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 07-19-11, 04:12 PM   #1
Camilo
Senior Member
Thread Starter
 
Join Date: Apr 2007
Bikes:
Posts: 4,263
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 111 Post(s)
Sram RD low/inner limit adjustment

Just installed a Sram Red drive train - shifters, crank, derailleurs, cassette, chain.

Got everything working well. Rear shifting is great - crisp and quick up and down the cassette. I think that cable tension is spot on. Front shifting is working fine.

I encountered what I have come to understand is a common problem with the rear shifting. I set the low limit screw according to Sram instructions. When on the innermost/largest sprocket, if I forget I'm there and attempt to shift again, the shifter clicks once and the chain drops to the higher gear (next smaller sprocket). Because of the limit screw, I can't force the shift past that first "upshift" click.

So I read somewhere that the solution to this is to ease off the low limit screw a little bit at a time allowing the derailleur to move slightly further inward. I did this in 1/8 inch stages until.....

Now when I'm in that large sprocket situation, I can shift "past" that first click, the shifter makes a very loud and rough second click and, for lack of a better term, "releases" rather than moving the cable, and the chain stays on the largest sprocket. But this actually takes quite a bit of force on the shifter. If I apply what I would consider normal force to down shift - in other words, if I just apply the normal amount of force I'd use to shift to a lower gear (which isn't there of course), the shifter will just do that first click, won't move past that, and the chain will move to the higher gear. If I really force it, that second, loud click will happen causing the cable to release and the chain to stay put.

Hope this makes sense. Does it sound right to you? Do I need to ease it off a bit more so less force is needed? I DO NOT want to shift into the spokes!!

I don't know if this is actually the proper way to set this up - I'm a little disappointed that Sram doesn't address this issue clearly and understandably.

Thanks.
Camilo is offline   Reply With Quote
Old 07-19-11, 04:38 PM   #2
kevin_stevens
Senior Member
 
Join Date: Jun 2011
Bikes:
Posts: 363
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I was setting up my Rival this week, and I was able to get it to the point where it allows for an attempted "pull" to a bigger cog, but fails to accomplish it and stays where it is. The issue is that you have to be able to push the shifter past the "downshift" point so it doesn't drop you to a smaller cog, and not so far that it succeeds in upshifting into the spokes. Unfortunately, I can't tell you what my recipe was, but most of it was tension adjustment (I was actually setting up the front after doing the limits in the rear, so I was paying more attention to chain rub than rear shifting.) But I'm happy with where it ended up.

Now if I could just get the darned front to both shift small-big reliably AND not have cross-chain rub...

KeS
kevin_stevens is offline   Reply With Quote
Old 07-19-11, 06:13 PM   #3
Camilo
Senior Member
Thread Starter
 
Join Date: Apr 2007
Bikes:
Posts: 4,263
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 111 Post(s)
Quote:
Originally Posted by kevin_stevens View Post
... The issue is that you have to be able to push the shifter past the "downshift" point so it doesn't drop you to a smaller cog, and not so far that it succeeds in upshifting into the spokes. ....
Thanks. Yea, that's what I've got now - it's shifting past the point where it would drop to the next smallest cog (which is an "upshift", i.e. a higher/harder gear, not a "downshift", i.e. a lower/easier gear). But I guess what I'm asking is - mine then makes a very hard click at that point and the chain stays where it is, on the largest cog. And it takes a lot of force on the shifter lever to get past the upshift point. I'm wondering if this is how it is supposed to be?
Camilo is offline   Reply With Quote
Old 07-19-11, 06:19 PM   #4
milkbaby
blah blah blah
 
milkbaby's Avatar
 
Join Date: Aug 2009
Bikes:
Posts: 2,520
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
The magic of double tap...
milkbaby is offline   Reply With Quote
Old 07-20-11, 03:30 AM   #5
kevin_stevens
Senior Member
 
Join Date: Jun 2011
Bikes:
Posts: 363
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Mine takes the same amount of force as it does for a normal shift, then it clicks and resets without chainging <= the derailleur position. That seems "normal" to me, it's the best response that I could expect.

KeS
kevin_stevens is offline   Reply With Quote
Old 07-20-11, 11:00 AM   #6
Camilo
Senior Member
Thread Starter
 
Join Date: Apr 2007
Bikes:
Posts: 4,263
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 111 Post(s)
Quote:
Originally Posted by kevin_stevens View Post
Mine takes the same amount of force as it does for a normal shift, then it clicks and resets without chainging <= the derailleur position. That seems "normal" to me, it's the best response that I could expect.

KeS
This is kind of what I'd expect too - a "normal" second click entailing normal lever pressure, normal click sound, but no chain movement because of the limit screw. This is what would seem like a natural design feature given the way this double click shift mechanism works. I'm thinking I might have to just back the limit off a tiny bit more so it takes less force to get that second click. I'll try that on the stand tonight. Other than that, the rear shifting is just great.

I don't mind that this is the way it works, but it's kind of frustrating that the sram installation instructions don't do a better job on the rear limit screw setting. They merely have a diagram with the pulley wheels directly lined up with the innermost cog which I don't think is best. I'll go through it all again and see what happens. Maybe I just wasn't precise enough in lining up the pulley and cog in the first place.....
Camilo 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 01:22 AM.