Sturmey 3 speed , adding extra gears

[BADGER.BRAD]

Hello all,
I'm thinking of an old folder ( Raleigh 20 or similar) which I would use to cycle from one side of the river Severn to the other , down a steep hill and then up another to the other side, leaving my car on the other side ( It's an 16 ish mile trip to the other side by car and I work that side of the river , 25 miles away) this would be no problem by just down gearing the thing so I could use it to go up hill but if I wanted to use it else where what would be my options for expanding the gear ratios using maybe a front Derailleur or any other method ?

Thanks all

 

[figbat]

I’ve seen someone fit a second sprocket onto the hub with a small derailleur. You can add a cassette to the hub but then you need to spread the frame. A front derailleur may also work but you’ll also need a chain tensioner.

 

[Ian H]

Simplest thing is just to fit a larger sprocket and put up with a lower top gear.

 

[Chris S]

Or to buy a folder with derailleur gears. All my bikes are Sturmey Archer 3-speeds but I wouldn't recommend one to somebody who had to pedal up a steep hill on a regular basis.

 

[MichaelW2]

Bottom bracket internal 2 speed.
ATS Speed drive is manufactured under license of Schlumpf Innovations GmbH, (Switzerland)

 

[Cycleops]

Just buy a folder with a 6/7 speed derailleur, plenty about.

This Raleigh Stowaway (7 speed and V brakes) is £50 on Gumtree.

 

[Low Gear Guy]

The other option would be changing to an eight speed hub gear. You would need a new wheel with hub gear and a suitable shifter.

 

[simongt]

Of course, back in the 'good old days', Cyclo did a three speed derailleur combined with a three speed hub gear giving nine speeds with one chainwheel.
Mildly surprised that no-one has re-explored that arrangement since. After all, the Brompton 6 speed works on a similar setup.

 

[tyred]

It's easy enough to put two dished sprockets back to back and use a basic derailleur. I did it myself for fun on my old Kalkhoff.

I can't remember the maths I did of the top of my head but I have a 3 tooth difference between the two sprockets which gains you a lower gear and fills the gap between the others.

Unless you like playing about with stuff like that, just fit a larger sprocket to lower the gear range TBH. My Kalkhoff works well enough in practice but the change sequence is complicated and it's a lot of complications for not much real benefit.