island rider

A friend of mine is confirmed clyde, and has been suffering from a recurring mechanical problem over the past year. I suspect two things... 1) that his LBS is worthless and has been trying to repair something that needs to be replaced, and/or 2) that his technique and stress on his equipment is causing the recurring problem. I feel bad because he loves to ride and you can see that his inability to finish chosen distances because of mechanical problems is killing him.

He runs a 'standard'(?) triple, and when he changes gears in the front, his chain will slip and get caught between the chainrings. He has had the bike into his shop getting repaired a few times, and I think they are not giving his problem the attention it needs because of the combination of his equipment and his stature. (He is riding a Giant OCR (of some sort) with standard equipment). It is so bad that he had to ride a 70 miler in just the granny gear.

Have any of you ever had this problem? Could it be caused by too much downward pressure on the pedals while shifting? (I haven't studied his technique, but he appears to pound pretty hard, particularly on a hilly course.) He is pretty strong and I was thinking that the force of his weight on the pedals coupled with his leg strength might be pulling the chain tighter during the shift than can be overcome by the derailleur.

Thanks in advance.

Barrettscv 

It could be either.

Make sure his chain matches his drive-train. If he has a 9 speed rear cassette, he needs to have a 9 speed chain. The dimensions of the chain get smaller as the number of gears on the cassette increase.

He also needs to think about his shifting technique, He needs to shift before the hill while turning the crank gently with almost no power applied.

Michael

CliftonGK1

Assuming a newer indexed system, on an upshift the chain will first be picked up by the pins before engaging the teeth of the next ring. If it's slipping there, you'd hear a loud "ping" as the chain pops off the pin and down in between the rings. Do this enough times and you wear that pickup pin down and shifting becomes unreliable even if equipment is properly adjusted.
Your pal may need to replace his chainrings.

ntime60

He might also try to be in the middle rear gears when he shifts to the different chain-rings. My 7.3 gets rather upset if I cross shift. (Cross Shifting is shifting to the front big gear when on the rear big gear or on the small front gear and the small rear gear.) Cross shifting is hard on all the components and will cause more wear on the affected components.. Think of the chain-rings having an overlap on the rear gears.



I also agree with Barrettscv that he should shift chain-rings while keeping the load light. Just like a tranny in a car, you slam it in gear at full power, sooner or later you'll be replacing components.

island rider

Thanks guys. No surprises there. I appreciate the information.

Greg_R

He couldn't manually put the chain on the center (or large) ring?

bigfred 

That was my second question.**********??

First question: By saying "stuck between" do you mean that the chain was literally wedged between the chain rings? Or, that the deraileur wasn't getting the job completed and the chain was subsequently left skipping on the next larger chain ring? Two very different issues with different causes and solutions.

island rider

It was wedged between the chainrings.

He could manually switch gears, but that would require stopping and starting. The small ring was the best option given the hills he was facing. Near the end of the ride, when things got a bit flatter, he put it in the middle.

DieselDan

Needs to have cable tension adjusted correctly.

Lord Chaos

Because this has happened a few times, he may have spread the distance between chainrings by bending the rings. Check for loose chainring bolts, too.

Strong people need to be careful when shifting the front. No power-on shifting.