The Schlumpf Drives are Swiss-designed, German-made gearing systems that fit at your cranks – like a hub gear, everything’s enclosed so it’s very reliable and you can change gear when stationary or moving, but the big advantage is they give you a much larger gear range than you can get with a standard double or triple front derailleur.
There’s three versions:
Speed Drive: This has a relatively small chainring and has ratios of 1:1 and 1:1.65, so it gears up.
High Speed Drive: This gears up more than the Speed Drive, it has ratios of 1:1 and 1:2.5.
Mountain Drive: This has a big chainring and gears down – it has ratios of 1:1 and 2.5:1, so it can give very low gears for hill climbing.
There’s lots of options and different fittings, so give me a call or send me an email for advice, or have a look at the Schlumpf website. As a rough guide, a standard drive is around £675.