Hello. I'm about to set off on the above build. Before I get stuck I was wondering if anyone reading this has built this combination before and if spacers are needed on the chainring side so that the motor assembly doesn't touch the chainstays when tightened down. If they are needed then what thickness is best? I'm expecting that I will need to exclude the lock ring if spacers are needed. Any advice appreciated.
BBS01 + Boardman MHT 8.6 27.5". Spacers?
- Thread starter Andy321
- Start date
Its not the latest model but the last model with 27.5" wheels. I took inspiration from the fact that the person here seems to have been successful although theirs was a BBS02 so might be a little different.
Ive just checked what i have now as stock. 34 tooth sprocket going to a 10x 11-46rear which I find perfect under human power. Tooth tip to chainstay gap of 4mm at 72mm away from the crank centre line. My kit has the Bafang 44t so I might find that needs swapping out for a smaller bling ring. I expect I will just have to suck it and see. If it looks like a no go even with spacers and offset sprocket then I might need to find another bike for this project.
My bike is a 148mm rear axle with a 1x11 cassette so the chainstay is quite wide. I tried the templates for tongsheng, bbs02 and bbshd and found the bbshd was the best fit. The bbshd has a larger but thinner main gear than the bbs02. There is a video on that bafang USA site where they found the same with their example bike. The bbshd also has a slightly longer threaded area for the locknut,
I had a job to get it to fit optimally but got there in the end.
I needed a 5mm spacer and I filed a depression in the back of the gear casing to allow me to get it in tighter to the chainstay.
I took about 1.5mm off and carefully measured the wall thickness of the casing before doing this to ensure I didn’t compromise it.
I also had to cut a 3mm thick ring off the other side of the bottom bracket so that I could get both lockrings on; I’ve effectively converted it from a 73mm bottom bracket to a 68mm.
Finally, I used a Leckie Pro 40t Pro chain ring which has the biggest offset and gives me a perfect chainline. I did a gearing spreadsheet and worked out this would give me 38mph which is way plenty. My cassette is 51 to 11t. The leckie ring was expensive but worth it.
I spent ages on all this stuff, but hopefully worth it.
I had a job to get it to fit optimally but got there in the end.
I needed a 5mm spacer and I filed a depression in the back of the gear casing to allow me to get it in tighter to the chainstay.
I took about 1.5mm off and carefully measured the wall thickness of the casing before doing this to ensure I didn’t compromise it.
I also had to cut a 3mm thick ring off the other side of the bottom bracket so that I could get both lockrings on; I’ve effectively converted it from a 73mm bottom bracket to a 68mm.
Finally, I used a Leckie Pro 40t Pro chain ring which has the biggest offset and gives me a perfect chainline. I did a gearing spreadsheet and worked out this would give me 38mph which is way plenty. My cassette is 51 to 11t. The leckie ring was expensive but worth it.
I spent ages on all this stuff, but hopefully worth it.
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Thanks for sharing this. It looks like a great build! I'm going to keep mine with the boring 250w. My hope is that it will be just enough to take the edge of a 1mile drag that I have to do coming home from work. Your chainstays are similar to mine so I think I my be in for a lot of work or another bike with a better chainstay profile.
I can't advise on the fitting issues, but I have the 250 watt BBS01, Bafang motor and I am really pleased with it. You mention 'boring', well it is certainly no motorbike, but it will help you along pretty well, and it will certainly take the edge off those hills. Mine has a throttle on it which I only use momentarily to take off at a junction where I am crossing a road, just to get safely out of the way, and I also use it sometimes on a really killer hill. On my set up, if I am in the highest pedal assist mode, the throttle allows the motor to draw about 600 watts, which is a huge help on a bad hill. I try not to use that though for long and only when I really need the help, because I don't like to pull a lot of amps through the controller. I am probably being over cautious, but there we are.
Another good thing about the BBS01 is that mine is virtually silent even when working hard. I can only just hear it if I try, so you get a very nice relaxing riding experience.
