Bouncing in the saddle

[laura*]

How do I measure the crankarms?

If you want to know what length they are, just look at the backside - almost all cranks have the length stamped/cast into the back side (aka inner side) somewhere. It'll be a number like 165, 170, 175, etc. This is the distance in mm center to center between the crank spindle and the pedal spindle.

However, I suspect you're asking how to measure for your correct size. Start by adjusting the saddle height to get good leg extension at the bottom of the pedal stroke. Your knee should remain slightly bent and you shouldn't need to "ankle" (tilt your foot) to reach the pedal. Now position the crank to check the top of the pedal stroke. Check the angle made by your knee. If this angle is too small, you can't make power at the start of the pedal stroke. This means the cranks are too long. If the angle is too large, you're giving up the potential leverage of a longer crank, and you're not using your muscles to their fullest. If you search the web, you'll find some recommended knee angles (for the top of the stroke). However, there's a significant personal preference issue here. You might simply prefer using a particular range of knee motion. And this might even change as your fitness level changes.

[indysteel]

Are we talking about spinning on hills or on the flats? It's perfectly normal for your cadence to slow down when you climb. If I tried to maintain 90 rpms when I climbed, my heart rate would go through the roof.

[Wasp]

Are we talking about spinning on hills or on the flats? It's perfectly normal for your cadence to slow down when you climb. If I tried to maintain 90 rpms when I climbed, my heart rate would go through the roof.

Spinning on flats. The hills I'm just grateful to pedal to the top, I have no idea what the uphill cadence is.
I think part of my problem is when I'm in the hardest gear on the small chainring I tend to bounce. But the easiest gear on the large chainring, causes knee pain after awhile. It seems like i need a in between gear, and im guessing thats something i need to train into?.

[Wasp]

Are we talking about spinning on hills or on the flats? It's perfectly normal for your cadence to slow down when you climb. If I tried to maintain 90 rpms when I climbed, my heart rate would go through the roof.

Spinning on flats. The hills I'm just grateful to pedal to the top, I have no idea what the uphill cadence is.
I think part of my problem is when I'm in the hardest gear on the small chainring I tend to bounce. But the easiest gear on the large chainring, causes knee pain after awhile. It seems like i need a in between gear, and im guessing thats something i need to train into?.

[indysteel]

I assume you have a compact crank on your bike. Unfortunately, I think compacts can make it hard to find the perfect gear on the flats because there are bigger jumps in the gears. Do you happen to know the specs for your cassette? Or just tell me what bike model and year you have. I might be able to look it up.

[indysteel]

I think part of my problem is when I'm in the hardest gear on the small chainring I tend to bounce. But the easiest gear on the large chainring, causes knee pain after awhile. It seems like i need a in between gear, and im guessing thats something i need to train into?.

After rereading this and looking at Sheldon Brown's gear calculator, I'm wondering if you're confused as to the difference between front and rear gearing. If your gearing is similar to mine, your big ring/big cog combination should be easier, not harder, than your little ring/litte cog combination. So, it doesn't make sense to me why you would be bouncing in your hardest little ring gear combination but experiencing knee pain with your easiest big ring gear combination.

Remember that the bigger the rear cog, the easier the gear. It's just the opposite in the front in that the bigger the chainring, the harder the gear.

Little chaingring + littlest cog = your biggest gear when you're using your little chainring.
Little chainring + biggest cog = your smallest gear of any front/rear combination.
Big chainring + littlest cog = your hardest gear of any front/rear combination.
Big chainring + biggest cog = your easiest gear when you're using the big chainring.

And if I'm way off track, I apologize. It's just that it's not uncommon for relatively new riders to think that the bigger the cog, the harder the gear.

[Wasp]

Indy,
Your not off track. After reading your post acouple times it dawned on me I've been making a mistake. This whole time I was thinking the problem was the bikes gearing. Apparently it's operator error...LOL OMGOD! I can't believe i never figured this out. The reason I been getting knee pain is I was riding in the largest chainring and littlest cog and just plowing thru even though it was killing me. No wonder it was pretty tough pedaling!!!!!
I seriously need to practice shifting....a lot!
All I can say in my defense is I started riding in June...lol.....geez I feel like a smuck! What a really dumb mistake!
THANKYOU!!!!!!! Your brillant ! My knees THANKYOU!!!!!

[indysteel]

Yay! I'm so happy to have helped you and your knees!

[indysteel]

One more thing. Try to avoid riding in your liitle ring/big cog and big ring/ little cog combos. That's called crosschaining, and it's hard on your chain.

[laura*]

One more thing. Try to avoid riding in your liitle ring/big cog and big ring/ little cog combos. That's called crosschaining, and it's hard on your chain.

I'm sure you meant to write: "Try to avoid riding in your little ring/little cog and big ring/big cog combos. That's called crosschaining, and it's hard on your chain." It is called crosschaining because the chain quite literally crosses from one side over to the other.