H chain.

By the way, I really like that original Recon. NICE bike! And I'll bet it's holding up well. My storm was identical, but black red and white colors. Correction: The recon came with knobbies. That's the only difference as I recall. I got dual sport tires that I got rid of within a month!

[red2003]

Gearing comes down to rpm. What rpm are you seeing when you feel you need more "bottom end power"? Changing the gearing isn't going to give you any more or less power, it just changes the rpm range of each gear. For example, if 25mph is currently 6000 rpm in your gear of choice, that's where your bike is prob building max torque. Changing gearing will have no effect for you. If 25 mph is only 4000rpm, then shift down a gear and bring the rpm's back into the torque band. To summarize, unless you are running out of gearing on the top end in 5th gear, or 1st gear isn't providing enough rpm at your slowest speed, changing gearing isn't going to help you at all.

[Thumper]

Gearing comes down to rpm. What rpm are you seeing when you feel you need more "bottom end power"? Changing the gearing isn't going to give you any more or less power, it just changes the rpm range of each gear. For example, if 25mph is currently 6000 rpm in your gear of choice, that's where your bike is prob building max torque. Changing gearing will have no effect for you. If 25 mph is only 4000rpm, then shift down a gear and bring the rpm's back into the torque band. To summarize, unless you are running out of gearing on the top end in 5th gear, or 1st gear isn't providing enough rpm at your slowest speed, changing gearing isn't going to help you at all.

Not exactly what he is asking, and changing the gearing WILL help him.

His 2nd and 3rd gears are too tall for his riding conditions. The engine isn't revving high enough to be in the more powerful part of the powerband under those conditions. He wants a little more torque under those conditions. Increasing the rpm by 11% WILL give him more REAL POWER, ACTUAL TORQUE difference in those gears under those conditions, because the engine will be running at a higher rpm. This assumes that he won't change his choices and start running in 3rd and 4th under those conditions!

The real difference will be that he has more gears to select from that keep the engine higher in the rpm range that produces more power. 1st is too low geared, and 2nd/3rd are geared too tall for what he needs. That 11% change will help in the gravel/sand.

[mattygritt]

Yes! Dropping a couple of teeth on the front will drop the ratio on every gear by about 11%


You will definitely notice 2nd and 3rd have a little more torque, and going 11% slower at a given rpm. Of course it also means 11% slower at same rpm in 5th on pavement!

It is actually amazing that you are still using the original chain, a 428. If the new gearing works for you, you might consider an upgrade to a RK Takasago 428H chain. Just $23. It will be quieter and stronger, and mate well during breaking in period on the new front sprocket.

I upgraded to 520 chain with sprockets on my Brozz (Bashan) Storm, but probably would have been OK with the better 428H chain.

By the way, I really like that original Recon. NICE bike! And I'll bet it's holding up well. My storm was identical, but black red and white colors. Even the tires were identical!
Good to know! I am really excited to see what the bike feels like when I make the change. I think that sounds like a good idea. I'll test things out with the stock chain and I'll upgrade to the chain you linked when. I feel like I am satisfied with the 15T front sprocket!

Thanks too! I love the look of the Recon. Really love the brown and black combo! It's been such a fun bike. Perfect for what I needed! I am really happy I got it. I'm still using the stock nobby tires it came with too, they've really outperformed my expectations I had of them lol!

[Megadan]

Gearing comes down to rpm. What rpm are you seeing when you feel you need more "bottom end power"? Changing the gearing isn't going to give you any more or less power, it just changes the rpm range of each gear. For example, if 25mph is currently 6000 rpm in your gear of choice, that's where your bike is prob building max torque. Changing gearing will have no effect for you. If 25 mph is only 4000rpm, then shift down a gear and bring the rpm's back into the torque band. To summarize, unless you are running out of gearing on the top end in 5th gear, or 1st gear isn't providing enough rpm at your slowest speed, changing gearing isn't going to help you at all.
Gearing does change the amount of torque at the rear wheel. That's what gear ratios do, divide rpm and multiply torque. Horsepower doesn't change because it is a function of rpm and torque. Changing gear ratios just alters the relationship between those two on their side of the equation.

