Adding hub gears to my single-speed

[Dave200]

Guys, I've fallen into a bit of a warren of technical jargon which is exposing my lack of cycle knowledge, so I'm hoping that someone here can help me cut through the bullsh*t. For reference, I'm a casual commuter cyclist, without any desire to take it too seriously.

I've been running my single-speed as a Central London commuter for about 3 years now, and it has been absolutely faultless. In this time, it's also done the occasional long ride (London-Brighton etc.). Having signed up for the Prudential RideLondon 100 (100-miler around the Olympic course) in a few months time, training is showing that I might have bitten off more than I can chew with one gear.

I would like to buy a geared hub with 3/5 speeds specifically to swap in for the next 6-8wks training and event. The bike will then revert to a single-speed, and the hub will probably not be used again - so I'm not looking to spend a great deal (<£100). However, I'm frankly a bit baffled by the options available to me.

I'm currently running a ratio of 52/18 (f/r), and I cannot seem to find a way to accurately compare the various offerings. If I'm honest, I probably only need 3 gears (one either side of the current ratio, and one for steep climbs), but I'm really struggling to choose accurately.

As far as I can see, I could either go for something like this (plus a shifter):
http://www.ebay.co.uk/itm/Tru-build-Wheels-700C-Re...

Or plug something like this into my existing 36H 700c rim:
http://www.amazon.co.uk/SRAM-Spectro-i-3-Speed-Hub...

What's worth knowing? What the hell do all of the numbers mean?

[jamiebae]

Maybe a silly question, but will those fit? My singlespeed has a 120mm hub which I'm led to believe means that I can't fit a normal geared hub to it, so check the spacing before you buy anything.

[Dave200]

Good question, and something I hadn't considered. Thank you - off to check...

EDIT - Looks like it's a 120mm hub. Does this limit my choice, or prevent fitting?

Edited by Dave200 on Monday 7th July 14:33

[jamiebae]

I'm told that it rules out any normal hub gears (I looked into this a couple of years back) but I think there is one company who make a two speed hub where you change gear by pedaling backwards?!

[r-kid]

Sturmey Archer do a couple of 120mm hubs:

SX3 for 3 speed or XRF5 for 5 speed

[Dave200]

Cheers for those recommendations. Any others worth looking at?

Assume that I'm going to need to change chains etc. to accommodate this? Might pop to Brick Lane or Brixton Cycles to talk to someone in person.

[Dave200]

Actually, it looks like the Sturmey hub is a fixie, which is not going to quite work for long downhills on big rides.