Slight skip when peddling

[billkilpatrick]

When peddling, as the pedal swings round and up to the top, a slight skip can be felt before it continues down and round again. Both chain wheels don't appear to be damaged and chain tension doesn't appear to be loose. The bottom bracket bearings were changed this afternoon from loose ball bearings to those contained in a ring - could that cause the problem?

 

[MR OX]

When peddling, as the pedal swings round and up to the top, a slight skip can be felt before it continues down and round again. Both chain wheels don't appear to be damaged and chain tension doesn't appear to be loose. The bottom bracket bearings were changed this afternoon from loose ball bearings to those contained in a ring - could that cause the problem?

Do you have a tight / stiff link in the chain? that can cause the problem you describe.

 

[mdvineng]

Sounds almost like a loose crank arm syndrome. I'd be checking the bb bearings again.

 

[averagebiker]

Is it always in roughly the same part of the pedal stroke? Could it be a pedal issue? Do you have a spare pair of pedals you can fit to see if it fixes it?

 

[billkilpatrick]

I'll have a look tomorrow in daylight but yes ... it seems to be in the same place - sort of a "clunk"sound.

Thank you all very much.

 

[Corsa of Course]

If it is the same place each time is it as the drive side pedal nears the top? If so check the crank is clearing the front derailleur. I have this where to change to the big ring reliably the derailleur has to travel to the point where it is just flicked by the crank, so you let it off a fraction post change up and it then runs happily. Maybe when you changed the bottom bearings the chainset is slightly further on than before.

 

[pigman]

So just to be clear, is it a skip as in first post or a clunk as in post #5?
Is there movement where it feels one crank doesn't move with the other, in a loose crank kinda way?

 

[billkilpatrick]

Crank arm was slightly out of alignment - skipped, clunked, wobbled - whatever - around slightly as I peddled. The ride back from the mechanic this morning was uneventful, however. We'll see.

Getting this bicycle up to snuff has been a costly learning curve. I tend to think of these beautiful road bikes as survivors ... resilient ... unchanging ... but stuff wears out. Who knew. Makes me wary of those "vintage" pieces for sale on line which might be pukka for L'Eroica but totally clapped out

 

[pigman]

If it's a cottered chainset, one of the cotterpins is loose

Or it could be the chain and/or chainring is worn to the point where it's not seating right all the way round and the chain is moving to accommodate the teeth

 

[Fifthgrace]

If it skips every other revolution in the same crank position, the culprit could be a chain connector/master link. They have a habit of stretching and then the master link skips off the rear sprocket teeth. Check by measuring across the section with the master link included using a chain wear indicating tool. Compare with other measured chain sections.