Go Back  Bike Forums > Bike Forums > Bicycle Mechanics
Reload this Page >

Stem replacement question

Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

Stem replacement question

Reply

Old 10-16-06, 01:24 PM
  #1  
DogBoy
No one carries the DogBoy
Thread Starter
 
Join Date: Feb 2004
Location: Upper Midwest USA
Posts: 2,321

Bikes: Roubaix Expert Di2, Jamis Renegade, Surly Disc Trucker, Cervelo P2, CoMotion Tandem

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Stem replacement question

I have a 120 mm 90 degree stem (quill) and would like a little less reach. I figured I could get a taller stem with a bit higher angle or an adjustable stem, but I'm having trouble identifying the correct size.

The specs from the bike say 24.5 mm insertion, 24.5 mm clamp. My understanding is that this means it is a 1 1/8" stem with a standard mtn bike clamp. I'm quite confused by the 1" vs 1 1/8" thing, and want to be sure I get the right size. I have not yet removed the existing stem to measure the opening, but how does the opening size relate to the stem size?

Bike is a 90s gary fisher Nirvana rigid mtn bike similar to this.
DogBoy is offline  
Reply With Quote
Old 10-16-06, 04:28 PM
  #2  
moxfyre
cyclist/gearhead/cycli...
 
moxfyre's Avatar
 
Join Date: Oct 2004
Location: DC / Maryland suburbs
Posts: 4,166

Bikes: Homebuilt tourer/commuter, modified-beyond-recognition 1990 Trek 1100, reasonably stock 2002-ish Gary Fisher Hoo Koo E Koo

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
From your description, it's almost certainly a so-called "1-1/8" stem, given the "25.4 mm insertion" spec. But to be sure of the size, measure the outside diameter of the quill part of the stem with calipers. You don't need to remove the stem to do this If it's 22.2 mm (= 7/8" exactly), then you've got a 1" headset, if it's 25.4 mm (= 1" exactly), then it's a 1-1/8" headset.

The measurements are confusing because the headset size (1" or 1-1/8") doesn't actually refer to any exact measurement of anything

See http://sheldonbrown.com/gloss_ha-i.html#headset for the definitive table of threaded headset sizes, and the required stem diameter for each.
moxfyre is offline  
Reply With Quote
Old 10-16-06, 08:45 PM
  #3  
DogBoy
No one carries the DogBoy
Thread Starter
 
Join Date: Feb 2004
Location: Upper Midwest USA
Posts: 2,321

Bikes: Roubaix Expert Di2, Jamis Renegade, Surly Disc Trucker, Cervelo P2, CoMotion Tandem

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
okay, no calipers, but I pulled the current stem and measured the diameter of the opening and got a max of 1" (assuming I didn't always get an exact cross through the center, so looking for a maximum measurement), so I'm going with the 1 1/8 inch replacement. If it doesn't fit I guess I'll know that its a 1"
DogBoy is offline  
Reply With Quote

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service