planning new ebike build - several questions

[TimJ]

Greetings!

I've been reading up on ebikes and options available recently but I feel like I've been drinking from the fire hose and have only scratched the surface on all the information in ES... After my initial research I believe I have a starting plan for my ebike build and have some time available during the holidays to get everything ordered. However, some of the details I am unsure about so I'd like to get some feedback.

Background info: I plan to use the bike mostly for commuting and for casual rides with my 21 year old son (mostly on paved trails but maybe the occasional off-trail ride also. In these cases, I would plan to mostly pedal anyway, with the motor power just to be able to keep up with my son and save face! ). My commute is about 12 miles each way, with rolling hills in eastern Tennessee but nothing too extreme. I plan to pedal but would like to maintain 20 mph, maybe 25, most of the time including on the hills. The longest hill is probably only 1/2 mile long with about a 7% grade. There is a bridge I have to cross that has serious traffic going over 45 mph, though, so I would like to be able to go at least 35 mph to get across the bridge as quickly as possible and just get out of the way of cars. Other than this, I can be on smaller roads or there is a wide enough shoulder that I don't need high speed, and at this point I am not sure if I will feel comfortable riding over 25-30 most of the time anyway. I would like to have enough range that I can do the round trip (~25 miles) on a single charge with a bit of spare in case I need to make a stop on the way home. I'm thinking 30 mile range would be good at an avg speed of 20-25 mph, so probably 1.5-2 kWh is what I estimated for battery capacity. I weigh about 190 lbs and am figuring on about 250-260 lbs for bike and rider carrying a backpack.

I bought a 29er before I learned that a 26" wheel is a better choice. I like the bike and at this point I don't really want to change horses mid stream. It is a Redline Monocog Flight 29er--steel frame with front suspension and disc brakes. It currently is 9 speed in the rear but I will probably change out the shifters with another bike I have and go to a 6-speed freewheel for the ebike conversion, and I am planning to use two gears on the front without a derailleur so I can manually change to the smaller chain ring for leg power-only rides if/when I need to ride home without the motor.

Based on the recommendations I have seen about smaller wheels, I am thinking about using a 26" rear wheel instead of the 29" but with a 38mm wide rim and 2.6" wide tire for a bit of added cushioning since I don't have rear suspension. I will keep the 29" front wheel either way. I think this will probably put the back tire's diameter more into the range of a standard 27.5" wheel, although maybe not quite. I am still somewhat ambivalent on using the 26" vs. 29" wheel. The bike looks fine with a 26" on the back and pedal clearance seems to be ok, especially for mostly on-road use, and with disc brakes I don't have to worry about the brake location. Any experiences from others and special considerations I may not have thought about concerning wheel size (and motor winding) would be appreciated. If I felt confident that the speed and efficiency would not be excessively penalized with the 29" wheel, I would prefer this, but it seems I can expect a hit in efficiency, generate more heat and decrease my range, as well as impacting top speed with the 29" wheel.

For the motor, I am planning to use the Leaf 1500W, and with the 26" wheel I would probably use the 4T winding on the wide rim:

http://www.leafbike.com/products/e-bike-hub-motor/gearless-20-24-26-700c-28-29-inch/wide-rim-26-inch-48v-1500w-rear-hub-motor-wheel-1112.html

Peter at Leafbikes recommended the 5T or even 6T motor for uphill performance for the wide 26" wheel, but from what I read it seems like the 4T, with sufficient power (>2kW) and current capacity from the battery and controller would still give plenty of torque and would allow a lower voltage battery to do everything I am looking for. I would prefer to keep the voltage at 52V or less. I plan to use a LiPo battery (probably Turnigy) with about 2kWh (40Ah at 48 or 52V). If I can use a 29" wheel, it seems like the 5T might be a better option but I may need to use a higher voltage to make a top speed of 35mph.

