Problems With Shifting: Help!

[rclouviere]

I just bought my first TT bike to compete in triathlons (2009 Specialized Transition). Had it tuned up and got a fit from the LBS. All was fine until I decided to get a compact crank. Once that was installed, I was no longer able to shift into the big gear. The LBS could fix it on the stand, but when it was test ridden, it would revert back. It was sent to Specialized in Utah for a "warranty repair." Just got it out of the shop and it did it again! It's back in to see if it can be fixed. Very frustrating. Does anyone have any ideas on how to take care of this?

Thanks, Rick

 

[ABNPFDR]

Without having the bike in hand, virtually impossible to know why it won't shift. My only guess at this point is that when the compact crank was put on, the chainline was moved in some way. That or the new chainrings just don't want to grab the chain and help it up to the large cog. But on a friction front shifter it almost does not matter. BTW - having worked at a specialized dealer, I've never heard of sending a bike back for a "warranty" claim for a bike that's not shifting especially after changing the crank. Not only that but the warranty for the bike only exists for the original user and the shop is required to show proof of original ownership when submitting a warrantry claim.

Something does not smell right.

 

[maydog]

You are supposed to have a big ring the size of a dinner plate on a TT rig!

Without the chain on (or just disengaged), you should be able to move the front derailleur to the big position and have the derailleur midpoint line up or just beyond the big cog. If it does not, then either the high limit screw is too tight or the cable is too long. Both are easy fixes.

Other thoughts:

• 
  Was the chain removed, shortened when the new crank was installed? Could it be one of those unidirectional shimano chains put on backwards?
  
• 
  Was the derailleur moved downward to accommodate the smaller big chainring?
  
• 
  Was the derailleur knocked out of alignment during the install?
  
• 
  Some chainrings are easier to shift than others. Very cheap chainrings lack the ramps and pins making upshifts very difficult.
  

 

[rclouviere]

Thanks for the replies. I don't know enough about it, but the LBS swears the change with the compact has no impact. He sent it to specialized and they did something about drilling a hole in the frame to allow for the cable to work more effectively? Frustrating! Only had the bike for 200 miles and loved it, but in shop for a month.

 

[maydog]

http://www.parktool.com/blog/repair-help/front-derailleur-adjustments