New Bafang Crank-Drives

[Russell]

Its a single up front so as long as your within the chain wrap capacity of your derailleur a short cage works just fine. Chain will be tighter too.

The "capacity" of a particular derailer model is the largest range of sprocket sizes it can handle:

36t - 11t = 25t chain wrap capacity and up and your good.

Manufacturers have to assume that their customers are clueless, and will expect the chain to have some tension on it even in the bad gears where the chain is using small chainrings with small rear sprockets. Thus, the rated chain-wrap capacity is very conservative. A competent cyclist who uses the gears properly can generally exceed this by several teeth with no problem.
Most derailleurs also specify a maximum size rear sprocket. This is often a pessimistic value, based on the largest sprocket that is normally provided as part of that group.

When you rip-off text from another site you should give them credit

http://sheldonbrown.com/harris/derailers-rear.html

The largest rear cog I've ever been able to get to work with a short (road) rear derailleur is 30T, and that was with the "B-screw" cranked all the way in. For more than 30T you do need a mid or long cage rear derailleur.

-R

 

[mushymelon]

Its a single up front so as long as your within the chain wrap capacity of your derailleur a short cage works just fine. Chain will be tighter too.

The "capacity" of a particular derailer model is the largest range of sprocket sizes it can handle:

36t - 11t = 25t chain wrap capacity and up and your good.

Manufacturers have to assume that their customers are clueless, and will expect the chain to have some tension on it even in the bad gears where the chain is using small chainrings with small rear sprockets. Thus, the rated chain-wrap capacity is very conservative. A competent cyclist who uses the gears properly can generally exceed this by several teeth with no problem.
Most derailleurs also specify a maximum size rear sprocket. This is often a pessimistic value, based on the largest sprocket that is normally provided as part of that group.

When you rip-off text from another site you should give them credit

http://sheldonbrown.com/harris/derailers-rear.html

The largest rear cog I've ever been able to get to work with a short (road) rear derailleur is 30T, and that was with the "B-screw" cranked all the way in. For more than 30T you do need a mid or long cage rear derailleur.

-R

SLAP

Ouch yes its a cut and paste i'm lazy, guilty.

 

[Russell]

I'm running a zee short cage with a 11 - 36t work fine its tight but fine.

The Shimano Zee rear derailleur is something quite different, it is available in 2 models:

•DH Spec - 28T Max Cog Capacity
•FR Spec - 36T Max Cog Capacity

http://www.jensonusa.com/!dAWXe7G5YWuKDvopdHAXdA!/Shimano-M640-Zee-Rear-Derailleur?utm_source=FRGL&utm_medium=organic&gclid=CNy6p-Th18ACFYU9aQodzF8AHA

It's definitely worth looking at

-R

 

[dumbass]

My understanding is that each electric motor system has some RPM that is optimum for maximum efficiency (range).

Can anyone tell me what that would be in PEDAL RPM for the Barfang drives? And is it different for different Wattage/Voltage models?

Thanks!

Yes for the most part your correct. I used to determine it by the sound of the wineing of the motor. But the mid-drive Bafand make so little sound I can't do it anymore and just ride it based on how it feels for my peddling ability.

Bob

 

[Tom L]

My understanding is that each electric motor system has some RPM that is optimum for maximum efficiency (range).

Can anyone tell me what that would be in PEDAL RPM for the Barfang drives? And is it different for different Wattage/Voltage models?

Thanks!

Have a look here BigBird: http://imgur.com/a/Z3cAJ

 

[Russell]

Have a look here BigBird: http://imgur.com/a/Z3cAJ

Guys here have been telling me the 36V and 48V motors are wound differently so that the crank speed is the same. Those plots however show the 36V is clearly slower. It would be nice if someone would actually measure the speeds of their motors and report back (I don't own one...yet).

-R

 

[Lenk42602]

Lenk, you can look up the published data from any of the manufactures on specific RD's and what they recommend max cassette cog size is. Unless they are specifically set up to adapt to large rear cassettes, you can not tell folks that short cage will work with a 36 tooth. Just does not work straight across the large spectrum of bike gear in use in my experience.

*****sorry for the OT derail, this will be my last.....*****


I look at published data for derailleurs every day. its my job. I also know exactly how far beyond the published data cog/derailleur configurations continue to work well together. This is from actually trying various configurations in order to determine what really works.

*the only* modification to the 1x9 set up was to install a longer b screw to clear the big cog. I pulled a longer b-screw from an old mtb derailleur I have in a pile. But that's just with the old 9 speed stuff. the new double clutch x9 rear derailleur has no problem moving across the 10th position, 42t Wolf tooth Conversion cog. no longer b-screw needed. That is a short cage derailleur as well.

I should be wrapping up the lead sled soon, and it will have a 1X9 with an 36t rear cog drivetrain. This is exact set up is moving from a pedal bike to this e-bike. I will be sure to capture the derailleur moving across the cassette for all to see.

1 x9 pre- op:

rd 5500 /105 9 speed short cage, longer b screw install, 11-36t cassette


that is, if ya gotta see it to believe it.

