Lowering the bike: front / rear ratio?

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XFer
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Joined: Mon Sep 02, 2019 3:56 pm

Lowering the bike: front / rear ratio?

Post by XFer »

Hi everyone,

I'm going to try lowering my VTR, 'cause I'm shortlegged and really tired of tiptoeing (had 2 crashes while standing still because of this).
Found a rear shock with adjustable length; can be shortened up to 8mm, which should translate to 16mm lowering (2:1 rear linkage ratio).
I have to lower the front too (pulling the fork at the triple clamp) because I want to retain the original rake (and of course I'll have to shorten the sidestand).

Now the question: how much should I pull the fork to compensate those 16mm of rear lowering?

Somewhere I read the rear:front ratio is usually 3:1 so I should pull about 5-6mm to maintain the original rake: is it a reliable information, in your opinion?

Thanks a lot for your support,

Fernando
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freeridenick
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Re: Lowering the bike: front / rear ratio?

Post by freeridenick »

I'm not sure Fernando but whatever the correct ratio you need to be careful of the fork travel and clearance on the lower yolk.

I fitted an alloy bottom yolk that's about twice the depth of the stock steel one and with 6mm pull through on the forks I've got about 2mm clearance on fork travel. For stock yolks I'd say the max you will be able to pull them through will be about 12mm.
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XFer
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Re: Lowering the bike: front / rear ratio?

Post by XFer »

Thanks a lot.
I think 5-7mm should suffice to even out front and rear, but very good to know that 12mm is probably the "hard limit".
tony.mon
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Re: Lowering the bike: front / rear ratio?

Post by tony.mon »

Working in the other direction, adding a 6mm shock spacer lifts the rear by 19mm.
So just over 3 to 1 ratio, but it's not linear.
Pulling the forks that far through the yokes us likely to cause all sorts of issues, and might leave you very short..... of ground clearance.
It's not falling off, it's an upgrade opportunity.
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XFer
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Re: Lowering the bike: front / rear ratio?

Post by XFer »

tony.mon wrote: Tue Sep 03, 2019 10:45 pmPulling the forks that far through the yokes us likely to cause all sorts of issues, and might leave you very short..... of ground clearance.
So you mean, the forks should be pulled by the same amount as rear lowering?

So if I lower the rear, say, by 10mm, I should pull the forks 10mm as well to retain the original rake?

I was under the impression that forks need to be adjusted by a smaller amount vs. the rear (because of asymmetries), but I could very well be mistaken...?
I don't understand bike geometry very well, I'm afraid.

Thanks for your support
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freeridenick
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Re: Lowering the bike: front / rear ratio?

Post by freeridenick »

The Firestorm has a rear weight bias so lowering the forks less makes sense. Even with a longer shock and pulling the forks through the yolks mine is only 48:52 front:rear.
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