21 inch front and 17 inch rear

Probably a dumb question but I have been unable to find a definitive answer.

I have the 250X and I also have a set of 21/18 inch rims and tires for dirt.

Can I skip swapping out the rear and ride off road with a 21" front and 17 " rear?

Thanks

Why not. Try it and let us know how you find it handles.

You'll have your answer.

Hmmm...sounds like you know it will not work.

I know 19" with 17 " works.

Also, I had a BMW 650 Dakar (single cylinder) that had a 21" front with a 17" rear.

It handled just fine, I guess only trying will tell...cautiously of course.

I suppose this should be under the rims and wheels section.

I had a KLR650 with a 17 inch rear wheel and 21 inch front wheel.
It worked fine.
The 17 inch dirt tires are pretty big and about as tall as a stock wrr 18 inch tire, it'll work just fine.

manybikes wrote:

Hmmm...sounds like you know it will not work.

I know 19" with 17 " works.

Actually I meant it will work, and that as soon as you try it for yourself, you'll know it works. Sorry if it sounded like I was being negative.

Evol wrote:

manybikes wrote:

Hmmm...sounds like you know it will not work.

I know 19" with 17 " works.

Actually I meant it will work, and that as soon as you try it for yourself, you'll know it works. Sorry if it sounded like I was being negative.

Thanks for the info, I will give it a try and post the results.
It would be way easier to just swap out only the front wheel.

Cheers

manybikes wrote:

Evol wrote:

manybikes wrote:

Hmmm...sounds like you know it will not work.

I know 19" with 17 " works.

Actually I meant it will work, and that as soon as you try it for yourself, you'll know it works. Sorry if it sounded like I was being negative.

Thanks for the info, I will give it a try and post the results.
It would be way easier to just swap out only the front wheel.

Cheers

I thought about just buying a 21" front for now (being cheap I guess) and was wondering how this worked out for you. Any chance to ride on this setup?

I have not tried just the 21" front yet, that will not be for another month (due winter)
I think it should be just fine, I agree that it would be a lot cheaper and a lot easier just to swap out a front.

will let you know when I try it.

Works fine, I think from memory I raised the front forks about 5-10mm or so as it felt sluggish to turn.

Tried the 21" front with a knobby on the front and left the 17" stock rim on the back (with a Michelin sport 4)
Okay..not the ideal combination of tires but my purpose was to see how it felt.
Yes, steering was sluggish, seat height instantly higher but so far so good.

Reason for swap:
With the 17" front it felt very unstable on gravel ,  could this also be solved with a 17" knobby tire on the front ?

I do not have a second rotor so I also have to swap the rotor to the 21" wheel, this adds a bit more time to the wheel swap.

Like I say, so far just a short initial cautious ride to see how it felt. Further evaluation to be done.

Anyone know if this combination of rim sizes is dangerous in anyway?...just askin....

For what its worth I've used mine in two Condo 750 offroad navigation rallys without issue. Adjust the forks til youre happy with the handling and you will be fine.

I daresay its more of a safety issue swapping rotors all the time. Do yourself a favour and buy a second set.

A lot of other bikes run this combo, DR650, F800GS as examples.

Thanks for the info.
Will be buying a second rotor.
Used blue locktite and proper torque when transferring back to the 17" wheels.

You are correct, not a good idea to constantly swap out the rotors.

My short ride with the 21 front seemed just fine, like having two bikes.

Gany wrote:

For what its worth I've used mine in two Condo 750 offroad navigation rallys without issue. Adjust the forks til youre happy with the handling and you will be fine.

I daresay its more of a safety issue swapping rotors all the time. Do yourself a favour and buy a second set.

A lot of other bikes run this combo, DR650, F800GS as examples.

I am curious, how far up did you move your forks where it felt good?

Thanks again

About 13mm:


For reference, my front tyre is 80/100-21 and the rear tyre a 120/90-17.

I went for as tall a rear tyre profile as I could. Note, Im not running a stock rear rim, its a narrower 2.15 one so I wouldnt try fitting anything narrower than a 140 width rear tyre on the stock rear rim.

manybikes wrote:

Gany wrote:

For what its worth I've used mine in two Condo 750 offroad navigation rallys without issue. Adjust the forks til youre happy with the handling and you will be fine.

I daresay its more of a safety issue swapping rotors all the time. Do yourself a favour and buy a second set.

A lot of other bikes run this combo, DR650, F800GS as examples.

I am curious, how far up did you move your forks where it felt good?

Thanks again

Oops, disregard that last question...you stated the answer in a previous post...sorry bout that.

Gany wrote:

About 13mm:


For reference, my front tyre is 80/100-21 and the rear tyre a 120/90-17.

I went for as tall a rear tyre profile as I could. Note, Im not running a stock rear rim, its a narrower 2.15 one so I wouldnt try fitting anything narrower than a 140 width rear tyre on the stock rear rim.

Alrighty then...thanks Gany, I will give that a try...you were quick on the reply there.
Lots of good info.
Looking for a front rotor for the 21" hoop, should be easy enough to find.

Cheers

no problems, just measured 13mm as per post above. You could probably go to 15mm just fine as well. Start with 13mm and tweak it from there.

What size rear tyre do you have?

Right now I am running a IRC 140/70 R17 on the rear.
It is a street tire but I should have a more aggressive tire than that for gravel running

No problems, should sit slighly lower than mine so maybe raise yours about 15mm in the fork clamps.

I'll give that a try.
Not too worried about a different rear tire right now, I only wanted the 21 for gravel running and some light off road.
I used to have a 650 dakar and it handled gravel very well with road tires.

I may even try a knobby on the 17" front and see how well that does.

Plenty have done that with good success too!

manybikes wrote:

Probably a dumb question but I have been unable to find a definitive answer.

I have the 250X and I also have a set of 21/18 inch rims and tires for dirt.

Can I skip swapping out the rear and ride off road with a 21" front and 17 " rear?

Thanks

Finally did the swap along with raising the front forks to compensate. I bought a 250x rotor to mount on the 21" rim so swapping will be very easy.


I raised the front forks 17.5 mm, so far this feels better than leaving the forks in the stock position. So far the X handles gravel much better with this setup, does not feel as planted as the 17" on the highway though.


Leaving the 17" rear on with a IRC 140/70 - 17, not exactly an adventure rated tire but it will do for now.Not easy finding a 140 wide aggressive tire, will a 150/70-17 fit ? like a Heideneau K73 ?


Here is a photo of the new tire for my 17" front, Heideneau K73 super rain 120/70 - 17. I have not ridden on it yet but I am hoping that because it is a 120 I will not have any rubbing issues. It measures the same width as my old 110. I am hoping that the 150/70-17 version of this tire will fit the rear without rubbing.

You could try a Mitas tyre assuming they are available there. I have a narrower 17" rear rim now but run an e09 dakar or a Dunlop 606.
The E09 according to the website is available in 120, 130,140 widths in 17". You should get around 10,000km out of them too with normal riding unless you flog and cook them.