WOW! Brain overload.

First, let me say I'm sorry. I'm sure there are numerous posts like this one, but I have searched and done research and I'm still at that point where there seems to be no clear answer or just too many choices.

Me: age 42, 150lbs and commute to work on my bikes nearly every day. On a good day, I average between 17-19mph for the 10 mile trip.

My commute: 20 mile round trip on relatively flat pavement. Probably nothing more than a few 2% grades not longer than a quarter mile.

My ideal: The ability to reach 25-30mph, but cruise on partial throttle at 20-25mph with no pedaling. I'd like to be able to do this without having to charge up until I got home, but I'm not opposed to charging at work if it decreases my cost or complexity.

My input: I don't mind pedaling to get from 0-10 or 15mph and adding some leg power on the inclines.

My bikes: I have 6 or 7 bikes total, but only 2 that I'm interested in converting or might be suitable for conversion.

1) Giant Talon 29er MTB- My concerns with this bike are that it has an 8 speed drive train, is heavy and not very aerodynamic. In it's favor is a decent front fork, and hydraulic disc brakes.

2) Redline 925 single speed (700c)- This is the one I'm leaning towards. It's all steel, lighter and more aerodynamic, but it has 120mm rear end, so I think I'll be limited to a front motor. My concern is that to reach the speeds I want, I'll be putting too much power through the fork, but if I'm only using the motor for cruise and not stop and starts (the high torque part of the curve) I'm not sure that will be a problem?

My questions:

1) Correct me if I'm wrong, but I think 500W for a motor should be sufficient. Should I be concerned with putting that much power through a steel road fork on the Redline? I'm thinking I'll be ok as long as I only get on the throttle once I've built up a little speed.

2) What voltage? From my research it feels like I need 48V to get the speed I want, but also feels like I might be wrong and I could get it done with 36V.

3) How much battery? I think 500 W/hrs minimum would be needed to get the job done, but when you factor in my only using the motor to cruise, could I get it done with less.

4) Battery type: Lipo is cheap and light, but complicated to operate in higher capacities. Lifepo is simple, but bulkier and more expensive. If you guys think I'll need significantly less W/hrs than I'm expecting then Lipo becomes more attractive, but if I need more than a 5-8ah battery then it becomes less so.

In summary: I could of course just throw money at the problem and probably end up with way more than I need or would want, but I'd really hate to spend $1400 when I could have spent $700. Or even worse, spend $700 and get half as much as I could have. There are just so many compromises. Either way, I really think it comes down to the battery and the fact that I have no real world experience with this stuff. And part of the battery issue is what volts I need to run. I think I know enough that I'm not restricted to a turn-key bike, but not quite enough to drill down the details.

Oh someone please help me because I just keep thinking around in circles at this point.

1. A 48V 500W kit would be a minimum. A 48V 1000W kit isn't much more but is a lot more capable. I would never use a front motor if I had a choice. If front fork breaks you fly over on your face.
2. 36V is usually good to about 20mph. 48V is the way to go imo.
3. Generally need 30wh per mile for 25mph. If you want to do round trip of 20 miles, I'd suggest 600wh minimum.
4. I use nothing but rc lipo. For round trip, I'd get 15ah of 12s (666wh), about $400 with good 12s charger. Or a 15ah lifepo4 pack.

While you can get a motor kit in about any size, 26" is the standard. If you have a 26" steel bike (or with steel dropouts) it would make things easier and probably cheaper imo.

This should work ok on the Talon since it has disc brakes. I've thought of putting a 26" kit on a 29er frame myself since I'm short and it leaves room for really big tires.
http://www.ebay.com/itm/48V1000W-Electric-Bicycle-LCD-Display-26-Front-Rear-Wheel-Motor-Kit-E-Bike-Hub-/291040998674

You can spread the rear wheel dropouts some if steel. rear rack mounts and front fender mounts are important. there are kits to add rear derailleur hangers to single speeds. also, the handle bars and stem can be changed for better aerodynamics.
but things cost

now how do the bikes in your stable compare?

d

wesnewell said:

1. A 48V 500W kit would be a minimum. A 48V 1000W kit isn't much more but is a lot more capable. I would never use a front motor if I had a choice. If front fork breaks you fly over on your face.
2. 36V is usually good to about 20mph. 48V is the way to go imo.
3. Generally need 30wh per mile for 25mph. If you want to do round trip of 20 miles, I'd suggest 600wh minimum.
4. I use nothing but rc lipo. For round trip, I'd get 15ah of 12s (666wh), about $400 with good 12s charger. Or a 15ah lifepo4 pack.

