AM dual motor = bafang middrive + rear hub motor

[John Bozi]

Pendragon havent seen you around here for years!

that's not my bike pictured, but that guy ruined another hub with his first try but the crystalyte hub he got is meant to be stronger.

There's way too much debate about rewinding still, just follow john cr, anyway I was going to buy a second hand one and try but man it looks incredibly complex it just put me off because I doubt Id do a better job of it...

the wrong gearing doesn't get solved compared to say running in granny gear.

I am about to pay for the bafang 750w, It has 1000w peaks, this is double what a drive train can handle in my opinion already, so yeah will be real careful at first until I piss it up ....

Actually Pend, you probably have idea of gearing with all your mid drive stuff recently.

I'm trying to find a suitable rear sprocket solution. Because once I apply 1000w to the thread on cassette there will be almost no chance of turning back...

I've read a bit on sheldon brown http://sheldonbrown.com/freewheels.html

The standard ISO threading for freewheels is 1.375 x 24 TPI, the same as for standard ISO bottom brackets

.

wondering if there is a way to get our thread on hubs work with splines because most products these days are. this 42t sprocket im guessing cant be run single speed? but its spleened for example

oneup

Our 4065 has M35 thread http://www.crystalyte.com/Dimensions_H40%20Series.pdf

studying sprockets I need to know chains: from wiki

Chains with 3/32" wide rollers are used on bikes with derailleurs such as racing, touring, and mountain bikes

Another thing is replacing my custom cut cranks
worried that these cotterless wont fit right, from sheldon:

Traditional cotterless cranksets use a tapered square spindle (axle) end. The sides of the end taper at a 2 degree angle compared to the centerline, 4 degrees compared to each other.

white industries single freewheel for trials

 

[pendragon8000]

I'm doing left side drive.
To put less strain on the chain use biggest cogs possible. Also your small wheel should help.
Swap new chain every 1000km or so

 

[John Bozi]

without a doubt I want to run this in granny at back and the 30t race face I already run at front.

Will most probably play around with the dnp epoch I have now as it looks more rearrange-able than my old shimano Mftz21.

Ive got the shimano in my hands now studying it but no chain whip

to pull it apart to look at the spacing and threading but it looks like this from google image...

japanese
http://katagiri.at.webry.info/201203/article_6.html

now even though it would nice if these splenes matched up, the 42t one up is designed to be shifted, which will suck for single speed

what would be perfect is actually the same race face narrow wide tooth concept to keep the chain in line such as this

so it looks like I am going to need some customised adaptor to join the two...

EDIT: have now put money down on the banfang 750w so no more speculation...

cranks

spent a lot of money on the cranks and now I have to buy new ones!

I am hoping these unicycle ones will do the job unfortunately though they have zero Q factor meaning my ankles might get shredded by the spinning chainring!

choices for these black Nimbus Venture2 ones are 114, 100, 89mm but it's hard to calculate because I don't know if they will hit the swingarm that narrow.

edit I bought these cranks $55 delivered...

Nimbus Venture2 cotterless cranks. Upgrade your unicycle with these robust, durable high quality and lightweight cranks.

Machined 7075 T-6 aluminium cranks, available in 114mm length. Sold in pairs.
Product Description
Cotterless cranks are often produced as cheaply as possible and consequently are of poor quality. The better cranks are only found on ISIS hubs. Nimbus Venture2 cotterless cranks are the exception.

These cranks are produced by a different process and create an excellent balance between weight, strength and toughness. Although the original Venture cranks are good... these are 40% stronger!

Material: 7075 T-6 Aluminium.
Color: Black.
Length: 114mm.
Weight (pair): 341g
Type: Cotterless
Q-Factor: Almost Zero Q-factor - This is the amount a crank bends outwards. Zero means it doesn't lean outwards at all. The straighter the crank the better for speed, the wider the better for ankle clearance and greater maneuverability.
Note: Crank length is measured from the center of the axle hole to the center of the pedal hole. Sold in pairs.

http://www.municycle.com.au/catalogue/UP-CR-N114COTBLK2_item.html?ref_cat_id=CranksCOT

 

[pendragon8000]

Could you bolt a spider onto a freewheel and a 38/42, then put a big 52 up front? That should favor the chain allot and reduce tension on it although the ratio may not be right. 38-38 would be amazingly low for a mid drive.

 

[John Bozi]

dont understand pend

putting a bigger chainring at front puts more stress on the motor as I understand. the smaller ring at front and the bigger at back is both slower top speed efficiency and less stress on the motor.

as for spider that doesnt work as I have discovered this week... as I posted on the last page:

you can see that there is probably some freewheel between the crank and chainring

 

[pendragon8000]

Yeah I mean for any given ratio making both gears as large as practically possible will reduce stress on the chain.
I think it would be quite possible to make a custom connection between a freewheel and a front chain ring. Normal gear setup would be OK anyway right?

