7
votes
6answers
2k views

Mechanic says not to use top three/bottom two gears or the chain will throw

I just bought a BTwin Fit 5, all stock, fresh from the distributor, Decathlon. Took it for light pacing at the store and things seemed OK. About 100 metres out the door, I shift up to the top end of ...
0
votes
2answers
81 views

Upgrading rear derailer and cassette

I recently got what most people would consider a cheap and toy road bike as a gift. It came with very primitive RD and cassette (shimano SIS? I think). I enjoy upgrading my stuff, my question is, ...
6
votes
5answers
4k views

Rear derailleur shifting poorly, skipping gears

I've got a Shimano Sora on a 8-gear cassette, and have odd behavior and skipping, shifting under stress. This started with a trip to the mechanic for a tune up which replaced the chain. I had some ...
3
votes
2answers
491 views

(Automatic Bike Project) amount of torque required to change gears?

I am planning to build an electronically controlled automatic bike transmission for my senior design project. I'm personally more of an electrical guy, so dealing with the mechanics is somewhat new to ...
1
vote
3answers
1k views

Gear up-shift not smooth

When I am pedaling hard and shift to a larger sprocket, the shift is not smooth or sometimes doesn't happen at all. Sometimes even double up-shifts don't work. There is no problem shifting when I test ...
18
votes
7answers
4k views

Is there such thing as an automatic transmission for bikes?

Has anyone ever designed or manufactured an automatic transmission (or automatic shifter?) for cycling? I imagine such a device would automatically change the gearing to allow the rider to maintain ...
0
votes
2answers
214 views

Unable to change from 14th to 7th

I've got a bike that I have had for about 8 weeks and it has already been back to be serviced twice. It's just returned from the second service and I've noticed that it is not shifting from 14th to ...
3
votes
3answers
282 views

Gear shift adjustments

I recently had to replace the shifters on my bike. The replacement was easy enough, but now when I shift the derailleur either jumps too far or too short. I've tried using the adjustment screws on the ...