Road Cycling - Stem problem...??

This is a piece to my headset, but I don't know what to call it. It's the other piece that holds the handlebars to the stem. I guess it would be called a stem cap??

As you can see (hopefully, if I did it correctly) attached is a picture of that piece. And by the picture, you can see that one hole is larger than the other.

I was tighening this thing cause my handlebars were slipping down (rolling) when I was on my bar ends. I know that's a MTB thing... but just bare with me :D When I was tighening it, I guess the screw pushed the washer right thru the stem cap!! :eek:

Now I need to buy another. Can I buy just that piece? or do I have to go out and buy another stem?? If I can buy just this piece, is it measured a certain way, or is it standard??

Any help is greatfully appreciated!

-Dan the Man-

If you look closely, I have BF running on my computer screen when I took the pic.... hehe.

-Dan the Man-

If the size is a universal size.... is it worth getting something like this....

http://www.nashbar.com/profile.cfm?category=119&subcategory=1186&brand=&sku=3500&storetype=&estoreid=

That's real cheap just for that piece.

-Dan the Man-

you should replace the whole stem. most MTB forks come with 1-1/8" steerers, so you should get one. But the older ones may have 1" steerers, and the stem should be compatibe, if its big, you can insert a sleeve/shim.

When you get a new stem, make sure you know which measurements will effect the ultimate handlebar position. Things to consider when replacing a stem include:

Steerer Diameter - This is the measurements of the steerer tube at the headset. In your case it's 1-1/8". The other two typical measurements are 1" and the newer 1.5" standards.

Handlebar Clamp Diameter - This is the measurement of the clamp to attach the handlebar. This is typically 26mm (standard) or 31.7mm (oversized) for road bikes. For mountain bikes, it's 25.4mm (standard), 28.6mm (oversized) and some people such as RaceFace with their Diabolus bar have now gone to 31.8mm (super-oversized).

Length or Extension - This is the linear length of the stem from center of steerer to center of handlebar.

Rise - This is usually given as the distance between the centerline of the steerer and the centerline of the stem (as drawn from center of steerer to center of handlebar clamp)

Stem Angle - This is given as the angle between the steerer tube and the stem tube. Sometimes it's expressed as degrees from horizontal instead.

Stack Height - This is the height of the stem that's added on to the top of the headset and needs to be pretty close to the total height at the top of the steerer tube. This is important because if the steerer is too short then you may not be able to use the stem without replacing the steerer tube (if you can). If the stack height of the stem is too short then you need to add spacers between it and the headset or above the stem in order for the top-cap preload to be effective.


http://www.habcycles.com/stemfit.jpg

How do I know what stem is a good fit for me? Should I measure the old one and just get a new one?

-Dan the Man-

Originally posted by ockey53
How do I know what stem is a good fit for me? Should I measure the old one and just get a new one?

The key measurements of a stem that affect handlebar position are reach and rise. Fiddle with the other measurements to achieve the same reach and rise as your current stem. This of course assumes that you like your current stem's reach and rise. :)

Originally posted by ockey53
How do I know what stem is a good fit for me? Should I measure the old one and just get a new one?


Originally posted by khuon
The key measurements of a stem that affect handlebar position are reach and rise. Fiddle with the other measurements to achieve the same reach and rise as your current stem. This of course assumes that you like your current stem's reach and rise. :)

I don't even know if the one I have is correct or comfortable? But is there a way you can tell that that particular stem is the "right" one? Like your elbows aren't bent, or something like that??

-Dan the Man-

Originally posted by ockey53
I don't even know if the one I have is correct or comfortable? But is there a way you can tell that that particular stem is the "right" one? Like your elbows aren't bent, or something like that??

-Dan the Man-

Well, bike fitting is fairly subjective. General rule of thumb has you sitting with arms relaxed and elbows slightly bent. Some people prefer a more upright position and others prefer a more race-oriented XC position. The main thing is that you should not feel cramped or too stretched out. If your top-tube is correct then anywhere between a 90mm and 120mm reach stem is common. Too much beyond that can introduce some steering problems. Likewise, going much shorter than 90mm may make the bike too twitchy on climbs depending on your fork rake and head angle.

Knees should not contact your elbows. This of course assumes that your saddle position is also "correct". Some people say KOPS (Knee Over Pedal Spindle when crank arms are horizontal) works, others debunk it. Your legs should also be slightly bent when your pedals are at bottom dead-center.

You can get replacement fronts for standard two-bolt stems as opposed to 3, 4 and odd 2 bolts. You can even get odd ones that give you an additional bottle mount on the face plate.

