Project Pompetamine - On One Pompetamine & 8fun watter bottle battery build

[KirstinS]

Morning,

my wife just rang me at work to say my 36v 250w 8fun front drive kit has just arrived I'll be fitting it to an On One Pompetamine

I've read a few threads on this kit and seems each build/bike has its stumbling blocks. I thought I'd try to give something back to the forum by detailing in this post. Hopefully it will be useful to someone(most probrably me when I get stuck and need help!)

Biggest problem predicted is the the front hydraulic disc brake (shimano m535 180mm rotor). I doubt very much that caliper will fit once the motor is in place. Either a new 203mm disc or possibly even a new front fork will be required

I'll get cracking this afternoon when I get home

 

[bazwaldo]

Hello Kirstin S,
This comes as a bit of a blow.
Because of your forum name I always assumed that you were a particularly well informed female fellow forum member!
Good luck with your new ebike project it will be interesting to hear how it goes.
Best wishes,
Barry.

 

[KirstinS]

Very sorry to disappoint there bazwaldo !

So conversion got off to a shocking start. The new motor hub will not fit I to the forks. They are 100mm wide at dropouts but narrow immediately. Forget room for calipers and disc rotor

Photos of bike and fork issue attached

Trip to lbs at lunchtime to see about a new fork I guess

Current one has 45mm take so guess I need to retain that ?

 

[KirstinS]

I should mention that my current fork is this one here

On-One Pompetamine Cr-Mo Urban Fork

If anyone is able to recomend a fork that will fit my bike AND the new hub then I'd be most grateful

 

[KirstinS]

a not so quick trip around 4 x LBS confirmed what I always knew - 3 of them are worse than useless

The other is excellent and recommended a Surly rigid fork that is both bombproof and wide enough to retain discs and calipers. It also has canti brake option

only downside is Surly take a Henry Ford approach to colour schemes - you can have anything as long as its black. Seems I'm going to have to sacrifice the asthetics

 

[KirstinS]

Today's lesson for me has been one needs to remember that wheels with a six hex bolt method of attachment take up way more room/width than the centrelock kind. So I'll be needing a new rotor as well as a new fork. Hoping this is the end of the purchase list required .....update tomorrow once Lbs supply the necessary forks (and fit as they'll do it for free while I'm at work)

 

[jackhandy]

Rotten luck with the clearance between motor & fork. I thought I was going to have the same issues when I checked the dimensions on the tech. drawing of the 8fun motor, but got away with it by a fag paper. It's tempting to bung a washer or two between hub & dropout, but then the torque washers don't have a lot to work against.

I had to fit a 185mm disc & caliper adaptor & I sometimes think I can hear the spokes singing as they pass the caliper, it's that close!

Best of luck with the rest of the project - I'm really enjoying riding routes I would have jibbed at without the assist.

Pete

 

[KirstinS]

Thanks pete - nice to hear of success ! Particularly as my bill just got bigger

In the end I've needed a new fork, new 203mm rotor and adaptor - I'm WAY over budget but cautiously confident that's it . Turns out my caliper really sticks in towards the wheel hence even a 180mm rotor wouldn't work. I'm clearing spokes by about 1.5mm !

Pics attached

Had to cycle back from LBS and really noticed the drag from motor more than extra weight. Hope this frees up a bit (won't make a whole rotation at present if spun by hand)

Hoping to fit electrics this evening once kids in bed

 

[KirstinS]

Oh dear , fitted everything but throttle not functioning , pedelec turns motor , dash board lights up, full battery lights . Only spun the pedelec sensor on the end of screwdriver to see if motor connections are ok- it turns so must be

I think the throttle must be defective in some way?

 

[shemozzle999]

Did you select an assist level ( low, medium or high ) before trying the thottle?
Some systems require you do this to activate the throttle.

 

[KirstinS]

Yes thanks , I tried everything including riding in case there was a low speed cutoff . 8fun confirm you need to hit the switch button on this system and use l/m/h assist settings for pedelec. However, no joy with this throttle

Still Paul at 8 fun was very responsive and agreed to send new throttle today (he emailed me back within an hour at c10pm at night)

Hopefully this will fix although I suppose it may be the wires in/out of controller .....fingers crossed

 

[KirstinS]

Pompetamine is go !

Knowing I had a new throttle in the post I took the old one and connectors to bits and resoldered the lot. Voila !

And went for a spin ( just on throttle ) with cables everywhere

Brilliant rotor rubbing but otherwise great . Pulled me up the dirty great hill with 20% effort at a guess. That's all I needed

Just cables to tidy and pedelec to fit

 

[jackhandy]

Glad you got it sorted: Everyone is different, but I find I use the pedelec on low & medium assist most of the time & hardly use the throttle at all.