[ProDigit]

Totally opposite of what I'd do, but, yeah, go with a 15t, and if you want more after that, get a larger rear sprocket. But I'm fairly sure 2 teeth on the rear will do a lot, allowing you more flexibility. It's just that, for loose sand, a 250 is kind of overkill. A 150 would've had the power you need, and you could've geared it to reach 5th gear, and still spin your wheel in the first 3 gears.
It's be a lighter weight bike as well, which helps when you fall.

[ProDigit]

Gearing does change the amount of torque at the rear wheel. That's what gear ratios do, divide rpm and multiply torque. Horsepower doesn't change because it is a function of rpm and torque. Changing gear ratios just alters the relationship between those two on their side of the equation.


Hp rating of the engine doesn't change, but changing to taller gears, definitely changes HP to the wheels.
Not only because one can now reach top speed at hp peak, rather than at redline (where the bike has lower HP), but also, by increasing the load on the engine, you can extract more energy out of it.

Hence, lower gears, net more torque, but lower HP.

The results of torque can be seen by how fast it accelerates,
The results of HP can be seen by how fast the bike can get.

[Thumper]

Totally opposite of what I'd do, but, yeah, go with a 15t, and if you want more after that, get a larger rear sprocket. But I'm fairly sure 2 teeth on the rear will do a lot, allowing you more flexibility. It's just that, for loose sand, a 250 is kind of overkill. A 150 would've had the power you need, and you could've geared it to reach 5th gear, and still spin your wheel in the first 3 gears.
It's be a lighter weight bike as well, which helps when you fall.

OP can drop two teeth on the front sprocket for a 11% gearing change, and probably won't even need to remove a link. Adding two teeth on the rear would drop rpm 2/50 = about 4%. He probably won't need a new chain with the larger new rear sprocket, but removing a link would be the opposite... Dropping 1 tooth on the front sprocket would give OP a 5% drop in speed at same rpm, with the same/similar gearing advantage to adding two teeth on the rear sprocket.

Front sprockets are less expensive, and OP wants to explore this gearing change. It may be the opposite of what you would do, but it is a low cost option/test. I was amused at your suggestion to use an ethernet cable to rewire a harness in another thread. Talk about opposite...Now that is a bold and fascinating proposal! Clearly you have novel ideas for motorcycle maintenance and repair. I recently wired up an isolated lighting system on my KTM. I used spools of 12, 14 gauge wire and brass end connectors with insulation. I guess I went a little more boring and "conventional".

[Megadan]

Hp rating of the engine doesn't change, but changing to taller gears, definitely changes HP to the wheels.
Not only because one can now reach top speed at hp peak, rather than at redline (where the bike has lower HP), but also, by increasing the load on the engine, you can extract more energy out of it.

Hence, lower gears, net more torque, but lower HP.

The results of torque can be seen by how fast it accelerates,
The results of HP can be seen by how fast the bike can get up to.

I never said HP rating changed, nor is anybody talking about at the engine... So your reply is confusing. We are strictly talking about sprockets, so the engine isn't even a factor here since this is about gear reduction between the counter shaft of the transmission and the rear wheel.

Gears do not affect horsepower. Period. Sorry, but you are wrong.

Torque does affect acceleration, nobody argued that. Again, not sure what your argument is here exactly.

Horsepower is the result of calculating an equation involving both torque and RPM. It's a measure of energy from Force over distance and time. That's it. Torque is the measured force. The Distance and Time is the Revolutions per minute of the rear wheel (in this instance). Since the gear ratios multiply AND divide said force and the rpm by the same ratio, the resultant horsepower figure remains unchanged.

This is algebra 101 stuff and I won't argue this further. I am correct on this. If you want to argue more, go hit up google and do some more studying. I have little time for know-it-all arguments.

[Thumper]

There are thousands of webpages on torque multiplication using gear reduction.
Here is one:
https://bauergmc.com/4-major-advantages-of-using-a-gear-reducer.html

OP will gain significant torque increases with a 11% reduction in gear ratio. This is what he needs. It will allow his 14hp engine to power him through high friction surfaces like sand/gravel with more torque. Chaindrive systems are actually more efficient than gearboxes, but they need more maintenance. This really is simple math.

[J4Fun]

I’ll bet the 15t sprocket will hit the sweet spot for what the OP was asking! The rest of the story should be called “The Driver and the Driven” and their relationship.;)

[red2003]

Not exactly what he is asking, and changing the gearing WILL help him.

