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 08-27-14, 09:18 PM   #1
corwin1968
Senior Member
Thread Starter
 
corwin1968's Avatar
 
Join Date: Aug 2011
Bikes:
Posts: 1,306
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 14 Post(s)
Another Bottom bracket question

I took a Takagi triple crankset off a bike with a 68mm x 124mm bottom bracket. The bike was from 1983-84 and probably had rear spacing of 126mm or so.

I removed the inner and outer chainrings and mounted the middle chainring in the position of the outer ring. I installed a 73mm x 127mm BB on a bike with a 73 BB shell and 135 rear spacing. There is no way the inner ring would fit without hitting the chainstays and the middle ring cannot even be mounted in it's original location without striking the chainstays.

I want to add the inner ring and make a double. Is it possible with this crankset/frame combination? The 127mm spindle is the longest I found in 73mm. I would need a spindle in the 130's to make it work as a double.
corwin1968 is offline   Reply With Quote
Old 08-27-14, 09:22 PM   #2
FBinNY 
Senior Member
 
Join Date: Apr 2009
Location: New Rochelle, NY
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
Posts: 30,839
Mentioned: 21 Post(s)
Tagged: 0 Thread(s)
Quoted: 865 Post(s)
Long spindles were typically asymmetrical. is there any chance you installed it with the short end to the right?

Otherwise, depending on the particular BB you're using, you might b able to put a shim under the right cup, and move the entire unit over to the right 2mm or so.
__________________
FB
Chain-L site

An ounce of diagnosis is worth a pound of cure.

“Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin

“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN

WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FBinNY is offline   Reply With Quote
Old 08-28-14, 05:11 AM   #3
corwin1968
Senior Member
Thread Starter
 
corwin1968's Avatar
 
Join Date: Aug 2011
Bikes:
Posts: 1,306
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 14 Post(s)
Quote:
Originally Posted by FBinNY View Post
Long spindles were typically asymmetrical. is there any chance you installed it with the short end to the right?

Otherwise, depending on the particular BB you're using, you might b able to put a shim under the right cup, and move the entire unit over to the right 2mm or so.
The BB I'm using is a cartridge so I know it's installed correctly. However, the original spindle may well have been asymmetrical (I just measured it end-to-end). I'll have to look at it more closely later today. I didn't know you could shim a bottom bracket. Is there a specific shim designed for this?

ETA: You nailed it!! The original spindle is 3-4mm longer on the right side!! Is a shim possible with a cartridge BB and is that the most obvious solution (besides a more modern crankset that uses a much shorter spindle)?

Last edited by corwin1968; 08-28-14 at 05:15 AM.
corwin1968 is offline   Reply With Quote
Old 08-28-14, 06:19 AM   #4
hueyhoolihan
Senior Member
 
Join Date: Dec 2010
Location: Above ground, Walnut Creek, Ca
Bikes: 7⃥ 9 road bikes
Posts: 6,401
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
IME, old road cranks, don't work well on MTB frames. the geometry of the crank is wrong. the arm is not offset enough from the spindle attachment point and so necessitates BB spindles lengths that are excessive. i've tried it... and failed. but, if you can find a BB spindle that is long enough, (i couldn't, but admittedly didn't look very hard), it should work. there are ways to add a couple millimeters clearance. smaller chainring, spacers on driveside of BB or inside of crank bolts, but they don't add much. take a look at the chainstays on the MTB frame and compare them to a road bikes's chainstays. they sit out much, much further in order to clear wider tires.

i just ended up putting my nice old road crank back on the shelf and lived with the beatup looking MTB crank the i had.
hueyhoolihan is offline   Reply With Quote
Old 08-28-14, 08:21 AM   #5
corwin1968
Senior Member
Thread Starter
 
corwin1968's Avatar
 
Join Date: Aug 2011
Bikes:
Posts: 1,306
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 14 Post(s)
The crank I'm using is an MTB crank but it's literally from the first years of production MTB's. The Suntour parts on the donor bike all have 1983 manufacture dates. I like this bike enough that I think I'll just start looking for a more modern crankset.
corwin1968 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 05:38 AM.