For the controller, I was looking at 18 fet options to provide enough amps to get to a 35mph top speed with the 26" wheel, but I also like the idea of giving myself some room to move up to higher voltage and power levels in the future. I will probably go with the "18fet Silent Controller" from Powervelocity:

https://endless-sphere.com/forums/viewtopic.php?f=31&t=75888&hilit=controller+bluetooth

I like the option on this controller to program it from my smartphone. However, I don't understand the tradeoffs and requirements with different controllers, and don't know if the 18fet is overkill or could negatively impact the performance in some way. If people can comment on this choice for my desired performance, I would appreciate it.

I know I will need torque arms for the build and will also need to get an appropriate charger. I will select the charger once I finalize the motor choice and battery voltage. I am also planning to get the CA3, although maybe not immediately.

Please provide me with any feedback you may have and let me know if there is anything I am forgetting. Thanks in advance for your help!

-Tim

 

[dogman dan]

FWIW, the leaf 1500w motor is so powerful, that you won't care if the wheel is 26" or 29".

However, you would realize a big difference in performance in any hub motor, if you went small, like 20" wheel. this in general, requires a custom built frame.

 

[Drunkskunk]

looks like you've picked a good overkill motor for what you want to do. combining that with a ~52v, 40A controller will give you 2kw of power, a bit more power than a moped in a vehicle that weighs 100lbs less. It should give you all the performance you need.

An 18FET controller is what I use on my 15,000 watt bike. It might be a little bit over the top for a 2,000 bike. A good 12FET would be a good match to that motor.

The Monocog is a good lightweight bike. It's known as a good XC, but there are a number of people who've posted on MTBR about breaking the downtube when riding it hard. While that probably won't be an issue for a normal rider, you plan to strap >70 pounds of equipment to it and put 20 times more power through the frame than it was designed for.

Also, 2kw of Lipo is a huge and heavy battery. it's not something you want to strap to the frame of a normal bike. If you really want to ride with lipo, you need to put it inside of a metal frame where it's protected.

To get past both those problems, you realy need a dedicated ebike frame. A frame like this could work: https://em3ev.com/shop/eeb-full-suspension-ebike-frame/

 

[ScooterMan101]

With wanting to go 20 mph and up to 25 mph, at least a 30 mile range , and up a 7% grade , you are right about needing large battery pack.
Shoot for 2 kw Wh

With those speeds you will also want to have a full suspension frame.

That 29 er would be find if riding at 15 mph and below , but faster than 17 mph and your watt usage goes way up.
and from others research it sounds like that frame will not take much extra weight before it brakes, which means time at/in the hospital and all the $ costs that go along with that.

Better to sell the 29 er cheep on craigslist, then get at least a Down Hill / All Mountain / Enduro Frame from around the 2009-2014 year range. ( any newer than 2014 and it would probably have a thorugh axle, and the Chineese ... Still have not developed a Rear Though Axle Hub Motor ) But Grin Technologies has available a , Front , Through Axle Hub Motor.

The best thing for you at the speeds , and , distance you want is to just buy a E-Bike Specific Frame that has plenty of room for a large battery pack. It will also be fully suspended . you can find/buy a used Bomber / Boxer / Fox 40 forks to put on it. and a used coil over rear shock.

 

[TimJ]

Good comments about the frame that I hadn't thought about. Thanks! I did see mention of the Monocog frame cracking with hard riding but I never considered that this would be likely on an ebike or that it could equate to injury other than to the bike itself. I figured a solid re-weld could put it back in service if it did happen, but you're right that I definitely don't need a total frame failure at 25-30mph!

I don't want to get beat up riding to work every day either, so I think I'll start watching for a full suspension frame as suggested. I have a really good front shock now, but it is for the 29" frame. I guess I can eBay that and get something of similar quality for whatever frame I end up with, assuming it is 26".