His 2nd and 3rd gears are too tall for his riding conditions. The engine isn't revving high enough to be in the more powerful part of the powerband under those conditions. He wants a little more torque under those conditions. Increasing the rpm by 11% WILL give him more REAL POWER, ACTUAL TORQUE difference in those gears under those conditions, because the engine will be running at a higher rpm. This assumes that he won't change his choices and start running in 3rd and 4th under those conditions!

The real difference will be that he has more gears to select from that keep the engine higher in the rpm range that produces more power. 1st is too low geared, and 2nd/3rd are geared too tall for what he needs. That 11% change will help in the gravel/sand.

Well, we don't know that is the case. Thats why I asked what rpm he is running now. If he is too low in the rpm range in 2nd and 3rd, then use 1st and 2nd in those situations. Thats what gears are for. He's a new rider and probably read that changing gears will give him more power. Well,as you are aware, it will not.

[red2003]

[QUOTE=Megadan;409536]Gearing does change the amount of torque at the rear wheel. That's what gear ratios do, divide rpm and multiply torque. Horsepower doesn't change because it is a function of rpm and torque. Changing gear ratios just alters the relationship between those two on their side of the equation.[/QUOTES

Sure, but we don't know that gearing is the issue here as we don't have information about the rpm he is hitting where he is looking for "more power". If he is currently turning 8000 rpm at 25mph, raising the gear ratio is going to move him even MORE out of the peak torque band. It sounds like the OP is looking for an easy answer to give his bike "more power", and gearing isn't that answer.

[Thumper]

I guess OP will find out. He will have more torque in the conditions he describes. I guess that is what he wants.

[ProDigit]

OP can drop two teeth on the front sprocket for a 11% gearing change, and probably won't even need to remove a link. Adding two teeth on the rear would drop rpm 2/50 = about 4%. He probably won't need a new chain with the larger new rear sprocket, but removing a link would be the opposite... Dropping 1 tooth on the front sprocket would give OP a 5% drop in speed at same rpm, with the same/similar gearing advantage to adding two teeth on the rear sprocket.

Front sprockets are less expensive, and OP wants to explore this gearing change. It may be the opposite of what you would do, but it is a low cost option/test. I was amused at your suggestion to use an ethernet cable to rewire a harness in another thread. Talk about opposite...Now that is a bold and fascinating proposal! Clearly you have novel ideas for motorcycle maintenance and repair. I recently wired up an isolated lighting system on my KTM. I used spools of 12, 14 gauge wire and brass end connectors with insulation. I guess I went a little more boring and "conventional".

I meant 2t down on the front sprocket, not rear (because I usually think in terms of going up on the front and down on the rear).
but yeah, 2-3 down on the front, and 3-4 up on the rear cause you to have nearly the same chain length setting on the adjusters.

An ethernet cable can handle blinkers and data/sensor wires just fine, provided they are LED lights. Might even run a tail light.
I wouldn't use it for break or headlights, unless you plan on using multiple wires. I think each wire handles about 1 amp, equals about 12W. The LED blinkers are about 5W, or half the maximum capacity of the wire.

You can also reuse some of the wires on the harness. Like the ground wire.
The ground wire on the blinkers and tail light are all the same. If you disconnect the ground wire on the tail light or blinkers, and disconnect it at the other end as well, it'll free up a wire on the harness for other purposes.

The tail and blinker lights can easily be grounded to the body of the bike, or to another ground point.
I'd rather do this, than replace an entire wire harness, for a few faulty wires.

[ProDigit]

I never said HP rating changed, nor is anybody talking about at the engine... So your reply is confusing. We are strictly talking about sprockets, so the engine isn't even a factor here since this is about gear reduction between the counter shaft of the transmission and the rear wheel.

Gears do not affect horsepower. Period. Sorry, but you are wrong.

Torque does affect acceleration, nobody argued that. Again, not sure what your argument is here exactly.

Horsepower is the result of calculating an equation involving both torque and RPM. It's a measure of energy from Force over distance and time. That's it. Torque is the measured force. The Distance and Time is the Revolutions per minute of the rear wheel (in this instance). Since the gear ratios multiply AND divide said force and the rpm by the same ratio, the resultant horsepower figure remains unchanged.

