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Discussion Starter · #1 ·
This thread taught me how the length of the damper rods in the front forks controls the length of fork travel. Cool project I thought, and then sort of forgot about it.

Then I stumbled on this thread, where a new owner of a used Wee discovered a spacer below the rebound spring in one of his forks, which reduced the fork travel.

Now here's the thing - I'm a little guy with stubby legs, and I've been riding with the bike lowered by 3/4" front and rear for 2 years now. I never ride off-road, so it works for me just fine.

This year I'm changing both the front and rear suspension. As an experiment I'm trying out a Progressive 465 rear shock that results in a 1' lower ride height - and I'll put the stock dog bones back on. I'd like to keep the bike as "flat" as possible though, but with ABS and a fork brace 3/4" is the limit. (Yes, I know, the accepted wisdom is less, but the brake lines have been rotated out of the way, and that works too.) :mrgreen:

Anyway, here's what I'm thinking. Since I'm taking the damper rods out anyway for an Emulator install, I could slip in 1" long PVC spacers below the rebound spring, and reduce the travel by the same amount without changing the compressed length of the fork. In other words I could mount my fork at the original height in the triple clamps, have no issues whatsoever with fork brace hitting brake lines, and still have the front end 1" lower than stock.

Am I missing anything here? :confused:

That leads to the next question. It seems to me that if I reduce the travel from a supposed 6" to 5", then I need to increase my spring rate by 6/5, or 20%. At 150# out of the shower the general consensus on front spring rate for the standard travel distance seems to be 0.85 kg/mm.

If I do reduce the travel in this fashion should I then be using 1.0 springs instead?
 

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Changing spring rate requires revalving of the dampener, else your wheel will bounce all over the road.
You don't need a guru, you need a voodoo witchdoctor.
Lucky for you, there might be a few of those around...

I have no experience with bike suspensions, but I've seen a ton of people fubar their car suspensions; I finally figured those out (after five year on the track), and I thank Deus that my wee felt right out of the box (I have no more time, money or energy to mess with those things).
 

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Merlin,
let me see if i understand you correctly:

You are lowering the rear (at the wheel) by 1 inch and you want to lower the front by 3/4. You have an ABS bike with a fork brace and you already rotate the brake line out of the way.

1) you can cut a little bit of the brace where it come in contact with ABS distribution block - not much is needed to achieve the result (see pic below) - You may find that you can get already lower as much as 3/4 by doing the cut (through pushing up the stanchions through the triples). But please check it by supporting the bike up, take off fork caps and totally compressed the forks to ensure clearance - might save you one day.
2009 ABS Front Brake Loss

2) the spacer under top out spring only reduce total travel by limiting extension - you want to limit compression - so it wont work. Spring and preload spacer and where the stanchions are clamp determines you relative position of the forks

3) it follows then, if you are willing sacrifice some compression travel - just reduce the preload spacer length and/or dial less preload and allow the bike to sag a bit more to accomplish what you want. again you have to measure it to be sure. But option (1) still is the best in giving you almost all the available compression as normal.

4) Check with sonic spring as to what rate spring suits you - you do not have to up-rated your spring just because you want a lower ride - you just need something to prevent everything smash into each other at maximum compression travel


 

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Discussion Starter · #5 ·
Merlin,
let me see if i understand you correctly:

You are lowering the rear (at the wheel) by 1 inch and you want to lower the front by 3/4. You have an ABS bike with a fork brace and you already rotate the brake line out of the way.
I think you've misinterpreted what I'm up to.

The bike has been lowered both front and back for 2 years now using just the stock suspension. 3/4" lowering links in the rear, and 3/4" raise of forks in triple clamps at front. Works just fine, but the stock suspension is too soft and damping sucks.

So, I'm upgrading the suspension for its own sake.

For the rear I am going to try a reduced travel shock (Progressive 465 -1" ride height).

For the front I was originally going to keep the forks raised in the triple clamps, and upgrade 0.85 springs plus Race Tech Emulators. Then I got to thinking that I could in fact artificially reduce the travel of the forks instead of raising them in the triple clamps, which completely solves the whole ABS + Fork Brace clearance issues.

If I introduce a spacer below the rebound spring then the length of the fork fully compressed does not change, but the full extension length gets shorter. That's a no-brainer.

My real question comes back to front spring rate.

Sag should be a percentage of total available travel. Say, for example, that with un-modified forks and 0.85 springs I can dial in the sag at 1.5" - 25% of travel. If I reduce the stroke from 6" to 5" then my sag should still be set at 25% of travel, but 25% of travel is now 1.25", thus I believe that a stiffer spring would be required to make that relationship work, not to mention prevent the forks from bottoming out too easily.

For comparison the spring rate for the Progressive 465 -1" ride height is about 20% greater than that for the same 465 shock with standard travel.
 

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................

So, I'm upgrading the suspension for its own sake.

....... Then I got to thinking that I could in fact artificially reduce the travel of the forks instead of raising them in the triple clamps, which completely solves the whole ABS + Fork Brace clearance issues.

If I introduce a spacer below the rebound spring then the length of the fork fully compressed does not change, but the full extension length gets shorter. That's a no-brainer.

.................

Merlin,

Please read my answers above especially (2) & (4) - they are all still valid.

Spacer under top out spring will NOT limit your compression travel - it only limits your extension travel - therefore does NOT solve your ABS +fork brace clearance issue. You need something that limits your compression travel like Greywolf with his fork gaiters.

