Gear Shifting Problems

[pablo180]

Sorry if this is in the wrong place...

I have a LOOK KG241 which has a Shimano Ultegra Flightdeck groupset. Bike just won't shift from the small ring to the large ring on the crankset whilst on cylcing. However when i put the bike on a workstand and spin the pedals with my hands, it shifts perfectly... The general shifting isn't exactly lightning quick but is pretty smooth and is fine shifting down from the large ring to the small ring.

Anyone know what might be causing this?

 

[Spoked Wheels]

It would appear that the stress of having you on the bike is causing the problem. You will need to adjust the front derailleur. There are some videos on youtube showing you how to do this. It's not as simple as adjusting the rear deleaileur though. I can't remember exactly which of the screws you need to adjust but it's probably the Low "L" screw.

My guess is that you need to adjust one of the screws a very tiny bit, so don't over do it or you will end up with problems.

 

[jdtate101]

Sometimes this is a case of not enough cable tension, especially if the bike is oldish as the cable stretches over time. Just shift it into the small ring, then undo the cable clamp, pull the cable tight with some pliers whilst doing up the clamp, then test....

Or just get a new cable it's it's really bad. If it shifts ok on the stand I doubt it's the limiter stop screws.

 

[TheJDog]

How much pressure are you putting on the pedals when shifting? If you're pushing more than a little, there's a lot of tension in the chain to overcome, and you might find you're unable to push the lever hard enough.