Heavy rider 350w vs 500W recumbent trike

[Oakenstone]

Hello Everyone!

I am fairly new to this, and have tried to absorb as much as I could over the last few months. I've read on this, and other forums until my eyes burned and my brain sizzled. Here's my (hopefully) short story.

I've been a recumbent rider for a long time and am making the switch to trikes. In my prime I was riding century rides. Do to some health concerns, I've only recently come back to biking. I want to convert to electric for the assist. I am not looking for a setup that mimics a scooter/motorcycle. I'd purchase those if I wanted. I will be taking time to rebuilt my legs and stamina. The assist is for if/when I find myself in a “cat-up-the-tree” situation, as that is still unpredictable do to my health. But even with assist I'd still like to eventually do half-centuries.

I test rode a 250w rear geared motored bike from Giant. I took it up very steep hills and it performed well. I felt that the “assist” level was about right. Level 2 (50%) seemed like it was, well, helping me out 50% of the work.

With this knowledge in mind I thought I'd get a 350w 36v rear geared setup. That way I'd be easier on the motor. I ride rails to trails mostly and the typical grade is 5-7%, with one trail being 2-5%. I got concerned because the grades on some of those trails will be miles. (sloooowly up up up, then sloooowly down down down) and I thought I still might melt my motor even with me doing most (or at least 50%) of the work.

In a thread I found here: http://endless-sphere.com/forums/viewtopic.php?f=3&t=62019&hilit=350w+36v+geared+rear+hub+motor, some of my questions were answered.

A possible solution was this setup: https://bmsbattery.com/ebike-kit/586-bafang-bpm2-48v500w-rear-driving-e-bike-motor-wheel-ebike-kit.html#/rpm-328

and this: https://bmsbattery.com/ebike-battery/715-high-power-48v30ah-lipo-battery-pack-battery.html

I am not a small man. I am 6' 4” tall and the total weight configuration (as per the above setup) would look like this (+/- a few pounds):


Rider = 240lbs
Bike = 34lbs
Battery = 20lbs
Water = 9lbs
Misc Stuff = 6lbs

Total = 309lbs

Max Payload of bike
=330lbs

I was concerned that 350W 36v would melt. This setup is 500W 48V. Is this going to be enough? Is this overkill? I don't really want a scooter remember, I normally ride between 12-15 mph. (I don't have a problem with the legal limit of 20mph, and if this setup would cruise at that speed, so be it) I do, however, want to be able to ride for possibly years without changing any of the setup. (unless it's to more efficient/less weight components)

Any thoughts?

 

[d8veh]

You need to choose the right rpm of that motor. 201 rpm should give you about 15 mph. I ordered the 260 rpm one, which gives about 24 mph. Those speeds are in a 26" wheel, so if you have different size, you have to calculate. That 500w motor with the S12S controller should give you everything you want. The bike I built was for a guy with only one leg who weighs about 220 lbs. He can hardly pedal and he has to go up hills of more than 15%, which the motor does easily. The S12S has current control, so on the lower levels, there shouldn't be any problem with over-heating. Make sure you get the PAS sensor and wheel-speed sensor to go with it, and of course the S-LCD3.

Do you really need such a big battery?

 

[docnjoj]

My wife and I have trikes and routinely do 20 miles several times per week. We use batteries that weigh about 16-20 lbs, and on a trike that weight is hardly noticeable if held down low under the seat. I have been recently using the 2 speed motor and have found it quite powerful. I weigh a bit less that 220 lbs (100 kilos)@ 6ft 3" with a trike that weighs about 80 lbs with all the electric stuff. I also usually ride around 15 mph max but can do 20 with my DD 9C motor (not geared). I loved the low speed power of the geared motor and this particular one was very quiet. Water weighs 8lbs/gallon so you are carrying a lot of it. Perhaps you need that much for 100 miles or even 50.
otherDoc

 

[Oakenstone]

Thanks for the quick reply!

