2012 Bonneville Handling Issues

Hi All,

I just bought a 2012 Bonneville which has been messed about with. It now sits on a spoked 17" rear and an 18" also spoked front wheel, instead of the standard spec 17". I seem to be fighting the bike to make it go round the bends and I put this down to the trail and rake being messed up because of the change in front wheel size. Is it possible to correct this without changing the front rim?

Albert

 

Is it just the wheel sizes that have been changed or have the forks been changed as well?
If original forks then may be a new 17" rim laced onto your existing hubs.

Can you post a few photos of the bike, it might help other members offer advice

 

When using a lowering kit it is advisable to lower the forks in the yolks by a small amount to maintain the trail and rake and hence maintaining the bikes handling. Fitting an 18" wheel will have raised the front and unless the forks have been adjusted to compensate the trail and rake will now be different. I read somewhere that lowering the front makes it easier for a bike to turn in so if I were you I would lower the front forks in the yolks probably by about 10 to 13mm and see if there is an improvement. I think there will be.

 

There could be a lot of other things causing the issue (tyres, poor suspension set up etc) but assuming they're ok, the Bonnie is a sweet handling bike on the 17" wheels (better than with the bigger diameter wheels).
So I'd say either switch to cast wheels and get the advantage of having tubeless tyres as well or, if you want to keep the tubed wire wheels, get a 17" rim put on as Samsgrandad suggests.

 

This is my Bonneville. I am not sure whether the forks have been changed or not but certainly the paint has been removed off the sliders and these have been polished up instead. I have taken some measurements of the new trail which amounts to 148mm. This seems too much to me when compared to the original factory figure of 117mm.
A

 

I believe this is the way to go dav.a. I have measured the new trail and found it to be 148mm. The original factory dimensions is 117mm so there is quite a bit to go. But I will try lowering the front as you suggest and see how close I can get to the 117mm figure. IThe bike is stable as is but I have to fight it to make it turn, hopefully lowering the forks will have the desired result.

Thanks,
Albert

 

And of course check your tyres aren't underinflated.

 

If the larger front wheel is causing the issues you could try to find a smaller tyre? Assuming the profile is a 100/90 then a 100/80 would get you within 2 or 3mm of where it should be. I don't know how common a profile like that is though and could be a problem trying to find an odd size.

 

Didn't that model originally have a 19" front? I'm sure the T100 did, for example. The alloy wheel 865 Bonnies like mine (SE) were 17" front and rear. Is it the 865 engine? What model is it, exactly?