VF500F - Sliding the Forks, 17" Wheel Conversion

Hi All,

I am working on an 17" wheel conversion for my ’84 VF500F using CBR600F Hurricane rims.

I have got most everything dialed in and I am down to the tire selection. I have narrowed it to two models, both are tires manufactured by Avon in the UK.

The first tire is their Roadrider the second their Azaro St. The Roadrider is a bias-ply tire, the Azaro ST is a radial tire.

In working out the rake and trail calculations (I have a Daugherty Motorsports F4i shock installed, which is longer than the stock mono-shock) I am coming up with:

110/70F 140/80R = 27 degrees, 100mm
110/80F 140/80R = 27.5 degrees, 112mm

The stock VF500F has a rake of 27 degrees and a trail of 104mm, so the 110/70 up front makes for a good fit - but - this size is only available in the Roadrider line (the bias-ply option).

If I go with the Azaro ST (radial tire) I will need to slide the forks up a bit in the clamps - about 5-6mm, to get back to the stock geometry.

My question is - given the 500's fender to radiator clearance woes - what is the maximum amount that you can comfortably side the forks up without getting into a sticky wicket on clearance?

Any intel would be most appreciated,

Thanks!

 

before i slid my forks back down they where up through the triple clamp a good 6-7mm's causes the bike to bottom out when you hit a hole or fully compress when corning got a big dent in my hindle header from it

 

Thank you for the post. This is my concern, I am not sure I can slide the forks up in the clamps the required amount (5-6mm) to get back to the stock geometry, if I go with a 110/80-17F tire. I have heard good things about Avon Roadriders (available in a 110/70) so this may be my best choice, even though they are a bias ply tire. On the plus side the Roadrider tires are a about $60 less, total, when compared to the Azaro ST tires - so a bit easier on my project budget.

 

It's a good idea to target a certain geometry, just like you have done. However, don't get too bent out of shape about it. It's better to just ride the bike and see what it's doing then make changes that correct it's performance.

FYI - Your trial numbers are both pretty big. Normally something on the order of 100-105 is better. To make this much of a change you would probably need different triple clamps. The real issue is the rake, the VF's are way too raked out.

 

Hi Jamie, thank you for your post.

If I could ask - I am not sure I understand your note about the trail numbers being too big. The 110/80F isn't great at 112mm - for sure, but the 110/70F is coming in at 100mm. I have the stock trail jotted down as being 104mm (based on my original calculations the stock bike has a rake of 27 degrees and a trail of 104mm).

With the taller F4i mono shock conversion - a most excellent upgrade b.t.w. and the 110/70-17F and 140/80-17R tires, things are working out to 27 degrees for the rake and 100mm for the trail - which looks to be good, as it is very close to stock.

If I go with the 110/80 tire up front I would need to slide the forks up in the clamps about 5-6mm - to get back to stock geometry. Based on the previous post this a no go for the fender-to-radiator clearance minimum dimension.

On a side note, I am not sure how you can get less rake when using 17" rims, unless you have custom clamps made - have you been working something up in the laboratory?

Thanks again!

 

Nah, nothing like that. I just think you'll find trail of more than 105mm to be too lazy and lower than 100mm to have difficulty with finshing a corner. As previously mentioned, you really should get out and ride it then make corrections based on what the bike is doing (or not doing, as the case may be).

 

Thank you for the post.

I am looking forward to seeing how the 17" CBR600F rims with the Avon Roadrider tires improve the handling. With the DMr F4i shock I'm, at least on paper ;-) very close to the stock geometry.

I didn't run numbers on an F2 wheel conversion with 120/60-17F and 150/70-17R tires but I have heard this set-up is also the bee's knees. If I could ask out of curiosity, do you have the rake and trail calculations jotted down for this set-up when using the DMr F4i shock?

 

No, I didn't. I custom make the shocks to each persons needs/wants so there are no standard numbers. Something that is often misunderstood is the relationship of rear ride height to front end geometry. You need big changes out back to affect the front. For example, on the VF500F if you add 25mm of rear ride height (that's quite a bit) you only decrease the trail by about 5mm. I've found that you really need a different triple clamp setup to get things where the should be. When you are getting to this point you need to juggle several variables. There are some targets for "the numbers" but it's really best to see what the bike does and correct it's actual performance rather than going to lengths to make things work godd on paper. I like to calculate the numbers to see if something looks way off and might cause a problem, but the biggest help they provide is to decide what changes would work best to fix a problem.

 

5x5

Thanks again.