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Need help shortening Pike RCT3 (160mm → 100mm) – shaft wall too thin for threading?

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Need help shortening Pike RCT3 (160mm → 100mm) – shaft wall too thin for threading?

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flag olodiabollo
Posted: Oct 11, 2025 at 11:11 Quote
Hey guys,

I recently bought a RockShox Pike RCT3 (160mm travel) and wanted to shorten it down to 100mm. I started by cutting 15mm off the air shaft just to test it, but I noticed a problem — after cutting, the inner wall of the shaft is thinner, and the M8 tap that normally fits perfectly now goes in loosely. When I tried to re-thread it, the tap just spun without cutting any proper threads because there wasn’t enough material.

It looks like the inner diameter of the shaft increases further down, so there’s not enough wall thickness for new threads. I’ve seen plenty of shortened Pikes online, so clearly it’s possible — but I must be missing something.

Has anyone done this before? How do you deal with the thinner wall section when shortening the shaft? Do you sleeve it, re-thread deeper somehow, or use a different insert?

Any tips or pics would be super helpful.

Thanks!
flag Vadio
Posted: Oct 12, 2025 at 3:12 Quote
If there’s so much hassle shortening the shaft- just spend $20-25 for a proper 100mm factory shaft.
Also don’t forget that 100mm Pikes has different Charger cartridges (or possibly different Charger adjustments), so be sure to figure that out too.
flag mossrider
Posted: Oct 12, 2025 at 19:59 Quote
olodiabollo wrote:
Hey guys,

I recently bought a RockShox Pike RCT3 (160mm travel) and wanted to shorten it down to 100mm. I started by cutting 15mm off the air shaft just to test it, but I noticed a problem — after cutting, the inner wall of the shaft is thinner, and the M8 tap that normally fits perfectly now goes in loosely. When I tried to re-thread it, the tap just spun without cutting any proper threads because there wasn’t enough material.

It looks like the inner diameter of the shaft increases further down, so there’s not enough wall thickness for new threads. I’ve seen plenty of shortened Pikes online, so clearly it’s possible — but I must be missing something.

Has anyone done this before? How do you deal with the thinner wall section when shortening the shaft? Do you sleeve it, re-thread deeper somehow, or use a different insert?

Any tips or pics would be super helpful.

Thanks!


Yep, exact same problem here. The inner bore expands deeper in the shaft, so you can’t just chop and tap. Either get a proper 100mm air shaft or machine a thin-walled sleeve that fits inside and tap the threads in that. Otherwise it won’t seal properly
flag olodiabollo
Posted: Oct 14, 2025 at 4:57 Quote
Could you please tell me where I can buy a suitable 100mm diameter air shaft?
mossrider wrote:
olodiabollo wrote:
Hey guys,

I recently bought a RockShox Pike RCT3 (160mm travel) and wanted to shorten it down to 100mm. I started by cutting 15mm off the air shaft just to test it, but I noticed a problem — after cutting, the inner wall of the shaft is thinner, and the M8 tap that normally fits perfectly now goes in loosely. When I tried to re-thread it, the tap just spun without cutting any proper threads because there wasn’t enough material.

It looks like the inner diameter of the shaft increases further down, so there’s not enough wall thickness for new threads. I’ve seen plenty of shortened Pikes online, so clearly it’s possible — but I must be missing something.

Has anyone done this before? How do you deal with the thinner wall section when shortening the shaft? Do you sleeve it, re-thread deeper somehow, or use a different insert?

Any tips or pics would be super helpful.

Thanks!


Yep, exact same problem here. The inner bore expands deeper in the shaft, so you can’t just chop and tap. Either get a proper 100mm air shaft or machine a thin-walled sleeve that fits inside and tap the threads in that. Otherwise it won’t seal properly
flag eshew
Posted: Oct 14, 2025 at 7:54 Quote
https://trailhead.rockshox.com/en/product/search/serial?silentAuthAttempted=true

Put your fork serial in the link above, that should either give to you the air spring options or a specific year to hunt down the proper air spring If it's available.

And when I say put your serial in there, just type it in rather than cutting it off the fork and placing it on your monitor, or shoving your fork through the monitor until the serial lines up... Just type it in.
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