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 05-08-06, 02:02 PM   #1
DvB
Senior Member
Thread Starter
 
Join Date: Aug 2005
Bikes:
Posts: 58
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Shimano Sora: indexed front triple to friction front double?

I've done a lot of searching on this topic, but have found no answers. If a thread already exists, please forgive me. (And provide the link!)

I'd like to swap out the heavy triple crank on my girlfriend's roadbike with a nicer, lighter compact double. I'm mechanically experienced and can do the BB and crank swap no problem. Only issue is the front brifter (Shimano Sora). It's indexed for a triple, and I don't know if it can be modified to be either: (a) friction, which I'd prefer; or (b) indexed for a double. Anyone know?

Knowing Shimano, I'm guessing the answer is no, the shifter can't be modified. If this is indeed the case, has anyone used the triple brifter with a double crank successfully? Is it possible, through proper set-screw adjustment and cable tensioning, to use only two of the brifter's three index positions?

Thanks a lot in advance for any assistance.

--DvB
DvB is offline   Reply With Quote
Old 05-08-06, 09:06 PM   #2
orange leader
B-b-b-b-b-b-bicicle Rider
 
orange leader's Avatar
 
Join Date: Apr 2005
Location: Northfield, MN
Bikes: 1997, stumpjumper S-works hardtail, Medici, Giant allegre (track dropouts and fixed gear), Columbia twosome, schwinn twinn, '67 raleigh 5 speed internal hub, Old triumph 3 speed, old BSA 3-speed, schwinn Racer 2spd kickback, Broken raysport criteriu
Posts: 739
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I haven't tried it with brifters yet (none of my bikes are that up to date) but I would think you could just set the derailleur's low side set screw so as to disallow the throwing of the chain down to the granny range. Or disallow the throwing to the high side, whichever works best with the chain rings you opt for. you may also be able to adjust your crank position depending on what type of bottom bracket you opt for, some BBs are more adjustable than others.

I've done similar things, in the past and always find myself trying to shift into gears that I know aren't there. It's just habit, the bike doesn't do it, because i adjusted those gears out, but the cable will dangle slack until I figure out what I subconciuosly tried to do.

Good luck, I'd say it's doable.
orange leader is offline   Reply With Quote
Old 05-09-06, 06:35 AM   #3
Landgolier
THIS SPACE FOR RENT
 
Join Date: Jan 2006
Bikes:
Posts: 2,849
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Just hook it up, set the limit screws, and see how it runs. Triples aren't really "indexed" in the way a rear D is, you actually do use the index positions to adjust where the FD is to prevent the chain from rubbing just like you do with friction shifters. I can't 100% promise it's going to work, but I'm betting it will shift from low to high with three or four clicks, and give you usable positions down one click from that and up one click from the low position.

Also, check out swap meets and maybe even put a WTB in your sig, sora brifters are pretty common components in people's parts bins.
Landgolier is offline   Reply With Quote
Old 05-09-06, 09:23 AM   #4
Sheldon Brown
Gone, but not forgotten
 
Sheldon Brown's Avatar
 
Join Date: Jul 2002
Location: Newtonville, Massachusetts
Bikes: See: http://sheldonbrown.org/bicycles
Posts: 2,301
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by DvB
I've done a lot of searching on this topic, but have found no answers. If a thread already exists, please forgive me. (And provide the link!)

I'd like to swap out the heavy triple crank on my girlfriend's roadbike with a nicer, lighter compact double. I'm mechanically experienced and can do the BB and crank swap no problem. Only issue is the front brifter (Shimano Sora). It's indexed for a triple, and I don't know if it can be modified to be either: (a) friction, which I'd prefer; or (b) indexed for a double. Anyone know?
It will work fine. Any shifter works for a front double, it's only triples that are fussy 'cause they index the middle ring. (On a double, the "indexing" is provided by the derailer's limit stop screws.)

Sheldon "Sora Fan" Brown
Code:
+------------------------------------------+
|  To have doubted one's first principles  |
|  is the mark of a civilized man.         |
|                -- Oliver Wendell Holmes  |
+------------------------------------------+
Sheldon Brown is offline   Reply With Quote
Old 05-09-06, 09:37 AM   #5
DvB
Senior Member
Thread Starter
 
Join Date: Aug 2005
Bikes:
Posts: 58
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by Sheldon Brown
It will work fine. Any shifter works for a front double, it's only triples that are fussy 'cause they index the middle ring. (On a double, the "indexing" is provided by the derailer's limit stop screws.)

Sheldon "Sora Fan" Brown
Code:
+------------------------------------------+
|  To have doubted one's first principles  |
|  is the mark of a civilized man.         |
|                -- Oliver Wendell Holmes  |
+------------------------------------------+
Thanks for the input, everyone. I know it will "work," i.e., the setup will allow shifting from big ring to small and vice-versa. I was just concerned about how well it would work. I could see the setup being quite annoying if the spacing between the two chainrings on the new double crank didn't quite match the two corresponding indexed positions on the old triple shifter. (I'll still never understand for the life of me why anyone would want indexing for the front changer -- whether the crank is a double or a triple.)

I will say that despite being a little annoyed at Shimano right now, the Sora stuff works really well (especially given its low-on-the-totem-pole spot in Shimano's lineup). Easy to work on, smooth, and so far very reliable.

Good suggestion to scour parts bins and message boards -- I think I'll just look for a cheap double brifter to replace the old triple.
DvB 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 10:38 AM.