I have a late 70s English made RSGP with original 5 speed freewheel, chain and derailleurs. The bike only has about 1500 miles on it....most of which have been put on in the past 3-4 months. Sudden interest in road cycling!! ;-)
I have no problem shifting smoothly from largest gear on rear to the smallest---in other words shifting down. I do have a problem shifting from smallest gear up to next smallest gear. Derailleur will chatter and skip to the middle gear of the 5 gear freewheel. This has been going on for several months...
Chain has been measured for wear and it checks good by both ruler and chain measurement tool. Freewheel gears all look in good shape. Derailleurs have been cleaned lubed and adjusted by local reasonably skilled mechanics during recent overhaul...but the problem persists.
What is most likely causing this derailleur skip and are there any other diagnostic tools to pinpoint the cause before I go buy replacements? Thanks in advance.
I have no problem shifting smoothly from largest gear on rear to the smallest---in other words shifting down. I do have a problem shifting from smallest gear up to next smallest gear. Derailleur will chatter and skip to the middle gear of the 5 gear freewheel. This has been going on for several months...
I think you're saying that when shifting from the largest cog, the chain skips over the next-to-largerst cog.
Is there a big jump between the two biggest cogs (e.g., 34T to 28T)? What kind of derailleur do you have?
When you shift from the other directiom, can you get the chain to engage the problem cog without chattering?
Things to check:
Proper spacers between cogs? Bent teeth?
Is the derailleur hanger on the rear dropout bent?
Sight from behind and make sure the der cage is parallel to the cogs.