For the controller, would 15fet be too much still? What are the negatives for a higher amp controller? As I said, I'd like to allow myself room to grow if I find I want more power/speed in the future. Or is it best to buy exactly what I need now and sell it if I need something different later on? I saw in a Leaf motor thread from Neptronix that he was pumping over 50A into the leaf (with 48V) when going up hills and at the higher speeds. If that's what it takes to hit full speeds with the lower voltage, I thought it would be better to go for the high fet controller and keep it from overheating. Will this make it much less efficient at normal speeds or is it more just a matter of cost?

Thanks,
-Tim

 

[ScooterMan101]

You have a " Good 29 er front shock now " ?

What is it ?

Year ?

Amount of travel ?

Is it through axle ?

Is it Tapered ?

There is some good news, there is a good posibility that after the first of the year one of the sellers of specific e-bike frames will be offering a frame that has a tapered head tube.
Seller is Artur and the frame is the Vector Light. ( in the For Sale New section ) I have been asking / writing here on E.S. for months now , for him to have that frame made with 1.5 inch lower headset .
As well as a better swing arm, will see in a couple of weeks if he has contacted the maker of the frame to make it more modern and better with those changes.
With a frame like that you will have plenty of room for batteries and more secure for the batteries as well.

You can use a 27.5 or even a 29 er front suspension fork on a 26 inch frame, since it will be disc you can use any 26/27.5 or 29 wheel with it.
The only thing it will do is to slacken the geometry , which means that for road riding the bike will be more stable, and more stable at speed. Down Hill bikes already come with Slack Head Tube angles to accomplish that.
From what I have been told , if you do use a 29 er fork, or a fork with more travel on the front than what the bike was designed for , that for technical single track trail riding it is not as optimum as stock angles and longer travel forks. But for a high speed street bike that is what I would want.
The faster you ride , the more stable the bike is the better ,
and a longer travel strong fork and wheel is what you want .

 

[TimJ]

Thanks for the info, Scooterman. My fork is a Manitou Minute 29er with 100 mm travel and it is both tapered and through axle.
It sounds like what you described might be a good option for me. I'll be doing some more research about the 29er fork with standard 26" frame and will have a look at the thread for the frame you mentioned.

Really appreciate all the feedback!

-Tim

 

[ScooterMan101]

The FUTR Beta looks to be a better quality frame than the Vector light frame,
However last time I checked the price was very high, and like all the other frames being sold that are copies of the Stealth Bomber or lighter weight versions like the Beta and Light , ...
the FUTR , or anyone of them , do not even come with rear shock or front fork !


100 mm of travel is not much these days , those forks are mainly for lighter weight fast steering XC bikes,
However
You could find a decade old full suspension frame with 100 mm of travel.
A stout XC frame bike.
( None of the Stealth Bomber clones or Vector light or the FUTR Beta is designed for only 100 mm of travel )
you want to match the front and rear, or the front have up to 25 mm more travel than the rear.


Those of us that want good performance always find out that it costs more than what we wanted and at first thought. And Good 200 mm rear shocks and front forks are expensive.

If you are on a tight budget then finding a used 10 year old or so Down Hill bike that spent most if its life parked in a garage is the least expensive. But then you are limited to 1Kw or so of battery pack.

You have the link from an above post on the Em3ev.com EEB frame .

A good article on the Victor light ... https://endless-sphere.com/forums/viewtopic.php?f=6&t=91406

Here is a good combination the Lightingrod's drive on a FUTR Beta frame.
https://endless-sphere.com/forums/viewtopic.php?f=28&t=89282

FUTR frames ... https://endless-sphere.com/forums/viewtopic.php?f=31&t=80490&hilit=FUTR+Beta+Frame

 

[TimJ]

I've been researching a bit more on the frames and suspension and associated costs. You really hit the nail on the head with your comment:

"Those of us that want good performance always find out that it costs more than what we wanted and at first thought."

