TallRider

I am building up a 1996 Trek 520 touring frame up for my girlfriend, and would like to use a Nitto Technomic stem with a long quill to allow for future bar height adjustability. But it turns out the quill can only insert into the upper half of the steerer tube. The frame is a 55cm, and the head tube length without headset cups is 90mm, so the quill could fit the full length of the steerer tube if it would fit into the fork. I've tried inserting other stems, and they all bottom out at the same amount of insertion into the steerer tube.

I assume the culprit is a very slight butting of the tube - I can't see any visible narrowing when I look into the tube. Perhaps this is butted because it's a touring bike, designed to carry heavier loads. I don't even know if any of my bikes have similar design, because all of my bikes have very long head tubes and steerer tubes. But I've seen quill stems insert all the way into the steerer tube of some smaller bikes with 1" threaded headsets, including a 52cm touring bike. So while the butting of the steerer tube isn't unheard of, I don't think it's common either.

Would it be safe to have a shop with reaming equipment (typically used to ream out seat tubes so a seatpost fits smoothly and doesn't get scratched) to ream out the steerer tube so it fits at 22.2mm the whole way down? This will be ridden by a 135# woman (but every so often with camping gear). Even so, it's less stress than I put on a bike every time I ride.

fietsbob

That is 'butting' , thicker tube wall at the bottom for greater strength required,
because of the leverage of the fork, supporting the front wheel.

Bikes have been that way for many, decades , leave it as it is (or risk injury ).

Wrong priority, ,... get another stem with a shorter quill than the 'technomic'..


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Asi

Or shorten the quill stem (need a precise angled cut - doable with a miter chop saw and some filing and sanding. Or even a hacksaw and a good way to measure that angle to adjust it by filing) and shorten the bolt (might need to extend threads with a die, or a shorter bolt).

All forks I've seen are butted near the bottom race. Leave it alone!

TallRider

I don't mean to ream it all the way down, but the stresses at the fork crown down extend halfway up the steerer tube. But this may be a bad idea in creating stress risers if the new butt spot isn't smooth between the diameters. Something I'd have a a shop do with reaming equipment, if I were to do it.
I can use a shorter quill, of course, but that wouldn't allow for future adjustability same as the Technomic.

AnkleWork

A shorter stem is the quickest, easiest, and cheapest solution which will allow future adjustability -- just swap stems. Reaming is not reversible and has unknown consequences, but permission granted; just do what you want.

Andrew R Stewart 

I won't ream a steerer ID, whether at work or home. Andy

TallRider

Thanks for the responses. It sounds like this isn't a viable option. It's too bad the fork was manufactured with the but halfway up the steerer tube (I've worked on other smaller bikes that have 22.2mm internal diameter much closer to the fork crown (although not all the way down).

I'll just need to get a new stem, probably a 90-degree or slightly more rise, and removable faceplate. Will let me get the fit range I'd wanted, and swap without unwrapping the bar if it turns out to be a poor guess.

fietsbob

If the stem quill wedge is so far down it contacts the butted portion ,
that is not good either..


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