New Bafang Crank-Drives

[amigafan2003]

I've been off-road at Gisburn trail centre and I didn't find anything I couldn't climb with my 48v500w bbs02 unit on 15s Lipo. It has a 46t front ring and 10spd 11-36t on the rear. Slx shadow plus rear mech, deore shifter, kmc 93 chain.

I've programmed the unit to give more power in pas modes and have that power lower in the cadence range.

I'm not even considering an adaptor at the front also because the chainline is poor enough already - spacing it out another few mm with an adaptor would be too much.

 

[amigafan2003]

I've have had to change dérailleurs when I've added big rear sprockets. The biggest I use is 34. The biggest shimano dérailleur I could find specified a maximum 32 sprocket. It seems OK on 34 but it couldn't go any bigger as the idler is almost touching the sprocket.

Erm, when a deralieur says it's rated for 32t, that doesn't mean it only works on a cassette with a 32t rear sprocket. The rating is how much chain difference/slack it can take up - it means it's rated for a total 32t capacity and it's calculated by working out the tooth range across the system. If you have a single front chain ring and an 11-36t rear cassette, the difference is 25t (36 minus 11) so a 32t rear mech would be fine. If you had two front rings, say 24 and 32 then you'd add that to the capacity - so 32 minus 24 = 8. 36 minus 11 = 25. 25 + 8 = 33t. So a 32t mech would just about work with that combination. Does that make sense?

If your idler is touching the big sprocket at the rear then you need to adjust the b tension spring to move it away. You only need a few mm clearance. The closer the wheel to the sprocket the better the shift performance.

 

[arclarke]

I've have had to change dérailleurs when I've added big rear sprockets. The biggest I use is 34. The biggest shimano dérailleur I could find specified a maximum 32 sprocket. It seems OK on 34 but it couldn't go any bigger as the idler is almost touching the sprocket. I don't expect the larger sprocket would fail but I've been wondering if the narrow chains required for 10 speeds would hold up with 750W motors. Narrow chains break quite often without a motor. You see it in professional bicycle racing sometimes, where you'd expect them to be trying hard to avoid such failures.

A friend of mine has had a 10 speed with a Bosch mid drive for a couple of years with no chain problems. My personal theory is that front mechs are what stresses chains and lead to failure, and of course these bikes don't have one.

For bigger back sprockets you need a mountain bike rear mech - but note Shimano 10 speed ones only work with mountain bike shifters not road ones. A decent 9 speed shimano mountain bike mech will work with their 10 speed road shifters and 10 speed mountain bike cassette though.

I have a Hope 40t cog on my leg powered mountain bike - it doesn't feel at all fragile to me - but one snag is the quality of the shifting where you have to take out another cog to make room for the new one, which might cause problems under electric power.

 

[m4s73r]

Droner,

Rather then all that with front derailleurs look into a Sturmey Archer CS-RK3. Rear wheel hub 3 speed with a cassette. will give you a .75 under and 1.33 over.

 

[teslanv]

Another good option is a Nuvinci CVP.

You can get the developer's kit with the autoshift & older model N171b hub for $125 from Utah Trikes.

http://www.utahtrikes.com/PROD-11617994.html

They will even lace it into the rim of your choice for a reasonable price.

In my opionion, the Nuvinci CVP with the autoshift would remove the one major negative about a mid-drive set-up (the need to shift) while retaining the primary advantage of a Mid-drive (the ability to change gear ratios).

The N171b does add about 8 lbs of weight to the rear wheel, and there is some debate about how efficiently it operates, but given that this set-up could be tuned such that the motor is ALWAYS running at it's most efficient rpm range, I would think that efficiency loss could be minimized. And the weight of the rear wheel is not much different than a 1000W rear Hub motor.

 

[m4s73r]

N171 would be ok if you never planned on going off paved areas. But hilly terrain/trails dont do well with the slippage. IMO the 8 lbs kinda defeats the point of a mid drive.

 

[teslanv]

N171 would be ok if you never planned on going off paved areas.