 

[John Bozi]

mmm interesting point... I was always getting confused because we know smaller front is going to be less stress on the motor and really keeping the motors cool is all I care about. Chains are the least of my worries and will become disposable as batteries or faster I guess.

Anyway I made huge progress on the bike today with dad god bless him. 6.30am till about 1pm we worked like crazy on a bit of alu bending, hammering, drilling and then hose tube clamping until success I finally got 24 cells 4x6s to fit in the triangle!!!!!!

this is so important right now because I will need more battery for the mid drive, even though I know 2p is best I am carry a shit load already... I imagine I'll start out at 12s1p which shouldn't be too bad at 25amps on the bafang. I know it will run out before the rest of battery runs out but for now I have to give somewhere.

I'll probably once my 3s bats get old give up on the 21s and go down to 18s for the hub.

Now that we made this triangle piece we have a better idea of customing more brackets for the rest of the bike areas. Would be perfect to get either 12s2p or even better but more annoying to charge with more wiring to get up to 14s1p or 2p.....

 

[John Bozi]

Interesting bit of pedaling I hadn't tried before.

Chose a consistent bit of road, and then watched the watts as I pedaled like crazy to keep it at 20 kmh.
Then do it again keeping it at 20 kmh this time only with throttle.

You can calculate from this that my legs produced about 350 watts in granny gear.

Being totally unfit I could only do it 100 metres. This is on a very heavy bike with DD drag and inefficiencies of course too.

So my drive train will have absolutely no problems if I run the mid drive at half power, which is actually what PAS runs at if I'm correct. This will add a really cool dimension to trying to get the most range out of my bike.

12s1p 5ah will probably not be a problem on the battery considering I'm running 2p at 65amp peaks now on the hub.

Even at 25 amp draw the 25c x 5.8 = 145 / 4 ("rule") = 36.25 peak. They'd always be running at below their continuous rating what ever I throw at them.

Received the motor.

EDIT ADDED:
First thought picking up the box not too heavy, picking up the motor I'm thinking this is going to add quite a bit of weight, wondering if the added efficency of having granny gears will not just compensate as that would not be improving things. This drive has to over compensate because the hub will be working harder also and it will to some degree heat more but hopefully there will be no more need to heat rests... Feels like the bike will be pushing about another 5kg which is substantial, and added battery but I dont count that as bad because it would give more range anyway you look at it.

 

[John Bozi]

The old Penny Chopper girl is wondering what's in front of her.

Unicycle cranks at first looked like they weren't going to fit on the shaft but they seem to be ok... Won't know till I pull it all apart, but don't want to be without a bike until I have all the parts I need = adapter for starters and another 12s1p... to run in dual mode.

 

[drew12345]

John, you have a lot of space between rear wheel and seat tube. Ever think of putting batteries or controller there?

 

[John Bozi]

John, you have a lot of space between rear wheel and seat tube. Ever think of putting batteries or controller there?

Almost everyday I think I can put something there and have measured it out many times including full suspended down shape. this controller won't fit, the last one barely fit but the wiring was problematic, a 6s would fit but wiring would stick out badly and really each point should be 12s.

So no, nothing fits there comfortably and even if it did, apart from being lower on the bike I need stuff which is more forward to counter wheelies. I'd prefer higher if it could be more forward.

Temporarlily I will put 12s next to steer tube. Once the motor is mounted and I can measure the new Q factor of the cranks I'll know if 12 cells or 24 cells are possible below the downtube in front of the motor....

EDIT:
Just bought 2 more of the same battery I've been running.

I ummed and arhed for a long time because I was thinking to get 4x8s and 8s chargers to limit the bike to 4 sets of 2p charging batteries, but that's added investment and I'm not sure about running too much power through the drive yet, and wanted to go 8AH batteries but, staying with the same batteries means they are all interchangeable... and I am sure of the dimensions for the saddle bag near the steer tube, and for now the weight of the bike is going to be more than I like.

It doesn't matter if I change my mind and buy 8s in future because my other lipo have some not so healthy cells... I can always use the older lipo on my old bike for short distance rides while working on or charging my Penny Chopper or eventually have enough for work commuting where I don't care at all if it gets stolen...


RPMs

from wiki: http://en.wikipedia.org/wiki/Bicycle_gearing

If the bafang runs at 120rpms peak then my idea of going 44t x 30t front with the addition of 20" wheel running so incredibly slow that I am now reconsidering 22t white industries again at back to bring me closer to my average riding speed of 20kmh.

 

[John Bozi]

I have roughly mounted everything, it mostly looks like it works. Except I have a bolt head pivot from the swing arm touching the side of the part holds the chainring. I'm not sure how much that rotates (guessing a few mm at most.) it should be ok.. or if anything just make its own graze and then become perfect...