Craig F, the 9 speed set up I have was originally a low buck experiment with parts laying around, but has worked well enough that I have continued to use it. I used a short cage because of the super crisp shifts one could experience on the drivetrains of this era from shimano. The newer clutched derailleurs help to keep chain slap at bay, but they have lost a bit of the feel rom the 9 speed stuff.....

A mid cage should suit you just fine.

 

[johnrobholmes]

The cage length limits your overall ratio change, but not specifically the sizes of cogs that can be used. If you take a regular 3x9 speed and make it a 1x9, one can also go to a mid or short cage and normally get away with it. As Lenk stated, trying something is the only way to know. I rock short cage road deralliers on mtb 11-36 cogs all the time, just can't have more than one ring up front and have to get the chain length exact.


I have a road cassette and shifter on my bb drive bike right now. Dont need more than a few gears anyway, more than 2:1 overall ratio is mostly excessive when e-powered.

 

[neptronix]

FYI... disabling PAS on the BBS02..

1) take off the chainring guard and chainring.
2) unbolt the controller ( 3 bolts )
3) find 4 pin connector ( to the left )
4) unplug connector
5) remove the grey wire from the female side of the connector by pushing the pin that locks it into place with a small screwdriver and tugging on the wire. Cap the wire off with electrical tape or however you wish to do it.
6) plug connector back in and reinstall all parts.
7) enjoy!

Important note: if you free-spin the motor without any load for ~3 seconds, you will get an 'error 21' on the screen. This is not because you just did the modification. The bafang just complains about not having any load on it. Operation on my old 6FET 750W unit is not affected in any negative way.

 

[Craig F]

I'm running a zee short cage with a 11 - 36t work fine its tight but fine.

The Shimano Zee rear derailleur is something quite different, it is available in 2 models:

•DH Spec - 28T Max Cog Capacity
•FR Spec - 36T Max Cog Capacity

http://www.jensonusa.com/!dAWXe7G5YWuKDvopdHAXdA!/Shimano-M640-Zee-Rear-Derailleur?utm_source=FRGL&utm_medium=organic&gclid=CNy6p-Th18ACFYU9aQodzF8AHA

It's definitely worth looking at

-R[/quote]

Thanks Guys .....I think I will go with the Shimano M640 Zee Rear Derailleur..It sounds specific to my application,,I assume it would be ok to use with a SRAM 10 speed shifter.???..http://www.chainreactioncycles.com/au/en/shimano-zee-m640-shadow-10-speed-rear-mech/rp-prod82431

 

[Aushiker]

Short cage is only good up to a 28 or so tooth cassette. You will need a long cage or one that can run a 36 tooth rear.

I believe you are mistaken. Cage length does not determine max cog size.

Sheldon might choose to differ ...

Andrew

 

[tahustvedt]

10 speed chain is weaker than 7-8 speed chain, because it is narrower and there is just less metal... if you are running a BBS02, it could wear at a significant rate to be a problem..
You will probably be okay with a BBS01 however.

I have an 8 speed chain here, and the plate thickness is 0.96 mm. I also have a 10 speed chain and the plate thickness is 0.8 mm, so yes, the 8 speed chain is potensially stronger, if the material is the same (on the other hand I also have a Dura Ace 10 speed chain with 0.92 mm plate thickness). However, the strength of the plates is still way more than we need to worry about unless something is very wrong. 8 speed chains probably wear slightly slower due to wider wear surfaces in the rollers/hinges though.

 

[astmacca]

Hi all. Am setting up to buy a Bafang drive and have a query about the install.

Kit comes with brake levers that include cut off switches for the motor. Sooooo..what if you have hydraulic brakes?? Can you get levers with cutoffs for such, or has anyone transferred the switches to hydraulic brake levers??

 

[speedmd]

10 speed chain is weaker than 7-8 speed chain, because it is narrower and there is just less metal... if you are running a BBS02, it could wear at a significant rate to be a problem..
You will probably be okay with a BBS01 however.

I have an 8 speed chain here, and the plate thickness is 0.96 mm. I also have a 10 speed chain and the plate thickness is 0.8 mm, so yes, the 8 speed chain is potensially stronger, if the material is the same (on the other hand I also have a Dura Ace 10 speed chain with 0.92 mm plate thickness). However, the strength of the plates is still way more than we need to worry about unless something is very wrong. 8 speed chains probably wear slightly slower due to wider wear surfaces in the rollers/hinges though.

Chain topic has been covered many time on multiple threads. It really belongs in a the general or technical section under "bike chain", "derailleur chain" or "Ebike chain" . So many times we see the falsehoods repeated and it really needs some consolidation and facts added to become meaningful / useful to the ES community. Without test / breakage / wear data, it is mostly just opinion or casual observation IMO. Lots of great experience/ information here among the group, but getting a bit out of control as to it being highly usable data for anyone and much too easily becomes a pissing contest.

 

[cycborg]

has anyone transferred the switches to hydraulic brake levers??

