How much can a longer travel Rockshox fork be shortened?

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How much can a longer travel Rockshox fork be shortened?
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flag Trailboss-89
Posted: Aug 30, 2019 at 8:17 Quote
I’ve been snooping around for quite a while and I’m looking to upgrade the fork on my Roscoe. My budget is fairly small so I’m exploring options I might have to get a decent fork for my bike. I’ve seen where folks have shortened Pikes and other Rockshox air forks by cutting the air shaft and re-tapping the end to a custom length.
My question is this: how short is too short? Do I need to be looking at forks in the travel range my bike’s geometry can handle? Or could I reasonably shorten a say.... 160-180mm fork to suit my needs. (Looking to maybe go to a 130mm-140mm from 120mm)

I have a metal lathe and metal shop at my disposal, and would feel confident in cutting the shaft down(if that’s all there is to it) Obviously purchasing a fork in the correct travel length would be ideal, I just want to know if I have another option. I’m a hands-on kinda guy and don’t care about tearing into things early on to gain an understanding of the internal workings of a piece of equipment.

Thanks!
flag TibZ
Posted: Aug 30, 2019 at 20:58 Quote
Trailboss-89 wrote:
I’ve been snooping around for quite a while and I’m looking to upgrade the fork on my Roscoe. My budget is fairly small so I’m exploring options I might have to get a decent fork for my bike. I’ve seen where folks have shortened Pikes and other Rockshox air forks by cutting the air shaft and re-tapping the end to a custom length.
My question is this: how short is too short? Do I need to be looking at forks in the travel range my bike’s geometry can handle? Or could I reasonably shorten a say.... 160-180mm fork to suit my needs. (Looking to maybe go to a 130mm-140mm from 120mm)

I have a metal lathe and metal shop at my disposal, and would feel confident in cutting the shaft down(if that’s all there is to it) Obviously purchasing a fork in the correct travel length would be ideal, I just want to know if I have another option. I’m a hands-on kinda guy and don’t care about tearing into things early on to gain an understanding of the internal workings of a piece of equipment.

Thanks!

Pikes exist in 130-140 mm... Why not buying one of those?
flag doggparadox
Posted: Sep 5, 2019 at 23:24 Quote
It's gonna depend on the fork. But I swapped out the airshaft on a lyrik to 130mm and it works great. I don't think you can go "too short". It's not like there will be clearance issues or anything since all forks should be designed to use all of their travel.
flag ebrooker
Posted: Sep 9, 2019 at 16:51 Quote
Yes you can probably reduce the travel by cutting down the air shaft on a RockShox fork (Lyrik/Yari/Pike design). The 29+ Yari for example can be bought new with travel ranging from 100mm to 180mm. Pikes and Lyriks will be similarly modifiable, essentially you're cutting down the part of the shaft that sits in the lowers, the actual air chamber stays the same, which is why the shorter travel forks can take more volume tokens. Some considerations, don't scratch the anodizing on the air shaft, and don't get any metal chips in the seals.

All that being said. Don't bother cutting down the air shaft, just buy a new one they're like $55 CAD (feel free to convert that to freedom bucks or whatever). I'm going to guess that you're looking at used forks, which will benefit from a fresh air spring(new seals) and new oil. You can then sell the old airspring and recoup some of the cost. The only downside would be the added weight from the larger fork, something like a Yari/Lyrik will be heavier than a Pike, without getting the benefits of the added travel.

Sram have excellent guides on how to service RockShox forks, they will show you exactly what you need and how to do this.

As for how long you should set the new fork to. There are a lot of factors that go into that, so try to consider how and where you ride and what you're looking for. Its also worth considering that your geometry changes as you increase your fork length, which may make the bike higher than you'd like. Play around with some geometry calculators to get a rough idea of what's going to change.
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