I had the chain replaced as soon as it was confirmed to be worn out. During this maintenance a whole load of other adjustments were made, mainly tweaks and minor things, but a LOT of them. I have been to 2 main shops. The bike was purchased new from Performance and I have a great relationship with their mechanics. I had a professional bike fit and maintenance performed at a triathlon specific bike shop.

2 days after my chain was replaced, the professional bike fit was complete, and all the updated mechanics were done, my chain jammed during a triathlon race, at the base of a climb. I was not driving hard on the crank, nor was the grade of the road very steep at this point.

I just can't imagine that me (5'1, 120lbs) am putting such a load on the crank that it is jamming so consistently. It has been about 3 months worth of the same issue, and it just isn't adding up to me.

This week we replaced the small chain ring with a new small chain ring and the problem has completely flip-flopped. The chain is dropping down without problem and NOW will not transition from small to large fluidly. Again- I consider first, what I might be doing incorrectly. I went through a check-list
-am I shifting hard enough to move the chain completely
-am I applying too much pressure to the crank at the time of shifting

The only thing that allowed a smooth transition was switching to a near-coasting position and slowly rotating the chain into place. Ugh!

Keep sending ideas!!! I really appreciate the insight!