Widening a motorcycle rim

**gav** · 7th September 2011, 22:48

Any one had any success with this? I'd like to know if it would be possible to widen a rear FXR150 rim from a 2.15 rim to at least 3.00 or 3.50 ? Yeah, I know it might be easier just to find another rim that fits, but so far, havent had too much success finding something. Do have one rim here that might be suitable but its causing issues trying to get it to fit with the disc and sprocket carrier fitting etc. I also do have a spare FXR rim here as well. Was also wondering if you could cut the outer rim off each and fit the FXR inner wheel minus the rim inside a wider rim and weld the "spokes" to the new wider rim. Would this work? Its for a bucket racer ...

**Grumph** · 8th September 2011, 07:39

Can be done - has been done. Jim Landrebe widened the front rim on the Honda Bros he built some time back.
In ChCh see Thorpe's - they have a machine shop on site.
Won't be cheap.....

**p.dath** · 8th September 2011, 12:59

Way out of my area, but I know a lot of mathematics are involved in rims. We used to have a client that had simulation computers set up, and they were commission to "test" new rims. You don't want rims deforming or coming apart, or them becoming unbalanced through minor deformation under load, or simply failing under mechanical stress at some point in the future.

Simply making an existing rim wider might solve one problem you have, but make sure it doesn't create several others ...

**bogan** · 8th September 2011, 13:02

Originally Posted by Grumph

Can be done - has been done. Jim Landrebe widened the front rim on the Honda Bros he built some time back.
In ChCh see Thorpe's - they have a machine shop on site.
Won't be cheap.....

There are a few other RC-31s over at hawkgtforum.com with widened rims, a google site seach will show some good info. Having a weld bead all the way around the rim also looks a bit different but in a good way

**tigertim20** · 8th September 2011, 13:52

agree with pdath, unless its done really well, it could cause other issues wheels need to be properly weighted and perfectly round (or damned near), neither of which is particularly conducive to the amount of heat in welding the circumference of the wheel.

**bogan** · 8th September 2011, 15:07

Originally Posted by tigertim20

agree with pdath, unless its done really well, it could cause other issues wheels need to be properly weighted and perfectly round (or damned near), neither of which is particularly conducive to the amount of heat in welding the circumference of the wheel.

It's pretty easy to check the runout on the wheel after they are done, definetely not a job for amteurs though

I dug up the link for the place hawkers use http://kosmanspecialties.com/service...g-and-weldups/ Some info on what they do too.

**Crasherfromwayback** · 8th September 2011, 15:23

Gary McPhee has done a few for me, always perfect. Not sure if he's still doing such work/things. Was too busy being the Mayor of Carterton for a while there! I would be happy to get hold of him and ask if you'd like.

**p.dath** · 8th September 2011, 16:16

Originally Posted by bogan

It's pretty easy to check the runout on the wheel after they are done, definetely not a job for amteurs though

I dug up the link for the place hawkers use http://kosmanspecialties.com/service...g-and-weldups/ Some info on what they do too.

I can see how you can check the run out on a slow moving wheel. What about one on a bike pulling .8g on a 30 degree lean going around a corner at 200kmh/h - when the rim is under some stress?
Like I say, I don't know anything about it. But I do know a lot of complicated maths is involved in rim design.

**Crasherfromwayback** · 8th September 2011, 16:34

Originally Posted by p.dath

What about one on a bike pulling .8g on a 30 degree lean going around a corner at 200kmh/h - when the rim is under some stress?
Like I say, I don't know anything about it. .

On an FXR150? Don't think there's much chance of that.

**Grumph** · 8th September 2011, 16:36

I pointed the OP at an outfit in ChCh who have done the job before and know their metallurgy well. The important point when doing the job is retaining ductility.
Math and computer simulations only come into play when you're trying to pare a wheel design down to the bare miimum weight. In this case where the original rim is for a lightweight bike and the proposed use is still a lightweight bike I see no need for computer simulations....A competent welder and an equally competent machine shop to ensure the finished job is acceptably round will do nicely.
As far as cornering loads and wheel stiffness goes - find a vid of wire wheels under stress to see how far things move.

**pete-blen** · 8th September 2011, 18:28

The guy on the speedway sidecars do it all the time..
BUT..the rims balance/trueness is not as important on the dirt
compaied to a road unit....

**F5 Dave** · 12th September 2011, 17:52

I've had it done a few times welding on a larger RIM to RG wheels. Mixed success, it is hard to get the wheel to not ovalise & be central. I have however corrected a little for this with some careful lathe work to recentre the rim where the tyre hits rim which is what is the crucial part.

Failing that someone

is selling a Gixer thou front wheel (see bucket parts for sale thread) & it isn't too hard to make a rudimentary RS style rubber donut cushrive & bolt a disc on the other side.