New build. Full carbon 29er weight weenie Super Commuter.

[Kepler]

I really like the Bafang CST motors and the fact that you can fit a decent cassette to the wheel. I think one of the things that lets my build down slightly is the lack shift smoothness on the rear derailleur. Would love to have it shift like my Dura Ace compact on my road bike.

I don't know where you're at with the above. I could not find any info on a Bafang CST Mini based on the SWXH, other than what someone posted on the new ES wiki.

You can get Dura-Ace level shifting with a new XTR derailleur (I use a RD-M971 carbon) and if you build your own freewheel based on an old Dura-Ace MF-7400 7 speed freewheel. I start with an MF-7400 12-13...21 or whatever you can find. You only need the body and the 12,13 cogs. Take it apart and add cogs from the new SIS MF-HG37 or MF-HGxx 6 or 7 speed. Now you have a Dura-Ace 12-28 freewheel You retain the first two cogs from the Dura-Ace which are Shimano UG SIS UniGlide, but they are small and you don't notice that they are not Shimano HG SIS HyperGlide. 7 and 8 speed SIS freewheel/cog SIS spacing is almost exactly the same, so you use the spacers from the 7 speed newer freewheel, which are lighter. Than you can use 7 speed Deore XT Thumb shifters or 8 speed legendary Deore XT SL-M739 rapidfire shifters (or XTR equivalent). The XT M739 pod shifters are actually smaller and lighter however. Get the Dura_Ace or XTR 8 Speed chain. It works for the 7 speed freewheel you just built and also works in the 9 speed M971 derailleur. (A 10 speed derailleur would probably not work). For a crank, for trail, the Shimano Deore XT FC-M770 44/32/22, or for street, Shimano Deore XT FC-M771 48/36/26. These are very light or an XTR 9 speed triple will be lighter. You won't find a 48 top cog 9 speed XTR unfortunate. I like to use and old FD-M900 or FD-901 for the front derailleur. Front shifting is better with this setup with an older 8 speed front derailleur. The M900/M901 is bottom swing, is as light as they get, and will shift almost any 6-8 speed drivetrain. Prob okay with 9 speed too but I have not tried that... Well I digress. You get the idea. You can swap in road parts instead of the same grade to achieve the above.

I've built two of the above setups and shifting is Ace I run the rear Cute 100's from BMS battery and Grins torque arms. BMSbattery KU63 controllers are super light and tiny and work good enough for me.

Thanks for the heads up on that.

So you are saying you can fit the cogs on a standard screw on type 8 speed cluster or only on a CST style motor?

 

[zukster]

The Cute 100 I use requires a thread-on freewheel. I don't like the DNP freewheels. They have the 11-32 range but they rust quickly on the West Coast in Vancouver, BC. They generally shift okay.

But I like my gear and wanted to do better and lighter that also accommodates Shimano index SIS shifting. The old Dura-Ace road bike thread-on freewheels from the late 80's/90's is one of the best ever made and you can pick them up on ebay for < 50. They usually come in a cog range of 12-19 or 13-24... For mountain bikes we generally want 11-32 or so. The closest I could get was 7 speed 12-28 Dura-Ace MF-7400 from the conversion I explained. It shifts like a charm and weighs 437g after the conversion.

To expound on the conversion a bit, you use the 12/13 from the original Dura-Ace, and its body. These are Uni-glide cogs (UG). They are SIS but the teeth are twisted at the top to help shifting. These are different than the newer Hyper-Glide (HG) SIS cogs currently the industry standard for up to 9 speed drive trains.

The other cogs used for the conversion are from a new HG SIS MF-HG37 (13-15-17-19-21-24-28) and MF-HG37 (14-16-18-20-22-24-28). These cogs are ramped HG SIS and provide the smooth shifting we have gotten used to since the mid-90's. The 12/13 UG cogs are not ramped like the newer HG cogs, but because they are the smallest ones it does not diminish shifting smoothness. I should mention that you have to file about 1mm of the side of a notch to get the MF-HG37 cogs to drop onto the Dura-Ace body. It only takes a minute with a hand file.

What I ended up with after selecting the cogs I wanted is a Dura-Ace MF-7400 (12-13-16-19-21-24-28) which provides a uniform shifting range up to 28. You could combine however you want.

I also tried a Suntour Microlite freewheel that was < 200g. It was from 12-21 or 12-24 or similiar. Unbelievably light, but it did not shift well with the new HG SIS shifters. It probably work fine with the old Suntour 7 speed indexed thumb shifters of the Shimano SIS/friction LX/XT thumb shifters - these can shift by friction or Shimano indexed SIS.

