Xtracycle cargo bike conversion questions

81forest

100 W
Joined
Jun 11, 2018
Messages
105
Location
Issaquah, WA
Hi everyone, first time poster here, thanks in advance for any comments or suggestions! Like most newbs on here, I’ve done a lot of research but the questions just keep coming!

I am building an xtracycle free radical “long tail” conversion on an old favorite mountain bike that I hope to use for commuting and kid hauling. I am about to pull the trigger on Luna’s BBSHD mid drive kit with a 48v 17.5ah battery, UNLESS one of you has a better suggestion!

My commute is about 22 miles each way, and I ride it regularly on my regular bike (human power). I am an avid cyclist and enjoy the commute, but recently I’ve needed to carry a lot more weight, hence the cargo bike conversion.
I also have two kids that can fit on the “hooptie” child carrier kit, so I’m hoping to leave the car parked for errands and shopping, etc.

I have lots of experience as a bike mechanic, but zero ebike experience. I do not care about top speed, what I really want is RANGE! We live at the west end of the John Wayne trail, a rails-to-trails project that crosses our entire state. My dream ride would be to take my cargo bike with camping gear and maybe a kid or two, ride up and over Snoqualmie pass (about 40 miles), campout, and then ride back down to my house, without charging the battery. I plan to ride the bike “unassisted” whenever possible in order to save juice.

Am I looking at the right battery, or should I spring for the massive 23.5ah version? Any comments are super appreciated. Excited to join the community, you guys are very generous with the knowledge and I’ve already learned a ton!
 
Based on my and my wife's experiences with three BBS02's, I can't imagine you using less than 20 wh/mile with two children and/or camping material. 17.5 watts probably will get you there, but not home. You might be able to keep the usage down to 10-15 wh/mile on your commute with lots of pedaling.
 
Thanks 2old, I think you’re right and I was being too optimistic with my wh estimate. I definitely intend to pedal a lot and don’t mind getting to work all sweaty (sorry co-workers), but even then it looks like I would really need two batteries for anything beyond about 40 miles.
 
You have chosen a pretty good setup for what you want to do but battery size is alwsys an issue. BBSHD will both carry weight and ride in hilly country as long as you use appropriate gears. You need to travel quite slow to be able to contribute much pedaling, like less than 20 mph. Chainring sizing is important to balance between pedaling and motor power. My bike with 38 tooth chainring you only pedal on the biggest hills, the rest of the time your spinning but not adding any power.

This same bike gets 50 km (31 mi) from a 15ah battery with light pedaling.
 
Great info, thanks. It shows what a noob I am that I consider 20mph to be “fast”, because on my best days riding a 15 pound racing bike I am averaging about 17mph. Lol

So it sounds like a smaller chainring like yours allows you to contribute more human power, keep speeds lower, and get more range, is that correct? I think I would rarely exceed 20mph unless going downhill, but I think every noob says that at first...
 
A few notes, based on my experiences with my long cargobike Crazybike2, and my SB Cruiser cargotrike:

Between 15-20MPH, air resistance starts to make a lot more difference in power usage than below that. The boxier with more stickey-outey-stuff there is, the worse that problem becomes--although the longer the bike is, the less of a problem it can be, if most of the surfaces along the sides are parallel(ish). Sometimes. :)

The heavier it is, the more power it will take for acceleration from a stop, and also on uphills.

Conversely, it'll have the potential for greater regenerative braking energy recovery on the downhills or slowing down from speed, if you used a DD hubmotor. (though the DD hubmotor has disadvantages over a middrive for some of your situations).


Middrive, if gearing is optimized for your speeds and loads, and you shift properly as needed, will be more efficient than the DD hubmotor, if you are at different speeds under different loads.