Is the motor still dragging, or do you not notice it now?

Pete

 

[KirstinS]

Motor does feel like it is dragging and there is a knocking noise on each rotation. This was quite strong but is much less noticeable after jut a few miles. To be honest I'm not sure what noises are coming from motor and what from the new rotor/brake bedding in

I'll just run them for a while and hope it beds in

 

[Deleted member 4366]

Motor does feel like it is dragging and there is a knocking noise on each rotation. This was quite strong but is much less noticeable after jut a few miles. To be honest I'm not sure what noises are coming from motor and what from the new rotor/brake bedding in

I'll just run them for a while and hope it beds in

Should be a one minute job to sort. Remove the two screws that hold the brake caliper to let it hang by the cable; spin the wheel in the forward directiion - should spin freely (you can use the throttle to test it at speed); re-assemble the caliper to see if there's a difference. Most likely the disk is rubbing, but it's much better to get it sorted than worry about it!

If you need helpto get the caliper properly adjusted, ask again. Sometimes the motor set-up doesn't allow for correct adjustment, so you have to get the file out.

 

[KirstinS]

Thanks d8veh, part of the reason I have left it is the old rotor was not very deep and did not wear on entire pad. New rotor is deeper and so the unworn part of the pad is rubbing. It'll wear down soon enough I thought !

The freewheel capability is a bit different

Question is this - how much freewheel should I expect from this motor. One or two revolutions if spun by hand?

I do realise this is near impossible to answer but any pointers from your treasure chest of experience is much appreciated!

 

[KirstinS]

My thoughts so far on completed conversion after around 100miles

1)The pedelec doesn’t suit me - I don’t really like the way assist/leg power ratio works. So much so I have removed it to reduce wiring. Throttle all the way

2) The motor functions as I thought it would - I get 14 mph on the flat unassisted (GPS) and it provides good assistance up steep hills whilst still requiring input

3) The motor functions better than I thought it would when the weight on bike goes up. I feel little difference when its just me on the bike compared to me and my 3 year old son and his centre mounted seat (whichs weights 4kg on its own). So better torquey power than anticipated

4) The motor is much larger than seems really necessary - I hope because its bullet proof but I reckon it can also take a whole lot more than 36v 14amp (search on this site seems to confirm)

5) The 9ah battery is lasting me about 30miles - far better than I had hoped. Perhaps this will drop as I become lazier and more reliant on the motor ! Battery life is extended to 30miles when I use throttle rather than pedelec as I only take power when I need it

6) Motor has significantly freed up. It would only manage a few rotations when spun by hand at the start, now spinning freely

7) There is WAY too much wire supplied - to the point where it feels like you could fit the kit to a tandem. Yet a bizarrely short battery wire so you choices of controller mounting location is very limited. On the whole not especially well thought out. I will aim to cut these back to size and resolder….but I'm also realistic and this will probably stay like it until Christmas.


Things left to do

1)Properly tidy up wires and controller into a frame mounted triangle bag. I am repurposing a old doc martin leather boot for this (so it matches my the various tan leather grips/toolbag/brooks saddle)

2)Enjoy !

Overall very happy with finished result and real world tests. I can take my boy out for much longer trips on seafront/south downs which he loves (I live in Brighton). Our range and things we can do have hugely increased as a result. Two happy chappies


I will post a photo of the finished article in due course

 

[IanA]

Motor 'drag'

6) Motor has significantly freed up. It would only manage a few rotations when spun by hand at the start, now spinning freely

Sorry to be replying so late to this post but thought I needed to question the motor drag so that nobody mistakes ill fitting rotor bolts for drag.

The Bafang motor that came with my 8Fun kit came with small bolts for a disc rotor. I then bought a new 203mm disc rotor which came with it's own longer bolts. When I fitted the rotor the first time I used the higher quality Avid bolts that came with the rotor and the motor then appeared to drag. I quickly changed to the smaller bolts and the motor instantly freewheeled with no drag whatsoever.

So I presume the motor hasn't got enough room for normal bolts and that's why they supply smaller bolts with the kit. I've heard people say that after a few miles the 'initial drag' of the motor wears off but in reality what has probably happened is the longer screws have gouged a groove into some internal plastic or soft metal part of the motor so it's no longer rubbing as much!

 

[jackhandy]

OUCH! That sounds expensive.

 

[KirstinS]

My drag was in part due to the motor but in part due to poorly setup pads rubbing. Hard to know which was worse but all fixed

Use my bike everyday for commute. And love it everyday too

Yes you can get better but for the money with a uk guarantee I'm not convinced you can get better value