I would agree with that. The N171b is probably best suited as a commuter set-up.

 

[tomjasz]

Droner,

Rather then all that with front derailleurs look into a Sturmey Archer CS-RK3. Rear wheel hub 3 speed with a cassette. will give you a .75 under and 1.33 over.

I have a new wheel 26" with Alex DM 24 rim and brand new SA 3 speed with drum brakes, built by a pro shop. $250 rig for $150 and actual shipping.

 

[pexio]

...I'm not even considering an adaptor at the front also because the chainline is poor enough already - spacing it out another few mm with an adaptor would be too much.

I ordered one of these chainrings from Italy for my forthcoming BBS02 MTB build - 42t AND improved chainline.

 

[Kepler]

Not cheap at 79EUR but could be money well spent to get that perfect chain line with a smaller chain ring. I think i will order one. Thanks for the headsup.

 

[dirkdiggler]

Double post

 

[dirkdiggler]

Amiga,

I've been off-road at Gisburn trail centre and I didn't find anything I couldn't climb with my 48v500w bbs02 unit on 15s Lipo. It has a 46t front ring and 10spd 11-36t on the rear. Slx shadow plus rear mech, deore shifter, kmc 93 chain.

My problem was the speed was too high for switchbacks and needs something to go a bit slower. Are you using throttle when you are climbing the steep stuff or just using the reprogrammed PAS? On big hills my legs couldn't turn the pedals at all and I would have to just use the throttle. I might need to just toughen up! The bad part was the throttle delay would kill all my momentum and then the tire would just spin out when it did kick in.

As for chainline - mine is better with the adaptor because I don't have to worry about the chainstay. My bike wasn't built for a 46 tooth ring. The chain was almost diagonal with the 46 tooth in front and biggest in back. Not good.

 

[tomjasz]

Not cheap at 79EUR but could be money well spent to get that perfect chain line with a smaller chain ring. I think i will order one. Thanks for the headsup.

How does one measure or determine the ideal chainline?

 

[pexio]

How does one measure or determine the ideal chainline?

http://sheldonbrown.com/chainline.html

 

[Ken Taylor]

I've have had to change dérailleurs when I've added big rear sprockets. The biggest I use is 34. The biggest shimano dérailleur I could find specified a maximum 32 sprocket. It seems OK on 34 but it couldn't go any bigger as the idler is almost touching the sprocket.

Erm, when a deralieur says it's rated for 32t, that doesn't mean it only works on a cassette with a 32t rear sprocket. ... Does that make sense?

Erm, you've got the wrong specification. Looking at http://www.chainreactioncycles.com/au/en/shimano-105-5701-10-speed-rear-mech/rp-prod85966 a Short Cage mech specifies "Maximum low sprocket 30T" and a Medium Cage specifies "Maximum low sprocket 32T". The specification you are referring to is "total capacity" which for the Medium Cage is 40T. It is this Medium Cage that I found works with 34T, outside the 32T spec.

If your idler is touching the big sprocket at the rear then you need to adjust the b tension spring to move it away. You only need a few mm clearance. The closer the wheel to the sprocket the better the shift performance.

If you have the wrong dérailleur there is no b tension spring adjustment that allows the idler to clear the sprocket. I doubt the medium cage will go to 40T but given there is a short and medium, I'd expect a long, however I couldn't find one for sale. Another thing I wondered is whether the dérailleur mounting point is always the same distance from the axle centre because if this dimension is different on different bikes the idler may clear the sprocket on some and not others?

For bigger back sprockets you need a mountain bike rear mech

Yes.

A friend of mine has had a 10 speed with a Bosch mid drive for a couple of years with no chain problems. My personal theory is that front mechs are what stresses chains and lead to failure, and of course these bikes don't have one.

That sounds like a convincing argument. Based on your advice I will try 10 speed on a bike I'm building at the moment when I was previously thinking I better stick to 7 so I could have a full strength chain. I guess the Bafang chain ring can take any width chain. Does that sound right? It is expensive to change this later and bothersome if it breaks.

