8fun conversion of new Carrera Subway Hybrid bike

FJJ

Pedelecer
Feb 7, 2011
76
0
West Lothian
After getting into ebiking with my Urban Mover UX33X which I bought at the beginning of the year, I decided that I wanted something which was a bit lighter, I could tinker with replacing parts as I saw fit and that had a bigger range. The obvious solution was for me to get a conversion kit and get building! I use my bike mainly for commuting where I drive to a park and ride then bike the 15 mile round trip into Edinburgh, however I do ocassionally do the 37mile round trip from the house, but this was definitely at the limit of the Urban Mover's battery capacity.

I settled on the 8fun kit eventually after much consideration and trawling of the internet. I liked the idea of UK support and quick lead times over BMS battery and at £440 delivered it seemed a reasonable price - I think I would have been around £100 cheaper going for the BMS battery kit assuming that their on-line shipping quote was correct at $125. I did consider the Juicy kit but it was that bit more expensive and I didn't like the seatpost mounted battery.

I purchased the bike on C2W from Halfords and got it in an offer for £280.

I went for a front wheel bafang 250w 36v motor and with a 9Ah Li-Ion bottle shaped battery and two chargers. I went for the front motor for weight distribution and ease of swapping to a regular rim if I want to go 'normal cycling' at the weekend, the bottle battery was again to aid weight distribution (as I generally have a laptop and a regular pannier on the back) and because I really like the pannier rack that I have as it has rails for the side mount panniers about 15mm below the top part of the rack meaning that it's really easy to fit and remove side panniers with a top mounted rack bag in place (I use it for a basic tool kit, waterproofs etc).

My kit arrived within 48hrs of ordering from 8fun and was well packaged. The instructions weren't great but I had a good idea what was required from reading the forum.

Step 1
I decided that the first job was to check that the motor fitted in the dropouts as I have a tapered fork; then to test it all worked. I removed the rim from the front of the bike then popped the new one on, it fitted perfectly and the anti-rotation washers were flush with the outer side of the dropouts, so far so good... I connected the motor up to the controller and the controller to the battery - I had to crimp some included (blue 15A) bullet connectors to the battery power cable. Initially nothing happened when I moved the throttle, but it seems on the control panel you have to press 'switch' to enable the throttle - so all was well and the kit seems to work perfectly.

Step 2
The next potential issue was the disc brakes so I removed the wheen and bolted on the disc from the old rim, it turns out the plastic spacer on the bafang motor needs to be left in place (i.e. between the motor and the disc), it's best not to tighten the bolts too much I stripped the threads a little on one of the bolts... On fitting the wheel, it seems that the edge of the motor rubs the inside part of the caliper just a little and that the I-160mm mounting adaptor for the caliper has a screw which is now rubbing the brake disc. Also just got a reply from the forum to say that the controller is water resistant, not waterproof so I'll need to deal with that too!

Step 3
I've made a shopping list and am off to Halfords, B&Q and Maplin! The list is: B&Q - M10 and M6 washers; self amalgamating silicone tape; black zip ties 100m and 200mm; a file; and a 15mm spanner for the hub nuts as it seems to be a size skipped in my spanner set! Halfords - A crank puller. Maplin - a 'General Purpose ABS Enclosure' 150x80x46mm IP54 rated for the controller; cheap multimeter as my decent one is on my boat; cable grommets 23.7mm diameter.

Step 4
I used an M6 washer on the brake mount post to stop the bolt rubbing the disc (stopped the bolt going all the way through the adaptor) then filed a bit off the back of the caliper hosing to stop it rubbing the motor. All seems good with the front wheel now so I took it off and popped a Kenda typre and innter tube in and inflated it to 65psi on the compressor. After that I mounted it and tightened it up properly. This 8fun motor has a side cable exit rather than the cable exiting through the spindle, would be great if that meant they could start to use QR skewers in them soon!

