small frame, stem insertion problem
04-15-08, 03:28 PM
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small frame, stem insertion problem
I just bought a Soma Rush frame, 51 cm, with a Soma threaded fork. I
bought it from thebikebiz, they installed a Miche Primato headset. I
had planned to use a 100mm Dura Ace quill stem, one of the "aero"
stems Peter White has on this page:
https://www.peterwhitecycles.com/stems.asp
When I installed the stem, it went in so far as to just cover the
markings for minimum insertion (on this stem is says "MAX" and has a
series of vertical lines) and then stopped. However after about a
quarter of a mile the stem would loosen and slip, leading me to
believe that the expander bolt was tightening inside the steerer at
the top of the butted section, as described on Sheldon Brown's page
here:
https://www.sheldonbrown.com/handsup.html
under "too low! danger!"
This loosening happened several times, after repeated tightening,
messing around, taking to bike shops, friends, etc, before I googled
the problem and found a post by Sheldon with a link to the above page.
(no thanks to the two shops here who didn't spot this first) Since it
exactly describes the problem I believe that is the case, although
when I called thebikebiz the person I spoke to was surprised that that
Soma fork was butted. I emailed Soma but haven't heard back if their
forks are butted.
So, the solution seems to be to raise the stem a little bit. Which I
did, and now the stem has not come loose after much more riding than a
quarter of a mile.
BUT the stem is now raised ABOVE the minimum insertion mark, about
10mm or less.
Soma's threaded forks, according to their site, have 50mm of threads.
Thebikebiz said that they probably cut the steerer for such a small
frame combined with this Miche headset, so there are even fewer
threads. After careful measuring I am convinced that the expander bolt
is BELOW the threads on the steerer, so I don't think that I am in
danger of breaking the steerer at the threads.
I went to both bike shops near me, and the bike co-op, and could not
find a stem that had a SHORTER insertion length. Someone at one of the
bike shops said I would be alright, and would not likely break my
stem.
So finally, after all this, my question is:
Is that right? Am I asking for a bad crash? Or am I reasonably safe?
There is about 55mm of stem inside the steerer.
If this is dangerous, in other words if I am in danger of breaking the
stem, what are my options for stems? I've done a lot of shopping
around, all the quill stems I could find seemed to have as long an
insertion length. Does anyone know of a stem with a short insertion?
From reading other posts, it seems like the problem tends to be
finding LONG stems, not short ones.
Thank for any help and any ideas!
Yamada
PS I'm sure many of you frequent rec.bicycles.tech, I cross posted this moments ago. I apologize is this is egregiously against etiquette. I'm at a loss here, since I have done a lot of searching with little luck.
bought it from thebikebiz, they installed a Miche Primato headset. I
had planned to use a 100mm Dura Ace quill stem, one of the "aero"
stems Peter White has on this page:
https://www.peterwhitecycles.com/stems.asp
When I installed the stem, it went in so far as to just cover the
markings for minimum insertion (on this stem is says "MAX" and has a
series of vertical lines) and then stopped. However after about a
quarter of a mile the stem would loosen and slip, leading me to
believe that the expander bolt was tightening inside the steerer at
the top of the butted section, as described on Sheldon Brown's page
here:
https://www.sheldonbrown.com/handsup.html
under "too low! danger!"
This loosening happened several times, after repeated tightening,
messing around, taking to bike shops, friends, etc, before I googled
the problem and found a post by Sheldon with a link to the above page.
(no thanks to the two shops here who didn't spot this first) Since it
exactly describes the problem I believe that is the case, although
when I called thebikebiz the person I spoke to was surprised that that
Soma fork was butted. I emailed Soma but haven't heard back if their
forks are butted.
So, the solution seems to be to raise the stem a little bit. Which I
did, and now the stem has not come loose after much more riding than a
quarter of a mile.
BUT the stem is now raised ABOVE the minimum insertion mark, about
10mm or less.
Soma's threaded forks, according to their site, have 50mm of threads.
Thebikebiz said that they probably cut the steerer for such a small
frame combined with this Miche headset, so there are even fewer
threads. After careful measuring I am convinced that the expander bolt
is BELOW the threads on the steerer, so I don't think that I am in
danger of breaking the steerer at the threads.
I went to both bike shops near me, and the bike co-op, and could not
find a stem that had a SHORTER insertion length. Someone at one of the
bike shops said I would be alright, and would not likely break my
stem.
So finally, after all this, my question is:
Is that right? Am I asking for a bad crash? Or am I reasonably safe?
There is about 55mm of stem inside the steerer.
If this is dangerous, in other words if I am in danger of breaking the
stem, what are my options for stems? I've done a lot of shopping
around, all the quill stems I could find seemed to have as long an
insertion length. Does anyone know of a stem with a short insertion?
From reading other posts, it seems like the problem tends to be
finding LONG stems, not short ones.
Thank for any help and any ideas!
Yamada
PS I'm sure many of you frequent rec.bicycles.tech, I cross posted this moments ago. I apologize is this is egregiously against etiquette. I'm at a loss here, since I have done a lot of searching with little luck.