For my CrazyBike2, I might get 20-25wh/mile power usage, none of it from pedalling, with a 2WD hubmotor setup, cruising at 20MPH (average somewhere around 15-17MPH I'd guess), accelerating to that speed from a stop in ~4 seconds (which uses a lot of power). Lower wh/mile on longer trips with less stops than shorter trips with more of them, so a small but significant part (several wh/mile) of my power usage was accelerating the mass, rather than overcoming wind resistance at speed. Could've reduced the power usage with a fairing, even partial, like a tailbox instead of the squared off backend from the cargo boxes and seatback.




Batteries: The higher the battery capacity, for the same c-rate of cell, the lower the load on each cell, and the easier it is on them, and the less each will sag in voltage.

Generally cells that are meant for higher capacity per-cell will be less capable of supplying that energy quickly, while cells that are meant to suply that energy quickly will be less capable of holding as much energy total per cell.


Batteries can get heavy. My EIG NMC lithium packs are 20-something pounds for a 14s 20Ah pack in a steel 50cal ammocan, and under 40lbs for a 14s 40Ah pack without a case around it.

There are lighter cells/packs; but generally I'd anticipate nearly 1lb/Ah for 14s packs with a sturdy crash-resistant enclosure, and then if they're lighter, well, bonus. ;)


48v can mean 13s or 14s, but usually it is 13s, and 52v is usually 14s. Typically doesn't matter which it is, as far as the cotnroller/motor/etc are concerned, only for the top speed of the system, for the most part. See the http://ebikes.ca/simulator to play with different systems to see what I mean.
 
Great info, thanks Amberwolf! After spending a couple of hours reading about the latest tongshen torque sensitive motor offered by biktrix, I am thinking it’s a better set up for my needs. As someone who wants to be pedaling hard all the time, I really like the idea of torque assist rather than the on/off of bafang’s PAS. That plus the smaller 500w motor should get me more miles per watt-hour, correct?
 
TSDZ2 is a good motor but you will need to be careful in your stiuation stessing the motor while starting with a load. One of the drive gears is plastic and acts a bit as a sacrificial part. It will strip before something else goes so you should have a spare. Swapping it out is not to hard. You can switch to a metal gear but risk the next week link going. Yet to see what that is.

If your ever near by you could try mine, I-have both types running.
 
Thanks, I would take you up on that offer if I could, I love BC. I’m on the fence between the two motors, especially with the problems reported with the latest firmware in the bafangs. All things considered, I’m leaning toward the BBSHD again but need to confirm that the issue has been solved. I inquired with biktrix, Luna, and em3ev, whoever responds first will probably get my money.
 
I guess I’m lucky enough to have a bbshd that has throttle in level 0, I pretty much just pedal and use thumb throttle as required. The pas is if you want to ghost peddle and cruise along under motor power. Doesn’t sound like how you ride.

Kinda hard to keep thumb off throttle for me too much fun.

I’d love to find an extracycle kit for this bike its a bbshd and 31 ah 25r battery.


av3 - 1 (1).jpg
 
Sweet ride! That’s some range you’ve got!!

Two vendors responded and basically said, we’re working on it, no solution yet. So the Bafang is out for now. You must have one of the good ones I guess? From what I read, the current firmware requires you to actually go in and physically cut the PAS wire in order to pedal at all under throttle, even at “0”. That’s a non starter.

Yeah the free radical conversion suddenly became pretty rare since extracycle stopped selling them. I had to buy a complete bike and strip the kit off of it for my bike.

I am now thinking of going a different route altogether, with a DD front hub motor from Grin in your neck of the woods. Called them and they were super helpful, very nice guys (typical Canadians, haha). I will post an update when I finally make up my mind...
 
Everyone has there opinions on the different types of setup. I’ve had 2 front hubs and ditched them both pretty fast as being unsafe for where I ride. Maybe they are fine on pavemant only but any gravel and the front wheel spins out. I have a mix of road types in my area so no way am I spinning out my front wheel.

