danh123

Hello,

I have started toying with the idea of turning one of my bikes into an ebike and have been doing tons of research and reading. Still have a few questions and maybe people here can help me out. I mainly want an ebike to get places faster and do longer distances in less time. For example I have a 17mi. one way ride into the city I go to for work. I would like to be able to get there faster and not as sweaty. My area is hilly so I would like to take the edge off of the hills also. On flat sections a slight boost is fine. I am not looking to go for top speeds. I would also like range to be able to do 40-50 mile rides. Do not need a throttle, just looking for pedal assist.

-What do you use as a rule of thumb for calculating range? I read somewhere to first get the watt hours of the battery and then use 20 watt hours per mile to estimate the range. Does that sound accurate or is that 20 number more for using the throttle?

-Do you need to factor in the size of the motor in that calculation?

-I was looking at luna cycles website and was thinking of using the bbshd mid drive motor and their 52v 21ah battery. With that battery should I expect about 50 miles (1092 wh / 20wh/mi) range? Would this setup be overkill for my use? Am I way off on the numbers?

-Any other cheap kits that would work? I have two steel road bikes, I was thinking of converting one of them or I also have a no suspension mountain bike I could use.

chas58

Lotsa good questions.
I like hub motors as they are light and cheap - but a mid drive is probably more suitable for you if you have a lot of hills. Those Bafang motors are some of the best. I like the smaller version, but I don't need a lot of power - I like to pedal a lot too. a 52v bbshd is going to be a lot more powerful than you - that is gonna be more light a light moped.

a 36v motor at 10-15 amps (i.e. 350 watts) is going to be a lot like a very strong cyclist. But, very few people complain about having too much power (although they might complain about weight).

for your range questions use the calculator at https://www.ebikes.ca/tools/simulator.html
That is amazingly accurate. I don't think it makes too much difference what motor you choose as far as range goes. Play with the battery parameters to get what you need. Certainly range depends on what percentage of power you use - using 100% power with no rider input is obviously a worse case scenario.

So, no the size of your motor doesn't really matter for range (it does with overheating and maximum possible power). its the voltage and current that impacts your range.

Yes, the BBSHD is the best kit you can buy if you need that much power. I'm abnormal, and want my bikes to ride like bikes (and to be easy to ride with no power), to be light, and to feel like I'm adding some of the power to the whole system. If I was to buy a mid drive, I'd go for the smaller, lighter, torque sensing TSDZ2 https://lunacycle.com/torque-sensing...shark-battery/ The intriguing things are the lighter weight (and size), and that it is torque sensing - that it senses the amount of pressure you put on the pedal to apply its power (this is a pretty rare and high end feature).

Not sure how many builders there are around here (there are a few). https://endless-sphere.com/ is the place the builders hang out.

2old

C58 is an expert (look for his builds). I've had extremely good luck (five years of off road use) with a BBS02 and 52V 10 ah Luna battery. Unlike many, the RPM-based assist works as well for me as the many more sophisticated versions I ridden, and the Haibike -Yamaha I own. The BBS02 adds about 10 pounds and seems like consumes 10 - 20 wh depending on the level of assist (i rarely use more than level "3" of "9"). I ordered a three and a half pound battery (52V, 4 ah) that should be adequate for one of my "normal" rides, 15 miles with 1000' - 1500' of ascent. We'll see when it arrives.

danh123

Thanks for the info. I am like you I want to be pedaling and doing my part on the bike but want a small boost and a boost up hills. I still want to get a workout I just want to be able to expand my range and also make commutes quicker. I was looking at the bigger motor so that I would be covered but if that is more for people who want to throttle all the time and have max speeds then maybe I would be better off with a smaller motor. The bbshd and that batter are heavier also. Thanks for the link you shared, I didn't know they had that motor. I was going to ask about the torque sensor too, does it make a big difference in the feel of pedaling?

What motor and battery do you have on your bike and what kind of range do you get? That site for calculating range is a bit confusing, do you have a quick rule of thumb you use to estimate range for a battery?

I also want to end up with a lightweight bike and plan to still do a lot of pedaling. I will probably put this on one of the steel road bikes.

I tried to set up an account on endless sphere but I couldn't get it set up for some reason. I sent them an email.

danh123

Thanks for the reply. What sort of range were you getting from the 10ah battery? Did you ever feel like the BBS02 was short on power or is it just right? By RPM based, you mean not torque sensing right? How would you describe the difference?

danh123

Chas, can you share some links for some of your builds, would like to see.

2old

Many individuals feel like there's a big difference in torque vs rpm assist, so maybe I'm insensitive. My battery is capable (at five years old) of powering the rides which don't exceed about 15 miles and 3,000' of climbing; there's always at least 30% remaining (based on voltage measurement; probably not extremely accurate). Doesn't bother me either way since the bike(s) can be pedaled without the "e" power, but hasn't been necessary. So much depends on weight, wind, how much pedaling you do, hills, how fast you want to go ....... that it's very difficult to predict range for an individual. My guess is that you could complete your commute with 52V, 10 ah.

2old

Many individuals feel like there's a big difference in torque vs rpm assist, so maybe I'm insensitive. My battery is capable (at five years old) of powering the rides which don't exceed about 15 miles and 3,000' of climbing; there's always at least 30% remaining (based on voltage measurement; probably not extremely accurate). Doesn't bother me either way since the bike(s) can be pedaled without the "e" power, but hasn't been necessary. So much depends on weight, wind, how much pedaling you do, hills, how fast you want to go ....... that it's very difficult to predict range for an individual. My guess is that you could complete your commute with 52V, 10 ah.

danh123

So the RPM assist has the amount of assist linked to how fast you are spinning the pedals and the torque sensor senses your force on the pedal and amplifies the power right?

2old

Right and many OEM systems use both along with speed to determine level of assist. Many of my rides are climb up, descend back, so i set the assist to how hard I feel like pedaling, then on the return no assist.

danh123

I ended up using a miyata road bike and the tongsheng tsdz2 motor.

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gsa103

The Bafang RPM assist is frequently more of a binary assist. If you're pedaling, it adds a fixed amount of power depending on assist level. There's a lower power for initial start-up, then a temporary boost, then a long-term power that's applied. The crank on a Bafang mid-drive can freewheel, so pedal RPM does not have to equal crank RPM.
Especially at high assist levels, it's possible to spin the pedals at 60 RPM to keep the assist active, but to engage the crank you would need to be at 90+ RPM.

Leisesturm

Which is exactly why torque sensing is preferred by many, the bike can't (won't) outrun the pedals like that, when it senses that you are no longer keeping up the assist will drop off regardless of what level you have it set at. It is a more natural dynamic, more like how an unassisted bike would behave.

gios

onemotor