All this info will soon be for naught when the hub manufacturers accommodate for CST cassettes on the lighter hub motors like the Cute 100/Q100. I should really get this info into its own thread. Didn't mean to hi-jack yours. I just put a lot of time researching this stuff and wanted to get it out there.

 

[zukster]

It looks like I spoke too soon. A light weight cassette capable Cute 100 is now listed on BMSbattery's web site.

http://endless-sphere.com/forums/viewtopic.php?f=2&t=54297

 

[Kepler]

Fitted the 15mm front axle and installed the Fox Floats. Bike feels more comfortable to ride with the nice compliant front end.

 

[dbaker]

What does the bike weigh?

 

[Rix]

Bike feels more comfortable to ride with the nice compliant front end.

This is especially true when you are getting on the binders hard to stop quickly from speed.
Very nice build Kep.

Rick

 

[zukster]

What does the bike weigh?

I was wondering too. I have a MTB Santa Cruz Blur XC Carbon Frame. I just got the build to < 30lbs (no batteries) but it was a lot of components upgraded to XTR and carbon seatpost, handlebars etc. Full suspension Fox Float 23 front and rear shocks. Its a nice ride and trail capable. Once I switch to a Q100C and cassette, I'll do a build article on it.

 

[Rix]

I am guessing around 23kg or about 50 pounds.

Rick

 

[Kepler]

The bike is around 14kg (31kg) without batteries in its current configuration. The bike has put on a bit of weight with all the latest editions but I think well worth the trade off.

I carry various sized packs depending on what sort of ride I will be doing. Typical pack is 3 x 6S 5000 Turnigys. Adds about 2.5kg to the bike including the bag.

Range varies with high speed commuting (between 40kph and 50kph) sees a range of around 20kms. If I knock it down to 30kph to 35kph, range doubles.

 

[Rix]

The bike is around 14kg (31kg) without batteries in its current configuration. The bike has put on a bit of weight with all the latest editions but I think well worth the trade off.

I carry various sized packs depending on what sort of ride I will be doing. Typical pack is 3 x 6S 5000 Turnigys. Adds about 2.5kg to the bike including the bag.

Range varies with high speed commuting (between 40kph and 50kph) sees a range of around 20kms. If I knock it down to 30kph to 35kph, range doubles.

Kep, I was guessing with 18s 2p with 6s 8000mAh cells ready to run at 23kg. But yah, with the power supply variations, 30-40 pound range easily. Thats just awesome. Your machine is trully Stealth. A very keen eye would be needed to see something was up.

Rick

 

[zukster]

The bike is around 14kg

Awesome. Lets start an under 30 club!

 

[DIY_turbo]

Awesome. Lets start an under 30 club!

I totally with you on this.
I really would like an under 30 club. This is an awesome ebike category.

 

[deepfraught]

Great work Kepler!

I'm keen on the original BB location friction location, where I can't fit the CB beta, or on some smaller frames or mud guarded bikes.

Will you be replicating the BB mount and engagement hardware? I have CB beta parts I can hopefully interchange between mounts/bikes.

 

[Kepler]

Small update to the bike's config. Gone from 18S to 20s LiPo with an end charge voltage of 83.5V. Battery config is 3 x 6S 5ah plus an extra 1 x 2S 5ah added to the series. I am using my older packs out of the Fighter which are 300 odd cycles old and quite tired. They still have reasonable capacity and hold good balance, just a bit saggy underload. However, they are fine for a low powered setup as on this bike. Watt limit has been kept the same @ 800W max so the bike feels similar in relation to acceleration but it does feel a little more crisp. Added a couple of clicks to the top speed of the bike also.

The Little SWXH seems happy so far with a few rides to work now completed.

So I thought I would give it a bit of shakedown this morning with blast up the local hill climb known as the one in twenty. http://theclimbingcyclist.com/climbs/mt-dandenong/the-1-in-20/ This is a well used time trial climb that is very popular with the lycra set both comp and recreational. An A grade comp rider strives for sub 14 minutes but a time under 20 minutes is considered reasonable. My PB on my road bike is 18.35 so not too bad for an old bloke.

Anyway, enough background preamble. Time to see what the Super Commuter could do. After a 12km warmup ride to the base of the climb, I stopped and set a 500W PAS profile to be a little conservative with the motor. Sat there for a few minutes with about 20 riders going past me and none of the them giving me a second look.