While you can get a motor kit in about any size, 26" is the standard. If you have a 26" steel bike (or with steel dropouts) it would make things easier and probably cheaper imo.

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How complicated is your charging system for the lipo's?

1) Giant Talon 29er MTB- My concerns with this bike are that it has an 8 speed drive train, is heavy and not very aerodynamic. In it's favor is a decent front fork, and hydraulic disc brakes.

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Bike kits are not compatible with hydraulic brakes. You will have to go to cable unless you add a switch and wire to your existing brake levers.

vptech said:

1) Giant Talon 29er MTB- My concerns with this bike are that it has an 8 speed drive train, is heavy and not very aerodynamic. In it's favor is a decent front fork, and hydraulic disc brakes.

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Bike kits are not compatible with hydraulic brakes. You will have to go to cable unless you add a switch and wire to your existing brake levers.

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Are you referring to the e-brake levers? I wasn't planning on using them. I have plenty of motorcycle experience and motorcycles don't have any kind of throttle cut on the brake. Seems like lawyer crap to me. Am I wrong?

worldpax said:

How complicated is your charging system for the lipo's?

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Well I run 24s2p but charge as 12s4p using a 12s balance charger. Takes about 5 seconds to split the pack into 12s and maybe a minute to start charging. Using a 12s pack, you could make it one plug if you want to. Doing that you could also use the cheaper 4s hardcase packs for easy charging. That's what I use for 24s. A 15ah 12s pack using them would cost ~$225 for the batteries. 12s charger would still cost $90 plus $0-$35 for a PSU. There's mor than one way to skin a cat. Just depends on how sharp your knife is.

worldpax said:

Are you referring to the e-brake levers? I wasn't planning on using them. I have plenty of motorcycle experience and motorcycles don't have any kind of throttle cut on the brake. Seems like lawyer crap to me. Am I wrong?

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Yes, he's referring to the cutoff switches in the ebrake handles. They also will cut power to the motor if you are in cruise control, and also start regen braking if you set it up. You could also set it up with a separate button and keep your current brake handles. Or not use it at all. Tapping the throttle also cuts CC.

wesnewell said:

worldpax said:

How complicated is your charging system for the lipo's?

Click to expand...

Well I run 24s2p but charge as 12s4p using a 12s balance charger. Takes about 5 seconds to split the pack into 12s and maybe a minute to start charging. Using a 12s pack, you could make it one plug if you want to. Doing that you could also use the cheaper 4s hardcase packs for easy charging. That's what I use for 24s. A 15ah 12s pack using them would cost ~$225 for the batteries. 12s charger would still cost $90 plus $0-$35 for a PSU. There's mor than one way to skin a cat. Just depends on how sharp your knife is.

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This is where things go wrong for me. If I get 3 12s1p 5000mah packs and parallel them to make a 15ah pack, can I charge the whole group through one plug? I thought the answer was no, but you seem to be saying that it is possible. Even if it is possible, is it cost effective and practical for someone who isn't an engineer. I haven't really dove through more than the first level of lipo because it seems like it gets really complicated or cluttered if you're dealing with more than just a single pack.