As far as bbshd and cutting the wire you could do the same by pushing the wire pin out of the jst connector. Its a 1/2 to 1 hour job. Its so much better suited to the type of riding you described.
 
you should read the post by mr scoot on the tsdz2 thread you may get excited about it again,

https://endless-sphere.com/forums/viewtopic.php?f=28&t=79788&p=1387104#p1387104
 
Argh! :idea:
I see what you mean about wheelspin; didn’t think about that, I will definitely be riding this bike off road. Sounds like the tongshen might be the way to go after all. OTOH, I bet I would be fine with no pas and just throttle, and I like the “known quantity” aspect of the Bafang. Dang it!!
 
A front hub system makes sense for a cargo bike on the road since it balances the weight somewhat, but off road there are problems. FMW, you need to transfer your weight forward when ascending a hill (off road) or the wheel won't provide traction.
 
I’m very grateful you and Marin took the time to steer me away from that one, I actually thought the front wheel drive would aid traction off-road but obviously it does not! I am back to really wanting the BBSHD, just nervous/not happy about disabling it out of the box in order to make it usable. The joys of diy? As Marin was explaining it, I think I may not really miss PAS anyway, I really want to ride it as a normal bike with a throttle option that I can use on hills.
 
Seems like the endless fear of front hubs continues here and other forums on the net. I have used a couple of front hub all road bikes, all speced with Grin hub motors one 9c and one Any Axle throttle only with cruise control via the CA3, the last few years here and never found them lacking for traction as long as the right amount of input from both the motor and human are maintained. This is a clip from a climb on a pretty steep old mining road down in the Steen's Mtns.. One of many I did there.

https://www.youtube.com/watch?v=s_ej4KeqGTc

The big problem is that hub motors are not as efficient overall for climbing or hauling heavy loads overall as they also can get pretty hot depending on how they are wound. I use a TSDZ2, 52v with brass gear, for my mtb and Monday we did the Ape Canyon Trail to Smith Creek and I almost made it back to the parking lot on 10ah. The Muddy River crossing towards the end was sketchy I might add....

It's not just the BBSHD, which we install on customers bikes a lot here in the PDX, but all cadence sensored PAS systems that lack the feel at the pedals that a good Torque Sensing system provides allowing it to provide a much more natural pedaling experience. That is the reason I only use a throttle on my front hub bikes so as not to have the motor override the amount of input I want to put in at any given time.

The BBSHD does provide a lot more power depending on how it is set v/A however and for the amount of load you anticipate carrying at times I would still recommend it over the smaller TSDZ2. Bottom line is that the heavier the bike is the more power it will take to balance out the assist you will need even with active input from the rider. I think that you will find that although you plan to only use the motor when necessary that with that much weight you will find it necessary more often than you think even if you are a strong rider.
 
Haha, “endless fear”. :lol:

Excellent info, thanks, and I enjoyed that video. Unfortunately I am not much closer to making up my mind but weighing the pros and cons of each, here’s what I come up with:

BBSHD
Pros:
adequate power for my needs, lots of experience from other users, parts available, cheaper than Stokemonkey
Cons: current firmware problem that requires disabling PAS, I do not want to “hack” a brand new full price product, tons of problems reported, can’t get wet (I’m in the pnw, that’s a big problem), can’t talk to the vendor on the phone or get a satisfactory answer about the firmware problem

TSDZ2
Pros: torque sensing, a little cheaper than Bafang, adequate power for my needs
Cons: not as much power as Bafang, can’t talk to vendor, not sure about long term reliability

DD hubmotor
Pros: cheap, reliable, simple, sold by an awesome vendor that answered a million questions and personally uses the same setup on his own cargo bike and loves it, throttle only
Cons: not as efficient for hills with a load, Front wheel might be squirrelly in the dirt

I gotta say that talking to the Grin guys is a huge pro, and all of the problems with mid drives, including components that don’t like to get wet, is a huge con. I think PAS is out for me. I was a shop mechanic for many years and I enjoy wrenching on my seven other “non-e” bikes, but I do not want to be constantly tinkering on this ebike project. I want it to work and forget about it. I also have a boat and four motorcycles that need my love and attention too (I know, first world problems :roll: )

Great info from everyone that has responded. Obviously there is a lean towards the mid drives because of where I posted this, but the simplicity/reliability of the dd hub really appeals to me.

