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

New: Take Part in the May Giveaway for a Change to Win the Thruster 27.5 Retrograde BMX Cruiser Bike


Chain tightens....
#1
My son has a BMX bike with freewheel. When you pedal the chain will get tight then loosen up. i checked the crank and it appears that it is not bent. i do not see anything on the back sprocket that is out of whack. Any suggestions on what to look for?

Thank you.
  Reply
#2
usual cause is the wheel out of line with the frame, check that the gap either side of the tyre is the same both sides at the chain stays and that it doesn't alter as you tighten it, can be caused by damaged drop outs.
If it persists, you may want to use a chain tensioner like these;
also check for damaged teeth and the chain ring out of round.
  Reply
#3
(03-22-2011, 12:36 PM)trevgbb Wrote:  usual cause is the wheel out of line with the frame, check that the gap either side of the tyre is the same both sides at the chain stays and that it doesn't alter as you tighten it, can be caused by damaged drop outs.
If it persists, you may want to use a chain tensioner like these;
also check for damaged teeth and the chain ring out of round.

Thanks Trevgbb.

the wheel is aligned with the frame okay. What are drop outs? i never thought to check to make sure the chain ring is flattened on one side i will do that.
  Reply
#4
I've found that this usually comes from the front chainring being out of round or not centered on the crank as trevgbb mentions. Depending on how the chainring mounts to the crank, you may be able to adjust this.
  Reply


Forum Jump:

[-]
10 Latest Posts
Adding brake to kids balance bike
Yesterday 11:06 PM
YABD - vintage Bernard Carré frame, etc
Yesterday 07:13 PM
What are your best tips for long rides?
Yesterday 10:34 AM
Classic MTB: Kirk Revolution DC magnesiu...
06-11-2024 06:03 PM
Forgot to introduce myself!
06-10-2024 10:19 PM
Problem > Solution
06-10-2024 09:41 PM
tried absolutely everything to fix these...
06-08-2024 04:05 PM
Tips for Cyclists
06-08-2024 01:39 PM
Hello!
06-08-2024 12:42 PM
SRAM chainring 48/35 torque settings
06-08-2024 11:10 AM

[-]
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. Jesper
47 posts
no avatar 2. enkei
29 posts
no avatar 3. Dusan
16 posts
no avatar 4. Amanda_W
12 posts
no avatar 5. meamoantonio
9 posts