Ok here's a baseline- MAC kit from EM3ev

1 x 48V (13S) Samsung Frame Mounted Pack (7.6-11.0Ah, 4P)
- Configuration 13S 4P, 29E cells, 48V, 11.0Ah
1 x Upgrade EM3ev vers. Mac , 500/1000W Pick'n'Mix Kit
- Controller Type 9 fet 30A (36-52V, IRFB3077)
- Motor Speed 255rpm loaded @36V 10T Upgrade
- Front/Rear Motor Rear
- Wheel Type 700C Alex DH19 CNC
- Throttle Type Half Twist
- Ebrakes No

Sub-Total: $836.00
Total: $836.00

Who thinks this would do what I need it to? Could I do better for the same money or do the same thing less expensively? I would install this on the 29er.

worldpax said:

This is where things go wrong for me. If I get 3 12s1p 5000mah packs and parallel them to make a 15ah pack, can I charge the whole group through one plug? I thought the answer was no, but you seem to be saying that it is possible. Even if it is possible, is it cost effective and practical for someone who isn't an engineer. I haven't really dove through more than the first level of lipo because it seems like it gets really complicated or cluttered if you're dealing with more than just a single pack.

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The answer is yes. A 12 lipo pack needs 15 wires to charge with a BMS or balance charger. The DB25 has 25 pins. Use 12 of them, 6 for + and 6 for- for charge cables. That would be good for at least 30A and you'll never use more than 10A. That leaves 13 wires to wire the balance leads to. The exact number you need for a 12s pack. One side will wire to the battery pack and the other side to the charger. Simple.
A bms is basically a balance charger built onto the battery pack without controls. You could also use one of these and just need 2 wires to the outside of the pack to charge it. Lipo is nothing more than modular batteries. You can make any voltage you want with them. Just keep plugging them together until you get what you want. Maybe this will help.
http://endless-sphere.com/forums/viewtopic.php?f=14&t=39666

worldpax said:

Ok here's a baseline- MAC kit from EM3ev

1 x 48V (13S) Samsung Frame Mounted Pack (7.6-11.0Ah, 4P)
- Configuration 13S 4P, 29E cells, 48V, 11.0Ah
1 x Upgrade EM3ev vers. Mac , 500/1000W Pick'n'Mix Kit
- Controller Type 9 fet 30A (36-52V, IRFB3077)
- Motor Speed 255rpm loaded @36V 10T Upgrade
- Front/Rear Motor Rear
- Wheel Type 700C Alex DH19 CNC
- Throttle Type Half Twist
- Ebrakes No

Sub-Total: $836.00
Total: $836.00

Who thinks this would do what I need it to? Could I do better for the same money or do the same thing less expensively? I would install this on the 29er.

Click to expand...

Not even close. It will get you half way and it'll cost you a lot more. Did you add shipping charges, which will be considerable? And it's a geared 500W motor. No regen, gears to fail, clutches to fail.

wesnewell said:

Not even close. It will get you half way and it'll cost you a lot more. Did you add shipping charges, which will be considerable? And it's a geared 500W motor. No regen, gears to fail, clutches to fail.

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By half way, do you mean range or speed? Are these companies just way overrating the capabilities of their motors. Where have I gone wrong? 48V at 25A is 1200W I'd think that would be enough to get at least 25 if not 30mph. At 50% power, that would be 600W (good for 20mph?) Then it's just a matter of do I have 600WH plus about 20%.

And that's just the easy straight math. not factoring in that I'm willing to do some pedaling in those high torque situations that seem to drain the most power. I really appreciate your advice.

I was looking at geared because I don't mind giving up regen in trade for no resistance pedaling at zero throttle.

Sidenote- MTB forums says that 26" wheels on a 29er isn't such a good idea due to BB height and pedal strike issues. That's ok though, once I decide on a powerplant, I can acquire a bike that will work if it turns out I don't have one.

Welcome to ES worldpax,

I’d use the Giant simply for better comfort - tyre choices and front suspension. Adding electric makes the commute a fun ride and weight is less of an issue.

I think that em3EV kit would be a very good quality medium power commuter in a rear 29” wheel for someone who likes to pedal.
Downside is I think you’ve forgotten the charger. Options for upgrade like Cycle Analyst plug, temp sensor and programming all good for the future.

There are excellent cheaper ebay & DIY options out there but you may not get the quality, plug n play or customer service that a beginner may want. You could do it a lot cheaper if you want to solder connectors, learn a lot more about lipo and not get any warranty (they're not necessarily bad things, it's what many of us do, but it's not for everyone).


