Dewbert

Hi folks--
I'm in the smoky mountains and having a great time. However, when I head up a steep but paved hill/mountain (and I mean so steep that I have to use 4wheel drive and low gear in our Jeep to get up it) my chain drops off the little ring when I really put the force to the pedals. Is this an adjustment or am I just expecting too much out of my road bike?
Thanks
Dewbert

cooker

If you mean the smallest cog at the back, you're in the wrong gear. You should be on the largest rear cog on steep hills. If you mean it slips off the small front chain ring, we need more information. Is it skipping, where it slips back a notch, or falling right off? If it's skipping, it means your chain and cogs are old and worn, and need replacing. If it's falling off there may be an adjustment that would help. Your front derailleur cage may be a bit too far to the left, and fine tuning the adjusting barrel might help.

MrCjolsen

Are you in the process of shifting to the smaller ring in the front when this happens and is the chain slipping off the small ring and making a mess between the chainset and frame? If so it's called "chain suck" and the best way to avoid it is to back off on the torque when shifting. Yes, it's not a good idea to shift a bicycle under a load.

twahl

If I read this right, the chain is skipping under heavy loads when in the mall chain ring. Assuming that the chain and cassette aren't overly worn, I'd try putting a little more tension on the rear dérailleur using the tension adjustment screw.

cooker

How would that help, Tom?

twahl

Shot in the dark really. If the deraileurs are adjusted properly otherwise it's probably a chain wear issue, or a stiff link maybe. Eliminating all of those, you may get some bump off the lowest gear if there's not enough tension to keep it off. Sheldon and Park both go into the adjustment, but if it's only in the small chain ring, it could simply be that there's not enough tension on the chain. As I said though, it's a shot in the dark, just something I'd try.

mayukawa

Do you have a compact crank?

cyclintom

1) As people mentioned, slipping off of the small ring is normally a sign of wear of the chain and the ring.

2) If these are in good condition then the chain TENSION is under question. This can be improper because the chain length was improper or because the gear ratios are to great for the rear derailleur tensioning mechanism. For instance if you put a 20 tooth on the front and have a 50 tooth on the large ring and a wide ratio rear cogset. A medium cage rear derailleur might be unable to maintain chain tension over the entire range and be too loose in the lowest gears.

3) A bent or maybe just knicked small ring can throw a chain.

My own guess is that you have modified the gears and the chain isn't the proper length.

fogrider

you need to give us more info. is it a 10 speed cassette? a friend had this exact problem. his was a shimano 10 speed system. he just changed the chain and in his lowest gear, the chain dropped on a climb. the shop said that the shimano chain pin was installed from the wrong direction. I can't really see how that would cause the chain to drop, but after the shop re-assembled it, it worked fine.

in your case, what is the chain? how many gears, etc.

Dewbert

Hi folks--
It is a compact crank. It is dropping off of the small chain ring in the front. It's a 9 speed cassette in the rear.

I haven't modified the gears and the chain has about 1500 miles on it. The teeth aren't terribly worn. The chain is pretty dirty, though.

It dropped consistently at the same point on the same hill when the grade got very steep and the torque got pretty high.

I've learned that it's quite an unsettling feeling to be climbing a steep hill and have the cranks start spinning freely and you suddenly start rolling backwards! CLIP OUT CLIP OUT!!!

bdcheung

Is your low-limit screw set correctly?

michaelmc

Just to cover all the bases: it does have the appropriate front derailleur, right? It's not a triple derailleur?

'nother

That's the first thing I would check. See https://parktool.com/repair/readhowto.asp?id=75 and at least verify your setup, first. If everything's adjusted properly and it's still dropping, come back and give us an update.