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

[spinningmagnets]

edit: it appears green bike kit DOES carry the 3-dimple wrench in the drop-down purchase menu, but does not show a pic.

I was curious and looked at the Bafang motor site, here is page-1 of 2: http://szbaf.com/product.asp?pid=1

I believe the wrench you linked to will only work for the SWXK, SWXK5, and BPM-II models (with 4 slots on the side of the case, rather than the 3 large dimples). It is nice to finally have a link to the 4-tang wrench, but I'm surprised the 3-dimple wrench is not also listed.

3-dimple wrench used on the SWXH

 

[-dg]

3-dimple wrench used on the SWXH

One more wierdness. A couple months ago I bought an SWXH from elifebike.com and it has the "held on by screws", style sidecover like a BPM. Not the "threads into the hub" style sidecover like a BPM2 or SWXK. So there was apparently a running change to the threaded cover style in the SWXH at some point and I have an old stock SWXH. I wonder what else might have changed.

I really like that greenbikekit.com are selling parts. Most of the failures on these motors appear to be gears, clutch, or the freewheel breaking off due to sidecover failure, so it it pretty sweet to be able to buy gears or a sidecover for under $5.

 

[t3sla]

Some versions have DUAL grub screws that you need to remove BEFORE you use the tool, else everything goes to hell
Seriously you do not want to realize this half way and have a grub screw wedged at degrees

One of the grub screws, I recall it being ~2mm from memroy

SWXK Model [Butchered the serial, figured if you owned the thing your wouldn't want it plastered on the net]

I assume the background in the first photo would have sparked someones imaginations so I added some context

 

[DIY_turbo]

I am using the 201RPM @36V rated motor which I think is the slowest wind they have. They dont seem to list a code in SWXH range of motors from what I have seen.

Running on 18S and around 72V so its now around 402RPM with my setup.

402 x 2180mm wheel circ = 876,360mm/Min or 0.88km/Min
= 52.8kph

In real life 45kph can be maintained but I can get it up to 50kph with some hard assist.

I am a big fan of the high torque low rpm motors as they tend to have thicker windings and as such can typically take a bit more abuse then the high speed windings.

Hi Kepler. Amazing build.
I'm considering doing a similar build.

I would love to have your advice onthe motor based on your experience.

I was considering Bafang CST 270 rpm @36V , mainly because it can use cassettes - do you see any advantages or disadvantages to this motor?

Too heavy for this kind of build (1.5 kg more) - but it could be more reliable. What`s your take

 

[Kepler]

Thanks for that.

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.

Size and weight of the Bafang CST didn't fit the bill for this build however I thought i did see a SWXH style motor CST and disc brake mount. Need to have another look at that I think.

Definitely would be more reliable if you don't mind the extra weight and size however, reliability with 750W on the SWXH has been impressive with the bike being used on most days for the last few months.

270rpm @ 36V on 48V would make a nice high speed commuter. = 360rpm = Theoretical 47 kph.

 

[DIY_turbo]

Size and weight of the Bafang CST didn't fit the bill for this build however I thought i did see a SWXH style motor CST and disc brake mount. Need to have another look at that I think.

Yes you did... thanks for the heads up

http://endless-sphere.com/forums/viewtopic.php?f=3&t=49685&hilit=cassette+hub+motor

http://www.elifebike.com/peng/iview.asp?KeyID=dtpic-2013-46-K3QJ.1WASD

Cute 201 rpm @ 36volt , like the SWXH - I'll be getting this ... almost double the price though

 

[DIY_turbo]

Hi Kepler,

I've been looking at the Cute as a small hub motor with cassette, but noticed that it is made for 140mm rear spacing at the dropouts. Do you think a carbon frame would be springy enough to accomodate the difference (5 mm), and do you think the additional pressure (lateral force) would compromise the carbon frame's solidity?

 

[Kepler]

Mine is sprung to 140mm to fit the 8speed cluster. Effort to spring it was very light so it didn't worry me too much. Just make sure the force is quite light to spring the 5mm and I am sure it will be fine.