Took off and quickly settled into a fairly consistent speed of 32kph. The CA showing 500W and me pedaling at a consistent level probably contributing around 250W to the mix. Wasn't long before I started passing rider after rider typically 10 to 15kph faster then what they we doing. The SWXH is very quite under these loads and certainly wasn't giving anything away. However I have no doubt I was kidding no one that it was just me pushing the bike up this climb.

Hit a section half way up that flattens off a bit with my speed now getting up to 45kph. At this speed some of the corners were getting a bit dicy but I didn't want to backoff. Was kind of happy as it started to get a bit steeper again so I wasn't traveling quite so quickly.

I could now see the final straight and pushed hard to finish it off. Cross the line and hit the stop on the timer. 12 minutes 45 seconds. The little overvolted Bafang performed flawlessly and I had a ball pretending I was some kind of super athlete.





Continued up the mountain and then back down and home. 53km and a total of 273 Whrs. Not to bad considering close to half of that capacity was used to race up the hill.

 

[Architectonic]

So, did you take the Strava glory? :lol:

 

[Rix]

Damn John, that just plain awesome that you are hitting some serious climbs and speeds and keeping your WH per KM that low. Very very impressive. Those front forks with the 15mm through axle probably helped with the handling when you started pushing speeds in the corners faster than what you were... "comfortable with" if I understood your comment correctly. My dad is doing something like your build, excepts his build is for a super lightweight Offroad capable machine. Pretty neat to see a guy pushing 70 building an Ebike. Thank Jay for this. When Jay put together the kit for the Yosemite ride, he unleashed the mad fabricating scientist in my dad. Not trying to thread Jack your build page, but here is a pic of what is coming down the pipe from my dad. Its 12s now but will be 18S when completed. Code 10 MAC, is on the rear. He has been fussing around with battery placement, I am going to show him your battery bag up front. Rear rack isn't an option, do you have any ideas for him? He is not computer savvy enough to create an ES account and start his own build thread nor does he want to. I told him I would ask around. Anyway, do you have any second person video of your machine taking off from camera view? Or climbing? These little MACs do amazing things with a very small amount of current.

Rick

 

[majornelson]

Kep,

How does the battery in the front bag impact handling. Intuitively, 2.5 kg on the front is nothing but can you tell a difference vs. when it was on the rear?

Love this thread...

 

[zukster]

I burnt out 2 SWXH motors running voltages of 16S and 18S. They overheated on hills so be careful. Now when doing long and/or steep climbs I jump off and put my hand on the motor after a hard stretch. If I can't keep my hand on the motor, I let it cool down. I also upgraded my two in use SWXH's to metal gears as one of the overheatings striped the nylon gears. The first overheating baked the coils.

http://endless-sphere.com/forums/viewtopic.php?f=2&t=10185

 

[Kepler]

Damn John, that just plain awesome that you are hitting some serious climbs and speeds and keeping your WH per KM that low. Very very impressive. Those front forks with the 15mm through axle probably helped with the handling when you started pushing speeds in the corners faster than what you were... "comfortable with" if I understood your comment correctly. My dad is doing something like your build, excepts his build is for a super lightweight Offroad capable machine. Pretty neat to see a guy pushing 70 building an Ebike. Thank Jay for this. When Jay put together the kit for the Yosemite ride, he unleashed the mad fabricating scientist in my dad. Not trying to thread Jack your build page, but here is a pic of what is coming down the pipe from my dad. Its 12s now but will be 18S when completed. Code 10 MAC, is on the rear. He has been fussing around with battery placement, I am going to show him your battery bag up front. Rear rack isn't an option, do you have any ideas for him? He is not computer savvy enough to create an ES account and start his own build thread nor does he want to. I told him I would ask around. Anyway, do you have any second person video of your machine taking off from camera view? Or climbing? These little MACs do amazing things with a very small amount of current.

Rick

That's great to see Rick. Just keep the Watt limit down with the 10 turn on 18S. 1500W should see it stay alive. Also make sure the controller is equipped with 100V caps and 4110 FETs. If the original setup from Jay was designed for 12S, then it may not be able to handle the voltage. Also you are going to need to be able to program the controller or use CA to setup the current limit correctly.

The front mount is a good option especially for double crown forks. Oatnet has done some great work with front mount battery packs. http://endless-sphere.com/forums/viewtopic.php?f=6&t=34230&hilit=oatnet The trick is to keep the weight as close to steerer as possible. With my bag setup, I angle the bag down so it just lightly rests on the head tube. When setup like this you can hardly feel the weight of the batteries in the bag.