This is algebra 101 stuff and I won't argue this further. I am correct on this. If you want to argue more, go hit up google and do some more studying. I have little time for know-it-all arguments.

If you say gears adjust torque, then gears also adjust HP.
Gears have everything to do with harvesting max torque or HP out of an engine, and have absolutely everything to do with this topic.

I don't see anything I've written out of line with the conversation. Just merely responding to an incorrect assumption on your part.
You think everything is math,but your math ain't mathing, if you agree that gears change torque without changing HP.

The formulas you're using aren't applicable to gearing, but just to engine testing. Once you add gearing to the equation, engine output and HP ratios change. It's just a fact.

[XLsior]

Oh boy, its going to be one of those...


We are not changing the crank and rod inside the engine to implicate the known engine out put.


Or changing the internal gearing at the output shaft...


The HP an torque of the engine is what it is.


Changing sprockets, wheel diameters, overall weight and chain type/length will merely shift the output dynamics.

[ProDigit]

Oh boy, its going to be one of those...


We are not changing the crank and rod inside the engine to implicate the known engine out put.


Or changing the internal gearing at the output shaft...


The HP an torque of the engine is what it is.


Changing sprockets, wheel diameters, overall weight and chain type/length will merely shift the output dynamics.


Changing gearing changes the load on the engine.
Engine ratings are done at a fixed load, and thus the rating of any dyno is fixed.
Increase the load, increases the efficiency, and thus also the HP output.

Try reading a dyno in 4th gear, and in 6th gear. You'll understand what I'm talking about about.

[bogieboy]

Oh boy, its going to be one of those...


We are not changing the crank and rod inside the engine to implicate the known engine out put.


Or changing the internal gearing at the output shaft...


The HP an torque of the engine is what it is.


Changing sprockets, wheel diameters, overall weight and chain type/length will merely shift the output dynamics.
And shifting the output dynamics changes the percieved torque in any given gear, which is what the OP is looking to do... we know the science behind what you are trying to say, but we also know real world factors make changing the final drive a viable option to get the powerband where we want it.... which is exactly what the OP was asking about...

Take a drag car, if you put a 2.22:1 gear in the rear end, its not going to accelerate (percieved torque) near as fast as a 4.60:1, or a 5.72:1 rear end. Has the engine output changed? Nope... has the acceleration changed, causing a percieved torque shift, absolutely...

[flopsweat]

I remember something like this coming up with a seemingly simple question I asked in my first days here. After getting very confused with what I was reading, I looked around this forum and realized... Megadan is probably right.

[buzz]

So true flopsweat

[Thumper]

And as described in posts #6, #8, #13, and especially #15.
Torque. Gear reduction provides TORQUE. It effectively increases power output by reducing the rpm of the engine through gears.

This is exactly what OP is asking about. The engine is spinning at MUCH higher rpm than the rear wheel which results in multiplication of power. So he can power through gravel and sand.

I have a planetary 6x gear reduction unit bolted to the direct digital drive with a variable speed controller on my chile roaster. It multiplies the output and provides low speed control. If I put a sprocket on the thing, it would drag a 1000 pound motorcycle into the air. Without that gear reduction, the stepper motor wouldn't have enough juice.

This is exactly the same thing that reducing the gear ration using sprockets does.
https://youtu.be/0dxtMj1nRZE

[Thumper]

Here is the stepper motor without the planetary gear reducer.

https://www.youtube.com/watch?v=zjHQwHmvtIo

The gear reduction box increases the power output of the stepper motor. As Megadan mentioned, this is simple math.

[red2003]

Here is the stepper motor without the planetary gear reducer.

https://www.youtube.com/watch?v=zjHQwHmvtIo

The gear reduction box increases the power output of the stepper motor. As Megadan mentioned, this is simple math.

Yes, it is simple math. But, the math you are leaving out is the resulting rpm. In your example, yes your drum has more torque, but at a sacrifice to its resulting rpm. Yes raising the gear ratio results in increased torque, but at a reduced speed. You cannot get more torque and not lose something on the other side of the equation. So, the OP stated he wanted more torque in 2nd and 3rd gears for his typical speed of 25 mph. Well, he can accomplish that by dropping from 3rd to 2nd and 2nd to 1st when more torque is needed. That's why bikes have transmissions. If he was running out of torque at the lowest possible gear, or rpm at the highest possible gear, THEN gearing would be beneficial.