 

[Rix]

Subscribed.

 

[DIY_turbo]

Hi Kepler,

Many thanks for answering all my questions. Really really appreciated.

I'd like to put a Thun Torque Sensor on the Bottom bracket with a Ultegra crankset.

Just wondering about some specifics. What type of BB shell do you have on your bike (BB30, BSA, etc) ? Which version of the Thun sensor did you get? I believe I cand read the 128L in one of your pictures, but I'm not sure. And why did you choose that model (spindle length requirement, etc). Did you need any shims, special screws (different threadings), adapters or do any modifications to make it fit with your crankset?

 

[DIY_turbo]

After researching this, I don't think it's possible. Square tapered bb don't work with Hollowtech 2. Is there a torque sensor solution for shimano cranksets (recent)?

 

[Kepler]

Unfortunately you need to spec down to use the Thun. That being said, I have had no issues with it as a bottom bracket.I fitted one of these http://www.cyclingdeal.com.au/buy/shun-track-fixie-crank-crankset-170mm-46t/SS8106 just for the cranks and spider. Then purchased a standard set of 53T / 39T chainrings. Works perfectly.

 

[DIY_turbo]

Unfortunately you need to spec down to use the Thun.

Not necessarily, I found a quality crank made in France that would do the job, the Vortex Crank by Spécialités TA - http://www.specialites-ta.com/gb/manivelle-vortex.html. Only 473 g. While scouring the mtb/road bike forums, I was surprised to find out that there are still many fans of the older/vintage cranks with square tapered axles. Spécialités is specialised in catering to that crowd with replacement chainrings for Campis, Looks, and Shimanos.

Jean Claude from Spécialité assured me that their CNC milled Zéphyr (N10) chainrings (52t and 39t) would match the original Ultegra chainrings.

Did you have any issues with the larger hub having an Over Locknut Dimension of 140mm. Did it displace the chainline ? Did you have any shifting issues requiring additional adjustments to the chainrings (like adding spacers) ?

Kepler - again thanks for all your help - I owe you several beers by now!

 

[Kepler]

No problems DIY_turbo.

That is a nice crank set. I am sure it would be a little more expensive then what I am using . BTW, the crankset I use is compatible with Ultegra chain rings also.

In relation to chainline, I didn't need to do any spacing to keep it in check. Remember the chain stays spring out in both directions so the extra offset is only 2.5mm. The Thun bottom bracket comes in 3 different spindle lengths also. I got the 119mm for my setup.

 

[majornelson]

Kepler,

Great build! I love a stealth ebike. The state of design with most ebike accessories is horrific. Most throttles, controllers, switches look cheap. Amazing what you've done... Impressive.

Quick question. I thought you were originally putting the controller under the seat. Bu after you switched to the hub motor, you placed it under your crank... Just curious what drove this.

Thanks for sharing the build.

Lee

 

[Kepler]

Thanks majornelson.

The Hub motor controller was simply too big to fit under the seat.

I opted to mount the controller under the bottom bracket mainly to keep it out of general site. Also it allowed me to keep the cabling nice and neat to the motor. Disadvantage was that the battery and CA3 cables needed to be quite long and of course the fact that it would get quite wet in this position even if it wasn't raining but the roads were still wet. Needed to make sure it was well sealed. With the addition of the custom junction box at the front of the controller, I managed to seal it all up quite effectively but still have it reasonably serviceable without having to cut through a mountain of sealant.

This bike is a real work horse and gets used most days as my main form of transport. I don't make a habit of riding if it raining but I have been caught a few times. Also its quite common for me to ride on wet roads with lots of water spray under the bike. So far not one electrical problem with the bike being super reliable full stop.

In a nutshell, the bike is a joy to ride and really lives up to its name as a Super Commuter.

 

[chas58]

Tons of good info here, I have to keep checking back!
(and I enjoyed the friction drive podcast too).

I’m curious as to why you use so many Volts (18s)? I was thinking of going in a similar direction, but then changed my mind. I really liked the light weight and simplicity of 36V and the lighter battery packs (vs higher voltage).

