Issues with a 19 rear and 18 front?

[pwizl]

As the title says, is there any issues running a bigger wheel in the back than in the front? I see most bikes have the same size or the front one is one or two inches larger than the rear. I ask because that's what I have and if I'm able to use I will. Rear is a 19 x 2.15 and the front is an 18 x 2.5. Tires are very close to the same diameter rear 100/90-19 O.D 663 and front 120/80-18 O.D 650, close to the same width as well.

 

[5twins]

I'm thinking you just may have to try it and see. There was a time when 16" or 17" fronts combined with 18" rears was the norm, but those bikes were designed around those wheel sizes. But, I don't see much difference between what you're contemplating and running longer than stock rear shocks. Many of us do that with no problems.

 

[lakeview]

Without a compatible rear wheel you may not be able to fit a correct size sprocket.

 

[pwizl]

Without a compatible rear wheel you may not be able to fit a correct size sprocket.

Everything is compatible, xs650 front and rear hubs so that's not an issue

 

[fredintoon]

Hi pwizl,
16" front with 18" rear was quite fashionable on 1980's sportbikes and they handled OK.
Mind you, their rears were way fatter than their fronts while your 18" front is ~3/4" wider than your 19" rear.
But the worst I can see with your set-up is that the handling will be a little bit different than that of a normal XS650, that's all.
Perhaps less than the difference between running a 110/90-18 rear vs a 130/90-16 rear.

 

[retiredgentleman]

For everyday dry street use, I think the handling will be similar to any stock XS650.

Edit:
The only thing is the narrow rear, having a smaller contact patch, would have a tendency to loose grip in
wet road conditions. When it first starts to rain, the oil on the road and water mix, making a very slippery surface. If you had need to apply the front brake stronger than normal, the weight transfer makes the rear end lighter, and the result can be the rear end of the bike sliding around, such that you are going sideways down the road. That can be exciting!

When its first starts to rain, I always drive a little more cautiously, and use only the rear brake, just for the above reason.

 

[pwizl]

The bike is primarily going to be a street bike for just cruising around town with occasional highway cruising, it will never be ridden in the rain, I'm a fair weather rider, also no track or real aggressive riding. I just want to make sure it's not going to be a safety issue, the diameters and widths are pretty darn close and I believe the trail won't be affected too much if I decide to use them


Would a 110/80-18 front tire make any difference? I know it's smaller diameter and about .5 narrower. It seems the width is the biggest issue