Equally important is the fact that your stepper motor is, well a motor. Electric motors have constant torque at all rpm. Engines do not, so using this as an example of the "simple math" involved here is not applicable.

[Thumper]

Yes, it is simple math. But, the math you are leaving out is the resulting rpm. In your example, yes your drum has more torque, but at a sacrifice to its resulting rpm.
...
...
...
Equally important is the fact that your stepper motor is, well a motor. Electric motors have constant torque at all rpm. Engines do not, so using this as an example of the "simple math" involved here is not applicable.

Yes, having lower gearing on 2nd and 3rd will give OP more choices with higher rpm at the same speed that he wants to go to power through the sand/gravel more easily. Hence the additional torque with lower gearing.
This is exactly what he wants.

[Megadan]

If you say gears adjust torque, then gears also adjust HP.
Gears have everything to do with harvesting max torque or HP out of an engine, and have absolutely everything to do with this topic.

I don't see anything I've written out of line with the conversation. Just merely responding to an incorrect assumption on your part.
You think everything is math,but your math ain't mathing, if you agree that gears change torque without changing HP.

The formulas you're using aren't applicable to gearing, but just to engine testing. Once you add gearing to the equation, engine output and HP ratios change. It's just a fact.

Say "I didn't read or comprehend what you said" without actually saying it. Try again, you are still wrong.

[Megadan]

Changing gearing changes the load on the engine.
Engine ratings are done at a fixed load, and thus the rating of any dyno is fixed.
Increase the load, increases the efficiency, and thus also the HP output.

Try reading a dyno in 4th gear, and in 6th gear. You'll understand what I'm talking about about.
The funny thing is, as long as the dyno knows what gear you are in, the only thing that changes is how good the graph reads. It will still show the right hp and torque figures. The only reason it doesn't? You have it programmed to read 4th but you run it in 3rd (or any other gear mix match you want to name).

Imagine being this confident, and still wrong. Baffling

[Megadan]

Yes, having lower gearing on 2nd and 3rd will give OP more choices with higher rpm at the same speed that he wants to go to power through the sand/gravel more easily. Hence the additional torque with lower gearing.
This is exactly what he wants.

Congrats on being the only correct person here, besides me

[bogieboy]

Say "I didn't read or comprehend what you said" without actually saying it. Try again, you are still wrong.

I like how the troll hasnt touched what i said, which is exactly what you said, but said in a little bit different way... :hehe:

Also, guess not everyone knows that HP is just TQxRPM/5252 To get the arbitrary number everyone drools about...

[Thumper]

Gearing comes down to rpm. What rpm are you seeing when you feel you need more "bottom end power"? Changing the gearing isn't going to give you any more or less power, it just changes the rpm range of each gear. For example, if 25mph is currently 6000 rpm in your gear of choice, that's where your bike is prob building max torque. Changing gearing will have no effect for you. If 25 mph is only 4000rpm, then shift down a gear and bring the rpm's back into the torque band. To summarize, unless you are running out of gearing on the top end in 5th gear, or 1st gear isn't providing enough rpm at your slowest speed, changing gearing isn't going to help you at all.

I hear what you are saying, and in another post that we don't know that OP will get the revs up (keep using same gear, at higher rpm).

OK. The thing is, he will have lower gearing available for more torque if he does. I'm thinkin he will. Well, it's how I explained it anyway... same speed at higher rpm. More torque!

[Megadan]

I like how the troll hasnt touched what i said, which is exactly what you said, but said in a little bit different way... :hehe:

Also, guess not everyone knows that HP is just TQxRPM/5252 To get the arbitrary number everyone drools about...

Don't go quoting math, you might give them the ability to figure out what we are telling them. :lmao:

Actually, maybe I can help them with it.

Just for fun, lets say our engine makes 10ft-lb's of torque at 4000rpm in 4th gear. Let's say the primary gear reduction is 4:1 and we are in 4th gear, which is 1:1 for some simplicity.

Total Gear Reduction: 4 x 1 = 4 or 4:1 at the counter shaft - where the front sprocket is located.