Step 5
I mounted the pannier rack on the back of the bike (A Topeak Supertourist DX Disc) and popped a Cateye LD600 rear light on the back of it. I then got to work on fitting the pedelec sensor as I will use it rather than using the throttle as I like to use low assist rather than a throttle (I do tend to switch it to high if it is tipping down with rain or I've been working late and I'm eager to get home!!). I used the crank puller and removed the RHS crank thinking that it would be much easier to mount it there than on the chainwheel side. It turns out that it can be held in place perfectly with a zip tie as the sensor lay flat against the tube. I popped the magnet disc on and tested it, but it only worked if I pedalled in reverse! I tried reversing the disc and the sensor but neither worked... So it was off with the chain wheel crank and time to pop to halfords for a bottom bracket removal tool! Once I got the tool the bottom bracket came out (you need a really big shifting spanner to use the BB tool) and I popped the sensor on, tested it and rebuilt it. Fortunately the sensor fits fine inside my cahinwheel. I then mounted the control panel on the handlebars.

Step 6
Time to wire everything up... I led and ziptied the cables from the motor and the control panel along the top tube to the rear of the bike and fitted the cage to hold the bottle battery in palace. I secured the battery power cable and pedelec sensor cables. I got the ABS box from Mapli and drilled two 19mm holes in the bottom with my holesaw for the cable grommets, and then fitted the grommets after filing the holes to smooth them. The grommets are much easier to fit if then are popped into a cup of boiling water for a minute. I then drilled a couple of small holes to secure the box horizontally on the arms that lead from the pannier rack to the frame lugs, zip tied it on and cut a couple of holes in the grommets. I fed the cables through and used the silicone self amalgamating tape to provide a better seal and seal between the multiple cables sharing the same grommets. Then I hooked everything up to the controller and put the lid on, easier said than done as it's a very tight fit in there.

Step 7
Mounted the battery, turned it on and went for a test drive! It was raining and 10pm so I just went for a spin around the block but all seems to be working fine.

Still to do - I need to sort out some brake cut-outs, the kit came with brake levers with microswitch cut outs but the levers I have are Shimano EZ fire which are integrated with the brake levers! I think I'll go down the reedswitch and magnet combo, I'll have a look at that over the weekend. I also have bits and bobs such as front light, computer, mudguards, pump etc. to fit and to 'slime' the tyres to help prevent punctures. I plan to get another rotor for my old rim so that I can use it as a regular bike too, with no motor and battery on the extra electronics and battery holder should only be adding a kilo or so to the standard weight. I also need to get my SPD pedals moved over.

I'll post some pictures soon and a review of the kit once I've used ot a bit. :D

Carerra Subway Hybrid 2011.jpg
 
Last edited:

eddieo

Banned
Jul 7, 2008
5,070
6
what do you expect te bike to weigh when finished?

I like this bottle battery kit, it looks good value
 

FJJ

Pedelecer
Feb 7, 2011
76
0
West Lothian
I'm thinking around the 21kg mark, book weight of the bike is 13.4kg, plus 6.5 for the motor and battery then another kilo or so for the pannier rack (not required for this kit), cabling, controller etc.
 

bluemoon

Finding my (electric) wheels
Nov 18, 2011
7
0
Cool look forward to the review particularly range and real world speeds as I am thinking of much the same conversion in the near future.
 
D

Deleted member 4366

Guest
A few suggestions:

The disk brake screws are not long enough with the spacer inplace. They'll strip as soon as you do an emergency stop. Yoy need to get some longer ones or get rid of the spacer.

The easiest way to do the reed switch (at least as far as the back brake is concerned) is to get one of those £2 bike computers from Ebay and cut off the sensor (reed switch) and then clamp the magnet to an exposed part of the cable like you clamp it to a spoke. You can cable-tie the sensor to your frame,

I thought 8Fun provided a special plastic box for the controller that clamps to the seat tube. I got one with my mark 1 kit. If they don't/didn't provide one, I've a spare one of these that you can have for cost price if you want it:
KU63 Controller Case - BMSBATTERY

Lastly, I heard somewhere that some bottle batteries let in water, so it might be a good idea to reseal it wit silicone sealant or whatever.

