Bosch Crank DIY, Possible?

[SRS]

Just curious at to why I do not see any Bosch DIY conversions?

Is the Bosch System available as a kit?

I appreciated that some cutting and TIG welding would be required but seems odd that I cannot find any references to home projects.

 

[oigoi]

Generally speaking kits are made to fit onto an existing bike in a manner that can be achieved without fancy tools.
A tig welder capable of welding an aluminium bike frame would cost as much as just buying a new bosch bike! And you'd have to have the necessary skills to use it

 

[SRS]

Generally speaking kits are made to fit onto an existing bike in a manner that can be achieved without fancy tools.
A tig welder capable of welding an aluminium bike frame would cost as much as just buying a new bosch bike! And you'd have to have the necessary skills to use it

Not sure that I would buy the welder. More likely outsource the welding for a few quid.

Well, I guess from the lack or responses that the answer would be nobody trying this conversion as yet.
Either that or the Bosch system is not available separately.

 

[banbury frank]

Hi

In a previous post somebody said OEM only from Bosch That means Electric bike makers only

Frank

 

[Old_Dave]

for a few quid

That was in the happy days, lol

Tig can be quite easily done (cough) on a reasonably priced (another cough) inverter .. its the argon that's the ongoing expense killer (I can't remember my sums but just for the gas.. I think that buying the best deal big bottle it equates to about 50p a min, using the cheap diy bottles is goes up to £'s a min)

I haven't seen the Bosh available for home users, but even if it was then IMHO the 'engineering issues' involved wouldn't be worth the effort / expense for the end result.. same as powder coated paint jobs, great results but at the end of the day its just a fecking bike that looks just like a factory job but ended up costing more

Foot note: I'm out of argo at the mo... and I doubt that I'll get any more, if I cant do somthing by arc, mig or brazing then I don't want to do it

 

[flecc]

Not really practical with these systems that have an integral bottom bracket, and probably too expensive. It could be bought as a spare, but the Panasonic unit for example is £500, the handlebar control unit with it's integral wiring might add another £100 or so and then there's the battery on top, all added to the frame conversion costs. So add between £900 and £1300 to the cost of a bike, depending on battery and frame conversion costs. Although that compares to some high end kits, hardly worth it when there's quite a choice of ready made Bosch e-bikes from £1300 upwards.

 

[Kudoscycles]

Bosch will only sell to OEM customers to fit into bespoke bikes,they are openly hostile to their motors being sold into the aftermarket-they need to be sure about the quality of the installation. The OEM price for the Bosch system is Euro 550 and now some of the big German suppliers are lowering their £ sterling prices it just is probably not a viable DIY fit.
Dave
Kudoscycles

 

[Old_Dave]

need to be sure about the quality of the installation

Maybe they saw some of my welds....

 

[amigafan2003]

Just get a gng crank drive kit.

 

[SRS]

Just get a gng crank drive kit.

The gng looks interesting but obviously still in the prototype stages.

Shall not be buying one nor building my own. I was just curious as to why people were not going down the crank route.

Thanks all, now I have a pretty good idea why.

 

[103Alex1]

^^ Not wanting a front wheel hub, it took me ages to come to terms with the fact that I needed to forget about hub gears because a crank drive conversion was going to far more than I was willing / able to consider.

I might in future think again if someone came up with a GNG-type kit which would offer high continuous output for consistent awesome hill climbing with a very high assist ratio, and an intuitive torque sensor management built in. Lack of both those latter options just made me feel the whole exercise was more trouble than it was worth in terms of end product goals.

 

[amigafan2003]

I'm waiting to see what the AEG crank drive looks like - although it's sounds like it'll be for OEM's only as well :-(

 

[Electrifying Cycles]

AEG will be OEM only

 

[Old_Dave]

Just get a gng crank drive kit.

Which of course is a great solution (which comes with other minor issues, lol)

I've ordered the spokes and a hub to convert my 350W to hub drive instead of derailer which will either go bang or be a major leap for mankind

 

[flecc]

Bosch will only sell to OEM customers to fit into bespoke bikes,they are openly hostile to their motors being sold into the aftermarket-they need to be sure about the quality of the installation. The OEM price for the Bosch system is Euro 550 and now some of the big German suppliers are lowering their £ sterling prices it just is probably not a viable DIY fit.
Dave
Kudoscycles

The Bosch unit slightly dearer than a replacement standard Panasonic unit which is €500 in the European mainland, translating as usual to the same figure, £500, when bought here in the UK.
.

 

[Deleted member 4366]

The gng looks interesting but obviously still in the prototype stages.

Shall not be buying one nor building my own. I was just curious as to why people were not going down the crank route.

Thanks all, now I have a pretty good idea why.

Many people have done crank-drive conversions. I've personally done three. Like everything, they have advantages and disadvantages.

If you're doing a self-builds, you can get a nice powerful hub-motor that will climb any hill, so this negates the advantage of the crank-drives, which are better at climbing for small motors.

To make a crank drive feel right, you need a torque sensor to control the power with your feet, and there's no suitable cheap torque sensors on the market that can do this. Cadence-based PAS sensors and throttles work on crank-drives, but they make it difficult to control the power in an efficient way since most controllers control speed, not power, so the throttle is trying to control motor speed, which doesn't make much sense when you have to keep changing gear except at full throttle. It works, but not as well as a hub-motor.

A powerful crank motor would damage the gear train.

So, in summary, not much advantage in a crank motor for a self-converted bike.

 

[Old_Dave]

so the throttle is trying to control motor speed, which doesn't make much sense when you have to keep changing gear except at full throttle

Indeed so.

However apart from the fact that the Q100 d8veh steered me towards is overall much more of an elegant solution (wish I'd of done it first rather than second) I was hoping to keep the gng throttle at fullish and use the AW hub gears as the speed control .. lol

 

[Deleted member 4366]

Indeed so.

However apart from the fact that the Q100 d8veh steered me towards is overall much more of an elegant solution (wish I'd of done it first rather than second) I was hoping to keep the gng throttle at fullish and use the AW hub gears as the speed control .. lol

That's what I do on my GNG Gen 1. I use a cruise control to fix it at half throttle, then use the gears to control the speed. Every time I change up, I get another surge of power as the controller attempts to equalise the motor speed. If I'm in a hurry, I use full throttle, but I have to throttle back for each gear change to unload the gears. It works more like a motorbike then.

 

[Old_Dave]

but I have to throttle back for each gear change to unload the gears.

Note to self: Must remember to do that

 

[muckymits]

Maybe they saw some of my welds....

Crows or seagulls?

Have you ever managed decent welds with the fluxed wire for migs on steel? I can stick things but it looks ugly