Stem help
09-02-17 | 07:09 PM
#1
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Joined: Sep 2017
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Stem help
Hey, so this is my first post on here and I do apologize if this has been asked before. I decided to purchase a shorter stem to hopefully get a better fit on my bike. I went with a relatively cheap 90mm one from amazon just to see if I'd like the fit. I just installed it and my bike seems to wobble when I engage the brakes and rock the bike back and forth. The new stem didn't come with its own top cap and the one in using from my old stem seems to not fit entirely on. Could this be the cause of the wobble? Or is it something else. I'm new to biking in general and I'd greatly appreciate any help or advice.
09-02-17 | 07:29 PM
#2
Senior Member
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From: Sacramento, CA
Bikes: old ones
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...the top cap is what you used to preload the bearings in the headset. It's pretty hard to guess what's goin' on without at least some pictures.
Those caps should fit stems of the same clamping diameter, so unless you got something off Amazon that's a different size, I have no clue.
...the top cap is what you used to preload the bearings in the headset. It's pretty hard to guess what's goin' on without at least some pictures.
Those caps should fit stems of the same clamping diameter, so unless you got something off Amazon that's a different size, I have no clue.
09-02-17 | 08:06 PM
#3
Generally bewildered
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From: Eastern PA, USA
Bikes: 2014 Trek Domane 6.9, 1999 LeMond Zurich, 1978 Schwinn Superior
Two points of wobble. As 3alarmer says, the top cap on the end of the fork (the "steerer tube") is used to preload the fork bearings. If that's not tight, your fork can be very loose in the frame. Make sure that before you tighten the stem bolts to the steerer tube, you have the top cap adjusted so that the bearings and fork are not loose (the fork should turn very easily, but there should be no play or rattle between the fork and frame). Then tighten the stem onto the fork's steerer tube.
The other place of wobble is if you don't adequately fasten handlebars down properly using the screws in the the stem front cap. If you don't have the right front cap, this could indeed keep you from tightening the bars.
I think the problem is the first one, though, no? I only mention the second problem because I'm building up a bike from the frame and the handlebars seemed loose. I'd forgotten to tighten and torque those front cap bolts. D'oh!
The other place of wobble is if you don't adequately fasten handlebars down properly using the screws in the the stem front cap. If you don't have the right front cap, this could indeed keep you from tightening the bars.
I think the problem is the first one, though, no? I only mention the second problem because I'm building up a bike from the frame and the handlebars seemed loose. I'd forgotten to tighten and torque those front cap bolts. D'oh!
09-02-17 | 10:00 PM
#4
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From: Rochester, NY
Bikes: Stewart S&S coupled sport tourer, Stewart Sunday light, Stewart Commuting, Stewart Touring, Co Motion Tandem, Stewart 3-Spd, Stewart Track, Fuji Finest, Mongoose Tomac ATB, GT Bravado ATB, JCP Folder, Stewart 650B ATB
Not all threadless stems have the same clamping length. A stem that's less "tall" at the clamp might allow the fork's steerer to extend up past the stem and not allow the preload cap to properly do it's job. Andy
09-03-17 | 02:18 AM
#5
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That'd be My first guess too.
Nothing wrong with the stem as such. Different, not worse.
