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I have an ailing friend who cant afford an ebike but would like to go down the diy conversion route. She hired one recently and it made a massive difference to her ability to ride again.
So, she would like a tongsheng tourque sensing motor unit. She doesnt have a frame at the mo but i have lots of build parts to help her out. If we are looking for a HT frame, other than cables/hoses under the BB shell is there anything we should avoid?
Is boost chainline ok? Or would standard be better? I think 1x10 will be fine for her, but ive seen some conversions where the low gear limit screw on the rear mech is used to stop it going into the bottom 1 or 2 gears. Im assuming this is a bodge due to dreadful chainline. How can i avoid this?
She has seen a Sonder Frontier frame secondhand, but it has cable exits low on the downtube? Is this ok as they can be routed around the motor unit?
Finally, is a rack mounted battery better than a downtube mount?
Any help will be greatfully received!
Ian
The key thing is that the chainstays are not too wide - IIRC you need 3" from the centre of the BB shell that is flat along the chainstay on the drive side ie the chainstay does not come out wider than the BB shell - you can fudge a few mm with spacers
I had no issues with 9 speed - usually the chainline ends up too far out but I had no issues. they come as standard with an offset chainring
Woosh bikes I found very helpful
There is usually a small amount of clearance to run cables between the BB shell and motor but its very tight - can be a pain
the anti rotation clamp can also be a right fiddle to get right - I have resorted to making up my own on some frames ( I had my motor on 4 different frames)
Downtube mount battery usually needs at least one extra rivnut put in for stability
I've recently done my old Charge Cooker 3 HT with the tongsheng and it's been great for me (knee replacement and heart issues).
1 x 10 is working fine for me with standard hub spacing (135mm??) and chain line being ok. I have a 11-42 rear cassette, so bottom gear is 42-42, I used a Shadow deore RD which is great for the 42t sprocket.
People have rerouted brake hoses and gear cables around the motor where they come out the down tube at the BB. A full length gear cable from shifter to rear mech means you can just cable tie it where suits best.
I got the 48v 20amp 960wh down tube battery. It's a bit of a beast and mounting it was my only concern and ive ended up buying a separate adapter to mount it. Adapter. If I was getting such a big one in future I'd put it on a rear rack for easier and a more secure mount,or get one of the frame triangle ones that seem to fit in the space more securely.
I bought a new carrera subway frame for £35 off eBay. It has all fitted perfectly.
Just be aware that the pedals have different spacing. My knees would suffer after a mile some people don't even notice. They can be levelled up with bafang cranks and pedal extenders. Mine are 10mm different now.
I've just been through a lot of research and chainstay clearance is the big issue. I got a Second hand voodo bizango and it just works. You need to space the motor out by about 3mm to clear the chainstay. But a great donor bike I reckon as there are loads of second hand good condition ones on eBay and the spec on them isn't bad.
Have converted 3 bikes now, two for my wife and one for myself.
Best/easiest was a Go Outdoors 29er (Point 9 or something iirc) with an ‘old school’ type alu frame with relatively narrow gauge tubing.
Also converted an On One Big Dog and a Titus Fireline.
I’ve found that 9/10 speed works better than 12 and indeed with the assistance is all the gearing you need. Since the Tongsheng delivers power best at lower cadences you don’t need massive dinner plate rear sprockets in our experience. Seems to help with the chain line not affecting shifting as well.
All 3 of ours have Leckie branded cranks which reduce the Q factor issues as well as looking like 90s CNC bling! Have also fitted N/W chainrings to a couple although the standard ring seems to be fine too.
Both the steel and alu frames had extra riv nuts fitted to hold the batteries a bit more securely, the Ti Titus has a smaller battery anyways so just used the bottle cage bolts and a couple of straps round it.
Cables under the bottom bracket needed some careful fiddling at install time, and like TJ I’ve found the anti rotation bracket a bit difficult to fit so have used a variety of home made substitutes.
I actually prefer the way mine rides to my Orbea Uurun!
I just ran my cables over the top of the BB .
Ps buy a black bike it hides all the zip ties you will need for the cables!
PPS buy the vlcd6 display( the small one) the big one takes up so much room and lights are difficult to fit.
My noble steed.
Thanks all. It seems that last get frame and drivetrain will be the way to go here. I will try and find her a 29er that will do the job.
I shall keep you all posted
Thanks
Ian
@mattbee what are your crank distances from the centre line?
I’ll have a measure tomorrow when I’m home.
I put a Tongsheng into a mid range Niner donor bike from Gumtree. Really enjoying it for localish off road fun, mainly getting to the woods and hooning home on the big soft tyres.
All very good advice above. Easiest way to carry the battery is in a small frame bag. I use a Lomo frame bag, keeps the connectors dry as well.
I bought the 10Ah battery from Whoosh, and the motor itself. The battery is a bit smaller than a fat brick and does me fine, I am usually on the lowest setting and just go to the higher settings briefly for big hills or off road climbs. A bigger battery might allow a less careful approach on the power settings
Hi, does anyone know if it's ok to block the small hole at the bottom of the drive side crank case? It's right on the bottom below where the wires go in
The reason I ask is because a little while ago I went through water that was too deep and Old Sparky didn't like it one bit!
Luckily he's still working, but seems a good bit noisier, so I've just stripped it all down to clean out and regrease it all. Looks like water has got into the electric motor side of it too judging by the frothed up dried/fried up grease in that side. Everything looks fine though, gears are all intact and bearings seem good.
Anyway I can't see a reason for the hole in the bottom of the crank case other than to let anything that gets in there out, but obviously it also lets water and potentially muck in there. Surely it's a bit of an obscure way to ventilate the motor, which is on the other side of the crank shaft? Does the electric motor even need that?
I'm thinking to gaffa tape it or bung it up as I can always remove it from time to time to see if anything needs to drain. Any thoughts on if this is a bad idea??
Edit: just had another look and wondering if that hole and where the big cables go in are where the water got in. Presumably I can just silicone seal it all??