ebike build questions (BBS02)

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Alfakrull   100 µW

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ebike build questions (BBS02)

Post by Alfakrull » Jan 24 2020 5:12pm

Hello,

This is my first post here at the E-S, but I've been lurking for a while.
I got a bike for free from a friend who didn't use it anymore, and I'm planning to convert it into an Ebike.

It's a 7speed REX roadbike (Shimano nexus7 IGH), front V-brake, rear coaster brake.
rsz_1img_20200124_215213.jpg
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I'm planning to equip it with a 500w Bafang BBS02 mid drive (or perhaps 750w).
Do you think the Nexus7 IGH would be able to cope with this amount of power?
I'm aware that the coaster brake won't work with this motor, so I'm planning to install a rear V-brake instead.
rsz_img_20200124_215245.jpg
rsz_img_20200124_215245.jpg (482.44 KiB) Viewed 556 times
Do you have any recomendations on a V-brake system that would work to install on this frame?
I'm thinking the center hole in this image could be used to install the brake.

The reason that I choose a mid-drive for this project is that I'm planning to get a good quality MTB in the future, and I want to be able to transfer the kit to the new bike. That's also why I rather get the 750watt motor if possible.

All advices are welcome! Thanks in advance.

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amberwolf   100 GW

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Re: ebike build questions (BBS02)

Post by amberwolf » Jan 25 2020 12:11am

a v-brake requires bosses on the frame tubes to mount the caliper arms.

there are clamp-on bosses, meant for situations like yours where you want to add brakes the frame wasn't designed for.
https://www.google.com/search?newwindow ... ake+bosses
https://www.google.com/search?q=clamp+o ... 1&tbm=isch

there's also versions that come mounted on horseshoe-shaped plate that clamps to the frame; one of these is show near the top of the image search above.

2old   100 kW

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Re: ebike build questions (BBS02)

Post by 2old » Jan 25 2020 12:25am

Seems like a lot of trouble to make the bike fit your plans. Might be better to find a used MTB.

markz   100 GW

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Re: ebike build questions (BBS02)

Post by markz » Jan 25 2020 1:25am

The front brake is what does most of the work!
I've ridden with just a front brake, also ridden with just a rear brake. I liked it better with just the front brake.

Find some adapters for the chain stays, or get a side-pull or center pull (not cantilever) brakes for that plate you pictured.
https://www.adventurecycling.org/resour ... rakes-101/

Alfakrull   100 µW

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Re: ebike build questions (BBS02)

Post by Alfakrull » Jan 25 2020 4:08am

Thanks all for your replies!
The thing with this bike is that it rolls really well, so I think I will give the conversion a shot. I will do mostly city-riding.

Re: Markz reply on just using the front brakes: I would like to be able to do that, but where I'm situated (Sweden) the temperature sometimes goes to -20 C°, so it's a bit sketchy to use the front break on ice, so I would like to have both rear and front brakes.

I found this break online for like 30$, do you think it would do the job?
Screenshot_20200125-095633.jpg
Screenshot_20200125-095633.jpg (267.56 KiB) Viewed 525 times
Also, do any of you have any experience with the Nexus 7 IGH? I get mixed opinions when I google it.
I do see that some prebuilt ebikes ships with this system installed though, but mostly low powered bikes. (250 w).

All the best!
Last edited by Alfakrull on Jan 25 2020 4:51pm, edited 1 time in total.

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Wolfeman   100 W

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Re: ebike build questions (BBS02)

Post by Wolfeman » Jan 25 2020 12:01pm

I have a 1300W BBS02 installed on a Dyno Moto 7 cruiser with a Nexus 7 IGH. It works beautifully, no chain alignment issues at all. Also, it seems to handle the power just fine, just don't shift under full power.
Trek 4300 w/ H3580 Crystalyte at 3600W
viewtopic.php?f=3&t=82738
Worksman Mover M2020-3CB w/DD 750W front hub
viewtopic.php?f=3&t=96873
Dyno Moto 7 BMX Cruiser w/BBS02
viewtopic.php?f=6&p=1467001#p1467001
GT Palomar Vintage hardtail w/BBS02
viewtopic.php?f=6&t=104255