11Ah should get you there and back but with a little to spare, a lot depends on your ride, weight, stops & starts, speed, wind, pedal input etc.
As batteries age the Ah goes down so you may not have that headroom in 3 years time.

Max speed should be around the lower end of your 25-30 mph ballpark, but remember drops off over a range of maybe 15% as the battery discharges.
30A controller may be a touch strong for the battery, but you only pull that briefly on unassisted take off, and it can always be configured down to 20A if needed - either in the controller or CA add on.

The only reason I’d use e-brakes was as a kill switch in case the throttle went full power or if I lent the bike to noobs.

Sounds like you've done your research.
Greg

Gregory said:

Welcome to ES worldpax,

I’d use the Giant simply for better comfort - tyre choices and front suspension. Adding electric makes the commute a fun ride and weight is less of an issue. ..........

Sounds like you've done your research.
Greg

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Thanks Greg,

I notice you have a MAC set up on a 700C. Can you tell me what your experience with that bike is? Speed and range? I'm guessing you kind of just did with your last post, but would like to confirm.

Comfort isn't a huge issue for me. I'm comfortable with 23c 120psi tires at 20-26mph on my road bike. Regardless of which bike I choose, it will be rolling on 35C slicks at 65-80psi. For me that's practically plush.

I am still thinking that the single speed Redline might be the better all around choice. I'm concerned about killing the fork with torque but also not planning to get on the gas until I'm rolling, thereby reducing the forces involved. Additionally, steel does tend to give you some warning before it lets go. The simulator on ebikes.ca shows 50% less torque at 15mph. So that's hopeful.

Yea if you look at electric motors they make 100 % of their torque at 0 rpm and 0 torque at max rpm. Do you have a pic of the bike you may use for the front motor?

This is the Redline from awhile back. Right now it has a flat bar in place of that wonky touring bar. All steel frame and fork.



and the Giant 29er with studded snow tires...



and since it's show and tell, here's the fast 3 speed I put together. Notice the gear selector on the brake lever. This one is staying just like it is.

Either bike will be a blast to ride.

I have zero experience with front wheel conversions, and my preference would be rear. But front does work with strong forks and <400W power (I just made up that number) or torque arms. Those racer forks look very skinny.

At 62V charged my 15S (57V nominal) does low to mid 40’s kph then slows down to maybe 36kph as the battery gets very flat, you feel that gradual drop off at the end. And you’d be 10% slower than that at 13S so guessing 26mph dropping to 22mph? Wish I could take it out and GPS it for you but I don’t get back home for 3 days. The em3EV numbers are pretty realistic.

I regularly ride alongside my GF to her work place un-powered which is fine on a geared hub, then switch on and zip home 11km full speed on 4 or 4.5Ah with some light pedalling, in a pretty upright position. Which works out as 12Ah over 20 miles, so I’d struggle to finish your commute without pedalling more, slowing down or charging at work. You couldn’t just use the throttle as an on/off as many here are guilty of (including me).
BUT I have also ridden 15 miles on 4.5Ah being quite conservative with throttle and pedalling lots.

Wes may be right if he’s saying 11Ah being a bit small, but it is easy if you aren’t WOT all the time. A Cycle Analyst would help limit power, speed and display usage, but costs $150.
So much to compromise on. Bet it hasn’t helped your brain overload one bit.

Whichever bike you choose also consider you may almost need a bigger chainring to pedal at 25mph and provide any useful input on the MTB (44/11?) or the single speed which is probably worse. Must be slow accelerating on a single speed, I don’t know how you do it up an incline.


I think mine is on 700Cx38 rubber and that’s fine for roads. Champion branded rim was before em3EV switched to Alex rims.

Does em3Ev even offer a wide Alex rim 29 for fat tyres?
Edit: no, DH19 in 700C that’s pretty thin, but I bet he could source something. And you need a spacer for 8sp freewheel.

Sorry for the long winded waffle.

