gearing changes

[fishingpaul]

my new giant revive is not very good at going up hills it has a 36tooth chainwheel and a 12 tooth rear sprocket and 20 inch wheels with panasonic assist,i was thinking of getting a larger rear sprocket,but have no idea what size tooth i need, for some fairly steep hills.also do you need a special tool, to remove the sprocket.thanks in advance paul.

 

[flecc]

The Revive came with various gearing systems Paul, both derailleur and hub gears.

I know the first Spirit models came with a Nexus 3 speed hub, and the low gear on that was too high at 43", which together with it's high weight made hill climbing poor as you've found.

If it's that gear hub, you'd need to go to a 14 tooth for a small improvement, a 16 tooth sprocket for a big improvement, but that last one would drop your assisted speed by about 3 to 4 mph at the same time, so the 14 tooth is probably best, not affecting the assist speed too severely.

The sprockets are just simple three spline fitting held with a wire circlip which you can prise off with a screwdriver.

Sprockets can be got by local bike dealers, or you'll find what you want at SJS.
It's the 1/8th size you want.
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[fishingpaul]

thanks for that flec

 

[fishingpaul]

i have now fitted a 16 tooth sprocket,but it was not so straight forward,the old sprocket was threaded, and needed a chaintool remover to remove,it has been replaced with a sturmey archer type sprocket (non threaded),and is now held in place by a large threaded o ring.also the chain needed an extra three links,to allow for the much larger sprocket.it is now a far better bike to ride without assistance,and much improved hillclimber.

 

[flecc]

I'm not surprised the sprocket was non standard, since it was an unusually small size, probably a special for the Revive.

That sounds much better though, glad it's improved for you.

Merry Christmas.
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