Wisper Gearing

[the_killjoy]

Has anyone changed the gearing on a 905, I get tired of my legs gong round too fast on the flat, I would like something a little higher. I assume the only option is to fit a larger front sprocket rather than trying to fit a smaller rear one.

 

[shemozzle999]

Fitting a smaller rear sprocket would only increase your top gear ratio; where as fitting a larger chain wheel will increase all the gear ratios - that would be my preference.
I also find I easily spin out on an ebike.

 

[neptune]

This seems to be a constantly recurring question, irrespective of make and model of bike. I do not pedal much on my old heavy Pwabyke Euro, except if I get a strong headwind, Or I am making an exceptionally long trip, and want to extend range. I do my pedalling on a normal bike, daily. So I have fitted a larger chainwheel. This would make hills difficult, but we don`t have hills around here. If you do have hills, think carefully before fitting a larger chainwheel.

 

[Mussels]

I changed the chainring on my 905 but I needed to reduce the gearing for hills, the best thing I did was to get rid of the megarange freewheel.
The only way I got the gearing I wanted was to buy a 906 instead. Strangely better gears had a negligable effect on journey times.
If you do change the freewheel then not all of them fit over the motor cable, search the forum to find out which tool to buy.

 

[Deleted member 4366]

With the risk of being boring and repetitive:
Get your self a 52/39T or 53/39T chainset from Ebay from a road bike for £20 - £25. Use the big chain-ring, but if the going gets tough, as it does sometimes, you hook the chain over to the smaller chainwheel with a twig until the going gets easy again, then you hook it back again with the same twig that you put in your pocket from earlier. You have the best of both worlds then - better climbing and higher speed or slower pedalling. Sounds crude but works well. No need for a front derailleur and no need to worry about changing your back gears, because you can now go higher and lower than you had before.

 

[Mussels]

With the risk of being boring and repetitive:
Get your self a 52/39T or 53/39T chainset from Ebay from a road bike for £20 - £25. Use the big chain-ring, but if the going gets tough, as it does sometimes, you hook the chain over to the smaller chainwheel with a twig until the going gets easy again, then you hook it back again with the same twig that you put in your pocket from earlier. You have the best of both worlds then - better climbing and higher speed or slower pedalling. Sounds crude but works well. No need for a front derailleur and no need to worry about changing your back gears, because you can now go higher and lower than you had before.

The problem there is that the 905 BB is already pretty wide and I found after changing the chainring (for another single) that the chain would often derail as the chain was being pulled towards the frame. That could have done with a derailleur just to keep it in place, keeping the chain on another outboard chainring will definitely need assistance.
For my 905 I used a MTB style chainkeeper designed for full suspension bikes and was mounted on the BB, that had problems as well as the battery got in the way of the arms. The 905 BB has changed since my bike so I don't know what will fit now but something like this might do:
Paul Component Engineering - Chain Keeper BB