Personally I think the Giant would be better to electrify. It has some suspension, disk brakes and will take fatty tires for more cushion as well. Running higher than normal speeds for longer than usual trips will take it's toll on your bod. Graduated to full suspension after 4K miles on the first bike and will not ride anything else again. So nice not to hurt when you get off of the bike after a 20 mile ride. You really don't need a steel frame unless you are going for high power. Have 10K on my Giant now and am very pleased with it. I did replace the crank set up with road bike stuff so 53 and 11t and went for the 203mm rotors for better stopping power. Prefer rear motors in case something goes wrong as its easier to drag the back of the bike and stay in control. Plenty of folks with front motors around though and only a few horror stories so if done up right they are OK. Just see that you get a motor that takes the disk brake set up if you go that way some do not.

worldpax said:

By half way, do you mean range or speed? Are these companies just way overrating the capabilities of their motors. Where have I gone wrong? 48V at 25A is 1200W I'd think that would be enough to get at least 25 if not 30mph. At 50% power, that would be 600W (good for 20mph?) Then it's just a matter of do I have 600WH plus about 20%.

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By half way. I meant one way. It's not enough battery to go 20 miles at 25mph. Would probably make 20 miles at 20mph. Not sure what top speed would be, but I'd guess around 25mph. Watt hours are nominal voltage times AH. Assuming that pack has 3.7V nominal cells, total wh of the pack is 529.1 wh.

Good kit. You have lots of bikes, but maybe not the ideal one. A hardtail 26" mtb with 7 speeds in back. If you decide to use the 29er, then choose a slightly slower rpm motor. So the Mac 10t, rather than the 8t. To cruise fast though, the 12t would be too slow.

Rear motor, and you will have to charge that 11 ah battery at work to make the distance at 25-30 mph.

A 48v 15 ah pingbattery would just get you that distance, but with NO extra for a windy or cold day, at 25 mph. 25 amps is all the controller you need for your modest desires.

Figure out how to charge at work, where you might not want to use hobby RC batteries, and you are good for the distance on the EM3ev battery. 1 ah per mile at 30 mph, is what you will get with 48v.

All this has been very helpful. It's nice to know I was on the right track.

Conclusions:

1) 48V through a 500-750W motor is definitely required to get the maximum speed that I want.

2) 15ah would be fine if I stick to 20mph, just barely enough if I run at 25mph, and not enough if I max it out. I do have the option of charging at work, so I can decide whether I want to carry all that battery (15-20ah) around full time or go with a smaller package (10-15ah) and buy an extra charger to keep at work.

3) Neither of the bikes that I was considering would be ideal. I do have this frame laying around .



...but it doesn't have discs and for the money I would spend converting at least the front to disc, I could just find something more appropriate on Craigslist.

I think I'll keep an eye out for some kind of road hybrid or crossover. Something sporty, but with good tire clearance. The type or specific bike I use is my least concern because I'm pretty confident in the mechanical stuff. I think my situation is probably pushing the limits of what I'd want to put through the front end, so I'm going to limit myself to a rear drive application.

Anyway, I'm now feeling a lot more confident on what my options are and what I need. You guys are an invaluable resource. It's really not that hard to do a little research and come up with some numbers, but when it gets down to applying those numbers to anyone's specific situation or desires then there's no substitute for real world experience.

Thank you,

With the 48V 1000W kit I suggested, and 20ah of 12s lipo that weighs <15lbs, you could make 20 miles wot at about 28-30mph or 40 miles @20mph for at total cost of ~$700. You can have these parts at your door in a week since they will ship from the USA. Or you can spend a lot more and not get as much. Your choice.

wesnewell said:

With the 48V 1000W kit I suggested, and 20ah of 12s lipo that weighs <15lbs, you could make 20 miles wot at about 28-30mph or 40 miles @20mph for at total cost of ~$700. You can have these parts at your door in a week since they will ship from the USA. Or you can spend a lot more and not get as much. Your choice.

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I may do that, although I probably won't use LiPo. If I was already into RC, that might make sense for me, but since I'm not, I don't see that making the effort to go that route would save me anything but a little weight. Pretty heavy downside there too. If I get it wrong then I burn my house or job down.

and would it really only cost $400 for the LiPo, and chargers, and balancers, and a soldering iron, and connectors, and wire...and the stress of not burning things down.