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I have an idea and I'm wondering if it's feasible.

For an upcoming recumbent cargo touring build, I wonder if I could say use an 8-speed hub gear connected directly to an identical 8-speed hub gear, or three hub gears 4*4*4, to get logically 64 gears.

What sorts of problems might there be? I don't have any particular parts in mind regarding ratios, but does anyone do this?

Are there any good examples of how to do a high number of gears right?

The whole point of this would be to be able to drive the bike up anything from a long ridiculous 30% grade at walking pace to an easy 100km/h on a straightaway with fairing. Is that feasible using a large number of gears?

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  • It's fairly common on bents and hand cycles to have a multi-speed hub combined with a derailleur setup. I've not seen multiple multi-speed hubs, but don't know why it wouldn't be possible.
    – Daniel R Hicks
    Feb 20, 2014 at 23:34

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The HP Velotechnik Scorpion is available with three front chain rings, three-gear internal hub, 8-speed rear derailleur setup. This has the additional advantage that you can shift while stopped, e.g. after emergency stops or similar.

I found it rather tedious to keep the overview over which gear I'm currently in. My Velomobiel Quest has triple front, 9-speed rear derailleur and that covers enough ground for me. Walking pace is not a problem and I spin out at about 70km/h, which is already pretty hard to keep up, even with race fairing.

Depending on where you live, riding 70km/h is already pretty dangerous taking into account that trikes cannot brake too well because the rear wheel will lift off pretty quickly.

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  • re braking -- my design is a quad with front-wheel-drive and rear brakes. But that's not the point of this OP -- it's just about whether it can work to use a series of two or three hub gears.
    – themirror
    Feb 19, 2014 at 18:03
  • Then yes, it can work ;)
    – arne
    Feb 21, 2014 at 6:42
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You will likely be using at least one of the hubs outside of its maximum torque specification when riding in a low gear.

Here's a random thread about a guy breaking a NuVinci by overtorquing it with a gas motor assist: http://forums.mtbr.com/internal-gear-hubs/how-much-power-will-alfine-handle-551706.html#5

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  • But if the bike is human-powered, and the gear range is similar to a derailleur bike, the torque would be likewise similar. Of course, both the your guy and the OP want to have a lower low gear, but the OP didn't express a desire for motor assist.
    – Daniel R Hicks
    Feb 20, 2014 at 23:42
  • If the output of one hub is fed into the second hub, there'd be a ton of torque going into that second hub when pushing a big heavy bike up a hill.
    – Alan Gerber
    Feb 21, 2014 at 17:26
  • No more than a gorilla driving the same load up the same hill. There's easily a 5:1 variation in the force different bikers can/will generate, and hard to say where the OP is on the gorilla scale.
    – Daniel R Hicks
    Feb 21, 2014 at 17:36
  • With 64 gears, if the lowest low gear doesn't have hub breaking torque available, it's likely many of the higher gears will be too high to be useful. As an extreme example, consider a bike with a Pinion 18 speed gearbox and a Rohloff 14 speed hub. That means you can maintain the same cadence at 1 mph and 33 mph, and have 252 gears to choose from, roughly 220 of them being redundant. Much more practically, a Shimano 8-speed hub with a Schlumpf bottom bracket hub gear gives around the same range as a Rohloff and is cheaper. (And a lot easier to fit on a standard frame than two 8-speed hubs.)
    – armb
    Mar 10, 2017 at 15:27
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A friend of mine has 2 wheel recumbent with 8 speed shimano in the wheel and a 5 speed sturmey locked in 1-3-5 as an intermediate box, like they do on pashley trikes. He says its not draggy and gives a good range with 8 speed multiplied by -33% and +50% With his permish I'll post a picture of an earlier attempt he made. I've been wondering about it for A Brox 4 wheel recumbent that has a dicky 7 speed fichtel/sachs. On his advice I'll probably try the 1-3-5 and and AW 4 speed. 12 gears and a span of 4.2 to 1.

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  • Cool, bring us pics!
    – Swifty
    Aug 22, 2018 at 20:01

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