Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

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.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 09-17-06, 12:48 PM   #1
FarHorizon
Senior Curmudgeon
Thread Starter
 
FarHorizon's Avatar
 
Join Date: Jan 2005
Location: Directly above the center of the earth
Bikes: Varies by day
Posts: 3,856
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
130 BCD cranks for MTB?

I've got a Specialized Rockhopper with a 4-bolt triple crank. The crank arms are "bent out" to clear the wide rear chainstays. I'd like to use a 130 BCD chainwheel (single) with chain guards instead. Does anyone make a 130 BCD crankset with "bent out" cranks for clearance?

Thanks!
__________________
Nishiki road bike, Raleigh road bike, Electra Cruiser Lux 7d, Electra Townie 3i, Electra Townie 1, Whatever I find today!
FarHorizon is offline   Reply With Quote
Old 09-17-06, 12:53 PM   #2
Retro Grouch 
Senior Member
 
Retro Grouch's Avatar
 
Join Date: Feb 2004
Location: St Peters, Missouri
Bikes: Catrike 559 I own some others but they don't get ridden very much.
Posts: 26,903
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 206 Post(s)
What size chainring are you planning to use? If your bottom bracket is long enough to make your chainring clear with a reasonable chainline I can't imagine you having a crank arm clearance problem.
Retro Grouch is offline   Reply With Quote
Old 09-17-06, 12:56 PM   #3
FarHorizon
Senior Curmudgeon
Thread Starter
 
FarHorizon's Avatar
 
Join Date: Jan 2005
Location: Directly above the center of the earth
Bikes: Varies by day
Posts: 3,856
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Quote:
Originally Posted by Retro Grouch
What size chainring are you planning to use? If your bottom bracket is long enough to make your chainring clear with a reasonable chainline I can't imagine you having a crank arm clearance problem.
The chainring is only a 46T. The chainstays, however, bow out CONSIDERABLY immediately aft of the bottom bracket (to clear any MTB tire that might be fitted). It is the crank-arm/chainstay clearance that concerns me.
__________________
Nishiki road bike, Raleigh road bike, Electra Cruiser Lux 7d, Electra Townie 3i, Electra Townie 1, Whatever I find today!
FarHorizon is offline   Reply With Quote
Old 09-17-06, 01:42 PM   #4
mechBgon
Senior Member
 
mechBgon's Avatar
 
Join Date: Jul 2002
Bikes:
Posts: 6,957
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Actually, almost any crankset should work on your Rockhopper if it's paired up with the bottom bracket it was made to use. I know it probably doesn't look that way when you look at yours, but there you go.

edit for clarity: with a 46-tooth ring, that is. If you slapped on a huge chainring, then it might have clearance issues.
mechBgon is offline   Reply With Quote
Old 09-17-06, 04:40 PM   #5
FarHorizon
Senior Curmudgeon
Thread Starter
 
FarHorizon's Avatar
 
Join Date: Jan 2005
Location: Directly above the center of the earth
Bikes: Varies by day
Posts: 3,856
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Quote:
Originally Posted by mechBgon
Actually, almost any crankset should work on your Rockhopper if it's paired up with the bottom bracket it was made to use. I know it probably doesn't look that way when you look at yours, but there you go...
Thanks, mechBgon! As I understand you, appearances are deceiving, and provided that the chainrings don't cause problems, the cranks themselves should clear even without the crook in the crank arm?
__________________
Nishiki road bike, Raleigh road bike, Electra Cruiser Lux 7d, Electra Townie 3i, Electra Townie 1, Whatever I find today!
FarHorizon is offline   Reply With Quote
Old 09-17-06, 05:27 PM   #6
mechBgon
Senior Member
 
mechBgon's Avatar
 
Join Date: Jul 2002
Bikes:
Posts: 6,957
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by FarHorizon
Thanks, mechBgon! As I understand you, appearances are deceiving, and provided that the chainrings don't cause problems, the cranks themselves should clear even without the crook in the crank arm?
Yeah. If you could measure the width across the inside tips of the crankarms on a bunch of different triple cranks mounted on their appropriate bottom brackets, there'd be some variation, but not tons.

To take an example, if you looked at an old Sugino AT crankset from the 1980's, its arm has no "crook" at all, it's basically straight. But it's made to go on a super-long spindle that still gets it out clear of the frame. Your cranks are the opposite... the spindle is short, so the arm has that kickout to get the crankarm clear of the frame. That crook in the arm isn't because of the shape of your particular frame, really, it's because the crank's made to go on short spindles.
mechBgon is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

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



All times are GMT -6. The time now is 04:26 PM.