Hope you enjoy your bike.
 

x332race

Pedelecer
Nov 9, 2011
55
0
Would be interested in some photos. I have ordered a kit and battery from BMS due to be delivered next week so I will be going through a build myself.

Did you fit a torque arm to the front forks? I have aluminum forks and am paranoid that they will fail..
 

FJJ

Pedelecer
Feb 7, 2011
76
0
West Lothian
A few suggestions:

The disk brake screws are not long enough with the spacer inplace. They'll strip as soon as you do an emergency stop. Yoy need to get some longer ones or get rid of the spacer.

The easiest way to do the reed switch (at least as far as the back brake is concerned) is to get one of those £2 bike computers from Ebay and cut off the sensor (reed switch) and then clamp the magnet to an exposed part of the cable like you clamp it to a spoke. You can cable-tie the sensor to your frame,

I thought 8Fun provided a special plastic box for the controller that clamps to the seat tube. I got one with my mark 1 kit. If they don't/didn't provide one, I've a spare one of these that you can have for cost price if you want it:
KU63 Controller Case - BMSBATTERY

Lastly, I heard somewhere that some bottle batteries let in water, so it might be a good idea to reseal it wit silicone sealant or whatever.

Hope you enjoy your bike.
d8veh, thanks for the advice. Re the brakes, I got a couple of cheap reed switches from Maplins so will see how I get on with them.

Thanks for the pointer on the disc brake spacer, I think I'll remove it and move the calliper accordingly using a couple of washers, probably a much better solution as currently the rotor is a wee bit close to the outer pad.

On the battery front, I guess Li-ion doesn't need to vent whilst charging so it's safe to completely seal? I've got some plumbers mait in the garage which doesn't set so probably ideal incase I need to troubleshoot anything inside, I'll wait till I'm 100% happy with it first though so I don't loose my battery warranty!

I made up a controller case from Maplin and it will do the job, but thanks for the offer of the controller case - maybe 8fun don't supply them anymore.

Cheers,
Fraser
 

FJJ

Pedelecer
Feb 7, 2011
76
0
West Lothian
Would be interested in some photos. I have ordered a kit and battery from BMS due to be delivered next week so I will be going through a build myself.

Did you fit a torque arm to the front forks? I have aluminum forks and am paranoid that they will fail..
Will do over the weekend when it's light when I'm home :) I didn't use a torque arm as it's just a 250w motor on a steel fork, from what I've read that should be ok...
 
D

Deleted member 4366

Guest
Did you fit a torque arm to the front forks? I have aluminum forks and am paranoid that they will fail..
You shouldn't need a torque arm for a 250w motor. Hardly any of the ready-made bikes have them. Just make sure that the anti-rotation washers are installed properly and the the nuts are tight. If you have a BPM motor, you might get away with it, but it would be safer if you had at least one torque arm as you need to file the drop-outs quite a bit. If you need any help in this area, post again.
 

Scottyf

Esteemed Pedelecer
Feb 2, 2011
1,403
-1
On my rear bpm build I'm not running torque arms. Only the anti rotation torque washers. The axel was a tight fit but didn't need filing.

FrOnt wheel 250 should be fine without. As long as you have the washers.
 
D

Deleted member 4366

Guest
On my rear bpm build I'm not running torque arms. Only the anti rotation torque washers. The axel was a tight fit but didn't need filing.
Just as well you reduced your current from those 27 amps!
The back drop-outs are a bit stronger because there tends to be more metal around them and nowhere for a crack to start, but the front ones have a shoulder just above the axle, which makes a stress raiser so that the front bit of the drop-out below it pops off leaving the rider in a lot of trouble.
 

Scottyf

Esteemed Pedelecer
Feb 2, 2011
1,403
-1
I still pedal alot. Well all the time as I still like the exercise. But I probably should run a torque arm as a just incase safety.