Yup (not me though). http://endless-sphere.com/forums/viewtopic.php?p=920909#p920909

I think there's a more detailed thread on here somewhere; try searching with words like brake, hall, switch, hydraulic, etc.

 

[speedmd]

I did it. First you need to cut the cable and disassemble originals to get the switch out and splice the cable back together when done. I bent up a little aluminum flashing as a holder and mounted the switch through it. Then, drilled / tapped the hydro lever body to hold it in place. Works perfect. Next one I will use slightly thicker material. Will photo it later when the rain stops and post.

 

[0utrider]

I did it. First you need to cut the cable and disassemble originals to get the switch out and splice the cable back together when done. I bent up a little aluminum flashing as a holder and mounted the switch through it. Then, drilled / tapped the hydro lever body to hold it in place. Works perfect. Next one I will use slightly thicker material. Will photo it later when the rain stops and post.

Nice DIY. I look forward to the photos!

 

[johnrobholmes]

Short cage is only good up to a 28 or so tooth cassette. You will need a long cage or one that can run a 36 tooth rear.

I believe you are mistaken. Cage length does not determine max cog size.

Sheldon might choose to differ ...

Andrew

Sheldon also assumes three rings up front, which is not the case with the Bafang crank drive. Short cage works fine with my 11-36 cassette and Bafang system 8)

 

[Russell]

Short cage works fine with my 11-36 cassette and Bafang system 8)

When you say this you need to specify the brand and model of rear derailleur used. It is a FACT that many short cage derailleurs will NOT work with large rear cogs. And yes there is always wiggle room if you crank that B-screw way in and if your hanger is longer than normal. If someone has a short cage already and they want to try adjusting it to try to make it work then I say go for it but if someone is in the market for a new derailleur they would save themselves some hassle by heading the manufacturer's recommendations.



-R

 

[speedmd]

I did it. First you need to cut the cable and disassemble originals to get the switch out and splice the cable back together when done. I bent up a little aluminum flashing as a holder and mounted the switch through it. Then, drilled / tapped the hydro lever body to hold it in place. Works perfect. Next one I will use slightly thicker material. Will photo it later when the rain stops and post.

Nice DIY. I look forward to the photos!

Hope this helps. After I did this, I saw that it would be best to fold a bigger section to cover the front more and fold the corner back toward the switch base, making it a double layer near the switch port of two overlapping layers glued together. It has hit the dirt a few times and is amazingly robust the way it is out of thick flashing material.

 

[Tom L]

Another example of custom ebreak cutoffs for you: http://endless-sphere.com/forums/viewtopic.php?p=836334#p836334

 

[0utrider]

Another example of custom ebreak cutoffs for you: http://endless-sphere.com/forums/viewtopic.php?p=836334#p836334

Ah! Magnets and magic putty!

 

[Rusty123]

Anybody seen brake cable extensions (similar to the speedometer cable extensions) for sale? Planning to put another one of these on my recumbent with under seat steering, which involves a longer than usual distance from brake levers to harness plugs.

 

[joshseitz]

Just completed my Cannondale Prophet all-mountain build. What a blast! Pleasantly surprised by the power. It it definitely a little twitchy and the throttle is very binary, so it will benefit from some re-programming when I get to it.

The battery is a EM3EV 50V 16.5AH unit in a camelbak. I cut a panel out of Dibond (thin stiff plastic within thin sheets of aluminum) to give it some structure and serve as a fire barrier. I am also working on a cable retractor to kelp keep the cable somewhat taught. It's connected to the bike with Andersons. I like that they easily disconnect if I become separated from the bike, but I would like a bit more secure connection. Maybe add a magnet or velcro. Connector suggestions are welcome!

I did experience a couple of errors in my initial trials. If you have any feedback let me know. I'll also post this in the finding faults and fixes thread.




1. Twice it took-off while standing over the bike. I wasn't touching the throttle and I don't believe I bumped the cranks, engaging PAS. I believe PAS requires a bit more than a bump to engage, and it felt like full throttle. The front-end rose right off the ground, but I managed to grab my back brake in time to prevent it from flipping right over. I now leave the bike off while mounting and dismounting and just turn it on when I'm ready to ride. If anyone else has experienced something like this, and particularly if you know of a possible cause, please let me know.

2. I purchased two "universal brake sensors" from Lectric Cycles so that I could retain use of my hydraulic levers http://lectriccycles.com/products/universal-brake-sensors-for-bbs01-bbs02-mid-drive-kits. I mounted the sensor to the lever body and taped the magnet to the actual lever for testing. When I squeeze the lever, the motor goes dead for several seconds and the display reads ERROR 30. Once or twice it flashed ERROR 4 before reading ERROR 30. Once I release the lever and wait for several seconds, the drive returns to normal operation UNTIL you use the brakes again. I tested both sensors with the same result. The factory levers work fine and don't throw an error. Any ideas?

Aside from the issues above and suspect programming, I'm stoked about this thing.

 

[Tom L]

Do a test to see if you get the same problem if you use the supplied mechanical ebrakes.