19" vs. 21" front wheels
 

I heard a YouTube comment that highway ride with 21" wheels gets more wobbly than with 19" (or less) wheels.

I wondered, "Is THAT why manufacturers fit 19" (or less) front wheels to LIGHT-weight 'Adventure' bikes?

Is that why I read/hear so many statements like "I wouldn't (want to) ride a dual-sport more than a few Exits on highway"? ... forgetting short-gearing and high cruising rpm's for a moment.

I'd be interested to hear what those of you who have ridden bikes with BOTH 19" and 21" wheels feel.

Thanks - in advance - for your insights.

The wobble may be more from the tire type and rake of the bike. On my Hawk with knobbies is very unstable at speeds over 65 mph where as the dual sport tires on my KPX is just as stable as my Vulcan S doing 70-75 mph. Both these bikes have 21" wheels.

My Lifan X-pect did not like hwy speeds, stability-wise. 19" wheel. My KPX is much more stable with its 21" wheel, and a bit more weight.

The Rim size is the easier thing to blame, when they don't want to see the whole picture.
John Johnson took his Crf450f to the highway, he didn't like the way it ride, so he put the blame to the rims...
Not the fact it's a lightweight motorcycle with a power to weight ratio that's amazing, high center of gravity and wheelbase that's somewhat short. Of course we can't blame the motorcycle, because it was never made for highway or on road use

But you know what motorcycle also use 21" as their front rim?? The Africa Twin Adventure sport.

There are things that are far way more important when it comes to wobble.


If we talk just about chinese motorcycles, tread type will be way more important than 19 vs 21.

I had motorcycles with 19 and 21 and they did behave the same, because i use the same type of tire.

Interesting observations, Thanks.

The centrifugal force generated by 19" (or 17") vs. a 21" didn't make sense to me that a 21" would be more 'wobbly' ... based upon just the size difference.

As a newcomer (NO bike, yet), considering motorcycling for exploring, I'm dismayed by motorcycle INflexibility, compared to alternatives (e.g. an ATV or Jeep Wrangler). The notion that you need a different bike and different tire for each road/trail leaves me disappointed. I recognize that part of that perception is marketing hype/bling; but, nevertheless ...

Street tires that slide out from under you on soft/loose surfaces and dirt tires whose knobbies squirm, especially in corners ... do not inspire confident riding.

Coupled with the oft-quoted 8x more vulnerability, riding a bike vs. a car ... and requirements to be constantly scanning the road/trail, I wonder if I'd ever see any scenery ... except at a STOP ?

I agree with JerryHawk and Wild Dog. Too many variables to answer with real definition. Are the rims true? Has the wheel/tire combo been properly balanced? What is the type of tire? I've ridden lightweight adventure bikes, heavyweight ADV bikes and dual sports bikes up to 95 mph+ without issue. Do you think it's a good idea to ride at high speed with non DOT knobbies?

Large diameter wheels roll over obstacles easier than small wheels so 21" is better off road but 19" is fine. There were some old dirt bikes that came with a 23" front wheel but I don't see those used any more. 17" front and rear is comon on street bikes for better, quicker cornering. Scooters are even quicker handling with 8" to 16" wheels. I've owned bikes and scooters with front wheel sizes of 8", 10", 14", 16", 17", 18", 19", 21".

If you care more about the dirt performance,get a 21 in.
If you care more about the pavement, get a 19 in.

Larger diameter = increased centrifugal force = more resistance to changes in direction. This is why sport bikes have 17" front and rear wheels with low profile wide tires. Great for handling and corners compared to the tall skinny wheels and tires of dual sports and cruisers.

That said, ad the rest have pointed out the chassis setup and overall geometry of the bike play a big role. Too. Lowering the back of my Hawk increased the rake and trail a decent amount, which lead to a much more stable and lazier steering bike. It loves to cruise along at highway speeds. When I had the.other shock on and the back of the bike sat higher than stock it was much more twitchy at high speeds. Same tires with both setups.

Let's apply the same mindset of some motorcycles riders to a Jeep Wrangler.

"Ohhh no it's a death trap that wrangler!!! you can't outrun a Ford Mustang in a highway!!!"

"Pff that Wrangler is not safe try to do a hard steer at 130 mph, you are going to roll over!! that won't happen with a nice car!!!"

The issue is not the Jeep, the issue are the folks that don't understand what's the main purpose of wrangler.




Adventure Motorcycles are quite flexible, some riders aren't.
For some reason some riders think that every motorcycle must be a super sport bike and those riders love to trash talk most type of adv motorcycles unless they are the top dogs like an African Twin, Super Tenere, some BMW.

Some folks just love to trash talk the Klr 650, because it has "vibrations", because it doesn't go 120 mph, because Kawasaki is not making a new engine every year.. But hey it's a bulletproof engine that been around for the last what 30 years?? The engine has proven reliability. It's not fast but it has more than enough torque to carry stuff and some good off road.
Yes is not a Yamaha R1, because it was never meant to be an R1.

A 19" is going to be more stable at higher speeds which is why I picked up the TBR7 over the Hawk.



I'm able to cruise 65 - 70 without any wobble.

Same here Slug, even new knobbies. Still running smooth, love my 2021 TBR7. 4800 miles and alls good. Back tire about half wore out, mostly driven on back roads,blacktop.

I'll be swapping out to some touring tires, likely Pirelli Scorpion Trail II around February as I don't really go offroad terribly much.



Even the KLX with a 21/17 experiences that higher speed jitter. So it's nothing to do with the Chinese bikes it's specific to those larger wheels.



But this 19/17 is perfect for daily commute and even hopping on and off highway from time to time.



There's a reason why sumos run 17/17; because they're much more stable.

So is the 21/18.

When i got my Loncin Sx2, it came from the factory with a pair of Yuanxing P82, which is a dunlop knock off.

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That tire even if it was 19, it would suck hard time on paved road. Not only turning is bad but braking is awful.

Changed it for
Metzeler enduro 3

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A much better tread for my type of ride.



With that 21/18 combo. I ride everywhere, from paved roads, highway, freeway, etc.

Even an 11 hour trip


Attachment 27895


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Both 19/17 and 21/18 are valid setups. Yes your on/off motorcycle is not going to ride like a super sport motorcycle with a lower center of gravity and better geometry. But that doesn't mean you can't or you shouldn't ride it anywhere you are allowed to.

Thanks SO much for the insights, comparisons and anecdotes, folks, ... and, THANKS for the encouragement.

Unlike some, you mentioned, I wouldn't expect ANY bike/tire combination to excel at everything. As long as I could toodle along on or off-road (not whooping through single-tracks, mud, beaches, mind you), safely sightseeing, with SOME single bike/tire combination, I'd be H A P P Y.


THANKS, again ...