As for needing a large battery I was calculating from this source: https://www.electricbike.com/watt-hours/

In short it says "To calculate the watt hours (WH) of a battery pack, simply multiply the voltage by the amp hours (Ah) of the pack. A 36-volt 10-Ah battery pack has 360 watt hours. If you are nitty with your energy usage, each mile you travel will cost you about 20 watt hours. Therefore a 360 watt hour pack will get you 18 miles. The range can vary widely depending on where and how you ride."

So in my case it was 48v X 30ah=1440 watt hours /20 per mile=72. So, yes that is more than 50 (less than 100) but it also had a built in fudge factor (Laziness, bad days in general, riding on roads not rails to trails etc...) I figured this might just be the middle road I was looking for. If you think I could get by on less, I'd like to save some weight.

Yes 20lbs is totally carriable. When I used to bike with a group, I was the only one who was on a recumbent and had a backpack on my seat. I was always asked if I could "just carry this one thing" I should have charged for mule service!

As for wheel size, the tadpole has 20" wheels. I was reading about fast vs slow rpm, and for 20" wheels I think it was fast rpm that it said I needed.

 

[wesnewell]

There's a couple of 20" wheels here with free shipping from within the US. These will give you plenty of power.
http://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_nkw=48v+1000w+rear+20&rt=nc&LH_PrefLoc=1

 

[d8veh]

For 20" wheels you need the 328rpm speed. You won't be short of torque with a 500w BPM in that size wheel

 

[dogman dan]

Sounds like you pedal strong, even after your health issues. I'm in a bit of a different health situation, I will never ever be able to pedal strong again. Sure I can, but after 5 min of it, I pay far too high a price for it. So I can pedal 50w, taking a break from pedaling as needed, perhaps pedaling as little as 50% of the time if I ride 50 miles.

Anyway, so for me I need to overkill the power for when I need it. And I suggest you do the same. Get something with 800-1000w of power, but then you will typically run it at 200w. But if you poop out, now or later when you get older, you have that extra power to just motor home, or up that hill, with minimal pedaling.

There is no requirement that you use it like a motorcycle or scooter, even if it can be. Up to you to roll back the throttle or not. Look for a kit with a selection of power levels. Then you can limit watts to whatever you like. Some kits come with that feature, some don't. The gold standard would be a kit with a controller that can accept a direct plug in Cycleanalyst. This is really nice, since you can set your max amps to any level you like. 36v battery, set your max amps to 10, and you have 350w max. But get in trouble, and with the right controller, you could set your max amps to 30, and breeze up hills without lugging your motor and melting it.

Too slow, because the wattage can't handle the weight, up a steeper hill is how you overheat motors.

You definitely want a geared motor, because you will still pedal some with the motor off, and will like the better coasting.

So you want the Ezee kit from Grin cyclery, The Mac kit from Em3ev, The 500w motor kit from E-Bikekit, or the BMC, not sure who is the best vendor for that, Wasn't it Illia? Oh, and of course also the 500w bpm just mentioned.

But if you have a line on a good price on a 350w geared, that will definitely do for you. But if you do end up changing your assist needs, then it does pose a risk of overheating on the steeper hills. Likely it will not though, because you don't live in the big mountains. So your motor will only be asked to climb relatively short hills.

And just to throw a monkey wrench into the whole decision, don't overlook the bafang BBso2, mid drive. In fact, mid drive might be the ideal for you.

 

[Oakenstone]

Dogman Dan, I used to pedal strong, in my prime. I am, however, just returning and will need to rebuild my strength and stamina. The assist will mostly be used as a training helper/safety net. Hopefully, as I get stronger, I can use it more for the sheer fun of it. I like feeling like I'm superman!

I have looked at the bafang BBso2 750w mid drive. I must say I did wipe a little drool off my face, but I also thought (before your post) that 750w would be too tempting to just use the throttle and thus defeat the purpose this whole venture. I do, however, see your point and am thinking about it.

I like the fact that the mid drive uses my gears more efficiently, but for my purposes, I might be just splitting hairs. Mid drive (from what I've read) is more efficient (with the gears), but the BPM geared hub looks like its easier to install.

