Single chain ring set ups

[PaulM]

I've been thinking about running a recumbent bike with a single chain ring. The advantages are probably less weight and less compllication. I installed a 9 speed 12-36 cassette on the GFs upright and didn't find it too gappy. I reckon a 10 speed 11-40 on a 2-wheeled bent would work quite well. I'd need to gear it for about 6 mph @ 50 rpm, which would give a top speed of about 22 mph @ 100 rpm. Below 6 mph I would probably want to walk anyway since things start getting wobbly and I'd only exceed 22mph going downhill so could coast.

I suppose having to change down from 9th to 3rd say before stopping might be a bit onerous but that's why I prefer twist grips to trigger shifters. Anyone gone to a single ring set up in this way?

 

[mrandmrspoves]

I wouldn't want any less than the 21 gears that I have on my PDQ. It achieves them via 7 speed rear derailleur mounted onto a Sachs 3 speed hub. The advantage of the hub is if I stop suddenly I can still change down before moving off again. Not a light option though. I don't think the weight you would save by going to a single chainring would be enough to compensate for the loss in gear range - but to each their own.

 

[PaulM]

All good points although your 21 gears wil have a lot of overlap. The SRAM XX1 groupset uses a single ring and a 10-42 cassette (11 speed) I think but they are still charging a premium for it. It has triggered a lot of MTB riders trying 11-40 as a poor man's version. Tha Alfine 11 IGH is quite popular with bent riders and that has a range of 409%, whereas the 11-40 cassetter has a range of 364% so about the same as a NuVincii 360.