Alfakrull   100 µW

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Re: ebike build questions (BBS02)

Post by Alfakrull » Jan 25 2020 12:13pm

Ok, that's great news, thank you for the info!
I just ordered a BBS02 750w with 48volt 12AH battery pack from AliExpress, very exited to get started on the build
Now I just need to sort the rear breaks.🙂

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Wolfeman   100 W

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Re: ebike build questions (BBS02)

Post by Wolfeman » Jan 25 2020 12:23pm

Just my opinion, but enjoy the bike as you put things together. Add the motor/battery, then ride it for awhile. You may find (depending on your intended use) that the bike is perfectly enjoyable with the coaster rear brake. Have fun. 8)
Trek 4300 w/ H3580 Crystalyte at 3600W
viewtopic.php?f=3&t=82738
Worksman Mover M2020-3CB w/DD 750W front hub
viewtopic.php?f=3&t=96873
Dyno Moto 7 BMX Cruiser w/BBS02
viewtopic.php?f=6&p=1467001#p1467001
GT Palomar Vintage hardtail w/BBS02
viewtopic.php?f=6&t=104255

docw009   100 kW

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Re: ebike build questions (BBS02)

Post by docw009 » Jan 25 2020 1:05pm

Wolfeman, I agree with you about enjoying the bike as it is, but you cannot activate the coaster brake with a BBS02 because the crank freewheels when pedaled backward.

Those single bolt rim brakes need a good mounting point. I would bolt a thicker steel plate to the thin plate already on that bike. That will give a non flexing attachment for the rim brake. You could even use two plates on opposite sides of the tubes, if that stamped steel piece turns out to be as weak as it looks,

Alfakrull   100 µW

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Re: ebike build questions (BBS02)

Post by Alfakrull » Jan 25 2020 4:37pm

The steel plate is actually ~3mm thick and looks pretty solid.
rsz_img_20200125_222720.jpg
rsz_img_20200125_222720.jpg (350.35 KiB) Viewed 491 times
I do however see your point that this area would be under a lot of stress, i have a friend that works with welding, maybe he could reinforce it further.

Or do you know if it's possible/not to complicated to install a roller brake controlled with a wire instead?
It seems like Nexus 7 comes in models with different types of brakes, but I haven't found any info if it's possible to swap from one to the other.

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amberwolf   100 GW

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Re: ebike build questions (BBS02)

Post by amberwolf » Jan 25 2020 10:00pm

fwiw, that type of caliper brake is likely to only fit a fairly narrow rim and small tire (less than 30mm, probably 25-28mm), like on "racing bikes". . not sure if that is what you want, since your existing wheel / tire may be much larger than will fit in that brake.

markz   100 GW

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Re: ebike build questions (BBS02)

Post by markz » Jan 25 2020 10:30pm

Where I am is the same as Sweden, winter wise and the front brake action on snow and ice is a delicate application. I am currently on rear brake only, and its holding up fine this winter. I plan on installing front brake soon, problem is the fat hub axle flats are a bit wider then the forks dropout. Disc brakes on it.

I had a bad fall this winter, but it had nothing to do with brakes. There was a fresh snowfall, which laid over some ice compacted from cars. First turn and the front wheel slide out. Front brake only from what I remember was delicate and had to apply it sparingly in spots where it was snow or snow+gravel/snow+sand or asphalt/concrete.

How do you get rid of the coaster brake action on that bike?

That 3mm plate, you could just add additional steel plate bolted to it, would be an option if no welder friend is available.

