Bicycle Mechanics - Spacers for threaded fork and headset?

I'm getting a fork cut for a threaded headset. Ideally, I'd like to have it cut ~2cm too long for the frame it's going to go on in the short term; it'll get moved to another frame (which it will fit better) in about 4 months.

Yes, I know that's a strange thing to do. But if I can get a few months use out of the fork before I get the frame out here, why not? I know exactly how long the head tube on its permanent frame is already, so I can have it cut now without risk.

So, here's the question. Is there any reason I shouldn't run a fork with a threaded headset and 2 cm of spacers? Secondly, can I get away with using spacers like those for a threadless fork (easier to find, maybe) or do I need to use the older style, the ones keyed to the machined slot on a threaded steerer - and if I need the old kind, any idea where I might be able to order some?

Thanks in advance, as always!

-chris

Threadless spacers work. No issues. All you need is enough threads.

Yes this is possible but you must remember the golden rule!!!!! You must insert the stem into the fork steer tube on your first bike so that the wedge that tightens winds up being below the threads. The threaded portion of the fork steerer is the weakest portion and a stem wedge should not be tightened in this area. it's possible that you can actually split the fork at the threads from force being applied in the threaded portion. This story will help you better understand. A young racer went over a erosion control log built into a trail on a down hill during a race. The force of striking this 2" raised spot in the trail and a weight forward landing caused the steer tube to crack at the threads. The rider was OK but the race organizers med team had him hauled away in an ambulance to make sure. The ambulance ride was over $500 and an important lesson was learned. His fork steerer sheered off two threads above the last thread and the resulting head forward cartwheel was amazing. Check out this link. See the handlebar position? Yikes!

Thanks guys - I appreciate it!

GM1230126 - I don't see your photo link, but thanks for the info

Yes this is possible but you must remember the golden rule!!!!! You must insert the stem into the fork steer tube on your first bike so that the wedge that tightens winds up being below the threads. The threaded portion of the fork steerer is the weakest portion and a stem wedge should not be tightened in this area. it's possible that you can actually split the fork at the threads from force being applied in the threaded portion. This story will help you better understand. A young racer went over a erosion control log built into a trail on a down hill during a race. The force of striking this 2" raised spot in the trail and a weight forward landing caused the steer tube to crack at the threads. The rider was OK but the race organizers med team had him hauled away in an ambulance to make sure. The ambulance ride was over $500 and an important lesson was learned. His fork steerer sheered off two threads above the last thread and the resulting head forward cartwheel was amazing. Check out this link. See the handlebar position? Yikes!Then explain to me how forks that are threaded extra long to accomodate a range of headtubes works.There will be cases where the expander will be in the threads. The split steerer fear mongering is overblown.Maybe more application to mtb where things get abused more. Simply don't overtighten.

simply don't tighten in the threads

Yes this is possible but you must remember the golden rule!!!!! You must insert the stem into the fork steer tube on your first bike so that the wedge that tightens winds up being below the threads. The threaded portion of the fork steerer is the weakest portion and a stem wedge should not be tightened in this area. it's possible that you can actually split the fork at the threads from force being applied in the threaded portion.

I have never ever seen this happen on a road bike before (I've seen lots of broken forks, but never this problem), nor have I ever heard anyone discuss it as being an issue.

Threadless spacers work. No issues. All you need is enough threads.

Wow, I was mulling this exact question. Yes, this make perfect sense. Thanks ;-) Now I can make use of some of that pile of threadless spacers I have.