The cost for the ebike frame and suspension components has really surprised me. I expected to spend something around $1000 for the electronics and was willing to go even $1500, but was counting on using the bike I already own. If I need to spend another grand or two on an ebike-specific frame and components, this really changes the budget. I'm reconsidering big time at this point and thinking I prbbly need to go for much less performance for the first time and make sure the ebike is what I want and that i will use it as regularly as I want/expect to.

The problem for me is that I really want to commute to work on the bike but I have to be able to cross the bridge that I mentioned safely. With traffic going over 45mph, if I don't have some speed to get across it quickly, I don't think I'll feel confident riding to work and will use the bike much less frequently. Unfortunately, this is the only option I have to get to work since the only other bridge over the river has zero shoulder and is single lane traffic going over 50 mph. There is at least a shoulder on my route, but it's still pretty intimidating for a bike. In any case, I am thinking I probably need to plan on a build that will let me experience the ebike and get my feet wet without spending a fortune, but I probably will use it only for occasional rides instead of a regular commuter. I need to do some more research and planning now, but I'm thinking it will be a 15mph sustained-speed bike with a motor around 1000w or less. This may become my older son's bike later on if I decide I'm ready to make the move to the next level of performance. He likes the idea of an ebike also and has been asking about getting one.

Scooterman, thank you so much for taking the time to provide the information on frames and what is needed for a safe ebike configuration. I'll keep the info for when I do decide to take the next step to higher performance.

-Tim

 

[ScooterMan101]

Tim,

I thought about your crossing that bridge and wanting to go as fast as possible for a short distance.
So
I took my Diamondback Lux bike out for a test , a Max speed for short distance test, up until now I have kept the amp draw from battery through the motor to 28 amps max. So I adjusted it by way of the Cycle Analyst V 2.3 to 30 amps and did 2 runs down the block.
The block is about 1/3 rd mile long, and about 0.5 % slight down hill one way and about 0.5 % up hill the other way.
Used full throttle about 100 feet from start .
Runs 1 & 2 ,
at full throttle ..
30 amps / about 1600 watts / at 30-33 mph

Then adjusted the amp draw by way of the C.A. to 35 amps max.

3rd run showed 35 amp draw at full throttle with about 1850 watts being used by the motor and speed of 33-34 Mph.

Total time riding 7 minutes, total watt hours used from the battery pack was 85.7 watt hours, total amps used from the pack was 1.6 amps used in that 7 minutes.

( That gives you an Idea how much battery pack you would need to go higher speeds for an entire trip , hence the links to those frames that can carry larger packs )

The first 2 runs I reached down and felt the hub and it was not even warm
( keep in mind no steep grade here )
The 3 run I saw a neighbor started talking and did not check it for a minute, hub was barely warm.

So you see if you do want to keep your first conversion to around 20 mph and under most of the time and just get up to 30-33 mph for crossing that bridge , it is possible on a budget that you have.
I have a route that takes me up a 7% grade that is about the same distance .25-.33 of a mile long and the Mac motor does just fine, before when C.A. was set to 26-28 amp max I showed about 1250 watts going up that hill.

I have the previous version of the Mac. The newer version can be matched to the newer version of the Cycle Analyst V 3 with the addition of new in the hub motor temp. sensor wire and then the C.A. V 3 can be adjusted to shut off power if the motor starts to over heat.

You could save about $ 100-$ 150 by buying a DD hub motor, However , a hub motor that would give you more power than the Mac would be about twice the weight. there are DD hub motors that would be about 50% more in weight than the Mac, but they would only give you about the same or very little more power than the Mac.
Mac Hub is 9.5 pounds, DD Hub motors are 14 pounds, but the ones most widely used these days for more power are 20 pounds for just the hub.

