35+mph Motor And Controller/Build Advice, Please?

[Electric Earth]

I have ~$2,000-ish dollars to put into making an around town car replacement. I want to be able to go at least 35mph. I have a 2020 Polygon Siskiu D7 frame and Fox fork that I'd like to use if it's suitable. The one issue might be battery fitment in the frame? Only ~3.5x12.5" between shock and top tube... I also already have nice hydraulic brakes(Hope Tech 4) and a drive-train(If I want to go derailleur and gears). Basically I just need to sort out the E part of it. Any suggestions on a motor and controller, and a battery or someone who would build a quality pack to fit the frame? I'd love to stick to a mid-drive and a robust single speed drive-train if possible, but if the gears are needed for hills, etc, that's fine. I don't care much about pedaling. I have four bikes if I want to pedal. This is more of a car replacement to get places quickly and easily. I'm a former professional bike mechanic, so I can sort out the bike stuff. Just need help with the E stuff. I've done one 36v ebike build in the past using a 2000s Trek full suspension frame, an amazon kit, and got a battery and throttle separately. I want to improve on that greatly, with a nicer bike and more powerful electrical system. Thoughts?

 

[neptronix]

Quality packs: see em3ev and ebikes.ca, you probably want 72v for these kinds of speeds.
Ideal hub motor: Grin RH212 ( 35mph continuous with short bursts to higher ), leafbike 35mm 1500w ( will handle 35mph all day, 40mph spurts for 5+ miles at a time )
Controller suggestion: Spintend VESC or Grin phaserunner ( only if running 72v, it's amp output is weaker. )

Also you'll want 2 torque arms, i strongly suggest the ones from ebikes.ca.

 

[scianiac]

I 2nd those suggestions if you want a hub motor build, which in many ways has advantages for a car replacement. If you wanted to do a mid-drive though I would say a Lightning Rods kit is the best option, depending on the version would either easily do that speed or way faster/get to that speed unnecessarily quick. Paired with either a High Voltage LEVs controller kit (pricey but plug and play) or a VESC (cheaper but more tuning required). If it is for just simple efficient transport the hub motor is probably the way to go but if you wanted to do some off road use too...

I wish I had a magic battery that fits any frame solution for you but we don't yet have that. There are some custom builders out there that would do it no problem but may be expensive. If you're going with off the shelf packs I would say being creative with how you mount them is probably the best advice. I have two DH bikes that have almost no triangle space, way less than that Sisku and I just sorta wrapped the battery around one and split the battery into two packs on either side of the frame for the other. One places my legs spread slightly apart to clear the split battery but I'm not pedaling anyway so it doesn't really matter. Similarly the under the downtube mount is common and while you often have to limit the fork travel for this you also often don't use very much of a MTB fork on the road anyway.

 

[99t4]

Car replacement so presuming you have some usual routes you need to cover. What are you range requirements and hill grades and length? This will help determine battery size and motor type.

NOTE: High speeds and long distances will force you to need a large battery.

 

[Electric Earth]

Thanks for the advice on where to get good packs.

I didn't even think of mounting the battery under the downtube! That might be the ticket. I'll have to do some measuring. As you mentioned, I'm not worried about a ton of travel on the street.
I hadn't heard of the Lighting Rods kit before. I'll have to do some reading on it. It definitely looks like more DIY project that some other things out there, but that isn't necessarily a bad thing if it's the best one for the job.
Any thoughts on something like the CYC X1 Pro Gen 4 kit? Seems like a pretty sweet plug-and-play set-up for $1,300 with controller built into the design. 72v and 6,000watt peak capable. But if others are notably better, I have no problem doing the work to put something together myself.

Plan is largely for commuting to work, where I can't arrive sweaty and disheveled. That trip is only a few miles each way, with one short steep climb. Otherwise pretty flat. I don't know the % grade on that climb, but google maps is telling me it's 100' elevation change, and I'd guess it's in the span of a football field or so. So Approximately a foot/yard of elevation, I guess. I'd also use it for grocery store trips when I'm tired and don't feel like biking or walking. I'd rather ride an "ebike" than drive when the weather is decent.

I'd rather not go with a hub motor.

 

[neptronix]

Oh the ride is only a few miles and barely hilly.. that makes a mid drive a preference and not a need.

You could overvolt/over-amp many a smaller motor and get away with it forever over such a short distance, if you're sure that this will be your only application for the ebike.

You don't need a large battery either, a very high output, small battery would do. Coincidentally that would be the easiest to build yourself.

 

[scianiac]

The CYC kits are in some ways nice but really better used for certain applications and this really isn't one of them. Their power ratings are peak power and they won't do that for very long before overheating nor will they be very reliable doing that for long periods of time. They are nice for very lightweight applications with torque sensing, basically building a higher power version of a commercial E-MTB and using it for that.

