Ass-u-ming that your chain is slipping a bit here and there, not slipping completely off. It could be the chain, OR the chainring. Usually your big ring will outlast your small one because of usage, but either one could be the cause. If you're not having the problem on the small ring, I'd be inclined say the chain's probably OK, but that can be checked easily enough

If you don't have a chain guage, get one. Always make sure your chain is within tolerance, because otherwise it tears up your gears, and chains are less expensive.

---

Cousin Elwood - Team Over-the-hill Racing
Brought to you by the good folks at Metamucil and Geritol...

When the chain slips...it comes completely off....

That's a gearbox problem. You're derallieur is out of adjustment (probably the high limit or the barrel adjustment) or possibly the bolts holding the chainring are loose and it isn't rotating properly (wobble).

A worn gear or chain would "skip" not fall off.

---

Cousin Elwood - Team Over-the-hill Racing
Brought to you by the good folks at Metamucil and Geritol...

agree...it is likely the derailleur cage is out of alignment - you can adjuest with the stop screws.

Two other things to look for:
1) make sure the derailleur cage it true and straight. If it is bent, it could be rubbing slightly.

2) make sure the change ring is true - i.e., when you sping it, does it appear to wobble? Don't ask me how I know this one.

Could also be a weak or broken spring in the Rear Der. That will cause the chain to be to slack and hop off the rings.

Does this chain only fall off shifting or will you be just riding allong and "POP" there it goes with no interacting with the shift lever?

---

----------------------------------------------------------

What if the Hokey Pokey is what it is all about?

I have little trouble getting my bike into gear...it is just when i apply max force the chain diconnects and falls off....

That sounds freaky. I would check your chainrings. Maybe make sure that your crank arms and BB are tight. Is there a clicking? Could be a broken frame that flexes more when you hammer on it. I would have that checked out ASAP. That is not safe. That is quite odd as well.

---

----------------------------------------------------------

What if the Hokey Pokey is what it is all about?

Does it always happen when you are going up a Hill? If so what gears are you in at the back? It could be that you are putting too much torque on you chain ie on the outside chain ring at the front, and inside sprocket at the back, the angle is quite large and when you really load it up, and it pulls of the front chain ring to the inside.

I'd say this wouldn't be your front deraileur adjusters, as the angle means its likely to be pulling of to the inside, and is you adjusted your deraileur to limit the big ring, you wouldn't even be able to use the small ring.

If on the other hand you chain pulls off to the outside, go ask the bike mech to adjust your limit screws in the front deraileur.

Also, try using the small chain ring to climb, thats why its there.

Big chain ring on the front and little chain ring on the back...

cross your chain that far. Don't use the big ring with the biggest cog, and don't use the small ring with the smallest cog. That's just begging for trouble.

53/23 is roughly equivalent to 39/17, so if you're running a 53/39 up front and am 11-23 on the back, just go to the small ring and shift up three cogs.

---

Cousin Elwood - Team Over-the-hill Racing
Brought to you by the good folks at Metamucil and Geritol...

That's a mistake I USED to make, but not any more...I am big on the front and little on the back which makes for a straight chain...it goes in without any problem...it's just that on the second or third big push, the chain gives an almight screech, I feel like I have snapped the chain and i look down the chain is off...

I don't know if you'll know this, but can you tell if this happens when you're on the downstroke of either foot in particular? (Is it always left, always right, or happens with both?) Does the chain fall to the inside, outside, or both? Is there any play in the BB?

I agree with Record9ti, it sounds to me like you're flexing the hell out of something and it's beyond normal. What kind of frame are you riding? Have you removed the chainrings and looked for any small cracks?

Do yourself a favor and take it to your local bike shop. Problems like this are virtually impossible to diagnose without seeing the bike.

Check the teeth on you chainring, one could be bent or broken, then check the bolts on the chain rings, they could be loose, then check the alignment of your front deraileur, or better yet get a bike store to check it. It might be angled across your chain a little too much.

Also to check: Chain, both general condition and tension as well as stiff links, Bottom Bracket, loose or worn? and then the rear deraileur, as this can have a bit to do with it (even the wear on you jockey wheels.)

Also how clean/ dirty/ lubricated is your chain/ gears? How well aligned is your wheel in the frame and why are you climbing in your biggest gear? Is your name Jan?

Let me know how you resolve this

Steve

Too the bike to the LBS last week...original diagnosis was a worn out chain...chain gauge was used to detect this...with that came the suggestion of a new rear cassette which was five years old...made sense to me...when this was fiited, the new chain was not able to fit with the front chain ring as the front chain ring was worn as well - the shark tooth pattern was fairly evident. It wa event more apparent when the old chain ring was placed over a new chain ring...the sprockets were clearly a different shape...LBS also commented that the bottom brack was past its best, and would need replacing in the next 6 months or before the next big race, whichever comes sooner...

So the upshot was a new cassette, front chain rings and new chain...and my beloved QR is like new (well almost)...thanks for all the advice offered.