muprocket

Let's see if I can explain this...

At the top of my pedal stroke on the left side, just as I begin to push down, there is a very brief moment where pressure is applied that there is absolutely no resistance, and then a brief 'jerk' when I get some resistance.

I recently removed and cleaned the bottom bracket area (my first operation on my new repair stand). I rode 90mi yesterday with no issue, and after about mile 10 today the problem started to get noticeable.

I've checked that my cleat wasn't loose, and there's no play in the pedal or the pedal attachment to the crank arm... Any ideas? I'm kind of concerned I didn't reinstall the bottom bracket correctly.

Al1943

And the components are...........

muprocket

Yep, sorry about that:

2002 Lemond Buenos Aires
Ultegra 9sp
Shimano BB-5500

thomson

My guess is a broken pawl in the hub

Tonycycling

I get the same feeling, not because I remove/replaced any components and/or parts but maybe because my bike is old. I did think it was strange and not normal but just continued riding through it.

1989 Performance Vitesse
Crankarm is Shimano Exage
Crankset/Bottom Bracket, components unknown
Rear Hub, unknown - 6-speed (13-28) screw-on cassette

How do I go about checking whether the problem is the Crankset or broken pawl in the Rear Hub?

Thanks.

DannoXYZ 

Just on the left side? Your crankarm is loose.

muprocket

Thanks guys!

I'm lucky enough to have a second wheel around (cracked rim, but good hub). I transferred the cassette to my old wheel and tried it out - problem's still there.

That seems to make the most sense, but I've tightened the hex bolt that pushes the crank arm onto the bottom bracket, and the problem's still there. There doesn't appear to be any play in the crank from side to side, either.

This is the only bolt that needs to be tightened, right? Is there any other way to test specifically for looseness here?

bumperm

Look at the crank arms to be sure both are aligned with one another, i.e. they make a straight line. Then get on the bike, stationary and balance against a fixed object. With pedals at 3 and 9 O'clock, put all your weight on them, bounce gently. Next, rotate the crank 180 degrees backwards and repeat putting your weight on them. If either time the position of the pedals shift, one moves in relation to the other, you should be able to discern this. Take things apart and see where the problem is.

DannoXYZ 

Exactly how tight did you turn that hex-bolt? How many times have you done it?

Do bumperm's test and report back to us.

muprocket

Thanks bumperm - apparently I have no idea how to make a straight line