Front derailler trouble after changing crankset, chain & BB
easybiker
Posts: 21
Just changed crankset, chain and bottom bracket on my Giant Boulder, now I just can't get the derailler working properly. It shifts fine from the little chain ring to the middle, also fine from big to middle, but will not change from middle to little or from middle to big! The chain is on the middle rear sprocket (7-speed). It just feels like the derailler arm is not moving far enough. I've adjusted both limit screws to give the maximum movement and I can now get the chain onto the big chain ring if I hold the shifter pressed hard for a second or two. But it shouldn't be like that. The new crankset is pretty much the same as the old (Suntour XCT 42/32/22). The derailler height is OK, about 2 or 3mm clearance from the big chain ring when centred on the middle chain ring. The BB is slightly shorter than the old one, and the chain rings are a few mm nearer the frame. I notice the derailler is just touching the frame (seat tube) when over the small chain ring but it looks OK relative to the chain. If I force the chain onto either the big or the little chain ring, it runs centrally through the derailler cage, which I have checked is not bent and is parallel. I'm at my wits end. Three photos all on middle chain ring.
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Comments
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The derailer cage is too high - that can be dropped a bit. Also clean and lube the cable and set up from scratch.0
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The gap is 2mm - I just measured it. I read somewhere that should be the minimum. I've just had another go at adjustment and found that in bottom gear I can't move the derailer cage free from the chain because the derailler is resting against the frame. What do I need to do to cure this? I was assured the bottom bracket was the right size for the crankset, they came together as a bundle.0
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If that is the case then you do indeed need a longer axle to give your old chainline back. Maybe your frame specifies a longer front chainline than standard? Also some front derailers do bottom out on the frame with certain poor designs or combos.0
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Thanks supersonic. I'm glad someone knows how to sort these things out.0
