Have just fitted some free-to-me decent forks on an old frame that’s waiting for winter. The steerer tube is coming up about 15mm below the top of the stem, no spacers in there just the headset. Is that really, really too short? What’s the max gap I should be looking at? What are the implications/possibilities of running it like that?

Ta.

Your biggest issue will be insufficient clamping strength from the stem on the steerer – depending on how the strong it all looks and the type of riding you’ll be doing it might be ok.

the other issue is how far down the steerer tube the SFN is, if its too far the bolt from your stem cap may not reach.

as above biggest problem is lack of clamp area for stem.

you can get low stack height stems and headsets – you could probably save 10mm over what you’ve already got with a crank bros headset (assumign standard headset etc).

15mm short is too short.

as wwaswas say try a Crank Bros headset and a lower stack stem.

I swapped my Pikes over when changing frames and the steerer was looking very short but I got back 13mm os stack height buy using the crank brothers headset and swapping hope stem for a race face one

What headset/stem are you using. 15mm is more than I’d be happy with.

FSA XR stems have a low clamp height of about 37mm. Got one off the classifieds which gave me just enough clamping area on the steerer.

I ran with about that much with no problems.
Key thing is that the top of steerer is plenty above the line of the upper clamp bolt. I put a section of cut steerer in, so the stem wasnt squeezing fresh air, so to speak. Then used one of them Amoeba stem bolts, that has a long bolt down to the underside of the fork crown. It never budged. And I didnt die.

Or get one of these: http://www.jejamescycles.co.uk/bbb-aheadstem-steerer-tube-extender-id21879.html

It’ll be fine probably. I’ve ridden with less.

Or get one of these: http://www.jejamescycles.co.uk/bbb-aheadstem-steerer-tube-extender-id21879.html

Hi Ashley,

I’ve got one of those – unused. Yours for £7 posted.

(Chas 🙂 )

I’d be most concerned about the stem coming off…but then it is held in by the top cap.

I fitted the extension onto my wife’s bike. It’s so safe that she said yesterday I can have the bike and all as she won’t use it anytime soon (have a strange feeling it’s related to the Ti frame waiting to be built). I’ll be using it, we all must die one day.

Thomson state no more than 3mm below the top of the stem, which isn’t much at all, but I thought that the rule of thumb was that the top of the steerer had to extend above the shaft of the upper clamp bolt.

— EDIT —

Missed takisawa2’s post which says just that!