Need some trailriding advice

Is it uncommon to run an 18" rear wheel when doing offroad? And if not, is it uncommon to also run a 20" front wheel as well? And when doing so, what would be the appropriate sprockets to run in either combination (21 front, 18 rear or 20 front, 18 rear)?

I have an 06 YZ450 with a 18" rear wheel. I like the way it rides on the trails.

I like the taller sidewall. The guys I ride with out here in Souther California run the IRC M5B 130 80 18 and the Dunlop 756 21" . We do mostly single track and the really tight stuff as well a hillclimbing.

Our gearing varies from a 13 countershaft and a 53 or 54 rear sprocket.

When it rains and the ground is tacky then we run the 12 coutershaft.

We dont ride the high speed stuff very often, but when we do, stock gearing is fine.

I rode a 450 with the 20" front, It did some strange things, kind of hard to explain. Maybe I'm too use the 21" wheel.

Good luck!!!!!!!!!!!!

ive heard that the 20 inch front tire can be hard to find,but it is better for desert high speed racing

i run an 18" back wheel on my yzf,purley for the pirrele mt43 trials tyre that alot of competions here in the uk only allow you to run,never heard of the 20"front thats a new on to me

Thanks for the replies guys. I'm thinking the 18" rear wheel will help quite a bit since I'll be doing nothing but trail rider and hill climbing. I wasn't too sure on the 20" front myself, but I figured I'd toss in the idea here to see if anybody's used one successfully on a 450.

While I have you guys responding, I have a couple other questions about bike protection. What bike guards are necessary for trail riding and what brands would you guys suggest? I don't care if I use metal opposed to carbon fiber. I'm thinking these: 1. A better chain guide/guard. 2. Front and Rear disc guards. 3. Skit plate. I'm not sure if the metal radiator guards are necessary.

I run an 18" rear on my 426 much for the same reason as I can mount up a trials tire. There is also a very large selection of tires for 18" wheels, and I like having the extra rim protection and the extra sidewall flex helps the tire find traction. The outside diameter of the 18" tires is the same as the 19" tires so there is no need for gearing changes.

For protection I run a Thumpertalk skidplate (which I have beat to death...very glad it's on there!), MSR radiator guards, handguards, and a front disc guard. I don't know that the front disc guard does very much as it is pretty flimsy, but by looking at all the gouges and scratches that are on it I am glad they are there instead of on my disc/caliper. The biggest benefit of the radiator guards is that they keep the radiators from bending in a crash.

There's no need to use a 20" front to make up for an 18" rear, because the 18 isn't any shorter than the 19.

In a tire size, the first number is the body width, the second is the aspect ratio, and the third is the rim size. A 110/100x18 is a tire for an 18" rim that has a 110mm width across the tire body, and is 100 percent as tall as it is wide, measuring from the bead base to the top of the tire body (NOT the tread).

That means that the tire is 4.33 inches from rim to top, times two (top and bottom) plus 18 for the rim, which is 26.66".

A 110/90x19 is 3.9" tall (4.33w x .90), again times two, plus 19" for the rim, for a total of 26.8. Not enough difference to matter.

You could run one of several tires available in a 90/100x21 instead of the more common 80/100x21 tires if you want a little more tire between rim and rock, though.

Thanks for the help guys.

I've selected a Dunlop D745 which is 90/100x21. It appears to have more bite on the walls of the tire, which I'm hoping will result in better grip in the trails. I'm going to stick with the stock 19" tire for now, since I've barely ridden the bike because last summer just got too hectic. I'll see how well the rear tire rides. Are there any other suggestions for a 19" trail oriented rear tire?

Now a really stupid question:

I come from riding quads, so changing bike tires is new to me, since I've never done it. Do all bike tires require a tube or is it optional? I can't even seem to find a tube on that will fit the 90/100x21 specs that I have selected for the D745. Any help on this would be appreciated.

Yep, they requier tubes. Any local bike shop will have them, as will the TT store. Invest in a decent set of tire irons and watch this video...,13190,1215721,00.html it will help you immensely.

The most important thing to remember when mounting a tire is to keep the tire bead opposite of where you are working with the irons pushed down into the well of the wheel. It gives you just enough slack to get the last third of the tire over the rim without too much effort. And use Windex.

Nice video. Appreciate the link.

I've noticed some bikes have real slick numbers. The side numbers sport the dirtbike dude in the air, shadowed in red and blue, sort of like an MLB or NBA player logo. Where do I get those numbered stickers at?

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now