 

[Kepler]

I burnt out 2 SWXH motors running voltages of 16S and 18S. They overheated on hills so be careful. Now when doing long and/or steep climbs I jump off and put my hand on the motor after a hard stretch. If I can't keep my hand on the motor, I let it cool down. I also upgraded my two in use SWXH's to metal gears as one of the overheatings striped the nylon gears. The first overheating baked the coils.

http://endless-sphere.com/forums/viewtopic.php?f=2&t=10185

Interesting. We must be doing something different though as this motor has done about 2000km on 18S and is still going strong. It spend plenty of time between 500W and 800W too.

Just thinking what might make the difference. Firstly I am using the lowest speed wind available 201rpm@36V from memory. My experience is that these low speed motors handle more power than the same high speed motor. I am not sure why this is the case I would love for someone chime in and throw in a bit of theory to explain this.

Secondly, I use a fairly soft ramp on the throttle which tends to protect the gears and one way bearing.

What wind motor were you using when you suffered the failures?

 

[zukster]

We must be doing something different though as this motor has done about 2000km on 18S and is still going strong. It spend plenty of time between 500W and 800W too.

Just thinking what might make the difference. Firstly I am using the lowest speed wind available 201rpm@36V from memory. My experience is that these low speed motors handle more power than the same high speed motor. I am not sure why this is the case I would love for someone chime in and throw in a bit of theory to explain this.

Secondly, I use a fairly soft ramp on the throttle which tends to protect the gears and one way bearing.

Also 201 rpm wind. The difference might be I was packing myself and a heavy backpack (or light trailer - still 60 lbs). So my weight + bike weight + 60 say. 150+40(older build)+60 = 250lbs. Its not that the 201rpm can handle more power - its more like it provides that power at a lower speed, or provides more torque at a lower speed. This will be most noticeable when first starting out. Combine that and your soft-ramping the throttle probably explains it. I've not had gear wear problems with the metal of course. I just watch for overheating now. I'm going to try the Q100C 328RPM wind next, just for having enough higher=end power to pass road bikes going 50km+ on the flats. The 328RPM should move the whole powerband up. I'll let you know how fast it is on the flats at 14S when I try it. Then an 11-32 XTR cassette and XT cranks that have 26/36/48 cogs means I'll be able to peddle at the higher speeds to. Not quite road gearing, but close.

My Son road a SWXH back and forth to school for about 4 years before the gears broke. That was at 10-12S. 10S at first. 12S when he got older. This is up a biggggg hill everyday though. I calculated the appx kms at 10000+ .

 

[DIY_turbo]

Hi Zukster,

Do you think putting a thermistor in your motor on the winding would help avoid this?

I'm thinking of doing this on my own build and was wondering how efficient it is.


thanks,

L.

 

[zukster]

Hi Zukster,

Do you think putting a thermistor in your motor on the winding would help avoid this?
I'm thinking of doing this on my own build and was wondering how efficient it is.

L.

I think others do this if they could comment? I like to stay low tech and keep my bikes simple. Motor, controller, batteries, and throttle.

I think some motors come with the sensor in them already and don't the CA have the ability to monitor? Anyone?

 

[--freeride--]

Hey there I am using a MXUX Motor very similar to the bafang at 14s 58,8V from the charger. It is a 250rpm motor on 26 inch wheel. It is running 46-48kph with no load the wheel spinning free.
With this motor i can commute easily with 37-40km/h (normal pedaling without sweating to much) top speed with hard pedaling is 43kph.

I am putting 900W through it while accelerating and never get any heat issues.
Take care that you don't go up hills full throttle at low speed.
If I keep up the speed to 30km/h (900W Motor 200-400W me) there won't be any heat issues.

The plastik gears don't like 900W of the start, so it is better to limit the phase current.

If you get serious heat issus your system is to fast. For example the bafang with 72V, will do more than 60kph with no load... so better use 48V instead.

 

[Gab]

Hi

53km and a total of 273 Whrs.

And on your CA it says 5.2 wh/km thats very low well done.

What was the average speed of this 53km trip ? and how long did it take in total ?

I wounder what the reason is for this efficiency ? is it the motor or the bike and tyres ? or is it your peddling effort ? or all of the above?

What is the full throttle NO load current of this motor by itself or in a wheel ?