Bicycle Mechanics - Stem Compatability (old BMX -> MTB)

Hi, I'm a college student who wants to do some biking this winter. I don't want to trash my good bike by leaving it outside, or annoy my roommate by bringing my slushy bike inside. My solution is to get a winter bike that I can leave outside if I have to. I picked up some bikes at a community clean-up day recently, so I have a few bikes to build from.

The MTB that I'll be starting with is missing the wedge part for the quill stem, and the thing on top of the stem to tighten it down with. I want to toss another stem on so I can get on (or off) the road again. It doesn't have to be pretty, just functional.

Will any or all of these stems fit?
-from BMX-style bike (don't know how they work...are they quill stems?)
-2 different road bikes (same style stem though)

Thanks for the help getting me rolling again!

Kevin

Holy nightmare ghetto bike, Batman! They're all quill stems form what I can see. The BMX one would be the strongest.

Cool, thanks for the reply! I'll give it a go when I get home.

The rear wheel was also taco'd when I picked up the bike. I tried truing it back into shape (my first time using my spoke wrench, I got it to look pretty good), but I think I might have to loosen all the spokes and just pry/jump on it until it is semi-straight, then tighten the spokes back up.


Holy nightmare ghetto bike, Batman!

Think of it as a good thing! Theft deterrence: No one else will want to steal a bike in the winter, I'll be the only one crazy enough to be riding! :D Besides, if they want to steal a bike, it won't be mine! I guess if I don't lock it, I won't have to worry about the lock getting frozen up. I wonder if it would get stolen...hmm..

Thanks again,
Kevin

Hi, I'm a college student who wants to do some biking this winter. I don't want to trash my good bike by leaving it outside, or annoy my roommate by bringing my slushy bike inside. My solution is to get a winter bike that I can leave outside if I have to. I picked up some bikes at a community clean-up day recently, so I have a few bikes to build from.

The MTB that I'll be starting with is missing the wedge part for the quill stem, and the thing on top of the stem to tighten it down with. I want to toss another stem on so I can get on (or off) the road again. It doesn't have to be pretty, just functional.

Will any or all of these stems fit?
-from BMX-style bike (don't know how they work...are they quill stems?)
-2 different road bikes (same style stem though)


It is a "quill" or "wedge" type stem, but it is not going to be the standard 22.2 mm (7/8"/.875") diameter where it fits into the stem.

That is the older American size, 21.15 mm (13/16"/.833") often associated with BMX bikes.

A standard 22.2 mm stem is too fat to fit. Basically any stem that you can physically fit into the fork will be the correct size, since there are no thinner sizes in normal use.

See also: http://harriscyclery.com/opc

Sheldon "http://sheldonbrown.com/cribsheet-headsets.html" Brown
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Oh, the one with the accordion bellows below it would work too. Depending on your bars, it may be easier to go with the BMX one though.

I should have made a *note about this before: the accordian stem pictured is the stem I'm trying to replace, as it doesn't have the wedge and tightening mechanisms. The stem falls out.

I think I understand this though.
*Out of these four stems, the BMX one is the oddball. It is .833" (21.15mm).
*The others (the MTB one I'm trying to replace and two road stems) are the same standard 7/8" (22.2 mm).
*Therefore, I'll have to replace the MTB stem with one of the road ones. Also good news: I think the handlebars are all the same size, so it should be a relatively straight foreward swap.

Sheldon, thanks for the links to your tables. They probably helped me understand better than any amount of words.

Any time I have a question about anything.. step one - Google "my question" + sheldonbrown step two (or one if I'm already browsing BF) - search BF. The wealth of knowledge I've picked up from Sheldon's site and this one account for - well nearly everything I know about bikes and some other stuff too! :)

I had a Schwinn for a while that had the old .833 stem size. Glad I never got around to upgrading that part of the bike (although it was about the only part left) as I would have kicked myself for buying a nice 22.2 stem only to not be able to use it. As it is I ran into the problem when I went to sell it. I was going to swap a 100mm length stem in for the guy buying the bike instead of the 90mm as he was a very tall fellow.

I'd say I've learned something, but I'm only confused now. I personally removed one of those 4 bolt BMX stems from an older MTB. It even had the V bars. Anyhoo, if all that's needed is the the bolt and wedge, why not just pinch that off one of the other bikes?

Yeah, I googled and searched bikeforums.net, and didn't find anything. I didn't dig through the good sites like Sheldon's though!

Expatriate, from what I understand, all bikes mentioned/pictured in this thread have quill stems. All but the BMX bike are 22.2 mm. The BMX bike is 21.15mm. That makes a whopping difference of 1.05mm! If you know anything about metric, that is a pretty small amount. It would work I guess, there might be a little gap and it might be a little loose. I don't know.

About just grabbing the wedge + bolt from another bike; that is a good idea. However, the stem on the MTB stem is missing something for the bolt to sit on. You can see straight through the stem, its just a hollow tube. I was thinking of putting a couple washers up top to hold the bolt up. If the rise of the MTB (accordian) stem will be significantly better than either of the others, I might go with the even more ghetto washer route.

I'm about 6' and have the seat maxxed on my 18" bicycle, and the Huffy pictured is a 19", so I might need to try to salvage the MTB stem to get the bars up as high as I can. At least now I know which ones I can and can't get parts from.