I got the 6 T Mac and laced it up to a 27.5 wheel .
I mostly use a 12s pack ( 2 6s lipo packs then another 2 packs for 12s 11 amp hours.
But
For the testing I did above so as to get the Max speed out of the motor , and to see what a Mac motor can do, I used my other batteries I use on my road conversion. 7s x 2 for a 14 s pack ( also known as a 52 volt pack )
Many of the Vendors are selling a 52 volt battery pack and charger these days. At least the Good/Better/more Trusted Vendors are selling them. For you 14s is best .

For speed you will want to use at least a 14s battery pack and keep the speeds mostly at around the 20 mph or lower , but for going up hill keep the speed to over 12 mph on the up hills so as to not lug down the Hub Motor. Good rule is to keep the speed to at least 1/2 max speed when going up hills. and for best Miles per Watt Hour keep the speeds to 16-17 mph max, any speed above that and you will have allot of aerodynamic drag , the faster than 16-17 and the more drag so the more energy needed to overcome that drag for the desired speed.

To see my Lux conversion just click on the link at bottom of this or any of my posts.

A complete Mac/12 fet controller/ C.A. and battery pack is well within your present budget. And it will get you very close to what you want in speed and performance.

You can often find a Used Down Hill MTB that is 7 or more years old for as low as $ 500 , Perhaps a little less under the right circumstances .
It will of course be 26 inch , but you would only loose 1-2 mph by using that wheel size.

 

[TimJ]

Hi Scooterman,

Happy New Year to you! Thank you for sending the data when running at different power levels on your Mac. This is helpful. I had looked at your build page before and like the setup a lot. I had actually considered the Mac motor for my build initially. However, I asked EM3EV about the speeds I want to run and the proper motor wind, and Joseph said it was not a good idea to run the Mac at the power levels needed to reach 35-40 mph. I was clear that it would only be for fairly short periods of time, but perhaps he can't recommend running over stated specs for liability/warranty reasons. I don't want to burn up the motor or gears doing extreme operation, but from some other builds I've seen using the Mac, it has been run even over 40 mph (for the 8T version of the older motor design), so it seems like the motor can take quite high power levels at least for short bursts.

That said, I am still thinking about going back to the plan of buying the Leaf motor and trying it out on my current bike but with a 26" back wheel and limiting it to lower power levels initially to try it out and see what I am comfortable with. I can get either the Mac or the Leaf within my budget but the Leaf seems to offer quite a bit better performance, and I like the idea of having room to grow. If I find the higher speeds to be excessive/scary on this bike, I will only use it for tamer riding until I can upgrade the bike, but I'll at least give it a try at the higher speeds and see if it could work for my commute. I'll try it out once or twice to decide if I am comfortable with it or just scrap the idea of commuting until I can get a better frame. In the meantime, I've started watching for a decent full suspension bike on the used market. It seems to be a bit difficult to find a steel frame suspension bike (I'm looking for something under about $600) but I'll keep watching and see what shows up. Or is it even that important that the frame be steel when going to full suspension? I don't know if I'll find a suspension with the longer travel in the shocks that you recommended, but my feeling is that riding the same route every day I will know where the bumps and holes are and can avoid them most of the time, so having the longer travel shocks is not as critical. Of course, there will be some surprise obstacles periodically but I think it should be ok for the speeds I plan to ride normally.

-Tim

 

[ScooterMan101]

Tim,

I do not any personal experience with the leaf motor, from what I have read the DD's can handle more power for longer.
DD Hub's are heavier so it is even more important to get a strong frame.

You do not need steel, Aluminium is fine Just get a Heavy , Down Hill Bike or All Mountain/ Enduro bike.
they are made for abuse and are made not only strong but to handle faster speeds than other bikes.
Sometimes it takes a while to find a good deal, they do not come up every week, only a few times a month where I live.
For a Rear Hub motor I like the Idea of ... Unified Rear Triangle Full Suspension
Bikes . Especially with using a Heavy DD Hub.
That Leaf Hub motor is 19.6 pounds so it is important to not only have a very strong rear frame , but also 1 or 2 torque arms.