What is the benefit of using a slow speed motor at high voltage vs using a high speed motor at lower voltage (36volts).

I can do 45km/hr on a 13 kg bike (Bike 8.6kg, motor 2.2kg, battery 2.0kg.)
(unfortunately, that is assuming I actually purchase the 2.0kg 36v8AH battery – currently I’m using a heavier 36v10AH LiFePo4 battery).

I guess one thing in my favor is I don’t have to worry about hills. Nothing on my commute, and even on the steeper hills north of my commute I pedal and keep it above 25km/hr.

The biggest tires I could shoe horn on were 28mm front, and 32mm rear gatorskins. With them at 90psi, the ride isn’t too bad…

 

[Kepler]

A few reasons for going with 18S.

Firstly I am big fan of the Volt up Amp down line of thinking. It allows you more kW out for a given size controller and sized cabling. This in turn is conducive to less wasted heated under most conditions.

Consider if I am using say 800W @ 70V to maintain 30mph. In this case I am drawing a tiny 11.5A which is a piece of cake for a 6 FET controller
If ruining a 36V system under the same conditions, I would be drawing closer to 22A and working the 6FET controller much harder.

18S is a nice easy battery combination to deal with using 6S series packs and makes for a nice compact package.

It is quite difficult to get a motor wind capable of 30mph on 36V and I find that these high speed winds are not as robust as the low speed windings when pushed hard. My SWXH hasn't missed a beat at 800W and spends plenty of time up there as i do enjoy a bit of high speed commuting.

 

[chas58]

So in general, increasing the amperage requires better cabling and may lead to more heat, while increasing power by increasing voltage does not have these issues?

I’m running a Q100 328rpm 36v with a 14 amp controller. This puts me at about 27mph, maybe 29 if I am in a hurry. But, like you I’m a fairly active biker so I’m probably providing half the power. The motor doesn’t mind (although the controller gets pretty warm). Hopefully I won’t have any durability issues, or I will have to volt up the low wind version of the motor.

Its my own little light weight Specialized Turbo commuter (at a fraction of the price of the official version).

 

[CORKY]

Hi Kepler,

I'm still following your Super Commuter with interest and want to build something similar.

I recall that you mentioned a similar frame but in Aluminum would be only 2 pounds heavier,
which is what I'd like to do.
Could you compare the weights and ride quality of a Carbon versus a fixed ChroMoly fork on
an Aluminum frame, and any examples that spring to mind ?

How many of the RC batteries do you need to make the 18S pack you suggest for 72 volts ?
What is the resultant weight of that pack ?

Thank you.

 

[majornelson]

3 6S packs would get you there...

 

[pendragon8000]

Hi Kepler,
I had a nice cruise ride yesterday on my 29er limited to 500watts the whole time .
On flat no wind I was getting 40kph fairly easily and had a go at pedaling it upto as fast speed as I could, surprisingly as I fatigued from sprinting the speed still increased so I didn't give up and just got 50kph. I'm running the hs3540 so just wondering how that compares to your experience on the super commuter?

 

[CORKY]

Thanks majornelson on the 3 x 6S answer.

 

[majornelson]

Still there? I live near Wilson and falls road...sort of near Landon school (we are on the Bethesda side of Bradley on Aberdeen road. ) Nice area for a bike!

Where did you live and go to school? Small world!

 

[Kepler]

Hi Kepler,
I had a nice cruise ride yesterday on my 29er limited to 500watts the whole time .
On flat no wind I was getting 40kph fairly easily and had a go at pedaling it upto as fast speed as I could, surprisingly as I fatigued from sprinting the speed still increased so I didn't give up and just got 50kph. I'm running the hs3540 so just wondering how that compares to your experience on the super commuter?

400 to 500W is about what I need to sustain 40kph. I can get it up to 50kph without trying too hard at 500W but to stay at 50kph for extended periods I need closer to 800W.

Hub motor setup has been removed from the bike for the time being so I can endurance test my latest friction drive on a high quality frame. Will post some pictures and performance comparisons soon.