My ePOXY solution to everything
23” Specialized Hardrock Sport Disc (2011) conversion using 8Fun kit with 9A 36V bottle battery and bafang 8Fun 36V 250W front wheel hub motor.
Part 1
I hope this step-by-step picture guide to overcoming the obstacles I faced when building this bike might give people some good ideas and if anyone has any good ideas for me then please let me know.
I suggest to anyone performing a similar conversion to follow the suppliers instructions as much as possible and to see this guide as a list of alternative ideas that may or may not be useful.
i.e. FOLLOW THESE IDEAS AT YOUR OWN RISK!!
My aim…
To start cycling again after a few years out of the saddle, to get fitter and TO HAVE A BIT OF FUN!!! - call it an antidote to national and world news.
I’ve been wanting an ebike of my own since my wife bought a Wisper 905SE Sport just over 18 months ago. We are both very tall and she just about manages with the Wisper’s 19” frame but I need an extra long seat tube and even then it’s way too small for me.
Most manufacturers build one-size-fits-all ebikes which is understandable due to the expense of having a range of sizes. Those that do produce larger frame sizes in my opinion have failings elsewhere, so I feel I have no alternative but to build my own.
Building my own also satisfies another concern I have – that this technology is still in it’s infancy and is changing from year to year, rendering any electrical components obsolete within a few years so I’d like to be able to keep the bike but upgrade the kit every few years.
Most of all, having done a lot of cycling (albeit many years ago) I wanted a FUN bike that felt as much like a normal bike as possible but also had an electric motor to assist when needed. To that end I wanted a full range of gears and for the bike to be as light as possible for it’s size so that I’m not totally dependent on the motor. If the motor fails I still want to be able to cycle home up all the hills (slowly!). I also expect that with a full range of gears I will be able to do more work myself, by selecting ‘inbetween’ gears thus saving power & allowing me to have a smaller battery. I find with the Wisper I frequently have the choice of a gear that is too high or too low and my solution is always to let the motor compensate for my lack of gear choices – and that is an extra drain on the battery.
So, I have taken a quality standard bike and added a kit which I see as disposable. I may be able to upgrade it in years to come but if all else fails I should always have a good basic mountain bike.
The anticipated problem areas…
23” Specialized Hardrock Sport Disc (2011) conversion using 8Fun kit with 9A 36V bottle battery and bafang 8Fun 36V 250W front wheel hub motor.
Part 1
I hope this step-by-step picture guide to overcoming the obstacles I faced when building this bike might give people some good ideas and if anyone has any good ideas for me then please let me know.
I suggest to anyone performing a similar conversion to follow the suppliers instructions as much as possible and to see this guide as a list of alternative ideas that may or may not be useful.
i.e. FOLLOW THESE IDEAS AT YOUR OWN RISK!!
My aim…
To start cycling again after a few years out of the saddle, to get fitter and TO HAVE A BIT OF FUN!!! - call it an antidote to national and world news.
I’ve been wanting an ebike of my own since my wife bought a Wisper 905SE Sport just over 18 months ago. We are both very tall and she just about manages with the Wisper’s 19” frame but I need an extra long seat tube and even then it’s way too small for me.
Most manufacturers build one-size-fits-all ebikes which is understandable due to the expense of having a range of sizes. Those that do produce larger frame sizes in my opinion have failings elsewhere, so I feel I have no alternative but to build my own.
Building my own also satisfies another concern I have – that this technology is still in it’s infancy and is changing from year to year, rendering any electrical components obsolete within a few years so I’d like to be able to keep the bike but upgrade the kit every few years.
Most of all, having done a lot of cycling (albeit many years ago) I wanted a FUN bike that felt as much like a normal bike as possible but also had an electric motor to assist when needed. To that end I wanted a full range of gears and for the bike to be as light as possible for it’s size so that I’m not totally dependent on the motor. If the motor fails I still want to be able to cycle home up all the hills (slowly!). I also expect that with a full range of gears I will be able to do more work myself, by selecting ‘inbetween’ gears thus saving power & allowing me to have a smaller battery. I find with the Wisper I frequently have the choice of a gear that is too high or too low and my solution is always to let the motor compensate for my lack of gear choices – and that is an extra drain on the battery.
So, I have taken a quality standard bike and added a kit which I see as disposable. I may be able to upgrade it in years to come but if all else fails I should always have a good basic mountain bike.
The anticipated problem areas…
- How could the hub motor fit on a mountain bike with front fork suspension and discs? Answer: motor fitted upside down for forks to avoid cable coming out of the motor and a 203mm disc rotor was needed to replace the standard 160mm disc (along with a 203mm brake calliper post mount adapter) to give enough room for the calliper to fit with a hub motor.
- How could I fit the pedelec magnets disc and sensor with a triple chainset and no axle available on either side? Answer: by attaching to the crank arm on the other side to the chainset and by moulding new fittings using epoxy resin (Ding All) surfboard repair stick!
- Where and how would the control box fit? Answer: on the seat tube extra water bottle mounts after some serious modifications to the supplied control box housing.
- Would all the cables reach on a 23” bike? Answer: Yes, in fact the battery cable is about 1 metre too long!
- Would the battery last long enough i.e. would my theory about the gears and the weight save enough power to cover good distances. Answer: Early days, but surprisingly good – the 9Ah battery appeared to outperform the Wisper’s 14Ah battery at the weekend (we did 34 miles). Mine still had enough for a few more miles whereas the Wisper’s battery was really flagging at the end. We shared the bikes, swapping over every few miles, so I’m assuming they both had similar demands put on them – primitive, subjective, non-scientific test – I KNOW! – but it makes me feel good, so it must be right!
- Would the bike be too heavy to ride as a normal bike and would the weight distribution upset the feel of the bike? Answer: It’s only 21kg in total and I’ve very quickly got used to the extra weight that I no longer notice it. In short it feels brilliant! (and very alive compared to the Wisper – my wife is getting jealous). I also have the option to fairly quickly swap over to the original wheel and go for a ride without the battery and it really would be very close to being the original bike.
- How waterproof would the kit be? Answer: Still don’t know as I haven’t been out in the rain yet.
- Would the kit be good enough quality? Answer: I am exceeding relieved to say that it appears to be far better quality than I expected. However, time will tell and I shall try to keep this forum posted if anything goes wrong. I am expecting to be able to get spare parts from the 8Fun shop on ebay as they seem to be very keen to help in whatever way they can but failing that I expect to be able to get alternative parts from people like BMS battery via China if necessary.
- Would the controller give smooth power transitions or would there be a ‘wall’ at 15m.p.h? Answer: No wall at the top end – tapers out very smoothly. Smoother than my wife’s Wisper when setting off and at low speeds. It’s equally smooth on all 3 power settings: low (up to 9.5 m.p.h.), medium (up to 12.5 m.p.h.) and high (up to 15 m.p.h.)
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