Help! Picking motor for my first touring build

Hey All,

So, I finally decided to build an ebike. I've never owned one, so I think some of my questions come from a fundamental lack of knowledge. That being said, I'm very excited to learn and have already read so much about everything!

Anyway, I want to build a bike that is _mainly_ for long distance touring, but will also work for trips to the beach or that really good restaurant your friend tells you about that is conveniently outside of metro service. I also will always be pedaling and am not looking for a throttle experience... I love biking and am seeing a motor as a way to extend the distances I can comfortably go and flatten out those pesky hills.

For long distance trips I would like to pull at least 100mi/day (120-140 would be ideal) on cycleways and some crushed limestone trails. I don't mind planning to charge every night, but I wouldn't complain if I had even more range . For more day-to-day use, I'm probably doing about 20-40mi roundtrip on asphalt.

I haven't decided which bike to build this on yet. I'm thinking I'm going to first select the motor/battery arrangements so I can find a bike that'll fit. Whatever it is though, it'll probably be a classic touring bike.

Battery wise, I was thinking about doing two 48V 24Ah batteries in parallel when touring and one 48V 13Ah. In the far future, I'd like to modify things to also have a solar panel on board to help give extra range or potentially fully charge the system when I'm camping, but that is not an immediate concern.

Motor wise, I'm debating between the BBSHD and the TSDZ2 (I'm open to others, but those are the main ones I've seen in my research).

Main thoughts on the TSDZ2:
- the torque sensor which seems to be suited for people like me who like pedal assist (again, any experience here is welcome)
- here is some open firmware which I would love to hack on
- lower wattage means better range?

Main thoughts on the BBSHD:
- Seems to be a huge amount of community support
- High power seems appealing for large loads / big mountains (but will this hurt battery when on straightaways?)
- Marginal programming ability... it seems like this may expand in the future?

Anyway... any thoughts or experiences or links to successful touring builds would be very useful!

What would you expect to get out of reprogramming the controller logic?

You've chosen to do something that e-bikes are not good at doing. You can make it happen, but it's a serious compromise of the bike's weight, handling, structural margin, and other virtues.

My advice is to decide on an amount of assist power as low as you think you can live with, and optimize your system to do that with maximum reliability and efficiency. BBSHD is a good system and it's highly programmable, but it's not optimal for the kind of range you're talking about. TSDZ2 or BBS01 would be better to make a reasonably sized battery yield that kind of endurance. A very lightweight geared front hub motor like Q100, configured for good efficiency at your anticipated average speed, would also be a fine way to go the distance. It would help less on climbs, but done right it would ration your energy out more sparingly than a mid drive.

You'll have to match battery capacity to desired range, but you'll also have to match your attainable cruise speed to the time you're willing to spend in the saddle. It's not useful to have 120 miles of range if it takes ten hours to go that far, and you don't want to spend that long riding between opportunities to charge. The faster you go, the more energy each mile will consume, so low speed makes a better, lighter bike-- but also longer sessions riding.

So I'd work backwards from how fast you want to go. Use the Kreuzotter.de power and speed calculator, with conservative assumptions about your bike, pedal contribution, and load, to estimate how much power you need to maintain speed. Then you can figure out what motor will give you that much power, and how much battery energy will be required for your desired range. Remember you'll need a lot more watt-hours of electricity from the battery than the watt-hours of mechanical work required at the wheel (not counting your pedal power). It's worthwhile to examine and understand the speed/power/torque/efficiency curves for motors that you are considering. That will help you choose the right winding and voltage for a hub motor, or help you understand the best operating techniques and cycle gearing for a mid drive.

Once you know how much battery you need, and decide how much added safety margin you're comfortable with, you can choose a battery and then refine your speed and power calculation based on a more accurate estimated bike weight and configuration.

Note that carrying a big heavy battery on a front or rear rack will impair the bike's ridability. Carrying a big heavy battery in the frame will impair your ability to pedal. This might be a job for a cycle trailer.

mynameisfiber said:

Hey All,

So, I finally decided to build an ebike. I've never owned one, so I think some of my questions come from a fundamental lack of knowledge. That being said, I'm very excited to learn and have already read so much about everything!

