Bicycle Mechanics - Dropping Chain

The last few rides I've had some problems dropping the chain when shifting down to the small ring. The limit screw is correctly adjusted and the bike shifts fine, front and rear, under all other circumstances.

It seems to happen under load, at higher RPM and when the drivetrain may need some lube - at the end of a ride.

Other than making sure the chain is properly lubed, are there any other suggestions? The chain has 755.5 miles on it since new.

Chain Suck!!

Originally posted by Precision Pedal
Chain Suck!!
O that really helps dosent it!

Woody.....your sure that the front derailleur is adjusted properly??? If it happens under load, then dont shift under load??

Klein,
Isn't your response similar to the "Doc my arm hurts when i do this" joke? Chain suck defined:
http://fagan.co.za/Bikes/Csuck/

Is there pattern w/regard to which rear cog you're on when it happens?

It sounds like the chain is flopping past the small chainring and falling off between the small chainring and the frame. Is that right?

Check the alignment of the front derailleur. The chain sounds like it's pretty new but you might want to check the length as maybe it's too loose.

Originally posted by roadbuzz
Is there pattern w/regard to which rear cog you're on when it happens?

I haven't noticed if the problem is associated with a particular cog, but I'm usually motoring along. I'd say it happens in the middle cogs, let's say 3-4-5.

I've watched it happen. It just shoots right past the lower ring. Since I had just put new cables on it, I attributed the problem to a stretched cable and out-of-adjustment low limit screw. I tightened the cable and adjusted the limit screw. It's better, but it still shot off last night.

I suppose I should mention it's an Ultegra double drivetrain.

My Ultegra double would occasionally jump the small ring. I adjusted it so there's a slight front der rub when I'm in the 39 and the next-to-smallest cog (a combination I don't have to use).

Get yourself one of those chaindrop blockers that attatch to the seat tube, end of story. The pros use 'em!!!

Ride Better
Pat

Before my ride last night I cleaned the chain and gave it two coats of lube, working the first in before applying the second. Then I tried to throw the chain during the ride. All was well and the chain didn't drop.

Previously, I had done a couple of rides in the rain and I suspect the chain was stiff and under lubed. Road grime and water had scoured the lube away, and I didn't lube enough after each wet ride.