Gepida Gearing

[Cyclezee]

I have just acquired a Gepida Reptilla 1000.
Does anyone know, or has anyone tried altering the gearing by replacing the motor or rear sprocket?

Many, including myself, have sucessfully done this to Pansonic crank driven hub geared bikes.
The Yamaha powered Gepida is quite similar, but the power cuts out abruptly in each gear as the motor reaches a certain (unknown) RPM, rather gradually tapering off as with the Panasonic system.

I wonder therefore, if by altering the gearing i.e larger motor sprocket and/or smaller rear sprocket would increase the speed and cut off point in each gear.
My simple logic says yes, but ther would be an increase in power consumption.
I would like expert opinion before giving it a try

J hn

 

[flecc]

It would definitely be ok as a way of putting the disconcerting cutout beyond normal cycling, and I'd say that it would be best to alter the motor sprocket first since that would put the cutout further up the cadence scale so less likely to be met in normal cycling.

The amount of tooth increase would have to be judged from your personal cadence preferences, and any further up gearing needed done at the rear sprocket.

No doubt you'd have to have the new motor sprocket specially produced, I doubt there are Yamaha alternatives.
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[Cyclezee]

Thanks Tony,

The good news is the Yamaha motor sprocket splined drive shaft is exactly the same as on the Panasonic as can seen from the photos. (worn Panasonic 9 tooth on the left, Yamaha on right).
I will try an 11 tooth.

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J hn

 

[flecc]

That's handy John, and doubtless Yamaha being crafty!

I wonder how Panasonic feel about not only their unit being closely imitated, but spares being made compatible.
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[quilly21]

That's handy John, and doubtless Yamaha being crafty!

I wonder how Panasonic feel about not only their unit being closely imitated, but spares being made compatible.
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Interestingly I remember Yamaha crank motor pedelecs being on sale in the UK many years ago, two models a mountain bike type and a road going one.
I was very tempted but at £700 and this would be about 11-15 years ago or thereabouts just too expensive.
They were used by the Yorkshire Constabulary and reported about on Radio 4. (disbelief on the faces of onlookers as the Policemen cycled effortlessly up steep hills)
Had I remotely realised how good these crank motor pedelecs were I would have shelled out and probably been much better off now as a result!
Yamaha pedelecs were first brought to market in 1994
So perhaps Panasonic are the imitators
Policeman

 

[flecc]

Yamaha pedelecs were first brought to market in 1994
So perhaps Panasonic are the imitators
Policeman

Yes, Yamaha preceded Panasonic by 6 years with crank drive e-bikes, but they were not the imitators since the Yamaha system at that time was very different, using a bevel drive and being a bit moped like, the subject of some criticism.

Panasonic's system was far superior in bicycle terms, truly mimicking the cyclists actions in a bionic way so was unique. The Panasonic system was so much better it was widely accepted as the best in the world earlier in the last decade, forcing Yamaha to abandon a number of markets including Britain, though they remained on sale in France for a while longer before disappearing.

It is this superior Panasonic system that Yamaha have closely imitated 9 years later, in order to get back a market position.

You can read about the Giant Lafree history in my support site on this link.

There's also my Panasonic support site on this link.
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[Mussels]

What came first, the Panasonic system or the Japanese pedelec law? I'm guessing the law was moulded tightly around the panasonic unit* and Yamaha have little choice but to copy it.

* just as Panasonic are trying to do in Europe.

 

[Cyclezee]

I have now replaced the 9 tooth motor sprocket with an 11 tooth. It was quite straight forward and the result is much improved performance through the gears.

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J hn​

 

[flecc]

What came first, the Panasonic system or the Japanese pedelec law? I'm guessing the law was moulded tightly around the panasonic unit* and Yamaha have little choice but to copy it.

* just as Panasonic are trying to do in Europe.

Japanese law came first, Panasonic modelled their power reduction-with-speed system on it's formula, which they are compelled to do for their home market.

The Yamaha copy is virtually a slightly reshaped clone of the whole thing, not just the power reduction, the latter system just being part of the electronics circuit within. They don't seem to have achieved Panasonic's smooth power cut off point though, as John's alteration to mask it indicates.
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