Belted Rohloff Bafang build

Teifun01

100 µW
Joined
Aug 17, 2017
Messages
8
it works pretty good...

California Ebike BA130 Bafang chain ring adapter
26" 1and1/8 straight steerer Boxxer front suspension
Magura MT-5 quad piston hydraulic disc brakes
KHE Mac26 × 2.30 "Park" 120psi tires
Chris King 36h disc front hub
Chris King 1 and 1/8" headset
Rohloff, 36h threaded spindle, disc brake version
Rohloff 180mm rear rotor, generic 203mm front rotor
Buck and Wing "Quill" saddle
27.2mm RaceFace Evolve aluminum seatpost
Deity nylon pedals
generic aluminum stem and bars
Gates CDX 50 tooth front, 20 tooth rear, 113 tooth belt
Luna Cycles 48V "Whale" battery with 17.5ah
Bafang BBS02 48V 750W motor kit
E-Rad brake sensor throttle cut-off
Swobo Folsom 26'er aluminum frame
SAS Halo 36h rims
Sapim spokes
Pitlock 10mm axle nuts
(about 52 lbs.)
 

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on flat terrain the transmission seems perhaps superfluous (with the current gear ratio of 2.5) because the 750 watts from the motor can easily power the bike starting in 14th gear from a standing stop to top speed (about 30mph before the assist cuts out).

going uphill the process of shifting is a bit clunky just like anything with a 14 speed transmission would be but it works well enough and the Rohloff doesn't seem to "mind" the motor (i.e. no shearing pins have failed).

perhaps one weakness with this particular setup is the small frame size which for me (at 6 feet) effectively means it's very hard to deliver power on the stroke while seated if i choose to assist with my own effort (which i generally don't) and so this bike is eminently unsuited for the pedalec concept.

also, i've already been over the handlebars during a traffic incident, so in hindsight a larger frame might have been a safer choice
 
Great combination. Does it have a gear sensor?
How quiet is it? Do you just hear the motor and not the belt?
Rohloff will be releasing an e-shifter but we don't yet know if it can be used with any mid drive (Bosch is a certainty). We'll find out in a couple of weeks. That would work really well in this setup.
 
it's pretty quiet to my ears (the noise seems like it's from the motor and not the belt) but i guess it's not like a Bosch or a Curry.

i don't have a gear sensor (i was informed that the E-Rad gear sensor is incompatible with this iteration of the Bafang) but it doesn't seem necessary because i've had no difficulty manually easing up on the throttle prior to shifts.

i think what i'm happiest with is the general cleanliness of this drivetrain and i really enjoy not having to roll my pants up for fear of getting them caught in between teeth and a chain.

anything that substitutes hydraulics or electronics for the current mechanical shifting cables (that stretch and wear) would be a desirable upgrade once it appears, assuming it's not prohibitively expensive like the PSH'R system (which lists at about $750 and doesn't look like it is actually available yet)...

https://www.cyclingabout.com/2017-bpod-pshr-trigger-brings-hydraulic-shifting-to-rohloff-hub/


https://www.bikerumor.com/2017/07/13/rohloff-introduces-e-14-electronic-shifting-speedhubs-bosch-e-bikes-get-first/
 
As you say "it works pretty good" and IMO it's pretty dam beautiful too. Such a tidy, clean, and low maintenance build. I like it and details like the seat, forks and color make it really nice. Great work and glad to hear it meets you needs albeit a little small.
 
