Pre-conversion help/research

[dan3572]

Looks like plenty of space on the mostly flat top tube.

If you mean on top of the top tube then yes but I was worried about the weight up high.

 

[Woosh]

you shouldn't place the battery on the top tube, it's not protected by the frame and can easily be ripped off the frame in a fall.
You can mount the battery under the downtube like in this example below but should strap the battery just in case you hit a pothole:

 

[dan3572]

I'd have to check the clearance very carefully in that position due to the wheel size and headtube angle i.e, with the forks fully compressed.

 

[dan3572]

Looking at the bike again this morning, I'll need to make fairly accurate templates of the available battery boxes and where the motor sits to see whether there's clearance under compression if placed on the underside of the downtube as it'll all depend on the taper of the box. I don't hold out much hope but it might just fit.

Otherwise I'm thinking a smaller battery and carry a spare or back to a bag on the basis it'll be fair weather riding.

It's that or buy a second hand electric hardtail with much lower spec components and heavier frame.

 

[Woosh]

Looking at the bike again this morning, I'll need to make fairly accurate templates of the available battery boxes and where the motor sits to see whether there's clearance under compression if placed on the underside of the downtube as it'll all depend on the taper of the box. I don't hold out much hope but it might just fit.

Otherwise I'm thinking a smaller battery and carry a spare or back to a bag on the basis it'll be fair weather riding.

It's that or buy a second hand electric hardtail with much lower spec components and heavier frame.

you have to be very careful but I think you can still fit the HL battery under the downtube. It's rare than riding on made up roads and unchallenging trails would compress more than about half of your 80mm travel. You can increase the compression stiffness and cover the battery at contact point with aluminium sticker to avoid accident.

 

[dan3572]

Measuring some more I've concluded the underside of the downtube is a no go. Given that she'll only want to go out in decent weather and not that often, I think I'll go for a bagged battery like the one in the earlier link. The cardboard cut out is based on the larger one which I think should be ok but I'll check further before ordering.

Regarding the motor, it seems like it should be ok to me but I'll need to either use a chain ring close to the same as the current middle ring or fit a custom 42t which takes it out to more or less where the current outer ring is now to avoid fouling.

Various pictures attached.

I'll have to send the shock for a rebuild too as it's leaking out of the lock lever or adjustment ring.

 

[vantage]

First time posting here but I've been a cyclist for 35 odd years so I hope my advice from my limited experience of ebiking is helpful.
Have you considered the Bafang BBSO1b 250w 36v model? A bottle battery rated at 36v 10ah will work nicely with your wifes bike.
I've only fitted my own BBSO1b to my touring bike just over 2 weeks ago and tweaked the software as I wasn't all that keen on the default settings. I know what you're thinking. Tourer. Not a mountain bike. However, I take my tourer mountain biking! The added weight of it already being a heavy brute and the lack of suspension make things a bit more fun and to be honest, the Bafang takes it all in it's stride.
I'm running the stock 44t ring with a 11-36t cassette. Chainline isn't great but I'm hoping to fix that with a 42t chinese offset ring. Not quite a blingring but from a report I read on this forum, it's better than bafangs offering.
My own battery is a downtube mounted 36v 20ah brick and I've had a good 50 miles out of it with 5-6 volts of useable power left. How far those last volts will go is untested so far but I would think a 36v 10ah bottle job would see your wife 20 miles easily based on my simpleton thinking. From what I've seen, most of these things are water proof/resistant and are small enough to carry spares if extra distance is in the menu.
I did try an aftermarket 36t chainring but it seriously messed up the chainline.

 

[dan3572]

That's the motor I'll be using. I don't think the 10 ah bottle type batteries will fit within the triangle either.

Now to work put where to buy from. I'm happy to buy from a reputable supplier in China but also willing to pay a reasonable premium for UK supply but stock seems low. I'm not yet sure what the savings are from self import.

 

[dan3572]

My cube is a 19 .5 and had to get a custom 20 ah pack it has the bbs01 250watt max 12 amps 48v fitted

Where did you buy your custom battery (and motor)?

 

[peter.c]

First option bbs01 48v from ebay uk stock
But was cheaper form https://www.risunmotor.co.uk/ options from £362 be sure to check the uk option
checked price today still same and in stock v-good price pay and then sent from uk warehouse
Battery from https://www.dhgate.com/product/strong-endurance-liitokala-48v-20ah-48v-lithium
only option /luck they had a size option that would fit takes months to arrive by boat from china .
Battery covered in 1mm hips plastic sheet then shrink wrapped and hidden under a cheap water proof battery cover

 

[dan3572]

After a lot of looking around I found a decent price for the motor from someone with UK stock but the price difference for the battery from the UK means I prefer to order from China (same model) which means I might as well order the motor kit from China too (as it works out cheaper with the gear sensor and a better chain ring choice).

One question, the supplier lists the 860c display but I notices there is a P860C and an 860C. Any idea what the difference is?

Thanks.

 

[peter.c]

Battery from china might well come by boat can take months ,check if vat and customs is paid in the price or extra and needs to be paid by you
Some of the newer displays can be used on different protocols that are for the new bafang motors my latest 850c has just one page just for basic motor and wheel size settings but 4 for the battery that required a paired bafang battery to be used

 

[dan3572]

Parts ordered. I ended up getting what I think is a decent deal all things considered from a UK shop. There's no going back now! Thanks for all the help and fingers crossed for a smooth build.

 

[dan3572]

A quick update. I've had a busy weekend so haven't done much.

The kit arrived and apart from the wrong 46T rather than 44T chainring being supplied (boxed up wrong in China by the look of things), it all looks good.

The battery fits the space with the bag but the routing for the battery wiring isn't obvious so I've asked for the supplier's advice rather than struggle with it. I'll explain more once I've sorted it or if I need help.

I've removed the cranks, bottom bracket, front mech and shifter and offered up the motor.

The good news is it fits. However it will need a smaller chainring. A 42T bling ring would probably do it but I may go for a 40T. However, the chain line looks good so with the bling rings I think I shall need two or three spacers depending which I go for.

I'm not sure how I shall route the cables around the motor. I think there is probably room for them to go between the bottom bracket housing and the suspension arm cross member if some go each side but I want to see what others have done to keep it reasonably neat. Doesn't look easy.

I'm also considering where to put the gear change sensor. If it can't be on a section of exposed inner cable I might add two pieces of outer with the sensor in between where the exposed section is between two guides on the underside of the top tube. I've not checked the wire lengths yet though.

Then there's the hydraulic sensors. I need to read up on them as I have no idea at the moment. Other things I'm wondering about are whether the bottom bracket thread should be greased as a bottom bracket would be or some thread lock added, whether I should be greasing the gears before fitting, whether to add some protection such as innertube rubber between the motor and downtube in addition to the helitape already fitted....

I'll add some photos of the build as it progresses but for now I'll be ordering and waiting for parts and sending the shock off for a service.