Anyway, I want to build a bike that is _mainly_ for long distance touring, but will also work for trips to the beach or that really good restaurant your friend tells you about that is conveniently outside of metro service. I also will always be pedaling and am not looking for a throttle experience... I love biking and am seeing a motor as a way to extend the distances I can comfortably go and flatten out those pesky hills.

For long distance trips I would like to pull at least 100mi/day (120-140 would be ideal) on cycleways and some crushed limestone trails. I don't mind planning to charge every night, but I wouldn't complain if I had even more range . For more day-to-day use, I'm probably doing about 20-40mi roundtrip on asphalt.

I haven't decided which bike to build this on yet. I'm thinking I'm going to first select the motor/battery arrangements so I can find a bike that'll fit. Whatever it is though, it'll probably be a classic touring bike.

Battery wise, I was thinking about doing two 48V 24Ah batteries in parallel when touring and one 48V 13Ah. In the far future, I'd like to modify things to also have a solar panel on board to help give extra range or potentially fully charge the system when I'm camping, but that is not an immediate concern.

Motor wise, I'm debating between the BBSHD and the TSDZ2 (I'm open to others, but those are the main ones I've seen in my research).

Main thoughts on the TSDZ2:
- the torque sensor which seems to be suited for people like me who like pedal assist (again, any experience here is welcome)
- here is some open firmware which I would love to hack on
- lower wattage means better range?

Main thoughts on the BBSHD:
- Seems to be a huge amount of community support
- High power seems appealing for large loads / big mountains (but will this hurt battery when on straightaways?)
- Marginal programming ability... it seems like this may expand in the future?

Anyway... any thoughts or experiences or links to successful touring builds would be very useful!

Click to expand...

Very exciting! It's rare to see someone who wants to make an electric touring bike. I have a electric enduro with a 1800 watt hour battery and just barely manage to squeeze out 100 miles with throttle only. So if you're running only pedal assist, you shouldn't need that much battery for 100 miles. (48v * 48AH = 2304 Watt hours).

Of course range can be very dependant on your rolling resistance. Thinner, slick and higher PSI tires have better rolling resistance.

I've never owned a TSDZ2 motor kit but I own 2 bafangs. The BBSHD has a torque sensor for pedal assist and just because it has higher power doesn't mean you have to use all of it. It is fun however

Edit: I have to admit my rear gets very sore after riding for a long time. Even with the moto seat on my electric enduro. Honestly from what I've seen, most people put really big batteries in scooter style ebikes when they want that much range.

@donn To be honest, I'm not 100% sure yet... but I'm a programmer who even just likes having all their stuff running open source code. I could imagine doing some custom power profiles for different ride types, but again, I'm not sure but it definitely means I'm not limited if I do have an idea in the future. Hackability is a thing I consider with most things I buy

@Chalo Wow... great thoughts! Thanks for the insightful response. I totally see what you mean about the various compromises.

Looking at kreuzotter with some very conservative numbers (ultra heavy 180lb load on the bike, 75% of my average cadence, wide tires), 150W will give me 16.3mph. So 120mi in about 7.5 hours using 1125Wh of power. Or if I kick it up to 250W I get 19.8mph so 120mi in 6h using 1500Wh of power. (and again, 120mi is my dream goal... 100mi is a perfect real-world situation)

If I want things to be leisurely, then I'll assume I can contribute 1700kcal (1976Wh), and that 22% human calorie efficiency that kreuzotter assumes, then I'm left with 690-1065Wh that the bike needs to generate from the above situations. This puts me right in the range 30Ah at 36V battery (for the tsdz2), assuming perfect efficiency. What sort of efficiency can I expect? Do you have a link to where I can find various speed/power/torque/efficiency curves for motors? Does this analysis seem correct?

@SirLongAss That bike looks great! What kind of trips do you get up to on that? Also... I didn't realize the BBSHD had a torque sensor... I thought it was just cadence!

