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 05-28-06, 10:06 PM   #1
allez
means go
Thread Starter
 
allez's Avatar
 
Join Date: Mar 2006
Location: Memphis, TN
Bikes: '06 Pedal Force RS
Posts: 613
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
triple to compact double.....what do i need?

I posted this in the "road" forum, decided to bring it here.......here goes:

i have a triple crank right now (52/42/30) with a 9-cog rear cassette (12-25). all came stock, full 105 components on my specialized allez (2001). i want to get a compact double (close to 50/36). can i just get it and slap it on (with some FD adjustments) or will i need to overhaul the whole drivetrain? new FD? new shifters? just trying to get a feel for the right way to go about this.....thanks!

ps-after a couple replys in the road forum, my answer to the "why?" question is because i never use the highest and lowest gears that i would be losing, and the weight savings (i know, minimal) and the convenience is worth it. plus i just want it.
allez is offline   Reply With Quote
Old 05-28-06, 10:40 PM   #2
thePest
Senior Member
 
thePest's Avatar
 
Join Date: May 2006
Location: Pacific NW
Bikes: none at this time
Posts: 130
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by allez
I posted this in the "road" forum, decided to bring it here.......here goes:

i have a triple crank right now (52/42/30) with a 9-cog rear cassette (12-25). all came stock, full 105 components on my specialized allez (2001). i want to get a compact double (close to 50/36). can i just get it and slap it on (with some FD adjustments) or will i need to overhaul the whole drivetrain? new FD?
to go 3 > 2 these are the problems

1.) you will need to shorten the B/B to a 109 or if you are running the 110 will work. But not the 113mm.

The frt derailleur on a triple has a longer inside plate. Looking at the drop above listed, there is normally a 26t diff. Which you should be a go on this one.
thePest is offline   Reply With Quote
Old 05-28-06, 11:50 PM   #3
fogrider
Senior Member
 
Join Date: Sep 2003
Location: fogtown...san francisco
Bikes: Ron Cooper, Time VXSR, rock lobster, rock lobster, serotta, ritchey, kestrel, paramount
Posts: 2,276
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
as thepest has said, a new bb might be needed, but to really take advantage of the compact, you might want a short arm derailluer. a short arm and less chain should result in quicker shifting.
fogrider is offline   Reply With Quote
Old 05-29-06, 03:25 AM   #4
sch
Senior Member
 
Join Date: May 2003
Location: Mountain Brook. AL
Bikes:
Posts: 3,086
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 42 Post(s)
You can get by with a new R crank with the desired CW and a shorter BB. Problem is Shimano is very proud of their compact cranks and wants $250 or so for it (no BB IIRC). FSA sells the Gossamer compact but you would need an ISIS BB. FSA also has carbon compact which weighs 3-4oz less than the Gossamer for triple the money (weight reduction at $50/0z), also ISIS. The der you have will work ok according to most converters that have posted in the past, but a shorter cage RD would be a little snappier. If your frame has a FD mount 'brazed' you might have a problem with the der height above the CW.
Steve
sch is offline   Reply With Quote
Old 05-29-06, 03:45 AM   #5
cs1
Senior Member
 
cs1's Avatar
 
Join Date: Feb 2004
Location: Clev Oh
Bikes: Specialized, Schwinn
Posts: 6,705
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 33 Post(s)
What works, what doesn't

The front der will work, but not too well.
The rear der will work, but not too well either.
The bottom bracket will not work too well because the chainline is too far offset.
The crank is obvious, at least I hope you can figure it out.
The brifters are a go.

IMO, you should sell the old 105 group, seeing as most parts will work marginally at best. If you had a double, you might be able to get away with just a crank change at best. At worst, you would have to swap out the the front der and crank. Good luck and let us know what happens.

Tim
cs1 is offline   Reply With Quote
Old 05-30-06, 09:50 AM   #6
oilman_15106
Senior Member
 
Join Date: May 2005
Bikes:
Posts: 6,900
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Ritchey makes a very nice compact crank for about $125-150. Also uses the octalink bottom bracket system. All advise fro cs1 is +1 from me.
oilman_15106 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 12:50 AM.