Don't be surprised in low gears that the pedal assist cuts off at low speed. When I first rode mine, I thought there was a fault, but the controller seems to limit the revs of the crank gear and stops assisting. This may be to do with the programming of your particular controller. This can be changed by users via a special usb cable Bafang sells. I haven't touched that. It is set at thevalues put in by the builder of the bike, Billy Milburn of Esh Winning near Durham. Changing up the gears of course lets the motor start up again and will get you up to its top speed.
Issues to watch out for during the running in period - if you start to hear creaks from the bottom bracket area, back off the outer alloy lock ring and tighten the large crank nut which secures the motor. If the motor has moved, readjust before tightening. This is a very common thing on builds and I had to have a go at mine about three times in the first couple of hundred miles. In the end, I hammered it tight using a centre punch and a good sized hammer. No more loosening after that. The nut is large and hard, so aside from the small punch mark, no marring. It needs to be REALLY tight.
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Thanks for the info and tips. Im looking forward to getting the kit fitted to whichever bike I settle on. Ive seen a second hand Ceres PT2 hybrid which might be a bit easier to work with.
I have a Boardman 8.6 with BBSHD you will need a few spacers 4-5 mm for the reduction gear to clear the chainstay you will also not be able to use the largest gear (1st) as the chainline is not very good but i have over 1800 miles on mine with no issues spacers from Ebay item number 184854041213
All finished and Ive been riding it for some weeks so I thought time for an update and pictures. Build went well apart from the moment that I forgot that the Bafang pedals were handed just like the ones I had just removed from the bike! Also found the little screw that holds the plastic runner for the gear change cable in place under the Bb was too long and stopped the motor assembly pushing all the way through the Bb. I soon sorted that. Battery is a tight fit. I used one of the existing bottle cage screws but I need to fit a rivnut further up the tube for the top fixing. It's bodged together with blutack at the moment. Used filed down 10mm spacers to pack out as seen. With the 3off 1.2mm bb spacers in place (to have the motor gear housing clear the rh chainstay) this build does not allow for lock ring but rather than use locktite on the threads I've gone with a single big blob of regular household paint on bb nut and all other cap heads etc that I don't want to come undone. My plan is to check the paint blobs every month to make sure it's all hanging together. Went for a ride before fitting battery to check out chain line. Although selectable it didn't sound too good in 9 or 10th so I made a mental note to try to avoid them if possible. Turns out 8th is more than low enough for the steep hills around here. Might have something to do with the 27.5" wheels and my 44 tooth front bafang sprocket. I found my 108 link chain a bit tight so that's now a 116. 500c display is great 12.5ah 36v battery does 2 work trips, around 30 miles easily all on level 9. It's really quiet too. I have a programing cable but tbh I may not mess with settings as its doing all I need from it. Great fun!
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An increasing creaking noise from my bbs01b seems to have been caused by a loose lock ring cover and lock ring - the cover easily came off by hand. Tightened the lock ring using the Bafang tool... I should threadlock that lock ring. Weeks of annoying creaking...
The lock ring is showing rust where it meets the bb - unsure if the lock ring is stainless steel, but the cover is aluminium. The cover may be protecting the rest of the lock ring from moisture, all but the edge. My frame is aluminium, so it's either the lock ring or motor axle which is a bit rusty. I've got an additional set of Bafang bbs01b bolts nuts etc, so have a spare if the lock ring is destroyed by rust.Not good.
After taking the pedal arm and lock ring cover off, it appears that the lock ring is not stainless steel and will need some form of protection from rust - I'm not going to threadlock mine, because I may transfer the bbs01b to a MTB and put a KT on the Dahon...Not good.
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Riding on wet salted winter roads doesn't help. I've just covered it with WD40, then went on to grease the big gear wheel with Aeroshell 22. @Nealh: yep, you're right - this 6kg can I bought on ebay will last me 1000 years, unless I use it to fry bread. Looks yummy and dessert-like.
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