When i finally settle on the bar height of my road bike I’m going to have around 25mm of spacers above the stem, so how do you go about trimming carbon tubes?
Bike shop job maybe?

fine toothed hacksaw blade, proper saw guide.

and do it outdoors wearing a mask.

+1 what he said

and do it outdoors wearing a mask.

That can be a bit impractical, especially when the cutting guide is vice-mounted and the vice is bolted to a workbench!

I’ve done a couple in the garage (mask on) and swept up/binned the resulting dust. Hopefully I will not suffer a carbon-dust related demise…

as above and def not with a sword 8)

chain saw

line the resulting dust up on your CD case with a credit card and roll up a 10!

snort away

As above a fine toothed hacksaw and try not to inhale the dust

Doesn’t even need to be terribly straight if you’re fitting 25mm of spacers above the stem!

Fine toothed hacksaw, try not to breath the dust.

Is there an exposure value on carbon fibre dust. These things are sometimes only harmful if you do it all day, everyday. Doing it once is unlikely to kill you.

A bit of water will remove the dust hazard.

Electrical tape around the tube, add spacers, stem and metal 0.25cm top spacer. Dampen wear mask and cut.

Otherwise, off to the bike shop. Ride it a lot before you cut it. You can’t go up again. I’ve done about 1000 miles on my new bike and am still refining up and down by 0.5cm depending on race or non-race.

Hope the new bike is fitting better. Post a pic.

EDIT: as an aside. I cut the steerer on my beloved Merlin the month before it was stolen. So now the only part I have left resides on my garage door keyring as a reminder of my loss.

I’ve cut plenty of carbon without a mask and I’m not dead yet. Not that I’d necessarily recommend not using PPE, just saying.

I’ve cut plenty of carbon without a mask and I’m not dead yet

Are you in your 60’s?

I used a brand-x guide from CRC, wrapped some tape around the steerer and used a fine toothed hacksaw. Goes through really easily and leaves a clean finish.

Do a practice cut high on the steerer to make sure you’re happy with cutting the actual desired length. If the practice one goes to poo then take it to a LBS 🙂

Ta for the info 🙂
For clarification i currently have 25mm of spacers above the stem and 10mm below it. Only done 130 miles since i got it on Saturday so still experimenting with bar heights etc.
fit is better, 4cm shorter seat tube but i still have a short 70mm stem on it – must have very stumpy arms!