Since Gear ratios multiply torque by dividing RPM, the Countershaft now has 40ft-lbs of torque and the counter shaft is spinning 1000RPM

We can plug in the engine figures to get hp with the equation:
10ft-lbs x 4000rpm/5252 =
40,000/5252 = 7.61hp

What about the counter shaft, let's do that math, shall we?
40 x 1000/5252 =
40,000/5252 = 7.61hp

So, having gone through ONE gear reduction the HP is the same at the crank and the front sprocket. Let's go to the rear wheel, shall we?

Then, let's say we have a 17 front 46 rear to start with, or 2.71:1
40ft-lbs x 2.71 = 108.4ft-lbs. 1000rpm/2.71 = 369rpm
So our stock gearing is producting 108ft-lbs at 369rpm at the rear wheel. (go ahead and do the math for MPH if you want).

Next, let's say we have a 15 front and 46 rear, or 3.07:1
40ft-lbs x 3.07 = 122.8ft-lbs 1000rpm/3.07 = 325.73rpm at the rear wheel.

So far, the new sprocket has increased torque at the wheel, but reduced maximum wheel RPM at the same engine RPM point - exactly as Thumper, myself, and bogfie boy said.

Not looking too good for you keyboard warriors/experts. But, let's keep going and see if it does indeed increase horsepower at the rear wheel.

To reiterate, HP = Torque x RPM / 5252

Let's do some math!

Stock gearing, at the rear wheel we had 108ft-lbs at 369rpm

HP = 108.4 x 369/5252
HP = 39999/5252
HP = 7.61hp
Huh.. Look at that HP figure...

Smaller 15t front sprocket gearing we had 122.8hp and 325.73wheel rpm

HP = 122.8 x 325.73/5252
HP = 39999/5252
HP = 7.61hp

Gosh... look at that. The HP is unchanged, just like we said.

So, gents, the math has spoken. If you argue past this point you are simply trying to sooth your hurt ego. Truth is, I don't care. We are right, you are wrong. The end.

P.S. If you want to try and argue driveline loss, it's irrelevant in this example as the loss is a fixed value that would apply to all of the figures. It would also be counter point to your argument since it is... a loss.

[ProDigit]

@megadan, you're still wrong tho.
You base all the torque figures off of a dyno with one specific load.
A small dyno may be showing correct numbers for a certain vehicle (like an economy car, or a bike), but put a truck or a real sports car on it, and the numbers will be off from their actual values.

Put an economy car on a truck dyno, where the rollers are much heavier, and the well tuned dyno will show that the economy car has higher HP and tq values than on the smaller dyno.

This, because the heavier rollers simulate much greater road resistance, like that of a truck, or that of a sports car driving real fast.

You think an engine has a fixed amount of torque or HP, but that's not true at all. Increasing the load on an engine, is likened to advancing the timing.
Your engine will run more efficiently with a timing advance, or a higher load, until either the load or the timing advances becomes too much.
Then it'll bog down and die, and torque and HP output will be zero.

The math you're using assumes nothing of engine load.
It's just a formula you'd use if you assumed the load on the engine is exactly the same in all gears. It is used often as a simplification to explain how HP and tq work, but it's flawed, and much more complex in real life than the formula indicates.

Added to an increase in efficiency, there are also added losses, like friction, heat, and other losses that counterbalance the increase in efficiency.

But generally speaking, especially with air-cooled engines, they run inefficient. And gearing higher, or advancing the timing are 2 methods to harvest more energy out of the engine, running the same speed for less fuel.

[Thumper]

Hah! Funny! :lmao:

Is this a race? No... a descension into hilarity.

It really is simple. Engines have a peak hp recognizable on their power output curves. If you can run at rpm that generates more hp, great! Lower gearing can help you optimize this since gearing down an engine provides more torque closer to the peak output/rpm.

Of course, the driver needs to know how to use it. That is the only question we can't really answer!

[bogieboy]

@megadan, you're still wrong tho.
You base all the torque figures off of a dyno with one specific load.
A small dyno may be showing correct numbers for a certain vehicle (like an economy car, or a bike), but put a truck or a real sports car on it, and the numbers will be off from their actual values.

Put an economy car on a truck dyno, where the rollers are much heavier, and the well tuned dyno will show that the economy car has higher HP and tq values than on the smaller dyno.

This, because the heavier rollers simulate much greater road resistance, like that of a truck, or that of a sports car driving real fast.

