Crank stiffness

[Azrael]

Hey everyone. I have a small question about my crank. When I hit them with all my power I can "see" the crank go to the left and to the right again. I'd say it's about half a cm. Is this a bad thing or just normall?
My older cranks didn't do this but they were twice as thick as my "new" ones.

 

[ed073]

Hey everyone. I have a small question about my crank. When I hit them with all my power I can "see" the crank go to the left and to the right again. I'd say it's about half a cm. Is this a bad thing or just normall?
My older cranks didn't do this but they were twice as thick as my "new" ones.

Normal...although it's probably more frame flex than crank, but you say it didn't happen with your old cranks? Weird....

what brands are we talkin'?

 

[Azrael]

Normal...although it's probably more frame flex than crank, but you say it didn't happen with your old cranks? Weird....

what brands are we talkin'?

It's an old Campagnolo crank that says nothing more than "Brev Campagnolo". I don't know what type it is. The old crank was an RX100 crank from Shimano that was about twice as thick.
The old crank was on another bike and this is a new bike. It's Reynold 531 steel. So you are saying it's frame flex? Odd......

 

[Blasp]

I think that it is normal, that crank arms move "from side to side" when you hit it with all your power. I have never seen bike (crank) that would not move. The movement is caused by frame and wheels flex. If you just stand by the bike and try to hit crank by one leg and watch wheels and frame, you can see it ...

 

[Azrael]

Must admit that I only "noticed" this on my new bike due to the sound the chain made while rubbing the derailleur cage , but haven't really looked at if when I had my old one since it never made a sound.
The problem was fixed when I put the high/low screws a bit more lose so there is more room for flexing when pedaling hard. I think I just never noticed it on my old bike due to the fact that the screws were correct on that one.