Originally posted by ockey53
How do I know what stem is a good fit for me? Should I measure the old one and just get a new one?

-Dan the Man-

That's where your good old LBS comes in. My LBS lets me try on different stems and let me ride my bike for a while. I can even take it home if I like, and just return it a day later.

Check if your LBS allows this, or at least ask them if you could try out diff. stems in the shop. I'm sure they will allow you to do so, as long as you will buy from them.

Ok, so I guess I'm going to have to find a good LBS around here that carries components. I got Back Bay Bikes like 2.5 miles away... I think they got some stuff, I'll take a swing over there tomorrow night or something to see what they can hook me up with.

-Dan the Man-

isn't it a stem face plate? I think that stem fit is one of the trickyist parts of bike fit. Especially now that all the new bikes have a threadless stem. Once you cut the steerer tube, it is impossible to raise the stem. Some over cut the steerer tube and leave a little stub sticking above the stem until they are sure that they are happy with the height of the stem. As khuon has outlined, there are some rules of thumb to follow, but in the end it is trial and error. Ritchey makes a stem that can be flipped so you can change the rise but you might need to get a different rise and length to find the right position for you. In the old days you could raise and lower a stem to fine tune your position.

I recommend reading the instructions when tightening down the face plate, there should be a recommended torqure. It is easy to strip the treads on the stem, as there are not too many of them. I like to put a small piece sandpaper in the between the bar and the face plate, this will stop it from turning.

Originally posted by fogrider
I like to put a small piece sandpaper in the between the bar and the face plate, this will stop it from turning.

I had experience with these sandpaper thing on the stem. It was pretty good when it was dry. But when it rains hard and you get soaked, it will make the handlebar slip, and gradually feel that your hoods are getting lower as you ride.
Anyway, this was a long time ago when I was still using threaded forks, and stems with expanders.

But these new stems are pretty good. It can really grip the bar very well, without any assistance, in my experience and opinion.;)

Originally posted by dexmax

But these new stems are pretty good. It can really grip the bar very well, without any assistance, in my experience and opinion.;)

... especially if it's a magnesium stem. However, that lends itself to some other issues. And you really have to be very very very careful not to overtorque the clamp bolts with mag stems. Don't ask me how I know. ;)

use wet sandpaper if water is factor, but I agree that most of the new stems are designed with some kind of gripping element to it...but it was the bar rotating that started the problem with Dan the Man.

Yeah, it was that I was up on the ends of the bar ends and then the handlebars rotated forward. So when I got home, I tightened the stem cap screws a little more, and then the washer was pushed right thru the cap!

-Dan the Man-

If the washer was pulled through the cap, I would think that's a warranty issue.

Originally posted by khuon
When you get a new stem, make sure you know which measurements will effect the ultimate handlebar position. Things to consider when replacing a stem include:

Steerer Diameter - This is the measurements of the steerer tube at the headset. In your case it's 1-1/8". The other two typical measurements are 1" and the newer 1.5" standards.

Handlebar Clamp Diameter - This is the measurement of the clamp to attach the handlebar. This is typically 26mm (standard) or 31.7mm (oversized) for road bikes. For mountain bikes, it's 25.4mm (standard), 28.6mm (oversized) and some people such as RaceFace with their Diabolus bar have now gone to 31.8mm (super-oversized).

Length or Extension - This is the linear
length of the stem from center of steerer to
center of handlebar.

Rise - This is usually given as the distance between the centerline of the steerer and the centerline of the stem (as drawn from center of steerer to center of handlebar clamp)

Stem Angle - This is given as the angle between the steerer tube and the stem tube. Sometimes it's expressed as degrees from horizontal instead.

Stack Height - This is the height of the stem that's added on to the top of the headset and needs to be pretty close to the total height at the top of the steerer tube. This is important because if the steerer is too short then you may not be able to use the stem without replacing the steerer tube (if you can). If the stack height of the stem is too short then you need to add spacers between it and the headset or above the stem in order for the top-cap preload to be effective.


http://www.habcycles.com/stemfit.jpg
Deda is the only stem that i have seen at 31.7 and that is for the bars they make.All other stems are the regular size or 31.8 and there are very few carbon stems to choose from at 31.8. and less with rise,most are 0 or - rise.

it sounds like it wasn't even on top and bottom, you have to tighten them correctly and evenly. If not this will happen, in the meantime find a longer bolt and big washer and use that for now. Ugly? Yes. Will it work? Yes.