I wonder why there seems to be no love for the Stokemonkey?
 
81forest said:
I wonder why there seems to be no love for the Stokemonkey?
Probably because people don't like the idea of being forced to pedal when using the motor, at whatever speed the motor turns their cranks for them. (this is how the traditional SM setup works, going into the leftside crank and then back out the right side into the bike's drivetrain). Most that reject it have never tried it, so don't really know what it's like, they just don't want to.

It works, and is otherwise like other middrives, except that most of the SMs I've seen use the Cycle Analyst from Grin Tech to do the controller limiting, monitorng/display, etc. That can make them more customizable than a lot of other middrives, depending on how the bike is setup.


Regarding PAS and a DD hub, there's no reason you can't have both. More than a few kits come with basic PAS, and if you use the CA3 from Grin you can do the same thing, with (or without) torque sensing if you like.


If you don't mind the weight, you can even use two DD hubs, one in front and one in the rear (a number of members have bikes like that, setup in a number of different ways). You can use independent control of each (like I do on CrazyBike2 and SB Cruiser; gives me more options for traction control, etc), or have them both setup to provide the same thing at each wheel, etc. Two motors will handle a load easier than one, with less heating in each hub.

However, that's probably pretty overkill for your purposes. You probably don't need to move pianos, or almost hundresds of pounds of dog food (or hundreds of pounds of dogs!), stuff like that. ;)
 
To clarify the comment about front hubs on dirt, I wasn't referring dirt roads where they function adequately, but steep dirt singletrack, and it's not fear, just the front wheel can lose traction or the system overheat.
 
There is another contender perhaps in the LB01 that was recently introduced? On the ride Monday the other bike along had one. It is basically a BBS02 with a torque sensing PAS. Word on the net is that it was designed by former Bafang engineers.

The LB01 bike was a heavier FS bike, 60+ lbs. with gear including a spare battery and even a can of Campbell's steak and cheese soup, with a heavier rider, 250 lbs. and he used half again as much ah as my lighter hardtail combination of 45lb bike and 200 lb rider. At one point in order to get out of a river bed we had to pull the bike up a steep loose embankment with a 4 fathom length of Spectra whereas I was able to get mine up without. As with any mechanized sport power to weight ratio is key.

Anyway the LB01 shows good promise we feel. The torque sensor is a different type than the TSDZ2 and lacks the feel at the pedals of applying more motor power when pressing harder but is smoother than a conventional cadence sensor. Power wise it peaks at 900w compared to the 780w of the TSDZ2. The other rider has a lot of time on a TS and compared it more than favorably to it overall and in fact commented several times he thought it would suit a cargo type bike better. There is a long informative thread on the TS here and a new one starting on the LB that you may want to monitor?

As far as talking to a vendor we have vended about 30 TS units here running from 36v to 52v, which takes either a firmware upgrade or switching to a factory set 52v controller. Somebody said that the TS doesn't have a throttle but that is not the case and the LB does as well. The main issue with the TS is the blue gear that is the first link in the reduction drive that is driven off the motor shaft is not up to the task of heavier loads. There is a replacement gear made of brass that solves the situation and is easy to retrofit although it does make it a bit louder. The LB has a much better blue gear engagement to its drive gear via deeper vanes and the stress it took getting that heavy load up and over the other day would never been possible with a stock TS. It also has helical gears which makes the overall system much quieter than a TS.

As AmberWolf said the constant engagement of the Stoke Monkey turns a lot of people off. I have total respect for Justin, Robbie and the entire Grin team but as a cyclist this type of drive would not work for me. I don't want my input to be interfered with by the motor assist which is why I use a throttle only front hub, like Justin does, on my all road bikes generallyridden at a higher cadence whereas my TS mtb that generally sees a lower cadence feels really natural off road and still does well enough on the road sections to and from the trails. In fact a few months ago I joined a group road ride here that was averaging in the low 20's and was able to keep up just fine even though I had 15psi in the tires using eco the whole time. It sucked the same 10ah battery I use for my road bike dry in 23 miles whereas on my DD road bike I could have broken wind the entire ride at that speed and had some to spare. As usual it's horses for courses as anyone with a quiver of bikes in their garage can attest to.

