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Old 05-05-10, 01:49 PM   #1
mattamatta
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Steerer tube length below stem top - How Short is Too Short?

Hey everyone.

What I'm trying to accomplish is to use two stems - one to hold my road drops w/ front brake, and one to hold my track drops without brake, so I can switch the whole stem/bar combo to go from street to track setup.

Unfortunatly, I ended up with two stems with a bit of a different stack height. My question is whether you think its possible to cut the steerer tube to a length that would work for both stems. The steerer tube is 1" unthreaded, and I've got a shim on there for 1-1/8 stems.



The road bar stem - the current height works fine for these bars - plenty of gap to get preload without hitting, and it doesn't seem to have any problems.


Track bar stem - as you can see, the stack height is shorter, and this stem sits with the steerer/shim just about flush - no good.



Spacer stack and shim on sterrer tube shot for good measure.


Do you think it would be workable to cut a little bit more off the stem and shim so that its just enough of a gap for the shorter stem, and more than ideal for the taller? Or would that be too much of a gap and cause problems? Seems to me like the main drawback of having too much of a gap is that the stem will be clamping onto less of the steerer tube, though I'd think that it would have enough to have a plenty positive connection for the needs of a stem.



Of course, the alternative is to use an additional spacer - I assume the ones I have on there are 1" spacers, as they seem to fit well on the tube, and won't fit over the shim. I'd need a true 1-1/8" spacer that would sit over the shim and hopefully the 1" stack has enough of a lip for it to sit on.

Ideally I'd like to just be able to swap the stems without keeping track of an extra loose spacer when it's not in use.


I asked at an LBS that seems to do good work, and they said they'd recommend just using the extra spacer, which I decided not to buy since I had a couple extra - of course only to come home and realize that the spacers I have are clearly not going to work.


Cut the stem shorter? Get a proper 1-1/8" spacer and quit whining? Cut the shim and use an extra 1" spacer below shim for the short stem, leaving the shim "floating" on the taller one?


Any advice is greatly appreciated.
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Old 05-05-10, 02:19 PM   #2
CACycling
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Maybe it is the angle of the picture but that road bar stem looks right on the edge of having the top clamp bolt even with the top of the stem. I'd go with a spacer.
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Old 05-05-10, 02:22 PM   #3
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Get the proper shim, and zip tie through stem when not in use
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Old 05-05-10, 02:49 PM   #4
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Maybe it is the angle of the picture but that road bar stem looks right on the edge of having the top clamp bolt even with the top of the stem. I'd go with a spacer.
That's what I think too. The road bar stem looks to me like it's clamping right at the bery top of the steerer tube. I definitely wouldn't want the steerer tube any shorter.
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Old 05-05-10, 03:00 PM   #5
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I'd swap out one of those thick spacers for several thin spacers. The stem in pic 1 may need to lowered just a touch. Is the top edge of the steerer completely above the upper bolt? The stem in pic 2 needs to go higher.
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Old 05-05-10, 07:48 PM   #6
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Looks like the top edge of the steerer is about even with the centerline of the upper clamp bolt. Sounds like its best to make sure you get contact across the whole clamp bolt area of the stem then?

I can change one of the thick spacers to one half as high, and road/#1 goes down a bit, although I find I need one more thin one on top of the stem, then, as the top cap hits the steer tube at about 80% of the way toward getting the play out of the headset. With one thin below, one thin on top it seems to have plenty of grip, and I can preload without hitting anything on that stem. It's still slightly awkward because the steerer doesn't stick up at all past the stem, so there's no auto-centering mechanism for the thin spacer on top, but it seems to work.

I was able to do the same thing using one thin below and one thick above with the other stem (in that case, the steerer sticks out a bit, so the spacer sits around it - the shim is further down the tube inside the stem's grippy parts). That seems to work as well, so I may be able to get away with that for now.
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Old 05-06-10, 09:33 AM   #7
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I can change one of the thick spacers to one half as high, and road/#1 goes down a bit, although I find I need one more thin one on top of the stem, then, as the top cap hits the steer tube at about 80% of the way toward getting the play out of the headset. With one thin below, one thin on top it seems to have plenty of grip, and I can preload without hitting anything on that stem. It's still slightly awkward because the steerer doesn't stick up at all past the stem, so there's no auto-centering mechanism for the thin spacer on top, but it seems to work.
Not sure how thin your thinnest spacer is but you might want to get a thinner one to replace the thin one you are using below to negate the need for one above the stem while still getting the clamping bolt below the top of the steerer tube. Much better and easier solution IMHO and shouldn't cost much for a thin spacer.
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Old 05-06-10, 10:03 AM   #8
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You have to set the preload every time.. seems like a pain.

I would do as sheldon does... get a secondary clamp and use it in lieu of spacers. then you just swap the stems and clamp them down and your bearing preload never changes.

You might keep the spacers for cosmetic reasons.

Sheldon explains it better than I would... scroll to "threadless without spacers"
http://www.sheldonbrown.com/handsup.html
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Old 05-06-10, 02:40 PM   #9
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Yeah, I thought about that option. I might want to look into one of those. I find that now, unloading the bearings every time, no matter how good I think it's dialed in, I often find the need to adjust it again once the track bars are on and the brake is off - and the brake really comes in handy when trying to adjust out bearing play.

Last edited by mattamatta; 05-06-10 at 03:00 PM.
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