You think an engine has a fixed amount of torque or HP, but that's not true at all. Increasing the load on an engine, is likened to advancing the timing.
Your engine will run more efficiently with a timing advance, or a higher load, until either the load or the timing advances becomes too much.
Then it'll bog down and die, and torque and HP output will be zero.

The math you're using assumes nothing of engine load.
It's just a formula you'd use if you assumed the load on the engine is exactly the same in all gears. It is used often as a simplification to explain how HP and tq work, but it's flawed, and much more complex in real life than the formula indicates.

Added to an increase in efficiency, there are also added losses, like friction, heat, and other losses that counterbalance the increase in efficiency.

But generally speaking, especially with air-cooled engines, they run inefficient. And gearing higher, or advancing the timing are 2 methods to harvest more energy out of the engine, running the same speed for less fuel.
No...no....no.... math doesnt lie... how thick is your freaking skull? A dyno has NOTHING to do with any of the math involved... its simple algebra... a dyno is just a tool used to measure those values... just stop filling this forum with your utter BS.... increasing load has ABSOLUTELY ZERO to do with any sort of timing advance... also has very little to do with efficiency....
Youre just spouting BS at this point to tey and prove your point...

We could just agree with you, but then we would all be wrong....:crazy:

[Megadan]

@megadan, you're still wrong tho.


If I am wrong, PROVE me wrong. Provide reputable sources to back your claim, or do the math yourself and post it here (like I did) to prove me wrong.

Otherwise, stop talking. You're not only wrong, you're just ignorant and arrogant.

The math I am doing doesn't care about engine load. Put in our own torque figure for a different load. Go half the torque, or a tenth of the torque I listed at any given RPM point. Pick a number, ANY number, and it will give you the calculated HP figure for that amount of torque at that given RPM point. Then do all the same math I did for all of the same gear ratios. The horsepower number won't change because of any gearing/sprocket changes. The ONLY reason the HP figure will change is because the torque value changes, which is kind of a "Duh" thing when you are changing the load.

Want quick proof? Instead of 10ft-lbs at 4000rpm, let's say we only need 5ft-lbs at 4000rpm. Let's run through the stock gearing examples above.

At the counter shaft, stock gear, 5ft-lbs of "load."
HP = (5x4) x 4000/4)/5252
HP = 20ft-lbs x 1000rpm/5252
HP = 20000/5252
HP = 3.8hp

At the rear wheel.
HP = (20x2.71) x (1000/2.71)/5252
HP = 54.2 x 369/5252
HP = 19999.8/5252
HP = 3.8hp

Different load, same result... Man, it's almost like myself and a couple other people here already explained all this or something

The argument was that sprockets change HP at the rear wheel, nothing else, and I proved that wrong with the math above. Period.


Evidence of your post making that claim:
Hp rating of the engine doesn't change, but changing to taller gears, definitely changes HP to the wheels.


The Post itself, number 12.
https://chinariders.net/showpost.php?p=409538&postcount=12

I also attaching a screen shot of that post to this reply, just in case somebody wants to get cute and try to edit things. No, I don't play around. ;)

It's linked, click to make it bigger.
https://i.ibb.co/yhRRNYX/Screenshot-2024-06-21-000054.png (https://ibb.co/yhRRNYX)

The ball is in your court, do it right or stop running off at the mouth. I just proved you wrong, end of story.

P.S. Your engine load theory is manure. Any difference you MIGHT see at the rear wheel would come down to margin of error or miscalibration. If you don't think one of these bikes is under enough load in 4th or 5th gear to put out max rated power (derived from a brake dyno, aka, loaded) you need to re-evaluate things. Heck, they can be loaded enough in third gear.

If your whole theory is based on a stock Hawk topping out at 59mph, and with a 17/45 capable of 68mph. That's down to where the engine peak power is in the RPM range, not the load on the engine. Peak Torque at 5000-5500, Peak HP at around 6500-7000. Do the math on the gearing and you will see what speeds you achieve at the power peak for each sprocket combination. gearingcommander.com

[bogieboy]

@megadan, i think the biggest problem is this guy still thinks HP actually means anything.... when its a completely arbitrary number, the torque value for the stated rpm is what means anything at all, which as numerous people have already gone over, changes with gearing changes yet that mythical number called hp always stays the same no matter what the gearing changes do...LOL however applied torque certainly will change with gearing changes... thats how ratios work LOL but this guy cant seem to wrap his brain around that FACT....