Getting back to your potential 80 mile r/t loaded down I personally feel that you would need a couple of 15ah batteries along to maybe make the trip even with the most efficient system you could source even considering the fact of what goes up must come down and that you are a strong rider and willing to work for it. With a lighter load like you would have to commute with for 22 miles you could get away with a 10ah and recharge at work.

The type of cell and their mAh rating used is key as well as the source of the cells from the supplier being good quality. These vary widely and you should source the best quality one you can no matter what motor you use. The new 20/21700 cells becoming available will up this game but are not readily available yet. We just got 40 of them, 4000mAh, from our supplier and haven't had time to build a battery with them yet but are excited to do so. They won't fit in any of the existing HL type cases but at least we can put something together now to give them a try.
 
Awesome!! Any new battery coming out is exciting news for sure. And that motor sounds like maybe perfect for my next project!!. Awd, if you work at a pdx shop with a retail space, I will be sure to check it out next time I’m in town. I had a great time chatting with the wrenches at Clever cycles last time I was there.

Anyway, after watching a video interview with Justin at Grin, and seeing his own personal Free Radical with a DD front hub motor, I pulled the trigger and bought the kit. Throttle only for now. It will be pretty rare to have this bike off-road, and it will likely never do serious singletrack. I have other tools for that purpose :wink:
Got the slowest winding for torque not speed, statorade, and the temp sensor cord to watch the temp. I chose the 25amp controller, hopefully that was correct instead of the 35amp...? I love the cycle analyst and the interface it provides, and all the components seem well thought out.

The battery I’m looking at is a 50v 30.6ah triangle pack from em3ev. Super excited to see what kind of range I get, and pretty stoked to get this thing up and running!!
 
AWD here. Due to Internet ignoramus somehow I ended up with different accounts for my mobile devices and computer.

Grin wIll treat you right. I have both the 25a and 35a controllers. Started out with two 25's but burned one up so I went with the bigger, also physically, one but still run it at 25a via the CA3 and it has been no problem since. I would recommend spending the extra $5. The size difference helps with heat dissipation.

Didnt see you mention a CA but it is a great tool. Via the CA3 you'll have the ability to set up cruise control, set v limits in stages, regen etc..

I thought of your project this a.m. on the way to work after following a bike with an extra cycle kit lightly loaded. It was going along kind of like a snake. Make sure you do what you can to stiffen it up!

Big batteries are a lot of weight to haul around on a daily basis and you might reconsider and get two that equal it's rating and carry the extra when needed. Frankly the triangle batteries are kind of a pain to mount compared to the ease of the HL type that have a mounting plate making it easy to attach to the dt, although you may need a riv nut, and are plug and play.

PM me here if you come this way and I'll beam you in. If time and opportunity allows I'll show you some sweet old school single track near by or take you on a tour of Forest Park.
 
Thank you AWD! That is very appreciated. I was definitely sold on the CA3 from Grin, and I think I will go with two batteries from AllCell.

I’ll post updates when I get it rolling :mrgreen:
 
I look forward to seeing how your build goes.

I've collected all the bits and pieces for converting my edgerunner swoop. Going with EZEE rear motor from ebikes.ca along with PAS, phaserunner, CA3. Battery from EM3EV. Conversion starts... soonish.

My bike friday tandem build has been with a grinhub front motor. No real traction issues to date, and so far has been throttle only. PAS planned, the parts just didnt fit at first try. It is going to be pretty neat to compare the bike outcomes.

My commute is very similar - 24 miles RT with a few 5% hills (10% peak) in between, preschool is at 3 miles from house. The tandem is getting right about 15wh/mile on the commute, doing well with a 14S4P battery that charges nightly to 80%.
 
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