Kawasaki Versys Forum banner

1 - 17 of 17 Posts

·
Registered
Joined
·
136 Posts
Discussion Starter #1
Something I have been wondering about for a while about is why a lot of folks want a 19" tire on a dirt bike or dual sport? I have seen many people discuss why the the almighty "V" is not as capable off road compared to a V-strom.

This is not to knock the bike for offroad as I have seen those who ride it everywhere, just wondering exactly what a 19" front tire buys you off road. I rode dirt bikes as a kid, but I don't recall the advantage of a bigger tire on the front.

Does it go over ditches better with a larger front tire or more stable in the dirt?

Inquiring minds wanna know..... :)
 

·
Registered
Joined
·
1,018 Posts
A 19" inch front mostly buys you a much wider tire choice to meet the different "off-road" needs. Whether you really need those knobbies to ride dirt and gravel roads is an entirely different question. The larger diameter wheel also helps going over obstacles (but I doubt it's a significant percentage of use).

Gustavo
 

·
Registered
Joined
·
69 Posts
A 19" wheel also LIMITS your street tire choices. Most people who buy a V-Strom never take it off road. The 19" tire is mostly for the "look" it gives the bike.
 

·
Registered
Joined
·
136 Posts
Discussion Starter #4
The more I am thinking about, see if my logic makes sense :)

If there was an 8 inch diameter log, laying across the road and I wanted to ride over it. I would think a bigger diameter tire would be an advantage.

This is an exageration, but if I had an 8 inch tire, I would just basically come up to the log and stop. If I had a 17 inch tire, I could roll over it as the right side of the triangle when the tire was against the log, would be straighter. This triangle would be the left side as the log, the bottom as the ground and the right side as the tire. This would allow it go easier over the log with less force. Go up to a 20 inch tire, it's probably a little easier.


I think I answered my own question now that I think about it......

I am not looking to swap to a 19" tire, just been trying to figure out the advantage of it.

David
 

·
Registered
Joined
·
69 Posts
I've always believed in using a tool for it's proper task. I don't typically drive screws with a hammer or drive nails with a screwdriver.

To me, that's what taking a bike like the Versys, V-Strom, Ulysses, GS, Tiger, Multistrada, etc. down a single track trail, up steep hills, or over big obstacles like.

Riding down an improved gravel road is something any motorcycle can do. Even sportbikes can navigate some pretty gnarly roads as seen here:



Anyone who watched the show "Long Way Round" which featured Ewen McGregor and Charlie Boorman circumnavigating the world on hulking BMW GSes will remember that Claudio, their camera man, ended up on a cheap, lightweight POS bike when his BMW broke down. He was able to maneuver much easier and cross obstacles the big GSes couldn't due to their weight.

Biggest bike I would ever want to ever take in the soup is a KLR. I tried it once, and got stuck. Had to drag that sucker out by myself. Even that bike is pretty dang heavy.

19" front wheel or not, a 400+lb bike is a heavy beast in the deep stuff. A 500lb bike is past the point of fun (unless you like destroying your motorcycle).

Now, piloting a trials bike over big logs and such is a great deal of fun. Drop it, pick it up, keep going.
 

·
Registered
Joined
·
459 Posts
Actually it is physics. The larger diameter front tires have a greater gyroscopic effect, that increases stability. So when you hit sand with a 17" front it is much easier for the sand/gravel/rocks to alter the direction of travel. The 19" (or better yet 21") front tires are deflected less and therefore track better in sand and gravel. However this means that on a twisty canyon road these larger diameter wheels are harder to flick through the corners. The increased stability is less desirable on the street.
 

·
Registered
Joined
·
670 Posts
this italicized portions are copied from a mtn bike website. bikes with 29" wheels are becoming more popular nowadays. the benefits of the bigger wheels on a mtn bike, relative to the standard 26" wheel, are similar to the benefits of a larger front on a motorcycle.

Better Roll Over: Okay, lets get this out of the way right off the bat. 29″ers have a different “angle of attack” in relation to trail obstacles you might encounter. This realizes itself to riders as a smoother feel. Sometimes it negates the need for front suspension for some trail riders, thus the plethora of rigid front forks on big wheelers. It is also interesting to note that what is good for the front wheel is also good for the rear wheel.