 

[amigafan2003]

...I'm not even considering an adaptor at the front also because the chainline is poor enough already - spacing it out another few mm with an adaptor would be too much.

I ordered one of these chainrings from Italy for my forthcoming BBS02 MTB build - 42t AND improved chainline.

Great find! Ordered!

 

[amigafan2003]

I've have had to change dérailleurs when I've added big rear sprockets. The biggest I use is 34. The biggest shimano dérailleur I could find specified a maximum 32 sprocket. It seems OK on 34 but it couldn't go any bigger as the idler is almost touching the sprocket.

Erm, when a deralieur says it's rated for 32t, that doesn't mean it only works on a cassette with a 32t rear sprocket. ... Does that make sense?

Erm, you've got the wrong specification. Looking at http://www.chainreactioncycles.com/au/en/shimano-105-5701-10-speed-rear-mech/rp-prod85966 a Short Cage mech specifies "Maximum low sprocket 30T" and a Medium Cage specifies "Maximum low sprocket 32T". The specification you are referring to is "total capacity" which for the Medium Cage is 40T. It is this Medium Cage that I found works with 34T, outside the 32T spec.

If your idler is touching the big sprocket at the rear then you need to adjust the b tension spring to move it away. You only need a few mm clearance. The closer the wheel to the sprocket the better the shift performance.

If you have the wrong dérailleur there is no b tension spring adjustment that allows the idler to clear the sprocket. I doubt the medium cage will go to 40T but given there is a short and medium, I'd expect a long, however I couldn't find one for sale. Another thing I wondered is whether the dérailleur mounting point is always the same distance from the axle centre because if this dimension is different on different bikes the idler may clear the sprocket on some and not others?

Ah - well didn't realise you were using a road mech! Seems daft to use a road mech on a BBS equipped bike tbh.

 

[Warren]

amigafan2003,

"Seems daft to use a road mech on a BBS equipped bike tbh."

If you are running a single chainring, it is foolish to run a long cage rear derailleur, when you don't need the extra chain wrap. You are forced to run a longer chain for extra wrap you will never use. The only reason to run a long, or even medium cage rear derailleur with a single chainring, is if you are running a rear cog larger than 34 teeth. And this is only because, as far as I know right now, manufactures aren't pushing single chainring roadbikes. They could easily make a short cage derailleur with the parallelogram angled enough to work with an 11-44 cassette. But maybe that will change soon? If MTB's do it, roadbikes will be next.

http://www.cxmagazine.com/shimano-xtr-m9000-11-speeds-single-chainring-first-look

When I started riding in the 1960's, most bikes were 2x5, and a few 3x5. And the bushed chains really didn't like running at full diagonal, so you really only had 8 or 13 gears. With a bushless chain, an 11 speed cassette, a short cage rear derailleur, you can have a very light, simple, and effective drivetrain.

I run several roadbikes with 1x9, and short cage rear derailleurs. They are great. And with a mid-drive eight gears is longer wearing and plenty.

If electric mid-drives really catch on, one of the OEMs could easily do a heavy duty, 6 speed, 13-39 drivetrain, that could handle 2 kW all day.

Somebody like Yamaha could even do a 150 pound electric moped with a derailleur system, with much greater efficiency, and much less weight than a gearbox.

 

[amigafan2003]

amigafan2003,

"Seems daft to use a road mech on a BBS equipped bike tbh."

If you are running a single chainring, it is foolish to run a long cage rear derailleur

I don't, I use a med cage SLX shadow + mech - works perfectly - and copes witt the 36t rear cog fine. I could have used a short cage Zee mech, but I prefer the SLX.

If electric mid-drives really catch on, one of the OEMs could easily do a heavy duty, 6 speed, 13-39 drivetrain, that could handle 2 kW all day.

Bigger jumps between gears equals poorer shifting though.

 

[Warren]

So your concern was in using a road derailleur on a MTB I guess?

As to the heavy duty drive...back in the day, Suntour had a 13-38 freewheel that worked fine. And that was before bushless chain, and ramps and pins. I would gladly trade a bit less buttery shifts for durability.