Alfakrull   100 µW

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Re: ebike build questions (BBS02)

Post by Alfakrull » Jan 26 2020 2:27am

amberwolf:
Yes I see what you mean, the largest compatible tire width of all standard racing breaks I could find is 32mm, which is too small. Also, the reach of the arms on these brakes are too short, I need something like 80mm+ which leaves me with only one option: BMX caliper breaks, something like this:
Screenshot_20200126-080654.jpg
Screenshot_20200126-080654.jpg (369.93 KiB) Viewed 468 times
Screenshot_20200126-080812.jpg
Screenshot_20200126-080812.jpg (289.97 KiB) Viewed 468 times
These breaks have enough reach and my tire would fit, but my main concern is how effective they would be🤔
At least better than no rear break I suppose 🙂

Markz:
Yes, riding in winter-conditions can be scary, and surprising, when you don't see what's hiding under the top layer of snow, glad you're ok!
Regarding how to disable the coaster break with the BBS02, I think the new crank will sort that automatically, since you're no longer able to make the chain run backwards, which is what normally engages the coaster brake.

docw009   100 kW

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Re: ebike build questions (BBS02)

Post by docw009 » Jan 26 2020 9:32pm

Here's 7 more mm.
https://www.ebay.com/itm/73mm-93mm-Bike ... UUeHSergLg

But there must a a local bike shop that can fix you up.

Alfakrull   100 µW

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Re: ebike build questions (BBS02)

Post by Alfakrull » Feb 01 2020 3:50pm

A small update,:
My sidepull break (Odyssey 1999) arrived and i made a beta-installment, to see how it works.
After about an hour of adjustments, I got the arms to work symmetrically. There is some horizontal movement of the arms when breaking while riding, but the mount seems solid so far.
The lever is tiny (2 finger BMX style), and i,'m not yet satisfied with the power of the break, but I hope the lack of power is due to the small 40mm pads that came with it.
My front break has 70mm pads so I will change the new ones to the same size shortly and hopefully that makes a big difference.
rsz_screenshot_20200201-213027.jpg
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rsz_screenshot_20200201-212954.jpg
rsz_screenshot_20200201-212954.jpg (85.89 KiB) Viewed 363 times
Also, I got a message from AliExpress today that my battery has been sent(DHL), and the rest of the kit (hopefully) arrives next week. 😊
Great times ahead!

All the best!

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jpacadd   10 mW

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Re: ebike build questions (BBS02)

Post by jpacadd » Feb 01 2020 4:52pm

Nice looking bike, enjoy!

After riding my first ebike all last summer I wasn't even satisfied with my stock (my2009) hydraulic disc brakes and bolted on larger rotors and adapters, much better.

I really don't know how easy, but you may want to consider adding disc brakes, especially for riding an ebike in the city, for safety.

https://lmgtfy.com/?q=bolt+on+bicycle+disc+brakes
July 2019 first build: 2009 Giant Trance X3 with stock BBSHD 52V
Next build: Just bought used 2009 Giant Trance X4, likely BBSHD also, maybe hotter controller/battery, undecided
Lots of other fun toys: Wildcat X, Xtrainer, 1978 KE100, Hypermotard 1100

Alfakrull   100 µW

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Re: ebike build questions (BBS02)

Post by Alfakrull » Feb 01 2020 6:01pm

Thanks for your reply!
I've looked into the possibility to install disc brakes as well. The thing is that it would be quite costy to do such an upgrade.
At the moment I'm saving up to be able to get either a full suspension downhill bike, or a hardtail MTB.

So hopefully, in a not to distant future, the BBS02 that will be installed on this bike will get transplanted to the new bike. I got this bike for free and spent like 25$ on it so far (not including the BBS02 kit of course, which I see as an investment).

This will have do in the meanwhile, i'm a lightweight guy, (149lb) so hopefully new breakpads in combination with me riding relatively sensibly will make the breakpower sufficient 😄
Will update with new pictures once the kit is installed!

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jpacadd   10 mW

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Re: ebike build questions (BBS02)

Post by jpacadd » Feb 01 2020 8:30pm

I don't know man that looks like about $15 worth of stainless fender washers too they don't give those away! :lol:
July 2019 first build: 2009 Giant Trance X3 with stock BBSHD 52V
Next build: Just bought used 2009 Giant Trance X4, likely BBSHD also, maybe hotter controller/battery, undecided
Lots of other fun toys: Wildcat X, Xtrainer, 1978 KE100, Hypermotard 1100

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