I was wondering about warranty if I shorten my wiring in parts?

Also, I'm having a bit of trouble with speed sensor, The hub motor doesn't give me much room to play with or use a screw driver...

Theoretically, if I don't have the speed sensor on can this thing work? (I don't care about the display...) Just looks fragile for off road riding... Had to put it right next to the hub edge, which I am worrying about possible magnetic interferece to the hub or the hub to the sensor....

Unfortunately I have a wider bottom tube and one bolt on the motor pushes down... so have lost a bit about 4cm which is quite a bit when I running (20"+ 26"/2 = ) 23" bike.

Chain line has gotten worse (just got the adapter 30 minutes ago...) The way I thought it would fit rubs.... so the race face is actually backwards to fit, because the 4 holes on the adapter are the size of the outer meat for the screws.. Chain looks perfect to run with the 11t sprocket, hopefully next year I can pull the freewheel apart and rearrange the sprockets to get the granny as wide as possible....

Edit 1

the bike is seriously heavier to lift. It really feels harder to pull up the front. This is bad for hopping up the gutters or roots etc. But this is seriously good to stop wheeling without wanting to. Keeping the front down will be easier I hope on climbing too.

I don't care if the mid doesn't suit, because it will be easy now I have lots of tools to pull it back off. I wouldn't regret buying it because I have about 4 other bikes that I could put it on. 3 of my own and one my bros,

 

[drew12345]

Did you take for ride yet? Pic of your bike with it on?

Edit: just re-read that you only mounted it. So how much longer? Anxious to see how it rides?

Also, I think next year doing dual hub.

 

[John Bozi]

A million thoughts.....

my 2 bats didnt arrive yesterday so I pulled off all my bats and just used 2 x 6s at 3.8v a cell. 45v and I worried all the time, but on my alarms and it has a perfect lvc at 41v so really no worry. remember this thing is still pulling the drag of the big DD....

first spin around the block

weird changing sound in the motor as it kicks in and out with delay - PAS weird
thinking this thing is slow
weird to back pedal - freewheel at rear stops much quicker so my worry about getting hd rachet sounding single freewheel is gone....
surprised how little power I used

second spin around 3.7v a cell

tried pas in strongest setting 9
Hey this is actually really cool, I'm digging this as an overall package, actually don't need any more power or anything to get around my mountainous suburbs
still surprised with how little power I used
granny gear is totally aweful gear and really don't need it for PAS because this pedals so nice in 11t 7th gear so well and setting the pas to just right help is sweet.
Will take a while to be comfortable with pas as sometimes you turn the crank just to get a better stance and then suddenly it kicks in.

third spin

I love it. I love the complexity of gears.
must get used to changing gears with PAS as in 9 strongest it changes hard on the freewheel with loud probably damaging click sound.

will get picks soonish. left hand thumb throttle bit weird and the display is just load of clutter - only good for setting pas.

 

[cwah]

pictures?

Wouldn't that be better to only have the BBS02 for the weight?

 

[drew12345]

I had pas on my first bike which was currie. I couldn't stand it. Felt like it was kicking when I didn't want it to and wasn't in complete control. If I ever get bafang, I will most likely disable.

Sounds like it might work out for you

 

[John Bozi]

NO pics, but here it is up the mountain on a morning ride

[youtube]L8KJdV4IedQ[/youtube]

PAS is not good for anything complex agreed drew. Not only for off road tracks but also anywhere near traffic or people.
Don't freak me out cwah, the thought has crossed my mind to let go of the hub.

I need to do a real long ride a few times to see the true overheating possibility. Also, being able to keep up with riding buddies is important. For me the bafang is fast enough, I'm not in a hurry, but with the other guys I reckon it's too slow. Changing gears all the time is fine on long roads but is annoying up and down and around complex trails. The hub is far better for this.

I am praying for no rain on Friday morning before work to go out on a long one (and have my batteries from HK) as my last ride of the year.... Thailand time.

 

[drew12345]

Thanks for vid! I like how small the bafang is. Looks like a good setup in addition to the hub. With the type of trails you ride, I would definitely keep the hub to keep the speed.

 

[John Bozi]

I like how small the bafang is. With the type of trails you ride, I would definitely keep the hub to keep the speed.

Yeah, for me it had to be as compact as possible and I think it's right at the power level I wouldn't want to cross through this cheap freewheel. And I didn't want another controller to stick out. Unfortunately I am stuck with this display...
Only time will tell if the advantages of having perfect rpm for slow climbs is worth the 5kg weight increase and lower ground clearance. I predict at some point I will hit the bafang on something like a rock or I always hit random branches....

Last night I tightened the shifter cable to get the two high grannies working, at a sacrifice of losing the two bottom gears.... The 7 twist shift has never worked perfectly with the 7 speed at the back... With the hub motor it didn't bother me, I just made sure the 11t worked perfectly... I might look into a 9 speed shifter having a wider range?