 

[dumbass]

HELP!!..................The story of my life..."If it can happen..It will happen to me". As time permitted I have been installing the Bafang crank drive and my battery packs. IDo to several other projects going on like painting the house. my bike project have been dragged out a bit. I thought I would finally escape for a few hours last week but I had problems with my derailleur and decided to take my "Old Blue" instead.

This morning I finally got to take it off the stand and actually go for a ride. First impression was "WOW, this puppy is really quite!". I had it set for 9 speeds and was clicked into #9 and using the throttle only. Everything was going great. Starting out in high gear on the derailleur (14t) it climbed smoothly to 20+ MPH using only the motor on flat ground. At the end of the block pressed the rear brake lever and released the throttle to turn around. The motor stopped and coasted through a 180 and hit the throttle again but got no response, totally dead. So I peddled home and checked all the connections and of course the brake levers. Nothing is loose or sticking that I can find. And the temp is in the 50s today so the motor felt very cool. What I did notice is when I hit the throttle I could hear a slight click from the motor. Just one single click each time I activate the throttle. To get another click I have to release the throttle and reactivate it again. But with ether brake lever activated there was no click when I activate the throttle.

Please note that while on the stand for the past few weeks I have test run the motor at least 100 times and used both brake levers many times and never had a problem. So it's hard to imagine the brake lever being the problem. But it is strange that the problem started when I hit the brake. But what about the clicking sound? The screen is working normally too.

Any thoughts, wisdom or comments would be greatly appreciated right about now.



BTW, This is the new version of the 750w with a 20a controller (built in March of 2014) and a C961 screen.

Bob

 

[skitime]

I am waiting for my battery from Lectric Cycles but have completed my 750 watt motor install. I bought everything from Lectric Cycles. I did the install with a NuVinci 360 hub from Lectric Cycles as suggested by LeGrand. He laced the rim with the NuVinci hub for me as well. He says he has had complete success with the NuVinci hub and the 750 watt motors. The motor is installed on a Diamondback Edgewood hybrid bike with 700C rims. I am very anxious to try the bike out with a battery. :lol:

With all this talking about changing the front gearing, this item on the US EBay seems to be the perfect solution. It is a 104 BCD Custom Spider Gearing for the Bafang 8fun Mid Drive. It would allow you to easily change to whatever gear you want. And it is only $40 with shipping.

http://www.ebay.com/itm/104-BCD-Custom-Spider-Gearing-Bafang-8fun-Mid-Drive-750W-500W-350W-BBS01-BBS02-/121341300801?_trksid=p2054897.l4275



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[pexio]

...With all this talking about changing the front gearing, this item on the US EBay seems to be the perfect solution. It is a 104 BCD Custom Spider Gearing for the Bafang 8fun Mid Drive.

Not quite perfect, imho, unless you were driving a single sprocket in the rear (like you and others are with the NuVinci and other IGH's). The problem is that for those of us using derailleur systems with multi-speed cassettes and freewheels find the 52mm front chainline of the inwardly offset 46/48t Bafang chainring marginal at best. The adapter you linked to is not offset at all which worsens the significant cross-chaining despite allowing the use of a smaller chainring.

 

[speedmd]

...I'm not even considering an adaptor at the front also because the chainline is poor enough already - spacing it out another few mm with an adaptor would be too much.

I ordered one of these chainrings from Italy for my forthcoming BBS02 MTB build - 42t AND improved chainline.

Would be nice if it had a 53 or 55 tooth ring built in also. I would get one for certain.

 

[pjgold]

I did the install with a NuVinci 360 hub from Lectric Cycles as suggested by LeGrand. He laced the rim with the NuVinci hub for me as well. He says he has had complete success with the NuVinci hub and the 750 watt motors.

I am keen to hear how the Nuvinci goes, I have an Alfine 8 installed but I'm looking at changing to a Nuvinci but there is not a lot of info on how they perform with the 750w. They are pretty pricey so I want to be sure its a good match.