One thing I was reminded about, when I proposed some calculations like that here recently - the "30Ah" battery isn't guaranteed to deliver 30 Ah. I discovered that in person a couple weeks later, when I ran one of my batteries down at 80% of its official capacity, and it's new. When they're old, even less to be expected. It's a fine point, but worth remembering if you have an important range target.

donn said:

One thing I was reminded about, when I proposed some calculations like that here recently - the "30Ah" battery isn't guaranteed to deliver 30 Ah. I discovered that in person a couple weeks later, when I ran one of my batteries down at 80% of its official capacity, and it's new. When they're old, even less to be expected. It's a fine point, but worth remembering if you have an important range target.

Click to expand...

I definitely agree with that! If I need 30Ah, then I'm going to aim to have at least 40Ah

This is a better simulator for ebikes:
https://www.ebikes.ca/tools/simulator.html

mynameisfiber said:

@SirLongAss That bike looks great! What kind of trips do you get up to on that? Also... I didn't realize the BBSHD had a torque sensor... I thought it was just cadence!

Click to expand...

I get like maybe 50-70km on that bike with a 72v 20ah battery(1440 wh). It's really crap for rolling resistance.

I'm pretty sure I read it has a torque sensor.

Edit! Looks like im wrong about the bafang. It uses a cadence sensor.

Peoples ability to pedal varies. Only very few are able to put out more than 100w of pedaling for 100 miles or more. Personally, my ass wants off that saddle desperately by about 60 miles, or 5 hours, whichever comes first. And that was a pretty leatherized ass too, since I was commuting to work by bike then.

When I toured, my ability to pedal was severely limited by an illness. And, I live in the southern end of the rocky mountains. So I needed enough power to pull 400-450 pounds up a steep grade more than a mile long. Me, bike and gear. Bike and battery alone was 100 pounds. gear included up to two gallons of water, since the next water or plug might be 60 miles. For me, 60-80 mile range was 48v 40 ah of battery. 2000 watt hours. My motor ( a hub motor) needed to put out 2000w without overheating to get up the mountains, so I went with a very large, heavy hub.


If you are fit, and can stand to camp with half the gear I carried, things change a lot. Rolling hills don't affect range that much if the grades are not above 5%. If you can get the load out below 300 pounds total, nearly any decent e bike can handle that up the grades. The BB can do serious grades, but if long enough, you still use the same watt hours getting to the top. That's laws of physics. 250w for an hour, same as 1000w for 15 min. But on the flat, if you can pedal up 100w, then another 150w from a motor will get you ( at 400 pounds) to 15 mph or a bit more. This depends on wind too, but I'm assuming 10 mph from one side for at least some of the day here.

If you can tour so that it includes a 3 hour stop at noon each day to charge, you can drop 15 pounds of battery right there, and carry 1000 wh. Not possible where I am, 60-70 miles of mountainous desert between towns.

You will absolutely need a cycle analyst for touring. You have to know your average watthours per mile, and you calculate each day how many wh/mi you need to get to make it to the next plug. The ca will show you this number on the fly, so if you calculate 25 wh/mi gets you there, you can ride along keeping that average close to that number. then at the end of the day if you have spare juice, you can then speed up and finish off the ride quicker. The CA will tell you what your real world, actual capacity is in watt hours. You can't even begin real world calculations till you know that number, which you find out on a test ride. That number goes down in the winter too, btw, cold weather will cost you about 20% capacity.

Nothing wrong with your plan. E bikes CAN tour. They just usually need at least double the typical 500 watt hour battery, if not quadruple it. And to keep weight down, the camp gear gets pretty frugal. I just couldn't stand more than two days in the tiny tent on the ground. If you can afford it, tour motel to motel as much as possilble.

dogman dan said:

If you can afford it, tour motel to motel as much as possilble.

Click to expand...

Not just for a comfy night's sleep indoors, the motel is also more likely to offer some quality time with an electric outlet.

I've been seeing a somewhat consistent theme here, on the discomfort that comes from a long day in the saddle. Which either calls for equipping the bike for faster speeds, or arranging a tour with shorter legs. I've done a couple long 100 mile days, a long time ago so the memory is a bit faded, but yes, now that you mention it - maybe discomfort isn't a strong enough word. But now I ride a recumbent bicycle.