[Megadan]

@megadan, i think the biggest problem is this guy still thinks HP actually means anything.... when its a completely arbitrary number, the torque value for the stated rpm is what means anything at all, which as numerous people have already gone over, changes with gearing changes yet that mythical number called hp always stays the same no matter what the gearing changes do...LOL however applied torque certainly will change with gearing changes... thats how ratios work LOL but this guy cant seem to wrap his brain around that FACT....

It's almost like Horsepower is just a measure of energy when a force is applied to do work over distance and time... or something like that. :hmm:
You know.. energy, like electricity, given in watts or something.
Maybe that's why you can convert Horsepower to Kilowatts... hrmmm....

Oh, wait, we're dumb and don't know anything. Oops!

[ProDigit]

Sorry, I've tried to explain to you. You just look at static dyno figures that aren't real world figures. All your math takes into consideration is one readout of one dyno result, that's stickered on an engine.

Surprise, you can actually get higher HP values out of your engine than whatever is stickered on it by the factory.

Anyway, you're hard headed and don't understand what I'm talking about, and I'm not going to spend any more time trying to explain the errors in your math.

Doesn't mean you're right, just means if you refuse to see where you're wrong, there's nothing else I can do.

[ProDigit]

@megadan, i think the biggest problem is this guy still thinks HP actually means anything.... when its a completely arbitrary number, the torque value for the stated rpm is what means anything at all, which as numerous people have already gone over, changes with gearing changes yet that mythical number called hp always stays the same no matter what the gearing changes do...LOL however applied torque certainly will change with gearing changes... thats how ratios work LOL but this guy cant seem to wrap his brain around that FACT....

I think you misunderstand.
I understand what you're saying, in fact I even see the flaws in that theory.
Just read my previous response. HP values are determined by the factory which did tests on a fixed load. Change the load on an engine improves efficiency, thus if we assume that the factory rating is correct, a higher gearing will in fact cause higher horsepower.

There's a difference between the rated HP values, and the actual HP values.

How else will you explain higher efficiency?
How can an engine run at a higher efficiency, and not produce more HP?
That doesn't make any sense at all.
And the proof is in the pudding.
Change the gearing, get higher performance, until you reach peak performance. After that (too tall gears) and the engine won't have enough power anymore, and will produce less HP than rated.

But if you really can't wrap your head around this,
Then think of it like this:

An engine rated at 11 HP, from the factory only makes 10hp. By changing the gears, you can make it do it's rated 11hp, transferring more HP to the wheels than stock, reaching it's rated HP values (what stock never could do).

[bogieboy]

Sorry, I've tried to explain to you. You just look at static dyno figures that aren't real world figures. All your math takes into consideration is one readout of one dyno result, that's stickered on an engine.

Surprise, you can actually get higher HP values out of your engine than whatever is stickered on it by the factory.



Anyway, you're hard headed and don't understand what I'm talking about, and I'm not going to spend any more time trying to explain the errors in your math.

Doesn't mean you're right, just means if you refuse to see where you're wrong, there's nothing else I can do.

Uhh.... no... volumetric efficiency changes with load and throttle position but does NOT change the maximum output of the engine.... what you are talking about that we cant "understand" is you blatantly ignoring the laws of physics, and the proven math that is (apparently ALMOST) UNIVERSALLY ACCEPTED as scientific law, and are throwing that out the window for your own hair brained theories.

Im done arguing with this :crazy:

[bogieboy]

Sorry, I've tried to explain to you. You just look at static dyno figures that aren't real world figures. All your math takes into consideration is one readout of one dyno result, that's stickered on an engine.

Surprise, you can actually get higher HP values out of your engine than whatever is stickered on it by the factory.

Anyway, you're hard headed and don't understand what I'm talking about, and I'm not going to spend any more time trying to explain the errors in your math.

Doesn't mean you're right, just means if you refuse to see where you're wrong, there's nothing else I can do.

One last point... if you have real math that you can show that proves either myself or megadan wrong, i will gladly consider it... show your work, like in 6th grade math, like we have done to show you... all you do is talk... you havent shown anything other than ignorance so far....

[cheesy]

Enough. This thread is closed.