Alternatives to Nuvinci no-turn washers

[Abradable Chin]

Nuvinci no-turn washers seem rather expensive, and are only available in a fitting kit with other extraneous gubbins.
The axle is 9,8mm OD, and across the flats of the axle is 8,0mm. Is there any chance either Shimano Nexus/Alfine or Sturmey Archer axles are the same size? Would someone be able to measure up and tell me?

Here's hoping,

[Brucey]

It sounds like NuVinci use an M10 thread. The nominal sizes for other common NTWs are as follows;

Shimano; 3/8" thread, 8.0mm width across the flats
SRAM/Sachs; 10.5mm thread, 8.5mm across the flats
SA; 13/32" thread, 7.9mm across the flats.

So SRAM are no good for you, Shimano won't fit unless they are filed (they are ~9.6mm ID on the curved parts) and SA ones are a loose fit on the diameter and a tight fit across the flats. In point of fact I think there is only one SA washer that might be durable enough for a Nu Vinci hub anyway, and that is the wrought one in 4mm thickness steel with a single tang; the others are variously too thin or made via sintering and therefore tend to crack when subjected to high loads. The wrought one is usually a bit slack on the 7.9mm dimension so would fit the NV axle with little or no filing.

However because you (presumably) need to time the shift control to your dropouts it may be worth filing/grinding Shimano NTWs to fit your axle. These NTWs are available with lots of different angles to them and also they don't tend to crack up in service.

cheers

[Abradable Chin]

Thank you, Brucey. Your reply was useful. The original Nuvinci no-turn washers are indeed very meaty.
I've today tried a brand new sintered S.A. one, and it is 8,0mm across the flats so it fits without fettling, so I'll obtain a couple of the pressed steel ones seeing as they are £1 each.
The Nuvinci hub is agnostic to installation orientation, so I'm free to use washers of any angle between flats and dropout. The interface sits on and communicates to the hub via a concentric splined shaft around the axle.

[rproctor]

on another forum https://electricbikereview.com/forums/t ... eak.25409/
I found some very thought provoking information as to why Al vertical dropouts can break under load when converted.

Very pertinent as my Kone Minute is Al and vertical

it includes this design.

If i could get one laser cut that could help on the drive side, with a torque arm, or maybe a derailleur arm.
For the left side I would need a NTW with a tang about 90degrees to the slot

[Brucey]

when looking at other NTWs, the fit is secondary to the timing of the tang; if that ain't right (and I think it isn't in SA ones) then it will be of zero use to you. Also most SA NTW are for the 11/32" axle size but they also make NTWs for other axle sizes too. The shimano ones are for 3/8" thread, which might be what you have in a Nu Vinci. [the NTWs for an N360 hub might be the correct fitment for the left of your hub; worth looking into?]

IIRC the axle size on the right side may be the same as some pedelec hub motors; if so I'd suggest getting a torque reaction arm for one of those and using a clip to secure it to the chainstay.

Most of them are utter rubbish BTW; this one is slightly less bad than average



To turn something like this into a secure arrangement at the rear. I'd recommend that

a) the parts are cut up and welded together to make an arm (the longer the better) of the correct geometry
b) something better than hose clips are used to secure it to the chainstay.

hth

cheers

[rproctor]

this one is pricey but looks interesting and adaptable
https://dillengerkits.co.nz/arc-torque-arm.html

[rproctor]

I note it's 6mm lasercut stainless ... that's serious

[Brucey]

the centre piece is very thin-walled so may split if it sees a high, repeated load. And (IMHO) the whole thing needs to be welded together if the loads into the frame are to be managed sensibly; the longer the arm the better. With a single-bolted joint in the assembly the arm is only ever as long as the first bit, meaning that the thrust loads off a small torque arm can be incredibly high.

For example if the axle sees a reaction torque of 100ft.lbs (which might be reasonable or even an underestimate perhaps) then on an arm 1.2 inches long the thrust would be 1000lbs. If the arm is twice as long then (for the same torque) the thrust load is halved, and so on.

I'd suggest that the thrust into the chainstay ought to be managed to be no more than ~200lbs or so (this would be like standing on the chainstay, more or less; most frames will withstand that but if you were to (say) bounce up and down you would be worried).

You may be thinking 'ah but the dropout sees the brake forces from a disc brake, surely they are higher?' Well yes they might be, but they are also much less frequent. If you see peak load from the brakes a few thousand times in the life of the bike, that would be a lot. By contrast pedalling soon imposes stress cycles in the millions. I therefore don't think much of a NTW design that reacts a very high load into the dropout alone; look at rohloff dropouts and see how they have had to be made to do the job reasonably well.

cheers

[rproctor]

This is getting interesting ....
given that the bike is rated for 300lbs, and that hub is rated as 190nm(?) and that I am looking at the CYC motor which rated at up to 5-6kw depending on voltage .... a cush drive might be desirable ... mind you, adjusting the ramping of the power in the controller should help with that.

After all, I am after an SUV not a Beyron.

I'll print out a template of that torque plate and see if it fits
https://www.cycmotor.com/
https://www.facebook.com/groups/407576456456280/
it comes with 3 presets, EU legal, US legal, & Ludicrous ... which would make for a good Q-bike.

I'm not actually chasing all that power, or speed. It seems a well built, easy to install, understressed option, good for a cargo bike tackling steep hills.
Here in NZ it does tend to go up and down a bit steepish in places.

I really appreciate your input, Bruce. So what are you riding?

[Brucey]

no worries, glad I can be of some help. I don't use these things myself but I've built/ helped out other folk with E-bikes, conversions, and NuVinci hubs, hence I have a smattering of potentially useful information I suppose.

My most used bike has SA four speed hub in it, converted to 5s. Sometimes it has my 'magic alpine double' system on it (which gives gear ratios from 22" to 100"), but sometimes not (it isn't hilly enough to make it a necessity where I am). in fact for the last year at least I have just the middle three gears, since the LH control rod needs to be replaced, and I have yet to do it....

The other bike I use quite a bit (for utility purposes) is an old post office bike, but with 700C wheels, fast tyres and modern hub brakes (to replace the rod brakes that used to be on it).

cheers