Here's a fault that has got the chap at my local bike shop scratching his head...
I've got a Specialized Sequoia road bike, about 6 years old, which has done around 10,000 miles on all original components. It has 24 gears on a triple chain ring set. The chain rings are 30 - 52. The cassette is 11 - 25. The set-up is Shimano Tiagra.
The fault started spontaneously a couple of weeks ago. One day, I started getting a 'click' on each revolution of the chain as it passed through the cassette. On the 3 highest gears - not on any of the others - the chain jerked, like it had slipped a tooth, at the same time as the click. This went on for a couple of miles and then, just as spontaneously, stopped and everything was fine again. It stayed fine for about 30 more miles, and then it started doing it again and carried on for about 3 miles.... and then it stopped again! And that's how it's been ever since. In that time, I've covered about 250 miles and the bike's performed perfectly for 15 or 20 miles... and then I get a 3 or 4 mile stretch with the clicking and jumping. Then it's back to normal for another 15 or 20 miles. All of my cycling is done on macadam roads, and my usual routes have a variety of hills (some quite steep) and flats. I cycle fairly hard and usually average 18 mph. The fault doesn't occur at any particular time or in any particular gear, and there's nothing I can think of - a multiple shift, a change of gradient, etc - that causes it to start or stop. It just suddenly starts... then suddenly stops!
I've had the gear cables changed and everything is adjusted correctly... but it hasn't made any difference. The chap at the bike shop has suggested that the transmission might be getting to the end of its life - and a replacement would certainly cure the problem. But he still can't account for the intermittent nature of the fault.
Does anyone have any ideas, please?
I've got a Specialized Sequoia road bike, about 6 years old, which has done around 10,000 miles on all original components. It has 24 gears on a triple chain ring set. The chain rings are 30 - 52. The cassette is 11 - 25. The set-up is Shimano Tiagra.
The fault started spontaneously a couple of weeks ago. One day, I started getting a 'click' on each revolution of the chain as it passed through the cassette. On the 3 highest gears - not on any of the others - the chain jerked, like it had slipped a tooth, at the same time as the click. This went on for a couple of miles and then, just as spontaneously, stopped and everything was fine again. It stayed fine for about 30 more miles, and then it started doing it again and carried on for about 3 miles.... and then it stopped again! And that's how it's been ever since. In that time, I've covered about 250 miles and the bike's performed perfectly for 15 or 20 miles... and then I get a 3 or 4 mile stretch with the clicking and jumping. Then it's back to normal for another 15 or 20 miles. All of my cycling is done on macadam roads, and my usual routes have a variety of hills (some quite steep) and flats. I cycle fairly hard and usually average 18 mph. The fault doesn't occur at any particular time or in any particular gear, and there's nothing I can think of - a multiple shift, a change of gradient, etc - that causes it to start or stop. It just suddenly starts... then suddenly stops!
I've had the gear cables changed and everything is adjusted correctly... but it hasn't made any difference. The chap at the bike shop has suggested that the transmission might be getting to the end of its life - and a replacement would certainly cure the problem. But he still can't account for the intermittent nature of the fault.
Does anyone have any ideas, please?