Steely, you were describing the angle of attack concept. it essentially makes the obstacle smaller; the climb onto the obstacle is not as steep, therefore it costs less energy.

Better Traction: 29″ers, by the nature of the diameter of the wheel, have a differently shaped contact patch than 26″ers do. (Some would argue that it is a bigger contact patch) However it really is, it is obvious that a 29″er has an ability to claw it’s way up steeps and technical climbs that smaller diameter wheels can not match. This is aided by the following attribute……

about mtn bike tires... it is said that the contact patch for the larger diameter tire will be longer and more narrow (for the same pressure) which seems to help the tire dig a little deeper thru loose stuff to gain purchase on the more solid ground beneath. the shorter, wider contact patches will ride on top and be subjected to deflection while providing less traction.

Better Momentum Conservation: One of the oft overlooked characteristics of 29 inch wheels is their propensity for carrying momentum better than smaller wheel sizes do. This helps in clearing climbs, but it also causes 29″ers to be a bit tougher to get going from a slow speed, or stopped situation. If a 29″er rider can learn to work with the momentum factor of 29″ers, it can become one of your greater allies. Less braking is necessary due to the stability and better traction of 29 inch wheels. So if you can learn to trust that, the momentum saved can be a big benefit. Smaller wheels tend to not have any of these traits in the amount that 29″ers do, so using momentum with smaller wheel sizes doesn’t work nearly as well.

Gyroscopic Effect: While this is very closely related to the above mentioned benefit, I broke it out because this is the one thing that makes 29″ers seem so “safe” when downhilling, or while attacking technical terrain. A 29 inch wheel by its very nature will want to stay upright better than a smaller wheel will. This can work for you not only in high speed down hills, but in slower technical terrain as well. It is one of the reasons why many taller riders feel that the 29″er bike is less likely to “endo” than smaller wheeled bikes.

Loose Terrain Traversing/Traction: There is a reason why early 29″er pioneers were winning mud bog contests and crossing sandy desert terrain better than their 26″er brethren were. The wheels seem to really excel at crossing loose sand, mud, and even snow. This is a direct result of many of the above mentioned benefits working in concert with each other, but is remarkable, so I mentioned it as a stand alone trait.

i have explored some roads on the old Transalp that i would not attempt on the versys. good thing, since more than once, this resulted in riding over obstacles that would have shut me down with this 17" front i have now; i have vivid memories of embedded boulders and half-buried culverts. the transalp certainly wasn't the right tool for the job, but i didn't know it until i was busting my knuckles. fortunately, tho' they may not be ideal, crescent wrenches can actually get it done sometimes. i guess that's the difference between bikes like KLR650, Tenere 660 compared to bikes like versys... the versys will talk some sense into you, while the others ask for trouble. :devil:
 

·
Super Moderator
Joined
·
8,624 Posts
Actually it is physics. The larger diameter front tires have a greater gyroscopic effect, that increases stability. So when you hit sand with a 17" front it is much easier for the sand/gravel/rocks to alter the direction of travel. The 19" (or better yet 21") front tires are deflected less and therefore track better in sand and gravel. However this means that on a twisty canyon road these larger diameter wheels are harder to flick through the corners. The increased stability is less desirable on the street.
I love this site, can even get a physics lesson. good explanation Lonerockz.

so a penny farthing will be the most stable bike through sand
 

·
Registered
Joined
·
136 Posts
Discussion Starter #9
I love this site, can even get a physics lesson. good explanation Lonerockz.

so a penny farthing will be the most stable bike through sand
Too Funny! I was actually thinking about the same bike with that big wheel in my head, going over a log :)
 

·
Registered
Joined
·
670 Posts
Edwardian Day, iirc. Kiwi, is that you?





i think the helmet is for the mount/dismount.
 

·
Registered
Joined
·
670 Posts

·
Super Moderator
Joined
·
8,624 Posts
Hey kevrider, you certainly get around, Christchurch is 100 mile north of me and where my fast orange V came from
 
1 - 17 of 17 Posts
Top