My rear granny is 32t x 30t front = unloaded in 20" wheel 10 kmh. I don't know what I was thinking looking at 44t!

Dam this rain!!!! got ready to go do some testing rides with dual motor full power, and it just keeps raining and probably the same tomorrow... first time in my life I'm going to have to discharge my batteries to storage charge.......

 

[John Bozi]

Amazingly it stopped raining this afternoon after many days of storms, I took the dual motor fully operational up on my usual long centre road circuit about 25kms I think .... so many thoughts again.

In order my thoughts as I rode.

The hub motor blows the mid out of the water!
There is no comparison at absolutely any level or speed, the hub is more powerful and more fun by far because it leaves the mid drive off the scale.

It would absolute madness to swap the hub out for the bafang. Of course it would be faster without the weight of the hub motor but I am saying this as I compare the hub motor also needing to pull the bafang, so it is relative.

My idea is that with all the weight and drag of the hub, the bafang produces as much power as I can but it can do it continuously where as I can do it in sprints and then need rest.

There is stuff that it bogs down in without a doubt and it is always at the point I need to depend on the hub to power up... actually with hub you dont need to change gears so it is so much easier to run up full power and keep it going until it start bogging down and then let the granny kick in to limit it bogging...

the cool thing about the bafang is that it so in tune pedal cadence, I was worried it would always be out.

there is no doubt Id enjoy this more if I could get perfect shifting but they arent and got some nasty loud changes.....

I know the hub is heating a bit faster because of the extra weight but cant tell how much because I hamered sections much harder than usual and without a break.

Cool thing was on one long relatively steep grade where the bafang was just perfectly comfortable at 10kmh, it was so cool I could hold the thumb throttle with my left hand and use my right hand to look at all my specs on the CA. Very cool and no rush, just pedal for a while till a bit tired and keep going.

so yeah the bafang would be cool if it fit on my carbon hardtail with just two batteries to get me to the top of the mountain, and then just enjoy normal single tracking down. but it is no fun compared to hammering everything as you can with the hub....

so so complex

complex thoughts with so many more thoughts I had...


Ah really loved some very steep bits where I realised how excellent having a 20" wheel is. You can drop your ass behind the seat so much more 6" lower!

I can't weight to do more rides

edit

it was also noticable how much smoother the hub is and sounds beautiful compared to the grunty, jerky grindy mid. It like smooth to grunge.
My favorite point was hitting a patch where the hub bogged down to 10km and could feel the bafang coming perfectly in tune to it with little spurts of more power. Its not a consistant motor but more sends like waves of power....

In order of video taken

[youtube]TuDtF5cKLRU[/youtube]
[youtube]J8ID9rAHCNI[/youtube]
[youtube]ZwDgranM_mg[/youtube]
[youtube]cfGyGzNEF6c[/youtube]
I got stabbed by a bit of lantana good thing Im fat...

 

[drew12345]

Oh yeah, that mid drive won't be anywhere near the speed of your hub. It will blow away AFT also. But the mid drives (at least AFT) can climb all over mountain and won't have heat problems that hubs usually do. At least won't overheat as quickly. This is IMHO since I have both setups.

 

[ziltoid81]

Well thats the perfect "do it all bike" solution.

A hubby to let it fly on the flat areas and a mid to crawl slowly and without any stress up the mountains.

Really love the build and the idea behind.

 

[John Bozi]

Drew,
I'm pretty sure (not 100%) that an extra 1000w that the AFT can give should get me through the steep parts the bafang bogs down on, but highly doubt the hub drive train could handle that much stress.

have you had any wear and tear anywhere on your drive train with AFT?

cheers ziltoid81,

it sounds like the perfect solution, but with time I am sure to see problems because of the weight and stress on all components.

I am tempted to shift a lot of different ideas around. For maximum distance but boring riding, to go 12s2p on mid but then needing to drop weight on the hub, possibly going 24s1p if I can get a true 60c battery. This way maximum crawl distance and maximum explosive spurts of power.

 

[Gab]

1000w that the AFT

Does the bafang peak at 2000w ? I thought they had 25amp controllers ? I have seen on other threads the AFT peaks at 3000w

 

[John Bozi]

1000w that the AFT

Does the bafang peak at 2000w ? I thought they had 25amp controllers ? I have seen on other threads the AFT peaks at 3000w

Just speaking roughly. 50v x 25 amps = 1250w that's already twice what a drive train would normally see. I could lift that up to 58v but don't think a couple hundred watts are worth the extra wiring and charging hassle. If I get an 8s charger and some 8s then I will try it...

I reckon another 1000w or 2000w that AFT would provide would shred the drive train somewhere or my hub.