I have a tadpole recumbent trike made by ZZ Merck (a Chinese import to the UK) with 36V 250W electrics.
I generally like it, but I'm finding the gearing on it rather low-range. I spend almost all my time in top gear and spin out on anything that's not uphill. Admittedly my legs aren't made for spinning around really fast & I prefer a slow, hard push.
It currently has a 3-ring set of sprockets on the front and a seven-ring freewheel sprocket set on the back. The front has 42, 34 and 21 (I think? not sure about the 21) tooth sprockets.
As far as I can tell, my options for increasing the gearing are:
- Put bigger sprockets on the front. This would mean replacing the whole set because the ones that are there are not made to be mixed-and-matched. My local bike shop has found a set that goes up to 52 teeth and we can go bigger than that, but it starts to get pricey (I'm being quoted upwards of £60 per sprocket for 60-odd teeth) and eventually there's a limit to how big a wheel you can put on. 52 would give me just under 25% extra gear ratio - good but not as much as I'd like.
- Put smaller sprockets on the back. I'm not sure how feasible this is with what's there, I haven't tried taking it apart. I suspect there's not a whole lot of room to move here.
- Something else. There is an idler half-way along which sits on a bolt that's screwed into a nut that's welded to the frame. I'm considering replacing the idler with a stub axle with two sprockets on it, locked together, in about a 2:3 ratio. I'd then split the chain into two loops. This would give me 50% extra, but I'm worried about the forces on the stub axle & the nut weld.
So three questions:
- What sort of gearing setups do people use on their recumbents?
- What do people think of the idea of replacing the idler?
- Is there some other option that I've missed?