Of course if you are willing to cut a little of the fork brace like i did in the picture above - your clearance will be mostly solved even if you set forks 3/4 above the triples. You might, in combination with the cut, still need to reduce increase your rider sag a bit to get the overall lowering you preferred.

the 25-to 33% sag setting is a recommended one, not a law - if you choose to set it at 40%, the sun will still rise from the east:mrgreen: This is the case as long as you are aware you now have more extension travel and less compression travel - your posts indicate you are already happy to accept that anyway.

With the spring just go with what you would normally do - putting a 1.0kg spring (at your weight) will mean you will be miserable except for the occasions you are doing a landing from jumping in the air. I think 0.85kg spring is fine - just reduce the air gap to give you a bit more bottoming resistance. Vstrom has a oil-lock piece which is a device to stop hard bottoming anyway.
 

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Don't over think the spring rate. If you're a normal touring/commuting rider go with 0.90s, if you're pretty aggressive then 0.95s.
Just so you know, the actual fork travel is closer to 5.5", so a 1" spacer will leave you with 4.5". That's about what most street bikes have, so no worries there.
 

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Discussion Starter · #8 ·
Spacer under top out spring will NOT limit your compression travel - it only limits your extension travel - therefore does NOT solve your ABS +fork brace clearance issue.
Sorry, but no.

Simple thought experiment. I have my stock forks mounted flush to the top of the triple clamp. I then take those off, do the spacer surgery and put them back on. What happens? The fork is now 1" shorter (no load), but the distance to oil lock is the same. The wheel cannot travel any further than it could before.
 

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Discussion Starter · #9 ·
Don't over think the spring rate. If you're a normal touring/commuting rider go with 0.90s, if you're pretty aggressive then 0.95s.
Just so you know, the actual fork travel is closer to 5.5", so a 1" spacer will leave you with 4.5". That's about what most street bikes have, so no worries there.
Thanks Rich! :thumbup:
 

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Sorry, but no.

Simple thought experiment. I have my stock forks mounted flush to the top of the triple clamp. I then take those off, do the spacer surgery and put them back on. What happens? The fork is now 1" shorter (no load), but the distance to oil lock is the same. The wheel cannot travel any further than it could before.
Merlin,

Assuming you are talking putting the spacer underneath the top out spring

The fork will drop 1 inch shorter (extension) when u have the wheels in the air -yes - but when u pushes the forks right up against the triples (compression) - it will make no differences from stock - yes it will not travel any further up nor less further up.

this is okay for if u have the forks flush to the top triples (as it is the case stock) - but you have not really lower the bike (which u wanted) if the preload is the same as stock.

Your bike can sit lower if you new rider sag is adjusted to 25% of the new shorten full travel length with the new spacer in by cutting the preload spacer and/or wind less on the preload adjuster. But it begs the question, why wouldnt you leave everything stock (ie without the spacer) and just adjust preload so that the whole bike sits lower. You have not gain anything new by putting a spacer under the top out spring by doing this surgery.

By just playing the preload spacer/adjustor only, you would end up with the same reduced compression travel as you would with the proposed surgery but the benefit is having more extension travel compare to doing the surgery.
 

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He is lowering the front end by adding the top out spacer.
If he keeps his sag at the same percentage of total travel and uses a 1" spacer he'll lower it by 1 - that %. For example, if he's at 28% then the bike will be .72" lower at the front.
 

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understood that - but just dont understand why not just having more rider sag to achieve the same thing- with the benefit of more extension travel when going over potholes etc.... more extension travel has got be better than less i think.

I still think doing a cut on the brace achieve the same lowering without sacrificing the compression travel is the best but i understand not all people are comfortable with hacking a part of brace - i think Rickland rick is developing a brace with a a cut-out for pre 2012 abs bikes anyway.

Each to their own anyway.
 

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What you are doing is right on track to lower the height of your fork. On my DR650 the factory procedure for lowering the front end is to take a spacer that the factory has sitting on top of the fork spring and move to a location on the top out spring effectively changing where the travel starts. The only thing I believe you have to put some thought in is that you may need to shorten the spring because the area that the fork spring occupies will be less with the spacer under the top out spring.
 

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understood that - but just dont understand why not just having more rider sag to achieve the same thing- with the benefit of more extension travel when going over potholes etc.... more extension travel has got be better than less i think...
There's a limit to that, you can't have negative preload.
As with anything suspension related, it's all about balancing the compromises. :)
Given his goals, on this particular bike, I think he's on the right track. If we were starting out with 4.5" of travel I'd have a different opinion.
 

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Discussion Starter · #17 ·
Well I decided to go for it last weekend, and I have to say that I'm very happy with the results. :mrgreen:

I already had a set of 0.85 springs sitting in the basement, and oil to match, so inspired by Rich's advice not to over-think the spring rate I put them in anyway. They may well prove to be too light, but having done all of the other mods any spring changes will be quick and easy from here on.

The front end is now dropped nearly 1", but the forks are flush to the top clamps and all the ABS bits are way out of harm's way.

I had my first chance to go for an extended ride today, and the forks felt really good. No more annoying bounce on stopping. What I noticed more than anything else was that I wasn't noticing my forks, or cursing them, just enjoying the ride. Well worth all of the wrenching. :thumbup:
 
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