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 03-11-09, 08:05 PM   #1
Divinitous
Junior Member
Thread Starter
 
Divinitous's Avatar
 
Join Date: Dec 2007
Location: Orange County, NY
Bikes: '01 Jamis Dakar Expert (Great bike but I've broken the seatstay 3x)
Posts: 16
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Ok to mix chainrings?

I have a Shimano crankset with rings that are getting worn out. I swapped in a new chain and it's skipping. So I need some new rings. The problem I'm seeing is i cannot find replacement shimano rings for my Deore XT M751 crankset.

I plan to make a large order through Universal Cycles and they only have a middle ring for a m752. Will it work?

And since the granny gear is just a flat ring i assume i can slap anything there, correct?
Divinitous is offline   Reply With Quote
Old 03-11-09, 08:08 PM   #2
sooprvylyn
I suck, but you're worse
 
Join Date: Jun 2005
Location: LA
Bikes: Motobecane Fantom Uno-Got rid of the rest when I moved to LA:(
Posts: 672
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
If the new chain is skipping it is more likely your freewheel or gear cluster that is worn out.
sooprvylyn is offline   Reply With Quote
Old 03-11-09, 08:09 PM   #3
sooprvylyn
I suck, but you're worse
 
Join Date: Jun 2005
Location: LA
Bikes: Motobecane Fantom Uno-Got rid of the rest when I moved to LA:(
Posts: 672
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
If you are going to replace your drivetrain start with the rear gears and then get chainrings if that doesn't fix the problem
sooprvylyn is offline   Reply With Quote
Old 03-11-09, 08:37 PM   #4
Divinitous
Junior Member
Thread Starter
 
Divinitous's Avatar
 
Join Date: Dec 2007
Location: Orange County, NY
Bikes: '01 Jamis Dakar Expert (Great bike but I've broken the seatstay 3x)
Posts: 16
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Sorry, forgot to mention that I had changed the rear cassette/chain at the end of the last riding season.
Divinitous is offline   Reply With Quote
Old 03-11-09, 09:07 PM   #5
Homebrew01
Super Moderator
 
Homebrew01's Avatar
 
Join Date: Jul 2004
Location: Ffld Cnty Connecticut
Bikes: Old Steelies I made, Old Cannondales
Posts: 19,707
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 110 Post(s)
Tight link in the chain ? Mismatch between sizes of cassette & chain ? Rear derailleur adjustment needed ? The chainrings are the last thing to cause skipping.
__________________
Bikes: Old steel race bikes, old Cannondale race bikes, less old Cannondale race bike, crappy old mtn bike
Homebrew01 is offline   Reply With Quote
Old 03-11-09, 09:12 PM   #6
sooprvylyn
I suck, but you're worse
 
Join Date: Jun 2005
Location: LA
Bikes: Motobecane Fantom Uno-Got rid of the rest when I moved to LA:(
Posts: 672
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Then you need to measure the distance between the holes on your crank arm to determine what size chain rings will fit your crank. You should be able to find out on google how to do the conversion. You also need to be sure that the rings you buy are designed for the number of chainrings you will have on your crank. As to the Granny Gear Question you can't have too great a difference between your large ring and the granny ring unless your front derailure has a very long cage. Basically the top of the cage goes just above the chain on the largest chainring, and the bottom of the cage is just below the chain on the granny gear. It is best to use the same number of teeth that is already on your bike so you don't have to muck around with that front derailuer, otherwise you will need a mechanic.
sooprvylyn is offline   Reply With Quote
Old 03-12-09, 11:12 AM   #7
DMF 
Elitist Troglodyte
 
DMF's Avatar
 
Join Date: Jun 2006
Location: Dallas
Bikes: 03 Raleigh Professional (steel)
Posts: 6,924
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
C'mon guys, front rings do wear out. Wear there isn't easy to detect visually, either.

Divinitous, is it skipping in all front gears? If so it isn't a front wear problem.

The middle gear on a triple is usually first on a road bike, but sometimes a heavily-used granny goes too. (Fewer teeth means more wear per tooth, but some gears are used more frequently than others.)

There are definite differences in front chainrings. I have an old thread here where I measured several models of road cranksets and few were identical. Some were radically different. However, between versions of the same model - like M751 and M752 - they should be interchangeable. Did you look at the interchangeability chart on the Shimano exploded drawings? So long as you stick with 32T, the middle rings are 'A' rated for interchangeability.

One can't make blanket statements about the granny. Two of the variables are plate thickness and tooth offset (from the spider mounting surface). Also ring bolt countersink. Unless you know what you're doing, best to stick with the spec'd parts.
__________________
Stupidity got us into this mess - why can't it get us out?

- Will Rogers
DMF 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 07:40 AM.