Have questions or want to discuss cycling? Join Now or Sign In to participate in the BikeRide community.

New: Take Part in the March Giveaway: Coming Soon 3/24


Replaced crank
#1
Hi I replaced my crank that was 170m to a 175m do i need to replace the derailleur also? the reason im asking is the derailleur would not go to the high gear. if you have any ideas pls let me know thanks
  Reply
#2
You shouldn't need to replace the derailleur. I just did this swap on my bike and I dropped down to a smaller large gear in the front. I just had to lower the derailleur on the frame and then readjust the high and low limit screws since the new crankset had a little bit more spacing between the gears than the old one.
  Reply
#3
i tried everything the derailleur wouldn't go all the way out so the chain can go on the larger gear. I released the cable to see if that helped but it did not
  Reply
#4
changing the crank arm length would not have any effect on the gears unless, you also changed the tooth count on the chainset?
or, the chain line has been affected?
  Reply
#5
i kept the teeth count the same 42-32-22 was the count
  Reply
#6
well I just checked it out and my teeth count did change went from 42-34-24 to 42-32-22 do you think that's the problem?
  Reply
#7
rokee - changing the arm length or the tooth-count that you have now, will not result in the problem you described.

What WILL cause this problem is installing a crankset (other model or brand) that requires a shorter bottom-bracket spindle.

If you did, perchance, replace like with like, just a diff arm length - I would guess that you have a square spindle. The aluminum arms will, over time, distort/ enlarge. This is why we need to check the tightness of the crank arm bolt during a maintenance session.
As they are repeatedly tightened, they move inboard and we compensate by adjusting the Hi limit screw on the drlr. When you install a new crankset of the same, the drlr Hi limit screw must be backed out until the shift will complete.

Make sense?

Rob
Wheelies don't pop themselves. (from a QBP fortune cookie)
  Reply


Possibly Related Threads...

Forum Jump:

[-]
10 Latest Posts
Santini fluted frame
Today 01:39 PM
Expensive bikes with crappy wheels
Today 10:15 AM
Where are you from and What is your favo...
Yesterday 11:43 PM
2007 Trek Pilot S.P.A. 5.2
Yesterday 07:06 PM
2010 Specialized Hardrock
03-26-2024 09:16 PM
1990 Specialized Rockhopper How to Fluff...
03-25-2024 07:05 PM
Thread busted on right pedal crank
03-24-2024 08:52 PM
Trek domane tyre
03-24-2024 05:48 PM
Modern rims crack at spoke holes
03-24-2024 05:32 PM
Cup & Cone — Simple & Durable or PITA & ...
03-24-2024 04:53 PM

[-]
Join BikeRide on Strava
Feel free to join if you are on Strava: www.strava.com/clubs/bikeridecom

[-]
Top 5 Posters This Month
no avatar 1. Painkiller
21 posts
no avatar 2. Jesper
16 posts
no avatar 3. ReapThaWhirlwind
16 posts
no avatar 4. GirishH
15 posts
no avatar 5. meamoantonio
15 posts