Sorry if I seem to be hogging things. Second new thread today but they are related.
The gearing of any bike as it leaves the factory must always be a compromise. The fitness and capabilities of the rider and the gradients in the local terrain will all have an effect. A few months ago I took delivery of my 906 Alpino which I am very pleased with and with the help and support from the company.
However, being pretty ancient (and therefor not very energetic) and living in a very hilly area I found that the overall gearing did not suit my circumstances. The Shimano 8-speed hub is very good with a nice spread of ratios and very easy smooth change but the steepest hill I could manage in bottom gear was about 1 in 10 which meant that some local routes were not usable. We don't have any flat roads round here, you are either pedalling hard in the lower gears up hill or free-wheeling at high speed down hill. This means that gears 6,7 and 8 were hardly ever needed.
In the search for suitable sprockets I found that Shimano offer a 20 tooth for their hub in place of the 18 tooth original which got me part way but I still needed more change so started searching for a new main sprocket with 45 or 46 teeth in place of the original 48.
The original chain wheel is swaged on to the crank so a new chainset was required. Also, to retain the pedal-turn sensor mechanism for the motor control, it is necessary to retain the original over-length spindle so the new chainset must fit the square taper shaft. I eventually found an FSA Vero chainset with 46 teeth which did the job.
So I've gone from 48/18 to 46/20 which means that the equivalent wheel size in bottom gear has gone from 39.3 inches to 34 inches. I can now just about manage a 1 in 7 hill if I'm feeling really fit.
This not a criticism of the bike, there is no such thing as a perfect setup to suit every rider and every road. I thought the information might be useful to other owners who find themselves in similar circumstances to me.
The gearing of any bike as it leaves the factory must always be a compromise. The fitness and capabilities of the rider and the gradients in the local terrain will all have an effect. A few months ago I took delivery of my 906 Alpino which I am very pleased with and with the help and support from the company.
However, being pretty ancient (and therefor not very energetic) and living in a very hilly area I found that the overall gearing did not suit my circumstances. The Shimano 8-speed hub is very good with a nice spread of ratios and very easy smooth change but the steepest hill I could manage in bottom gear was about 1 in 10 which meant that some local routes were not usable. We don't have any flat roads round here, you are either pedalling hard in the lower gears up hill or free-wheeling at high speed down hill. This means that gears 6,7 and 8 were hardly ever needed.
In the search for suitable sprockets I found that Shimano offer a 20 tooth for their hub in place of the 18 tooth original which got me part way but I still needed more change so started searching for a new main sprocket with 45 or 46 teeth in place of the original 48.
The original chain wheel is swaged on to the crank so a new chainset was required. Also, to retain the pedal-turn sensor mechanism for the motor control, it is necessary to retain the original over-length spindle so the new chainset must fit the square taper shaft. I eventually found an FSA Vero chainset with 46 teeth which did the job.
So I've gone from 48/18 to 46/20 which means that the equivalent wheel size in bottom gear has gone from 39.3 inches to 34 inches. I can now just about manage a 1 in 7 hill if I'm feeling really fit.
This not a criticism of the bike, there is no such thing as a perfect setup to suit every rider and every road. I thought the information might be useful to other owners who find themselves in similar circumstances to me.
