Bicycle Mechanics - Ratcheting feeling when I pedal.

I am resubmitting this question which I have posted in the past, in the hope that some additional ideas may come up.

I am trying to correct a problem I have on my Trek 7300 hybrid.

For about a year there has been a ratcheting feeling in my feet when I pedal. It is mostly when I am in the highest two gears (smallest sprockets) on the rear derailleur, but can happen in the third smallest sprocket as well. It does not really happen in the low gears (large sprockets) of the rear derailleur and it does not seem to matter which of the three gears I am in on the front derailleur. This is why I suspect it is a rear derailleur problem.

My rear derailleur is a SRAM X7.

Four months ago the bike shop had to replace the rear derailleur’s handlebar twist shifter, as it was not clicking firmly into gears & was slipping out, but this did not affect the ratcheting feeling in my feet when I ride.

Do you have any ideas I could try? If you need a photo of the rear derailleur I could try to send them as attachments if the website permits it.

Can you describe "ratcheting feeling"?

Does it feel like the chain isn't quite engaging the smaller rear cogs because it won't wrap around them enough?
Not that I have an answer, except maybe try a different chain.
I was just curious if I understand the "feeling"?:)

MudPie & Bill: Tough to describe but I guess the best way is a "bumpy" feeling when I pedel. Only in those certain gears on the rear. The bumps are felt in the pedels themselves.

Babel .

Do your pedals spin freely?

Check your rear derailluer adjustment, I had a similar problem on a road bike when my derailluer wasnt shifting all the way (they were friction shifters, not indexing) over and the chain was rubbing the side of the derailluer cage. As I said, they were friction shifters, so the adjustment was just to high gear screw, but I think a similar problem could occur on a indexing shifter, and the fact that it's only on the smaller gears might explain this. You could check by shifting into the lowest gear and looking down the chain to see where the derailluer/chain line up over the cassette.

MParker: With the rear wheel off the ground, the pedel crankshaft turns freely forward & backward but only as long as force is applied. Or do you mean the pedels themselves? They spin on their ball bearings very freely.

Frankstoneline: I believe that the chain is lined up on the rear derailleur in the smallest sprocket. I ATTACH PHOTOS to demonstrate. What do you think?

(I don't know how useful the photos will be due to the 100 kb file size limit, but let me know).

Thanks.

Babel.

It appears from the photo the chain isnt rubbing...hmmm. Try back pedaling to check. Shift into the lowest gear, or the gear where it is the worst. If when you back pedal it looks like the chain sort of catches on the derailluer cage or goes loose that might be the problem. Otherwise you might try and isolate where the sound is coming from. I would pull the chain off and start with the pedals, if they seem to be the problem you could rebuild them. If they still spin smooth and it doesnt appear to be coming from the crank assembly (bottom bracket etc.) you could grab a bit of chain and run it across each of the gears on the rear stack in your hands and see if it's something going on there. If it's not that I would say it's safe to say it's the rear derailluer, though it could be a similar problem I described before in the front derailluer. If you check and the front derailluer seems to be rubbing, that might be the problem. Does the problem occur on all the chainrings on the front derailluer or just the smallest?

Edit: just read your original post, said it doesnt matter which front ring, sorry.

How many miles do you have on your current chain? When the chain is stretched out, it tends to slip a little on the smaller sprockets in the cassette. These smaller sprockets have less forgiving circumference to chain link length ratio than do the larger sprockets. This can cause a "grinding" or "ratcheting" type feeling when pedaling, especially powering through with the right foot. Sounds like "click-click, click-click"...

Then again, your bottom bracket might be borked, but I'd check out that chain first.

Are you a Clyde? I am, and on one of my road bikes, I can flex the frame enough on my drive side power stroke to see the alloy (Centaur!) crank twist 0.5-1.0 mm; the chain is obviously moving in and out too. When I spin the crank on the stand, the chainwheel and frame stay straght. I discovered this after occassionally seeing my chain rub the inside of the front derailleur cage if the derailler was not set just right.

form the pictures it appears that the adjustment of the dérailleur is off. The upper pulley is supposed to line up with the largest(smallest diameter gear). Adjust the high limit screw to align. If this is corrected have the hanger adjustment checked at your LBS.

Thanks for the suggestions, guys !

I'll be out of town until Friday and when I return I will try out some of these things.


Babel.

OK - back in town.

I've read over the thoughtful replies & I looked over the bike again.

My best guesses are that: [1] It sounds like it may be the chain, [2] I really need one of those things that hold up a bike so you can turn the pedels and not have the bike move away (not to mention having the bike at eye level), [3] changing a chain is probably not something I can do with my minimal leval of mechanical skill, and [4] I might want to try a different bike shop to see if a different mechanic has better luck with this problem than the guy at the shop I bought the bike at.

Babel .

Found out original bike shop has new mechanic.
I brought the bike over.
He put it up on the rack and immediately knew what I was talking about.
He said rear casette is deforming and chain may also be loose.
Will get new casette & chain as well as needed new tire.
Told him front cable needs tigntening as well.
Would be great if problem is solved.
Will keep all up to date.

I now have a new chain and a new rear cassette.
The bike rides beautifully.
Problem solved :)

Thank you everyone for your input.

Glad you solved the problem. But, is there a chance you were cross chaining, causeing the problem in the first place? Just be sure you aren't going to wear out the new one pre maturely.

Thanks, nodnerb.

What is "cross chaining" and how would I know if I were doing it?

its when you are in gear like 1,8 or 3,1 where your chain isn't in a very straight line from front gear to back gears. You can get a lot more power from a straight line witht the chain and it is better for the bike

Oh, I see.
The worst I get to is 1,6 which I might do for a short period of time if I am preparing to go down to 1,3 or so.
I don't really do 3,1 at all.