Throttle conversion for Bosch motor (ebike content)

Is it possible to convert the torque sensing Bosch CX motor to work with a thumb operated throttle/twistgrip?, i’m finding it increasingly difficult to get my legs to turn the cranks over for more than a mile or two and any hills are totally out of the question as i can barely stand up never mind any attempt to put power down, I’ve had a look online and it seems to be a no-go area – i.e. : not at possible due to the design of the motor but i thought i’d ask on here first.

My other option is to sell my Scott E-Genuis and convert my Cove Hummer that’s been hanging on the wall for the last 4 years into a throttle equipped ebike with a rear wheel hub motor and assorted battery gubbins/twist throttle or thumb throttle, but then it won’t cope as well as the Scott E-Genuis when bimbling about off road.

Has anyone got experience of hub motors and the assorted gubbins that is needed to convert a normal bike.

Cheers,

PS : MS is a **** so despite the illegality of such a conversion it’s either this or a wheelchair to get about in, and there is no **** way i’m getting into a chair.

I’ve mentioned this on here before but how does a non pedal e bike differ legally from a mobility scooter?

Speed. Mobility scooters are limited to 8mph

With it being torque sensing I think ( but dopn’t know) it would be very difficult.    A hub motor would be easier I guess – there is a pedelec forum I( found somewhere with people doing all sorts of things ) that might be able to advise

I dunno?, I’ve looked at the legislation and the only option (legal) seems to be using a type approved mobility scooter and that ain’t happening, to be perfectly honest i couldn’t give a **** about the legalities of a hub motor/thumb throttle,  my scott is used as my personal mobility aid as otherwise i cannot walk, if you asked me to cross a road then within a few steps my legs would give out and i would be on the floor so this is my only option to keep myself as mobile as possible.

http://www.pedelecs.co.uk/forum/forums/electric-bicycles.2/

I reckon your best option is to convert the hummer.

The bosch system is locked down so tight that not even the chinese have managed to produce a fake battery.

might be worth pinging an email off to TJ, I believe he has a decent bafang system.

im sure you can get mid mount motors after market.

I have a midmount kit – not bafung but sunstar so3 – it would be tricky to convert as well and is no longer made.  NOt much help

Stealth bomber?

Obviously, some modes would be illegal on road, but that battery would go some distance at 25km/h surely?

I don’t know about the Bosch, but the Tongshen TSDZ2 is a retrofit torque-sensing mid-drive motor/crank kit that I believe can be fitted with a thumb throttle – worth looking at to covert the Hummer? Kits are about £350 plus a battery.

If you Google “Tibor Marko Bosch Hack” it’ll take you to a YouTube video of a guy who appears to have managed to put a thumb throttle on a Bosch mid-drive motor – albeit with opening the case and soldering in additional wiring, presumably to dummy a signal from the torque sensor – so it is technically feasible.

I would expect not* the torque sensing will be integrated into the motor driver via some rpmm/ current sensing I expect.

*It would be possible not you are prepared to replace the kotmo driver. If you can get the specs of the motor this may well not be too tough but you would have to be careful in selecting a good driver ideally one with feedback so as not to push too many rasins into the motor.

Hi mate

Sorry to hear of the troubles – sounded like the Bosch was previously suiting you well.

I did a Bafang mid-mount conversion last year for a workmate’s wife. It definitely came with a thumb throttle and seemed reasonably well made (still a bit of a wiring mess compared to a Bosch but plugs etc were at least decent quality).

Came from here  https://www.brightonebikes.co.uk/

They seem to have converted some decent bikes rather than the usual crop of BSOs). They also have a high-torque version of the 250W and some bigger (obviously non-legal) options. And stock 36T narrow-wide rings, spare parts, thumb throttles etc. We made a converter disc at work to fit her a 32T (shout if you go that route and need a hand making anything). I think there was a specific lockring tool that I’ve still got somewhere.

Mick

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Cheers tj, that’s the forum I was trying to find earlier, will have a good through the topics later.

Ta very much to all for the other advice regarding motors etc, it seems there is more to a conversion than buying a complete kit/battery and throwing it at the bike, I have an unhealthy hatred of excessive cabling/wiring so if I can minimise the rats nest then all the better, I could entertain the idea of a new bike,  a custom built frame around the best motor for the job could be on the cards as I could hide the cabling internally, and perhaps even fit a rohloff hub gear, would it cope with the drive power from a mid drive motor though?.

Too many questions……. I’d best get googling and do my research.

mick,  the Scott was doing me fine over the past 2years, but the previous 6 months or so has seen my leg strength deteriorate quite alarmingly so I’d best start to find an alternative means of getting about before I run out of options regarding mobility. I was up at Aviemore last week and I couldn’t even get round Loch an Eilein on the Scott as there is a small gravelly climb about half way round that I couldn’t get up – bugger,

Ive still got my SOULCRAFT SS that Ben @ Kinetics repaired hanging on my wall, but I’d never sully that frame with an ebike build,  that’d be sacrilege.

Ho hum…..best get googling, anyone want to buy a very slightly used Scott 710+ E-Genius 😉

That Paradox thing looks interesting. Is that an exposed final stage gear drive? What stops it getting crunchy from eating dirt and rocks?

I think I will be speaking for many here when I say anything that keeps you on the trails for longer is a good thing.

MS is a bastard and anything you do to give it a kick in the nuts along the way is a victory.

Best of luck getting this sorted.

Jay

As the bosch cranks are not connected directly to the chainring they have the opportunity to fit a conventional torque sensor on the shaft of the cranks so it should be possible to spoof the signal.

The mid-drive conversion kits are a lot harder to convert to torque sensing which is what most people want as the motor and pedals both directly drive the chainring on the drive side, the TSDZ2 does manage it though and another way to DIY it would be strain gauged cranks (eg a DIY power meter) but this is not what you want anyway. The TSDZ2 can be fitted with a throttle but if I just wanted a throttle I would probably go with a Bafang setup as they look much more robust and are more popular.

If you dont mind voiding the warranty then hacking the bosch would be my first port of call, so much nicer to have a proper purpose built set up.

A rohloff will certainly work with a motor.  they work on tandems – key being how low you gear them.  Run it above the tandem limit they will be fine.  I ran my ebike with an alfine – no issues at all even on low gearing

Try contacting Ben at Kinetics – He does ebike kits I think and also all sorts of odd stuff for people so might have some bright ideas.

Electric Bikes

here’s my general thoughts on the bafang systems, thumbs up from me.

https://singletrackworld.com/forum/topic/emtb-question-if-i-may/

it seems there is more to a conversion than buying a complete kit/battery and throwing it at the bike,

There’s not really, it pretty much is just a case of throwing it on the bike.