Teifun01 said:
it's pretty quiet to my ears (the noise seems like it's from the motor and not the belt) but i guess it's not like a Bosch or a Curry.

i don't have a gear sensor (i was informed that the E-Rad gear sensor is incompatible with this iteration of the Bafang) but it doesn't seem necessary because i've had no difficulty manually easing up on the throttle prior to shifts.

i think what i'm happiest with is the general cleanliness of this drivetrain and i really enjoy not having to roll my pants up for fear of getting them caught in between teeth and a chain.

it looks like Rohloff e-shifting is still a long way off as an aftermarket add-on and it surely won't be cheap...

https://www.bikerumor.com/2017/07/13/rohloff-introduces-e-14-electronic-shifting-speedhubs-bosch-e-bikes-get-first/

That's strange, which iteration do you have? BBS02 or BBS02B? I guess you've looked at this one: https://www.eradkits.com/shop/gear-sensor-igh/
and this gear sensor:
http://www.ebay.co.uk/itm/Gear-Sensor-BBSHD-BBS02B-BBS01B-Bafang-Mid-Drive-Electric-Bike-Bicycle-Kit-Ebike-/322262448029

I emailed Rohloff a couple of weeks ago on whether it would be available to drives other than Bosch and they got back to me saying that more will be revealed at Eurobike as they couldn't say anything prior to that event, so may have a better idea at the end of this month.
Re. noise: I've found Bosch to be quite noisy compared with other mid drives so your Bafang is probably quieter.
 
re: gear shifting sensors

you must indulge me in my substantial ignorance of electronics- i had my LBS assemble this after i procured the parts online.

to quote from the E-Rad link you provided...

"Connects to the dedicated Gear Sensor cable that is included with all e-RAD drive units"

the LBS informed me that while E-Rad motors do have a compatible/matching plug to receive the end of this cable/housing my generic BBS02 (that i got on Ebay from i don't remember who in China) does not
 
Teifun01 said:
re: gear shifting sensors

you must indulge me in my substantial ignorance of electronics- i had my LBS assemble this after i procured the parts online.

to quote from the E-Rad link you provided...

"Connects to the dedicated Gear Sensor cable that is included with all e-RAD drive units"

the LBS informed me that while E-Rad motors do have a compatible/matching plug to receive the end of this cable/housing my generic BBS02 (that i got on Ebay from i don't remember who in China) does not

I don't own a BBS02 but many people on this forum do and I have seen videos of the sensor being used and working well, so I would find a Bafang BBS thread on this forum and look or post there; it seems highly unlikely that you are unable to fit or have fitted a gear sensor as both the BBS and BBSB models can have gear sensors fitted.
 
There was a post 1-2 weeks ago about the fidgetiness of the gear sensor, as even small vibrations to the brake shifters & sensor cause it to prematurely cut power to the motor. That would be an annoyance on hill climbs to have loss of power & momentum. Instead, folks have been using a push button cutoff on the left side handlebar while shifting with the right side.

https://california-ebike.com/shop/bafang-e-stop-brake-button/
 


while i'm not attracted to installing a gear shifting sensor right now (it seems pretty easy to just let up on the throttle) i do appreciate the suggestions and information about what's available (which i didn't know).

with regards to doing things right the next time, it's road stability issues that concern me most since i'm constantly surrounded by hard surfaces in the city and not getting any younger.

my next build is likely to use smaller, fatter wheels which i think are easier to maneuver and dismount from- think BMX crowd and the way they move all around the frame during their tricks.

here's an article from the Netherlands suggesting that the top tube on men's bicycle frames acts to inhibit rapid dismounts in an emergency (while i personally associate lesser situational awareness in traffic with a bent over posture)...

http://nltimes.nl/2017/08/16/mens-bicycles-unsafe-traffic-dutch-traffic-assoc

i wouldn't mind acquiring one of these new Terns...

http://www.electricbikeaction.com/terns-new-gsd-compact-utility-bike/

...If it were belt compatible but it's not- so maybe one of Jansen Tan's Goliath framesets (above photo) could be built up as a belted Rohloff/Bafang.

here's a link to an article about his company in Singapore, Coast Cycles, which focuses on minimalist, light urban transport...

http://straatosphere.com/coffee-jansen-tan-owner-coast-cycles/
 
Some of the talents on the sister forum commented. I'm learning...comments all addressed angle. What do you think?

Darren Eclair Head angle is way slack due to dh forks on a hard tail.
He will be booking corners in advance, in writing and still miss the junction.

