Following about 3 and a half years riding my Cytronex Cannondale CX-3 (http://www.pedelecs.co.uk/forum/threads/cytronex-quick-cx-3.10112/) the battery finally gave up. I bought a new regular bike to improve on the frame fit, found Trek hybrids to suit my build better. Tried regular cycling for a year but really missed the electric assistance.
I decided to electrify the new bike and combine the Cytronex set-up with a new lithium battery. I have been inquiring with Cytronex about the long-awaited lithium bottle battery but it didn't seem to be forthcoming (still in testing and development at the moment, I'm told).
It took me a while to hunt down a battery that was not too large in weight, size for reasonable capacity. In the end I came across these Samsung 10.4 Ah:
http://www.brightonebikes.co.uk/store/p2/Samsung®_cell_36V_10.4AH_E-bike_battery.html
They are relatively slim, and at 2.5 kg only marginally heavier than the 2 kg Cytronex NiMh battery they replaced. Quite nice looking too, as far as batteries go.
Bought from Darren at Brighton E-bikes, who provided great communication and customer service, and the battery arrived the next day after shipping. Recommended.
In terms of the transplant operation it was mostly straight forward, the only comments / snags of note:
- Motor axle and fork: Whilst the same fork/dropout specification, in reality slight differences in front fork shape meant I had to use some spacer washers to prevent the motor speed sensor magnets catching the fork. Some of these had to be 'open' washers since could not go over the motor cable connector.
- Electrics: As expected I had to cut all existing electrical battery connectors and crimp in some new ones. I removed the 5V lighting circuitry since I had already invested in separate lights. After removing all low current cable to lights, I noted being left with a single (yellow) thin wire linking the battery to the controller, which I was not expecting (I was only expecting 36V power supply cables to controller). I did not connect this little wire and it all works fine, so whatever it is, it seems optional! (guessing it is 5V in to the controller in the absence of which it must use an internal regulator).
- Pedal sensor: I had to order a set of 5 chainring magnets from Cytronex since the ones on the old bike were stuck fast. I only needed 4 for the chainring, the 5th magnet was used for the brake lever. Getting the chainring pedal sensor bracket off required local bike shop to remove and refit the bottom bracket to both bikes (I didn't have tools) which cost £40 (£20 per bike). It would have been cheaper to actually by a new bracket and sensor for £15 in hindsight and only pay for fitting to one bike. LBS did however manage to stop my annoying crank squeak...so the clean and grease was worth the extra. Much less clearance between sensor and chainring than on my old bike, I had to bend the bracket back on itself to create a little space. A bracket with more of a back-step in it would have been ideal, not sure if variations of the bracket exist for purchase. The bracket angle with respect to the frame matters, you need to be able to get to the back of it to screw in the sensor, also as to have clearance to be pushed back a bit and not contact the frame tubes. (recommend a down-to-forward position). This was the main obstacle.
- Brake sensor: I have hydraulic brakes which have different pivot points, but still found a position to glue the magnet that worked well (got to find a location that the magnet sits close enough to re-activate the switch, and moves far enough away to deactivate it)
- Tidying up: Getting all the wiring to sit within the cable tube was a bit like herding cats. Or maybe like opening a can of worms.
Anyway all works, and commuted on it today - I'm impressed!
I forgot just how much fun the little Tongxin setups can be. It is a comfortable bike, motor runs silently, and also has a silent freewheel on the rear as well so all very stealthy. Plenty of torque too, quickly gets up to 15 mph and drives up hills nicely with little hesitation. It feels really quick compared to how I remember it was before (I probably got used to a half-dead battery) - presumably that intoxicating feeling of unexpected silent shove must have been what it felt like the first time I rode one on a brand new battery. Great fun.
I will report on range when I have completed some more journeys.
I decided to electrify the new bike and combine the Cytronex set-up with a new lithium battery. I have been inquiring with Cytronex about the long-awaited lithium bottle battery but it didn't seem to be forthcoming (still in testing and development at the moment, I'm told).
It took me a while to hunt down a battery that was not too large in weight, size for reasonable capacity. In the end I came across these Samsung 10.4 Ah:
http://www.brightonebikes.co.uk/store/p2/Samsung®_cell_36V_10.4AH_E-bike_battery.html
They are relatively slim, and at 2.5 kg only marginally heavier than the 2 kg Cytronex NiMh battery they replaced. Quite nice looking too, as far as batteries go.
Bought from Darren at Brighton E-bikes, who provided great communication and customer service, and the battery arrived the next day after shipping. Recommended.
In terms of the transplant operation it was mostly straight forward, the only comments / snags of note:
- Motor axle and fork: Whilst the same fork/dropout specification, in reality slight differences in front fork shape meant I had to use some spacer washers to prevent the motor speed sensor magnets catching the fork. Some of these had to be 'open' washers since could not go over the motor cable connector.
- Electrics: As expected I had to cut all existing electrical battery connectors and crimp in some new ones. I removed the 5V lighting circuitry since I had already invested in separate lights. After removing all low current cable to lights, I noted being left with a single (yellow) thin wire linking the battery to the controller, which I was not expecting (I was only expecting 36V power supply cables to controller). I did not connect this little wire and it all works fine, so whatever it is, it seems optional! (guessing it is 5V in to the controller in the absence of which it must use an internal regulator).
- Pedal sensor: I had to order a set of 5 chainring magnets from Cytronex since the ones on the old bike were stuck fast. I only needed 4 for the chainring, the 5th magnet was used for the brake lever. Getting the chainring pedal sensor bracket off required local bike shop to remove and refit the bottom bracket to both bikes (I didn't have tools) which cost £40 (£20 per bike). It would have been cheaper to actually by a new bracket and sensor for £15 in hindsight and only pay for fitting to one bike. LBS did however manage to stop my annoying crank squeak...so the clean and grease was worth the extra. Much less clearance between sensor and chainring than on my old bike, I had to bend the bracket back on itself to create a little space. A bracket with more of a back-step in it would have been ideal, not sure if variations of the bracket exist for purchase. The bracket angle with respect to the frame matters, you need to be able to get to the back of it to screw in the sensor, also as to have clearance to be pushed back a bit and not contact the frame tubes. (recommend a down-to-forward position). This was the main obstacle.
- Brake sensor: I have hydraulic brakes which have different pivot points, but still found a position to glue the magnet that worked well (got to find a location that the magnet sits close enough to re-activate the switch, and moves far enough away to deactivate it)
- Tidying up: Getting all the wiring to sit within the cable tube was a bit like herding cats. Or maybe like opening a can of worms.
Anyway all works, and commuted on it today - I'm impressed!
I forgot just how much fun the little Tongxin setups can be. It is a comfortable bike, motor runs silently, and also has a silent freewheel on the rear as well so all very stealthy. Plenty of torque too, quickly gets up to 15 mph and drives up hills nicely with little hesitation. It feels really quick compared to how I remember it was before (I probably got used to a half-dead battery) - presumably that intoxicating feeling of unexpected silent shove must have been what it felt like the first time I rode one on a brand new battery. Great fun.
I will report on range when I have completed some more journeys.
