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


Go Back   > >

Singlespeed & Fixed Gear "I still feel that variable gears are only for people over forty-five. Isn't it better to triumph by the strength of your muscles than by the artifice of a derailer? We are getting soft...As for me, give me a fixed gear!"-- Henri Desgrange (31 January 1865 - 16 August 1940)

User Tag List

Reply
 
Thread Tools Search this Thread
Old 04-24-07, 10:29 PM   #1
bellweatherman
Senior Member
Thread Starter
 
bellweatherman's Avatar
 
Join Date: Aug 2005
Location: Austin
Bikes: Too many to count
Posts: 2,103
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Safe to file down a chainring?

This is really frustrating. My outer chainring is a 110BCD. My middle chainring is a 110BCD. I am using a MTB triple crankset on a fixed bike with one ring. I am trying to improve my chainline, by moving the outer ring to the middle position, but it won't fit.

Both rings use a BCD diameter of 110. Shimano has proprietary rings such that a MTB outer 110BCD ring is not the same shape as a MTB middle 110BCD ring. Therefore, a 110BCD outer ring will not fit in the middle position both rings are 110BCD. Hypothetically, you could go out and buy a 42T outer ring for a Shimano MTB crank and try to use it in the middle position, only to find that it won't fit in the middle position.

Is it safe to file down a small bit of the chainring near the bolt hole so that it fits on the crank? For example, I want to file the parts of the spider furthest to the inside of the chainring, but being careful not to file any part of the hole.
bellweatherman is offline   Reply With Quote
Old 04-24-07, 10:33 PM   #2
trons
yo yo yo yo yo
 
Join Date: Nov 2005
Location: delaware
Bikes:
Posts: 2,518
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
go for it
trons is offline   Reply With Quote
Old 04-24-07, 11:22 PM   #3
calf man
Senior Member
 
calf man's Avatar
 
Join Date: Apr 2007
Location: Atascadero, CA
Bikes:
Posts: 169
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
You might be better off filing the spider crank instead of the chain ring.
The small amount of metal between the hole and inside edge of the chain ring is critical for the strenth of that part, and by filing that area, you could end up with a chain ring that look like an old record that you left on the dashboard of your car on a hot day.
calf man is offline   Reply With Quote
Old 04-24-07, 11:23 PM   #4
chevy42083
steel lover
 
Join Date: Apr 2007
Location: Houston
Bikes: Bianchi Alloro, Miyata 710, Fuji Espree Fixie convert
Posts: 1,317
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I think you'd be fine... the bolts will keep the ring centered up just fine. Never done it though.
chevy42083 is offline   Reply With Quote
Old 04-24-07, 11:25 PM   #5
roadgator
raodmaster shaman
 
Join Date: Dec 2004
Location: G-ville
Bikes:
Posts: 1,431
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
so if i get what you are saying the shimano rings are squared off on the inside of the ring which is keeping them from mating up to the rounded lands on the crank?

i never knew this was an issue, but i dont see why it would matter to just knock that little bit of metal off.

edit: ill second removing it from the crank first. it has more metal to wrok with.
roadgator is offline   Reply With Quote
Old 04-24-07, 11:26 PM   #6
MKRG
Senior Member
 
Join Date: Sep 2002
Location: by a big river
Bikes:
Posts: 2,459
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Buying the proper part sounds easier.
MKRG is offline   Reply With Quote
Old 04-25-07, 12:03 AM   #7
pyze-guy
Yup
 
pyze-guy's Avatar
 
Join Date: Jan 2004
Location: where the sunbeams end and the starlight begins
Bikes: Kona Unit, planet X cx bike, khs fixed gear
Posts: 3,054
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Shorter b/b.
__________________
When sadness fills my days
It's time to turn away
And then tomorrow's dreams
Become reality to me
pyze-guy is offline   Reply With Quote
Old 04-25-07, 02:42 AM   #8
BoozyMcliverRot
Senior Member
 
BoozyMcliverRot's Avatar
 
Join Date: Jan 2007
Location: bradenton FL
Bikes: 06 Motobecane SS/FW, early 90's Specialized Sirrus fixie
Posts: 942
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
just but a SS ring with the same BCD.........nuff said.
BoozyMcliverRot is offline   Reply With Quote
Old 04-25-07, 03:51 AM   #9
bellweatherman
Senior Member
Thread Starter
 
bellweatherman's Avatar
 
Join Date: Aug 2005
Location: Austin
Bikes: Too many to count
Posts: 2,103
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by BoozyMcliverRot
just but a SS ring with the same BCD.........nuff said.

You have no idea. You can't just assume that because the ring you are buying will fit just because it is the same BCD as the one you are replacing. Maybe try reading the original message.
bellweatherman is offline   Reply With Quote
Old 04-25-07, 04:07 AM   #10
bellweatherman
Senior Member
Thread Starter
 
bellweatherman's Avatar
 
Join Date: Aug 2005
Location: Austin
Bikes: Too many to count
Posts: 2,103
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by roadgator
so if i get what you are saying the shimano rings are squared off on the inside of the ring which is keeping them from mating up to the rounded lands on the crank?

i never knew this was an issue, but i dont see why it would matter to just knock that little bit of metal off.

edit: ill second removing it from the crank first. it has more metal to wrok with.

That's kinda what I'm saying. See the above pic for reference. On this particular MTB crank (Deore), the 110 BCD Shimano Outer Ring has a little bit more metal around the hole than a 110 BCD Shimano Middle Ring. The way Shimano designs the crank, they force you to buy a 110 BCD Shimano Middle Ring as no other 110 BCD ring will fit in the middle position.

You think I should remove material from the shoulder/spider area of the crank instead of the chainring? I was going to file the chainring since it seems less drastic, ie. I would be altering a chainring as opposed to a crank.

PS- No BB spindle (other than a hypothetical 68x98) is short enough for me to move the outer ring in far enough to obtain a perfect chainline (52mm MTB fixed). The only solution is to have the big ring on the middle position using a 68x113mm BB which yields a perfect 52mm chainline.
bellweatherman is offline   Reply With Quote
Old 04-25-07, 05:57 AM   #11
me thinkst
mofo
 
Join Date: Oct 2006
Bikes:
Posts: 152
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
which to alter is your decision. weight weenies shave down both cranks and chainrings all the time. i would probably hit the cranks since then you can change rings w/o problems, also removing material around bolt holes isn't always that good. i imagine the middle ring was steel and the material supporting the rings at the bolt holes was sufficient.
file time flat bastard!
me thinkst is offline   Reply With Quote
Old 04-25-07, 10:56 AM   #12
squeakywheel
domestique
 
squeakywheel's Avatar
 
Join Date: Nov 2005
Location: off the back
Bikes:
Posts: 2,004
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Looks like an aluminum chainring. That would be easy to file down.

I bought a used steel 110 BCD chainring and found out it won't fit on my crank for the same reason. I'm planning to file it down a little. I'm expecting it to be a pain because I don't think the steel will be as easy to remove as your aluminum.
squeakywheel 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 04:42 AM.