My primary goal is distance. It's why I'm heavily leaning towards the 30ah battery. I've always been a long distance biker. My average "jaunt" used to be 50 miles. Ultimately I'd like to get back to 100 mile rides, but realistically if I can work my way back to 50 miles (assisted or not) then I will consider that a success. I don't expect this to happen overnight, or even in a season, but over time I should be able to regain this distance. (and if I don't I'll have an awesome e-bike to putt around town!!)

 

[999zip999]

At 100 miles you need a good size battery 20ah would be to small. How much battery ? There are a few others here riding your style bike it might take a little more reading here on E.S., people will chime in.

 

[Oakenstone]

999zip999, thank you for that! I've read and keyword searched google and this forum for how to calculate amp hours needed for ____range ___weight etc. So far the only thing I've come up with is this article: https://www.electricbike.com/watt-hours/ which gives a "good rule of thumb". This is the information I was using when looking at this battery: https://bmsbattery.com/ebike-battery/715-high-power-48v30ah-lipo-battery-pack-battery.html

All this is good information, but I don't know (or can't find) anywhere to calculate what I would actually NEED in amp hours to make the distance. If I calculate:

Rider = 240lbs
Bike = 34lbs
Battery = 20lbs
Water = 9lbs
Misc Stuff = 6lbs

Total = 309lbs

Also 5-7% grade. Is 30ah going to be enough? Can I "get away" with 20ah? Do I need two 20ah? It's all just theory floating around in my head as I have no actual experience with any of this. :lol:

But, I am learning. (this is half the fun right?) It's all very exciting to me, and am looking forward to putting my bike back on the road! I am very appreciative of the excellent advice I've received so far!

 

[wesnewell]

You won't use 20wh per mile on a recumbent bike or tadpole trike. It will be <12wh per mile at 20 mph. And if you pedal with it, it will be less than that.
http://www.ebikes.ca/tools/simulator.html
Your cheapest option is always from a volume seller within the country you live. And most all of them advertise on ebay.

 

[d8veh]

I like the fact that the mid drive uses my gears more efficiently, but for my purposes, I might be just splitting hairs. Mid drive (from what I've read) is more efficient (with the gears), but the BPM geared hub looks like its easier to install.

It sounds logical that the mid-drives should be more efficient, but the tests I did back to back with a BPM over some moderately hilly terrain didn't show any significant difference. The main advantage of the mid-drive is it's greater speed range, but the downside is lots of gear-changing, so not so relaxing to ride. They make very crunchy gear changes when you change down as you go up a hill, and chains and sprockets don't last very long. The 500w BPM is the same size and weight as the 350w, so not much point in getting the 350w version.

 

[dogman dan]

A mid drive would only be more efficient, if compared to a hub motor that is being abused.

Example, 400w max hub motor and controller, weight 300+ pounds, up an 8% grade. The motor is going to slow to a very low rpm, and under full 400w load, is going to waste energy heating the motor.

Same thing with a mid drive, in the right gear, could crawl up the same grade at 2-3 mph, but the motor would spin in an efficient rpm.

But both motors, cruising 15 mph on the flat, will use almost exactly the same energy. Since you are a heavy rider, you might be better off with either a big 2000w motor, or something like the mid drive that can climb hills efficiently, though slowly.

But you said steep hill, not long steep hill. I have no idea where you live. Short steep hills won't kill your motor. I tend to default think, long steep hill when giving advice. Where I live, there are motor killer hills everywhere. 10 miles of nonstop 8-10% grade anyone? No problem if you weigh 190, big problem if you weigh 325 pounds.

 

[Oakenstone]

I typically ride rails to trails paths. For those who maybe unfamiliar with the term, "rails to trails" is a bike path that in its former life was a railroad line. Since locomotives cannot climb steep hills, the tracks were graded to between 5-7%. The lines cut through large hills at this grade rather than go over them.
While this makes for a smoother ride, it does present some challenges. For those of us who ride these trail systems, we know all to well where the "up" grade is and look forward to the down. Like I said loooong slow up up up followed by loooong slow down down down with maybe some flat thrown in for good measure.
The non-rails to trails paths just follow the contures of the land. (Aka...just normal bike paths)
This is the path I will be focusing my longer rides. http://dnr.wi.gov/topic/parks/name/militaryridge/
Its grade is 2-5%. Otherwise, I'll be riding shorter distances (just around town) where we have short but sometimes steep hills.

