Rear Hub Motors and Obsolete Freewheel Technology

[ElephantsGerald]

I thought I'd try and move the debate on this Wisper specific thread into a more public space in case non-Wisper interested folk have missed it.

The situation as I understand it is as follows:

Rear hub motors require an spindle of large diameter to allow motor wiring pass through the hollow centre whilst retaining strength.

The large spindle means that modern cassette type sprockets can't be fitted to rear hub motors, and old tech multi sprocket freewheels are used instead.

The problem is that freewheels seem to be rapidly becoming extinct; several suppliers (e.g. Wiggle) no longer stock these items and some members have reported problems obtaining specific freewheels that were widely available until recently, but are apparently out of production now (e.g. Shimano Megarange 11-34T).

Here are a few questions that spring to mind:

1. Is there any way to modify rear hub motors to use cassette sprockets?
2. How often do sprockets sets need replacing (after how many miles)?
3. Is my lovely new (and quite expensive!) bike going to be hard to maintain because parts will become increasingly hard to obtain?
4. Should I buy up all the available freewheels I can find in case they're impossible to get hold of in future?
5. Do WEVCO know about this problem and have they got a solution for it?
6. Should manufacturers be selling bikes which use obsolete technology?

Regards,

Elephants

 

[Mussels]

I don't imagine them stopping production completely because freewheels do sell and they don't need any money spent on tooling or development. So I think they are more obsolescent than obsolete.
Doesn't help me tailor my gears to my local terrain though.

 

[flecc]

Is there any way to modify rear hub motors to use cassette sprockets?

No, for the reason given on the spindle thickness. Existing hub motors have the thicker spindle integral to the stator assembly, so it can't be changed and a thinner one to go into a cassette core isn't possible. A needle roller alternative cassette core is possible, but again the market is too small for manufacturers to be interested. However, see my next posting.


How often do sprockets sets need replacing (after how many miles)?

Very variable according to usage and sprocket size. The smallest sprockets go first, particularly on e-bikes which spend more time in the higher gears, but on the other hand, there is often less pedal effort on e-bikes. From 3000 to 8000 miles is fairly typical on derailleurs, depending on how maintained.

Is my lovely new (and quite expensive!) bike going to be hard to maintain because parts will become increasingly hard to obtain?

No, there will always be some available, but the choice will probably be very limited, and spares from the supplier will be available for the standard item originally fitted.

Should I buy up all the available freewheels I can find in case they're impossible to get hold of in future?

A good move if a different one like a particular megarange is wanted. Two spares should see out any e-bike's life though, given normal use and reasonable maintenance.

Do WEVCO know about this problem and have they got a solution for it?

I've no doubt they do, since the cycle trade is well aware of it, but they will always be able to get one manufactured by someone for their production requirements.

Should manufacturers be selling bikes which use obsolete technology?

It's only obsolete for normal bikes, still very relevant for rear motor e-bikes. Perhaps with time a cassette type system will be created for e-bikes, but that will probably only happen if e-bikes become very much more popular worldwide. While they are steadily gaining some ground in the west, the majority Chinese home market seems to be reducing as they get wealthier and upgrade to mopeds and cars, so the overall position isn't perhaps as bright as it should be.
.

 

[flecc]

An alternative way of tackling the problem would be to change the freewheel mounting to a rigid splined boss for cassette sprockets, directly driving the motor side with no freewheel incorporated.

Then mounting a freewheeling chainwheel like that used on the Cyclone motor, leaving the chain running all the time.
.

 

[Mussels]

Then mounting a freewheeling chainwheel like that used on the Cyclone motor, leaving the chain running all the time.
.

That sounds like a painful accident waiting to happen.

 

[flecc]

That sounds like a painful accident waiting to happen.

Not if you add a chainguard, unusual but perfectly possible on a derailleur bike like the one I made for my Q bike:

 

[Wisper Bikes]

Free Wheels

Hi

I have just finished 3 very busy days at Interbike in LV and am writing from my hotel room at the Venitian, I spoke to both Shimano and Sturmy Archer about this possible problem. They are both insistant that free wheels will be available in the future if only for the rear hub ebike market.

The worst possible scenario is that we have our own freewheel manufactured, I would be delighted to be the only supplier in the world but unfortunatley I can't see this happening!!

All the best David