Seemed obvious enough to me when I saw it, but that was later - they didn't really exist back when I started riding much. Today, fairly common, but in many cases maybe not a great fit for electric motors. The only problem with mine, really, is that there's no suspension, so everything really takes a beating when the road isn't perfect. Otherwise, it's like a lawn chair with wheels. I couldn't find any examples of real long wheelbase recumbents with suspension, but the HP Velotechnik Spirit is close to LWB and is a quality make, not a real glamorous look but I imagine it would be a good candidate.

48 Ah of battery plus an on-board charger is a serious load.
Due to the knowledge and extra care and handling required, I almost never recommend LiPoly, but in this case, it might be worth considering. It would be at least 5 lb.s lighter and up to a 1/3 rd. smaller than any other chemistry.
4) of these would be a 12S (45.6 Volts nom.), 40 Ah pack;
https://www.ebay.com/itm/Turnigy-MultiStar-6S-20000mAh-10C-LiPo-Battery-XT90-eBike-Multirotor-DJI-FPV-UAV-/322765722302?_trksid=p2385738.m4383.l4275.c10
On-board chargers-The typical genaric Chinese chargers are notoriously bad for this kind of useage. The insides giggle apart. It would need to be a potted charger like the Satiator or Mean Well HLG series. A HLG-320 could charge a 40 Ah pack(at close to full discharge) in 4 to 5 hours.

To ease the use of the best rear gear-set possible and for reliability, I would use a frt. mounted sm. gear motor, like a Q100H. Motor speed range would be critical and a mid-speed (260 rpm rated @36 V) in a big whl.(27.5" or larger), plus input of the rider should get close to 25 mph and still climb reasonably well. Closer to 20mph(but not less because it becomes boring)would reduce wind resistance and extend range.

Well then, you never even mention where you bought your "new" battery from.
I hope its not from any ole seller because they will give any ole specs to sell whatever they are selling.

Going to reputable sellers like GrinTech in Vancouver https://www.ebikes.ca you wont have no mystery about battery capacity, or a mystery as to what the cells that were used in the pack are.

donn said:

One thing I was reminded about, when I proposed some calculations like that here recently - the "30Ah" battery isn't guaranteed to deliver 30 Ah. I discovered that in person a couple weeks later, when I ran one of my batteries down at 80% of its official capacity, and it's new. When they're old, even less to be expected. It's a fine point, but worth remembering if you have an important range target.

Click to expand...

@dogman dan thanks for the tips on the tip on a CA. That is definitely a good idea and I'll never shy away from having some good stats on a trip. Also, my camping gear is normally _very_ light and minimal... sometimes I just bring a hammock!

I'm really hearing heavy support for hub motors but it seems from other research online people really advocate for mid-drive motors because of their efficiency. Is it because these mid-drive motors are more efficient at higher speeds, and not for the speeds that are best for touring?

Motor system efficiency is over-rated. Dogman himself has stated that what the rider had for lunch or how loose fitting his/her riding clothing is, probably has more effect on range than motor system efficiency. Imagine having to deal with dirty chain run problems on the side of the road. Fixing a flat on a rear hub motor is bad enough, which is one more reason I recommend a frt hubbie.
Think about it, if you are carrying 30 or so pounds of batteries, does an once more or less(which would be the difference in system efficiencies)make any real difference?
Think of a hub motor as a 3 speed auto in a car(in this day and age of 6, 7 or more speeds). The old 3 speed works fine if you only go 60 mph, it's when you need to broaden the envolope, or climb really steep hills that the mid-drive is worth the trade-offs it brings. You don't need to go faster than low 20's mph so as not to kill your range w/ wind resistence. And really strong legs can make up for a hub motor's weaker climbing abilities.
Your main concerns should be reliability and avoiding "range anxiety", which is mostly tires and battery capacity(and opportunity charging), respectively.

markz said:

Well then, you never even mention where you bought your "new" battery from.
I hope its not from any ole seller because they will give any ole specs to sell whatever they are selling.

Click to expand...

