TBR7 Front and Rear Sprocket

[TBR7-Rider]

I need help please. I have a 2021 TBR7-D. I am changing the sprockets and found I have a 12 tooth in the front and a 38 in the back. Does that sound right to anyone? I bought a 17 tooth for the front but I can get it on with out changing to a longer chain. So should I change the rear also when I buy a new chain, and what size rear sprocket should I go up to. I ride 100% on the street on off road. ( bad back ) I just want a smooth ride that's not to much of a dog on the street.
Thanks

[21_Xpect]

This may help, I don't know if you've seen it

https://sprocketcalculator.com/
It was very accurate for me

[Thumper]

Originally Posted by TBR7-Rider

...
...
I ride 100% on the street on off road. ( bad back ) I just want a smooth ride that's not to much of a dog on the street.
Thanks

Not sure which you mean... 100% on the street on off road? Maybe that is a typo. Also, how would it be a dog on the street? Gearing too tall would make it a dog? I guess the real question is do you want taller gearing or lower gearing? And how much of a change (% change from stock)?

TBR7 comes geared way down, most go for taller gearing (faster on the road).
TBR7 stock final drive ratio is lower than most at 12/48, at 0.250
Presumably, you want to drop the rpms so you can go faster on the street.
Right?

for comparisons, OEM ratios for...
Hawk is 15/50 = 0.300
Storm is 17/46 = 0.3696
Expect 15/46 = 0.3261

Here is a post showing options for those three bikes. You can make a similar chart for yours to see what the consequences (% change in drive ratio) would be, depending on what sprockets you choose.

https://www.chinariders.net/showpost...7&postcount=41

To translate the table, % increase (if you gear upwards) will translate exactly to THAT % increase in speed at the same rpm, any gear, compared to OEM sprockets.

[buzz]

hi you need a new chain with new sprockets

[dig4dirt]

Originally Posted by jeffrey

Those sprocket sizes on the OP bike sound like the 520 size chain not the 428.

More than likely.

I have a 2021 tbr7-d and it came with 15 front with a 428 chain.

I did upgrade sprockets 17/42 and bought a longer JT 428 HD chain (had to remove 1 or 2 links)

I will be riding 90% or more on street, so I wanted mostly low rpm/higher speed
I can feather clutch if I ever decide to go mud boggin' but doesnt seem to be any issue whatsoever.

[TBR7-Rider]

Originally Posted by 21_Xpect

This may help, I don't know if you've seen it

https://sprocketcalculator.com/
It was very accurate for me

:thanks that charts helps.
My chain is 520. I didn't know that when I posted my question. As to the off road, I meant to say no off road riding.
Thanks for all the help.


:

[Thumper]

Originally Posted by jeffrey

Those sprocket sizes on the OP bike sound like the 520 size chain not the 428.

We got a new TBR7 recently and it has a 46 tooth rear sprocket and a 428 chain. Same as dig4dirt. Those sprockets don't sound OEM (TBR7-rider). Someone already upgraded to 520 on it before TBR7-rider bought it ?

12/38 (0.3158) is pretty darned low gearing! It seems to be set up for more off road use.

[Nospark]

I have a 2021 TBR7 D, I installed a 17 front / 42 rear JT sprockets. Using both the 17 & 42 I was able to use the stock chain and the stock chain length. I soked the chain in gear oil overnight while I had it off the bike. I'm happy with the performance on the street thus far in terms of acceleration from dead stop, 1st gear range, and cruising RPM in 5th gear. I'm still breaking my motor in so, can't comment on top end speed. Based on what I believe to be left for top end speed, I believe 55 mph is easily achievable without rpm's getting uncomfortably high.

[Nospark]

You are correct. The stock chain length is too short for changing just the front to a 17 tooth on a 2021 TBR7-D. I had the same issue. I decided to go ahead and upgrade rear sprocket to the 42 at the same time. This allowed stock chain length to work just fine. I went and upgraded rear sprocket bushings since I was getting that deep into it anyway.
This set up works great to increase your towing capacity. I never towed anything but, I'm sure a TBR7 can out tow a Hawk 250 by several hundred pounds any day.

[TBR7-Rider]

Thanks everybody for all the input. I did buy a 428 chain with a 17 tooth front and a 45 back sprocket. As you remember I had a 520 chain with 12/F and 38/R sprocket. The old 12/F sprocket is thicker that the new 17/F sprocket. Should there be a spacer or washer behind it? Even when I tighten down the front keeper it still wabbles just a little. Thanks

[dig4dirt]

I have the same wobble.

Waiting for replies with you to see if it is ok.
I would assume so since I never read it among all the threads here

I just registered mine and on the road today for first time

[Megadan]

The front sprocket wobble is normal and just part of the design. Even the Hondas that use this style of sprocket keeper have that wobble to them. Nothing to worry about.

[buzz]

What Dan said!

[kyle]

Originally Posted by TBR7-Rider

:thanks that charts helps.
My chain is 520. I didn't know that when I posted my question. As to the off road, I meant to say no off road riding.
Thanks for all the help.


:

As you've probably figured out, the newer TBR7s are shipping with a 520 chain, so the standard 'just go to a 17t' doesn't work for you. You'll need a valid 520 sprocket that is closer to your stock size.