Trice Recumbent trike + NuVinci + Currie + LiFePO4

[paultrafalgar]

I've had a Trice T recumbent trike for a few months. I would like to fit power assist and was thinking of using the Cyclone motor driving a NuVinci hub with LiFePO4 batteries. However, I'm now picking up bad news about the Cyclone and am wondering if I could use a Currie motor adapted to drive through the chain. I am 63 years old and my Cateye computer tells me that my average speed is 6.2 mph and 2.5 mph uphill on the Forest of Dean cycle tracks! So I reckon that a hub motor won't do the hill climbing I must do round here. I wondered about trying a Currie with the normal spoke drive on the rear-wheel (tadpole) first and if that doesn't cut the mustard, then adapt it to drive the chain. Any thoughts?

 

[flecc]

I think that you're wise to avoid the Cyclone, though it superficially looks attractive for that purpose. The Currie has been fitted on tadpoles as you'll see here with the supplier on a Greenspeed, but the spoke mounting drive does have it's problems and I wonder about how long the spokes would last with the extra weight to drive.

The Heinzmann hub motor from Kinetics has been successfully used in recumbent trikes in it's rear wheel version, and given the speeds you mention, the lower geared version might well be of interest. In the interests of hill climbing, that can be supplied geared for about 11.5 mph top assist speed, and it's a powerful motor.

Ben at Kinetics can advise.
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[paultrafalgar]

NuVinci: Pudding the proof of?

Flecc, thanks for your prompt reply. Since I sent my first post I have read a lot of your comments about the NuVinci and you seem to be not very keen on it. For example, in your post here:

http://www.pedelecs.co.uk/forum/electric-bicycles/98-nuvinci-cvt-hub.html?highlight=NuVinci#post871

you say of the NuVinci:

"...It will work, but may well give up in efficiency loss everything it gains in it's gear variability. It will certainly lose quite a lot of the motor's power."

Your theoretical objections to the NuVinci seem to be overuled by the experience of Krow here:

http://www.pedelecs.co.uk/forum/electric-bicycles/384-nuvinci-hub-twist-lite.html?highlight=NuVinci#post4766

who says:

"...This has had a big impact on battery range. I ride the 15 mile round trip to work and use about 20-30% of the charge. With the Shimano Nexus-4 I was using about 50-60% of the charge. I haven't run the battery full out to see what the maximum range is, but I forsee some longer trips in my future to check that out."

... surely the proof of the pudding is in the eating?

Simplicity in engineering is surely often excellence, n'est-ce pas?

 

[paultrafalgar]

NuVinci + integration of motor and gear

Here:

http://www.pedelecs.co.uk/forum/electric-bicycles/654-light-fastest-climbs-mountains-pretty-efficient-3.html?highlight=NuVinci#post8895

you say:

Current "new" ideas like the NuVinci/Swizzbee etc are in my opinion over complex and/or doomed to early unreliability, and all too often have been tried before anyway

Here:

Rohloff, Shimano, SRAM/Sachs and Sturmey-Archer Internal Gear Bicycle Hubs

is a picture of a 14-Speed Rohloff Hub. It has a range of 526%. A little complicated isn't it? Therefore, expensive.

Here is the Shimano Nexus 7-speed:

Shimano Nexus 7-speed and 8-speed Internal Gear Hubs-Technical data. It has an overall range of 244%

The NuVinci has a range of 350% and is shown here:

Fallbrook Technologies

Now tell me that the NuVinci is "over complex".

Your ULTIMATE dream motor-gear described here:

http://www.pedelecs.co.uk/forum/electric-bicycles/654-light-fastest-climbs-mountains-pretty-efficient-4.html?highlight=NuVinci#post8918

is a driven version of one of these very complex gear hubs. There may be a genius out there who can simplify it, but I don't agree with what you say here:

http://www.pedelecs.co.uk/forum/electric-bicycles/654-light-fastest-climbs-mountains-pretty-efficient-6.html?highlight=NuVinci#post8994

that "The detail isn't important, it's for the final designer to decide, as are the possible mechanical and electrical change methods if used."

I suggest to you that (said genius not withstanding), the NuVinci is an elegant and simple solution to engineering a CVT (continuously variable transmision) and there is not much to be gained by integrating that idea with a superior design of motor. Keep them separate till the said genius arrives.

Or maybe you should just turn the top of the forks into a motor and put permanent magnets around the rim of the wheel...?

 

[flecc]

I won't go into a long complex answer Paul, but there seems to be some misinterpretation here.

I haven't argued about the NuVinci versus the Rohloff or any other hub gear, and I don't like the Rohloff anyway. All hub gears have a fair degree of inefficiency.

You've clearly not understood what I posted about using the orbital gears that are already in a hub motor for providing two gears, since those gears are already there and being used, so using them for gearing would add no inefficiency.

With respect to Keith in those postings, mixing the NuVinci with a Panasonic drive and attempting to assess the result by the subjective experience is a long way from reliable. Only the other day someone was posting in here that he'd gained two mph by using aerodynamic handlebars, showing how powerful auto suggestion is. In my experience people's performance gain is in direct proportion to how much they've spent on the alteration.

My biggest concern on the NuVinci is reliability though, as well as efficiency. CVTs have been around for a while as remarked in that quoted thread, but they are not usually around for long and adversely affect fuel consumption. That speaks to me very clearly.

I'm a patient chap and feel sure that the NuVinci won't be a success and will quietly disappear at some point.

It's an opinion of course, but I still stand by it.
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