Don't all the battery cells come from China, whoever you buy the battery from? Does any seller tell you, or even know, where in China, what factory? For me, I don't really care very much who sells me Chinese batteries, I'm going to have about the same expectations.

mynameisfiber said:

I'm really hearing heavy support for hub motors but it seems from other research online people really advocate for mid-drive motors because of their efficiency. Is it because these mid-drive motors are more efficient at higher speeds, and not for the speeds that are best for touring?

Click to expand...

Mid drives are a good way to make a low powered motor work through a wider range of speeds and conditions than would otherwise be possible. But if you can determine a typical usage condition and set up a hub motor to do its best in that condition, the superior raw mechanical efficiency of a hub can easily outperform the mid drive. If you can run a hub motor for hours at three-quarters of its no load speed, there's no way a mid drive will exceed its efficiency.

The advantage of a mid drive is that you can keep shifting to keep its (lower) efficiency sweet spot working in varying conditions.

Motomech has a point that there's not much to get worked up about in terms of the difference in peak efficiency between different motors. But if you goof it up-- run a hub motor too low in its speed range, or lean hard on a mid drive and overgear it to bump up the torque-- you can quickly get into a regime where you're throwing away as many watts as heat as you are turning into power at the wheel. The hub has an added pitfall in that its efficiency and power output both approach zero as it closes in on its no-load speed, but its power consumption remains significant. You can't keep changing gear to recenter the motor's happy RPM.

So getting good Wh/mile from a mid drive is mostly a matter of technique, but getting optimal efficiency from a hub is all about good planning to match power, torque, and speed to the most prevalent riding conditions you'll face.

FWIW, I only toured with a huge rear hub motor because at that time, mid drives were a bit primitive and breakage prone. Not the case now, and most of the better large cargo bikes built to haul heavy weights run a mid drive. Tons of advantage to mid drive, but the efficiency difference shows primarily when overloaded, on a hill. So my solution of a big motor prevented the overloaded condition, pretty much eliminating huge efficiency differences. Hypermiling on the flat at 15 mph, the huge motor on the heavily loaded bike uses 200w, and so does any motor. At that point, efficiency is obtained by pedaling harder, slowing down, shedding weight, or improving aero like a recumbent. All those things bury tiny differences in motor type, but again, overload one type of motor, and it will start to run inefficient. The key thing here is if you put a mid drive into the correct gear for the load and the grade, it becomes nearly impossible to run it overloaded. Or, leave it in too high a gear, you can melt er down very quick. Pick a big and powerful enough hubmotor, it gets just as impossible to overload it.

So I chose hub then mostly because they were cheap, reliable and available. I did a lot of testing then for an e bike kit company, and had lots of free motors to go melt down on the mountain. Those worked fine to 300 pounds, but like I said, add 40 pounds of battery, 15 of water, and your load is not going to be 300 pounds or less unless you weigh 115. So for me, a larger hub motor ( two small ones works just as good too) that could haul 400-500 pounds up that mountain worked good for me. It used more power up a mountain, but it got me up any grade at 15 mph too. I ended up with a gargantuan homemade longtail touring bike, but it would literally go anywhere. Full suspension, so dirt roads were no sweat.


A 1000w mid drive is going up that grade too, and possibly even a bit more efficiently. But it will do it at 5 mph, or less if the grade is steep, and you are carrying 40 pounds of battery.


But others here make good points too. Possibly the ideal combination would be a small geared front motor, plus a mid drive. The geared motor would only be used if the mid drive died for some reason. Again, I'm thinking like this because around here, its 60 or more miles of desert between towns that will kill you if you break down, and run out of water too. If there was more water and plugs, I would have only carried half the water, and half the battery. I would just carry a fast charger, so I could stop every two hours, and charge an hour. That would also give your ass a break. RE the ass, you just have to have a chamoix in your pants. So wear riding shorts, or sew the pad from some into your touring pants. Then lube your crotch, just like the bike racers do. Even with all that, I was pretty much in agony by mile 50, but continuing on would more or less go numb. Personal best was an 80 mile day. My best advice, plan on 40 mile days, or, do the 80 miles in 4 hours. After 5 hours of saddle time I'm done. This is still the same for me now that I do most of my riding on a very comfy gas scooter. I just start to chafe by hour 5.