The rear drop out on the bike is large though. Much more than the front as give said.
Maybe I should speak to a friend about cutting me some for a couple of beers. Could try get a few for other members if they want?!?
 

FJJ

Pedelecer
Feb 7, 2011
76
0
West Lothian
Took a picture yesterday, it's not very clear though - looks like taking photos using my iPhone when it's inside the Dahon Biologic case isn't a great idea... I'll try and get some decent ones next weekend.

I ended up putting new gear shifters on and getting rid of the combined shifter/brakes that were on there so I could use the levers with built in switches.

Got some mud guards on there today and my SPD pedals, first proper trip will be my commute to work tomorrow - looking forward to it!

eBike.jpg
 

jerrysimon

Esteemed Pedelecer
Aug 27, 2009
3,292
112
Cambridge, UK
Nice job. Enjoy riding it.

Jerry
 

Scottyf

Esteemed Pedelecer
Feb 2, 2011
1,403
-1
Good job. Let is all know how toy get on with it.
Brave man starting out commutes end november!
 

FJJ

Pedelecer
Feb 7, 2011
76
0
West Lothian
Well, got in fine this morning! Been commuting since Feb, tend to take the bike unless it's really high winds or if there's snow or ice.

Performance is quite different from the Urban Mover, it's a bit smother power delivery starting off and it's a little quieter, especially on hills. Hill climbing ability seems pretty good. Speed wise even on 'high assist' seems to taper off around 15mph, the UM did seem to have a little bit higher top speed on max assist, the level of assist also seemed a wee bit more, but this could be deceptive due to the 7 speed vs 24 speed gearing!

The controller case was cold to the touch so doesn't appear to be any issues having the controller in the plastic case.

All in all, I'm very happy with it. I did almost fall off though as I'd been doing all of my test rides at the weekend with regular pedals and I refitted my SPDs last night, 1st set of traffic lights I was almost over :confused:
 

Scottyf

Esteemed Pedelecer
Feb 2, 2011
1,403
-1
Good glad your happy with it so far and its not caused you any real problems.
Should be a solid build. Have you got any close up pictures of the bottle battery and its fitment?

As Flecc always pointed out that sometimes the weight of the bottle battery vs what the holes are designed for can sometimes put alot of stress on the fittings. But I guess time will tell.

Least it free's up the rack for more luggage options.
 

FJJ

Pedelecer
Feb 7, 2011
76
0
West Lothian
I'll get some closeups taken of the battery and fittings. The bolts and nuts at the bottle mount appear to be the same as those used for the upper pannier rack lugs so seem fairly substantial, I did consider using a bit of 'no more nails' tape on there, but it would likely remove the paint if I ended up changing it!

Does anyone have any experience of the 8fun control panel? It's got five LEDs on there for battery level, I are they reasonably accurate - I noticed one winking out when the motor was working hard once I was almost at work this morning - so after about 7 miles, does that seem reasonable for a cycle in on assist mode?
 

Scottyf

Esteemed Pedelecer
Feb 2, 2011
1,403
-1
The LED's usually work on a voltage amount.

So if it was 5 lights (I have the three light one) for a 36v type controller and battery the lights would sets for something like ...

1st light (Max) 41v+
2nd light....39.6v
3rd light....37.2v
4th light....34.8v
5th light (Out of battery) 3.24v or less...

This is all a guess to be honest but its generally how they work,. My figures won't be exactly right becasue of the voltage sag when you draw power. (Usually they drop a couple of volts when using power on a 36v batter and cell quality depending).
 
D

Deleted member 4366

Guest
I've seen the LEDs behave completely differently on similar bikes. The basic idea is not to take them too seriously. When you go up a hill, the battery voltage goes down a bit temporarily because of the larger current it has to give, so it's normal to see the higher LEDs go out. You can only get meaningful sense out of them after you've used your bike for a while and recognise how they behave. Maybe one day you'll flatten your battery, so you'll be able to fully relate the way the LED's go down with the battery, but try not to flatten your battery unnecessarily.