9 speed

[tommyh7]

Hi everyone just a quick question i have a 1000w hub motor wheel my bike is a giant trance x3 now at the moment it has a 7 speed freewheel on there but can only keep it in the second last gear my question is can i put a 9 speed freewheel on there as my bike is 9 speed before conversion

 

[sjpt]

If you changed from 9 speed to 7 without changing the shifter or derailleur that's probably why it won't shift properly in 7 speed. Changing it back to 9 speed should be fine. You need to check if the hub has freewheel or cassette fitting.

Campag have different spacing for 9 speed, but it is pretty unlikely either the original or what you want to replace it with will be Campag.
Having correct gears still won't make it legal to ride it on the road.

 

[vfr400]

The main problem is the width. You'd have to stretch your frame a bit to get it in, then the rim will be off-set to one side, so you need to dish the wheel. If it's not already dished at all, you have a chance, but if it is already dished, the additional dish would be too much to get a decent tension on the left side spokes.

What do you mean by, "but can only keep it in the second last gear". You should be able to use all the gears with 7-speed.

 

[sjpt]

The main problem is the width.

As the bike was 9 speed to start with surely this won't be an issue. I don't think an electric hub should be wider than its non-electric equivalent, or am I wrong there?

 

[vfr400]

As the bike was 9 speed to start with surely this won't be an issue. I don't think an electric hub should be wider than its non-electric equivalent, or am I wrong there?

It will be an issue. Thinking is OK for how one would like the world to be, but OP has to deal with facts.

 

[tommyh7]

it is a freewheel this is the one i am thinking of buying

 

[Nealh]

Freewheels have a stack height of about 41mm for 9spd and about 37mm for 7 speed, so one will need to stretch the drops out width a little and as vfr has said the wider gears will offset the wheel centre more it will require 2 mm of dishing or so.

The Gant previously in it's former life may well have used a 9 spd cassette ?
Compare a cassette 9spd to a 9spd freewheel and the difference is big 34.5mm compared to about 41mm respectively, the more a wheel has to be dished the more unstable it will be.

Cassette gears are pretty much the same stack height though use different gauge chains where as the freewheels use one size chain so every spacing for an extra cog means a wider stack height. 7spd is the std for freewheels as the wider you go the more stress is applied to the axle.

 

[tommyh7]

so it would be better to keep it as 7 speed? and yes it was SRAM PG950 nine-speed 11/34T

 

[Nealh]

Yes 7 spd, unless you want to add washers to spread the drop out width and then have to dish the wheel because it isn't centred correctly.

Cheap bikes and kits come with freewheels , that's why the cassette is king you can change from 7 - 10 spd with the same stack height just use a narrower chain for 9 or 10spd.

If you aren't getting the gears changing you should be able to do so if the shifters/derailleur are 9 spd, it will just need the adjustment screws adjusted so that the up/down shifting doesn't over ride.

 

[tommyh7]

OK got it thanks very much for your help