"Clunk at top of Right pedal down stroke"

[Prof Young]

Pedalists

I started biking this summer. Am riding several year old Schwin Varsity. It does the job. Anyway, I have a "clunk" that I can hear and feel at the top of the right pedal down stroke. Neither of the pedals is hitting anything on their way around. I suspect it has something to do with the mechanism that allows it to freewheel, but why would that happen at only one spot. Also, it won't do it when the bike is not the repair stand. It only happens when I'm riding. And while it's fairly consistent, it does go away for a few strokes once in a while. Learned to adjust derailed and it seems to be working fine.
Help.

Live well, be safe
Prof Young

[nfmisso]

how old of a Varsity? Does it have one piece or three piece cranks - picture is worth thousands of words.

[Prof Young]

(07-16-2012, 09:07 PM)nfmisso Wrote:  how old of a Varsity? Does it have one piece or three piece cranks - picture is worth thousands of words.

nfmisso:

Thanks so much for trying to help.

It's a 2006 with a three piece crank.

It's a Schwin Varsity sold via Pacific Cycle / WalMart and finding information about it on the internet was like pulling teeth.
Number under the crank is SNMNG06H01202
Numbers on Pacific Cycle Decal toward bottom of seat post are
S2678WM
MIN0815JF

My bicycling brother in law thinks I need new crank bearings.
The Crank is solid on the "axle" there is no play in it.
Any thoughts and help would be appreciated.

Live well, be safe
Prof Young

[nfmisso]

It could be a number of things;

Bottom Bracket (BB); as your brother in law suggests is high on the list

Pedal bearings is another high on the list probability.

You said the crank is solid on the axle - going to assume you meant that the cranks are solid on the axle - both sides.

Check the five chain ring bolts.

[Prof Young]

(07-17-2012, 02:54 PM)nfmisso Wrote:  It could be a number of things;

Bottom Bracket (BB); as your brother in law suggests is high on the list

Pedal bearings is another high on the list probability.

You said the crank is solid on the axle - going to assume you meant that the cranks are solid on the axle - both sides.

Check the five chain ring bolts.

Nigel:


Thanks. Yes crank on both sides is solid on axle. I check the pedal "bearings" and they seemed good. Will look at chain ring bolts.

So "bottom bracket" is the appropriate jargon of the bearings that go in the crank assembly.

Part of the thing that has me mystified is that it happens at the same place in every rotation.

Will let you know how it goes and thanks again.

Prof Young

[FredS]

Does it happen on the same chain ring and have you looked at the teeth chain ring? They could be worn or bent.

[Prof Young]

By way of follow up, repacking the crank bearings in grease got rid of the clunk. For the first miles or two there was a touch of "slap" still on the right power stroke, but it smoothed out and has been golden ever since.
Thanks for all the help.
Prof Young