 

[999zip999]

Get a 48v20ah battery for now. And one to add for range. Should always have a working battery ( if going cheap battery ) two chargers, faster charging. Two 5amp chargers 10 amp pack charge. Just thinking. Always carrying 35ah or more is heavy.

 

[d8veh]

Those sort of grade hills shouldn't be a problem for a geared motor. My all up weight is about 300lbs, so a bit lighter than yours, but some of my rides involve long hills with average 15% grade and steep bits over 30%. I've used Bafang BPMs, Bafang CSTs, GNG gen i and 2, and now my Xiongda. The 500w 48v BPM with a controller of around 25A does it the easiest. A MAC would be similar, but a bit more expensive.

Battery consumption is impossible to calculate because it varies with so many factors, though I'd be surprised if you used more than an average of 20wh per mile from what you've described.

 

[Oakenstone]

Thank you Lads and Lassies! I feel confident with 2/3 of my system choices at this point.

Motor: https://bmsbattery.com/ebike-kit/351-bafang-bpm2-48v500w-rear-driving-e-bike-hub-motor-ebike-kit.html 328 rpm (Don't need rim, as I've a good guy at the bike shop)

Controller: https://bmsbattery.com/ebike-kit/552-s12s-500w-torque-simulation-sine-wave-controller-ebike-kit.html

LCD Meter: https://bmsbattery.com/ebike-kit/670-s-lcd3-lcd-meter-for-s-series-controlers-ebike-kit.html

PAS: https://bmsbattery.com/ebike-parts/504-pas-pulse-padel-assistant-sensor-with-12-pcs-magnets-parts.html

Speed Sensor: https://bmsbattery.com/ebike-kit/550-speed-sensor-ebike-kit.html

Other than for where to get a 48v 20ah Battery without paying for duties or extra freight. (I live in the U.S.), I should be all set.

If I've left out anything important, please let me know!

 

[d8veh]

You might be better with the 260 rpm motor unless you have a 20" wheel. For mine, they sent code 14, which gives about 24 mph.

What about a throttle?

Also, you'll need one of their spoke keys to tighten your spokes.

 

[Oakenstone]

Thanks! I do have a 20" wheel. I thought about a throttle and might add it to the mix.

 

[d8veh]

If you have a throttle, you don't have to use it, but if your pedal comes loose or your chain snaps, it will save you a lot of trouble. I fell off my bike once and hurt my knee so I couldn't pedal. The throttle got me home.

 

[Oakenstone]

Thank everyone for your advise. I've been thinking hard about what people have said, and I changed my mind. I feel like the bbso2 is the choice for me, with a 48v 20ah battery.
Does the simulator http://www.ebikes.ca/tools/simulator.html have the bbso2? Is it called something else there? I am trying to determine if 20ah is going to be enough to get me 50 miles with the bbso2.

I am also trying very hard to determine a reputable place to buy said battery.

Ah, too many questions.

 

[Oakenstone]

A little more extensive searching on this site and google bought me some good results on 48v 20ah battery packs. The one I found especially interesting is this one: http://calibike.com/?product=48v20t-electric-bicycle-ebike-48v-20ah-lithium-triangle-pack-battery-and-charger-1-yr-warranty. Seems like he's legit and reputable. Any one have any experience with this gentleman?

Also, searching for bike simulators netted me this very cool one: http://www.ebikemaps.com/
What I like about this site is that it appears to plug in real world data from your location and calculates actual terrain when figuring distance/watt hours used etc.. I found it very enlightening. With this data I was able to more accurately gauge my "rule of thumb" for if the battery was going to be able to do the job. I was not too surprised as you good folk had already told me it "should" be sufficient. This just confirmed those theories.

 

[docnjoj]

You might consider asking Calibike if they could split the pack so it could be carried down low and beside the seat. It makes a huge difference in the handling compared to carrying it on a rear rack.
otherDoc