Strange Noise under Load

Quoted post said:

Originally posted by starship
Cannondale R800, S105 geartrain. Sometime under LOAD I get a strange noise from my rear end (the bikes!). Its almost a click and almost a thump and almost a grind. But only when I getting on the pedals and pumping hard.

ANY SUGGESTIONS WELCOME! PLEASE!

I had a similar problem and it was caused by the bottom bracket. When it was replaced the noise went away.

Bottom bracket? The supports for the bottom chain pulley?

Bottom bracket is the axle and bearing assembly that supports the cranks (the bits with cogs on them that u pedal with). There is often some minute amount of movement in this area and i have heard that especially in Cannondales due to their large section tubing, they resonate the sound a lot sompared to some other brands. If this isnt the case i just had a thought that it may be the replaceable tip (the part u bolt the back wheel on to) may be a bit loose, or sometimes the Quick Release skewer is not quite tight enough and this causes a grinding/squeaking noise to resonate throughout the frame. Good luck.

Quoted post said:

Originally posted by drewjc
Bottom bracket is the axle and bearing assembly that supports the cranks (the bits with cogs on them that u pedal with). There is often some minute amount of movement in this area and i have heard that especially in Cannondales due to their large section tubing, they resonate the sound a lot sompared to some other brands. If this isnt the case i just had a thought that it may be the replaceable tip (the part u bolt the back wheel on to) may be a bit loose, or sometimes the Quick Release skewer is not quite tight enough and this causes a grinding/squeaking noise to resonate throughout the frame. Good luck.

True....Cannondale tubing acts like an echo chamber. Little creaks and clicks are amplified to sound like your frame breaking in half. 😄

Bottom bracket all the way!

Quoted post said:

Originally posted by starship
Cannondale R800, S105 geartrain. Sometime under LOAD I get a strange noise from my rear end (the bikes!). Its almost a click and almost a thump and almost a grind. But only when I getting on the pedals and pumping hard.

ANY SUGGESTIONS WELCOME! PLEASE!

Quoted post said:

Originally posted by starship
Its almost a click and almost a thump and almost a grind. But only when I getting on the pedals and pumping hard.

Is it your knees?
🙂

I have almost the same problem exept that, with me, the same subscribed sounds occur when I sit sowd on the saddle. Finally I located the trouble. It's the rear axle. When I put grease on the quick release mechanism it disappears for 3 trips and then it comes back.

When I went to Campagnolo with my 3 year warranty on the new chorus hub they claimed they couldn't hear anything. Also they claimed they had been test riding for 5 days. Obviously the people at Campagnolo's (internationaly recognized) repair centre are deaf!!! When I cycle a short trip around here I get remarks about it from people in the street. Also my fellow cyclist complain about the anoying sound.

About your problem.... When the mechanic does not clean the BB the proper way, metal pieces stay in the bracket house. This creates the sound you describe. Metal on metal sound, right? (just like with my axle). Take the BB out. Clean the house. Put BB back in with a lot of Shimano lok not (or whatever the name is). I mean their assembly past. This is known to be able to take out the cracking sound. (Look at the label on the bottle!).

Regards, Frank.

If it's coming from the rear of the bike, it could be your hub. You can put your bike on a stand (or turn it upside down), put a little pressure on the brake or rear tire, and pedal to duplicate the sound...this may help isolate it. It can be hard to pinpoint that kind of sound due to the frame resonance that was mentioned, so you have to listen carefully...

Thanks, to ALL OF YOU who have responded. One thing I have noticed, when back pedeling on the two big rear rings, the chain trries to ride off. Maybe under load on those big rings, the chain is poping off?

Quoted post said:

Originally posted by starship
Thanks, to ALL OF YOU who have responded. One thing I have noticed, when back pedeling on the two big rear rings, the chain trries to ride off. Maybe under load on those big rings, the chain is poping off?

AH HAH! Go to parktools.com and look at the rear derailluer adjustment guideline. It will show you 1, how to adjust the limit screws, and 2, how to use the barrell adjuster to quickly tweak the jog pulley/derailluer alignment to your cogs.

That must be it...simple. When you really get on your pedals and push hard, as you described, you are flexing your frame a bit and that's when slight derailluer miss-adjustments get exascerbated. 🙂

Thanks! Will Do!

Could be the bottom bracket, could be the cassette, could be the wheel hubs need rebuilding. You can eliminate the wheel hubs quickly. . . .just pick up the wheel and see if you can wobble it side to side. If so, start there. If not, move on to the cassette. Same thing - can you make it wobble with your hand? If so, that's your clunk. Depending on the style, it may need tightening, or something worse. If these are both tight, then go with the bottom bracket. (I just had the same problem and frankly, all three areas were in need of attention.)