Darren Eclair
Darren Eclair Forks are too long for a hard tail frame.
Steerer angle is very slack like a chopper.

Hemdan Dizon
Hemdan Dizon the rake of the fork will slow steering. also makes turns wider.

Dave Kaufmann He can lower the forks with the dbl clamp

Manage
Dave Kaufmann
Dave Kaufmann Tom Jaszewski , sorry bad photo, loosen the clamps and slide up the tubes to change the rake on the forks

Dave Kaufmann Yes I lowered mine 3"
 
Don't forget if you lower the forks too much you will loose travel and may bottom the forks out under heavy braking. It would probably be better to fit a more suitable fork for the frame. I run 120mm fox 32's on my hardtail and they are a very good match in terms of both performance and geometry. Of course the other route would be to buy a frame to match the forks, although it becomes much more difficult to mount your battery on the frame with a downhill/freeride bike.
 
If you're not using the PAS on the Bafang, I wouldn't recommend a shift sensor. I tried one and while it does work, it's not perfect. I don't necessarily want a total cutoff of power for my shift, I just need to take off most of the forward tension on the chain. Things still need to be turning to affect a smooth, quick shift. A downshift is different from an upshift. Sometimes I'm willing to hit the driveline a bit harder than normal to speed up a shift (climbing a steep hill for example). Modulating the throttle and timing the actual shift allows me the flexibility to do those things, having the sensor with it's predefined behavior doesn't. Also, it seems to hit the clutch pretty hard when it reengages. Much harder than the controlled throttle roll on I do myself.

Same thing with the brake lever cutoff, I don't need several seconds with my motor power cut off AFTER I release the brake. Really ruins aggressive riding. I have a kill button hooked up to one of the brake connectors in case things ever go awry with the throttle, but since I disabled the PAS nothing stupid has happened to me.
 
My casual examination suggests that BBS02 can't be made to straightforwardly align with the Rohloff's sprocket. Did you offset the front belt sprocket inward?
 
tomjasz said:
Darren Eclair Head angle is way slack due to dh forks on a hard tail.
He will be booking corners in advance, in writing and still miss the junction.

Darren Eclair
Darren Eclair Forks are too long for a hard tail frame.
Steerer angle is very slack like a chopper.

Yep. I didn't bother to notice at first glance, but it's true that putting a long travel fork on a frame that wasn't designed for one is always a mistake. (Unless you are in fact building a chopper.)

One thing Darren didn't mention is that when you chopperize a bike, it becomes way, way easier to slide out the front wheel when you grab the brakes.
 
Chalo said:
My casual examination suggests that BBS02 can't be made to straightforwardly align with the Rohloff's sprocket. Did you offset the front belt sprocket inward?

my LBS did the assembly but my understanding is that the alignment was not an issue and required no correction but if i had used a Shimano or SRAM IGH it would have been

https://california-ebike.com/thinking-adding-bafang-mid-drive-belt-drive-bike/
 
Additional comments, I found interesting....


Viktor Michalek When lowering the fork, you have to add 15wt oil into lower legs to prevent bottom out.

Dave Kaufmann Viktor Michalek, great comment, I have that problem. What's the normal weight oil?

Viktor Michalek 15wt for lower legs. the normal amount is 15-20ml iirc.... but you have to remove spring cap and try adding oil until the travel is reduced to desired amount.

Viktor Michalek My comment was wrong! Do not pour more oil in the spring leg. To increase hydraulic bottom out level, you want to put more oil (and thus displace air) from the damping side lower. This chamber is sealed from the damping chamber inside the stanchion. As the stanchion pushes inside this chamber, the oil has nowhere to flow and the air gets compressed to a point where it provides enough resistance to prevent further compression of fork.
 
i'm kind of puzzled by most of the responses to this build.

its purpose was to demonstrate the feasibility of the Rohloff/Gates/Bafang triad which to me seems much more desirable than waiting for an overpriced proprietary bosch version if it ever comes
 
Dude, if you make it happen that would be awesome. However most of us simply have no idea how.
 
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