The LR kits are a completely different beast, even the smallest LR kit the Small Block (I have one of these on a bike) is vastly more capable than the CYC X1 Pro in every way and they are vastly more reliable and repairable. I mean if you look at the size of the motors you can see the sizes aren't even comparable and honestly the LR motors are of much higher quality anyway (IPM motors that respond very well to MTPA and not SPM motors that throw magnets in spite of how many times CYC has said they fixed it). Yes they look and are a bit more DIY (you have to figure out the controller yourself assuming you don't buy the controller kit from HV) but he's also been building them for a long time and refining the design, much longer than CYC in fact. Also the support for setup and install is much better. Big industrial motor, with massive bearings, driving way overkill 219 chain or gates belt (I have the belt version and highly recommend it) with no tiny gearbox, then you drive the rear wheel with a large gear reduction single speed to reduce stress on the chain if you use bike chain or he offers them 219 chain drive which again is crazy strong. Just a much more reliable system, you can actually use a derailleur if you want but the only purpose is really to shift into a gear you can pedal home on a dead battery with.

Cost wise all these options kinda depend on how turn key you want things, a Grin all-axle kit with controller and everything, CYC kit, LR kit + HV controller will all be up there cost wise but be pretty easy to install. If you buy just grin all-axle motor or the LR kit and use a cheaper controller and figure out all the controls yourself like a cheap VESC they will be much cheaper but setup is harder and a lot more invovled.

 

[Mongo]

Hi @scianiac, thanks much for the insight. Who/where is the contact/purchase point for Lightning Rods Motors - is it via High Voltage?

I'm also wondering if Electric Earth's bike is up to the speed task (as in not a squirrelly steering mess), let along handling biggish power. I'd guess it involves an individual's comfort level. Safety protective gear comes into the risk calculation as well.

 

[scianiac]

There is a contact on LR website: Lightning Rods and he's also very active on the High Voltage Discord. He's posted a lot of builds using his kits on the Discord and on his FB page.

I think his bike is totally fine for the power and speeds but the speeds is very much a personal thing, it's probably better than many other bikes I've seen used as it's a somewhat modern MTB so has a slacker head angle which I think is really the most important factor if a frame is suitable for a given speed, everything else, tires, brakes, etc can be changed.

 

[Chalo]

Plan is largely for commuting to work, where I can't arrive sweaty and disheveled.

[...]

I'd rather not go with a hub motor.

Sounds to me like you would rather not get to work every time.

Crank drives are great, but only until you have to drag them to where you can load into another vehicle. Redundancy is good. Not putting several times as much power through a pedal drive as it was designed for, is good. Hub motor bikes have these qualities, so whether or not they mash your jolly button as hard as you like, they will get you to work.

For a bike you depend on for transportation, I advise against all forms of featuritis. My fast, sturdy, get-there bike doesn't even have a display. It doesn't have a voltmeter. I have a smartphone, a power meter, and a multimeter with me if I need them, but I don't put any of them in between my battery and the road.

 

[neptronix]

^-- I totally agree with this.

For reliable transportation i would also go with a hub motor; it only has one part and doesn't transmit it's power through a chain that was designed for approximately 300w of human power output. It also has regenerative braking, which you will need some form of at high speed.

You will find gears to be an annoyance at such high power levels, and with such flat ground, you can't take advantage of the gearing at all.

You do have to be picky about mid drives because most of them are not built with long term reliability in mind; lightning rods seems like a good choice but with their single reduction kit does not allow for pedaling. Being seen pedaling at high speeds is a good thing for legal risk mitigation. I would not run that drive on that basis ( i also like to pedal )

 

[E-HP]

I don't know the % grade on that climb, but google maps is telling me it's 100' elevation change, and I'd guess it's in the span of a football field or so. So Approximately a foot/yard of elevation, I guess.

If it’s paved, that would make it among the steepest paved streets in the world. Do you have google maps coordinates?

 

[bengxe]

I've been using a similar bike for a similar purpose and I agree with what's been said here so far, you want a 72v hub motor if you want car-like reliability and speed. The only thing I'll add is you probably want to think about downsizing the rear rim and tire, both for motor efficiency and for frame geometry/ high speed stability. I'm using a 26" bike with a 24" rear hub motor, you could try a 26 or 24 on that polygon. The Grin All Axle is the only easy hub motor option for that through axle frame, and it should fit your needs. You may need to find a cheaper controller (than the phase runner) to keep it under your budget listed, but there are plenty of options there. I would start with the biggest 72v battery you can fit under the top tube. If you're not interested in pedaling it you could probably fit a suitcase shape on its side. It looks to me like under the downtube would have less available space if you were to actually use all the fork travel.

 

[Electric Earth]

Trying to look into the Grin All-Axle, but they don't seem to have it on their motor simulator. What is this thing capable of? Will it get me 35mph+ with good acceleration, and long term reliability? Will it climb a fairly steep, somewhat long hill?

As for the bike capabilities, as mentioned, it's a modern MTB geometry. It's designed with a slacker head angle and meant to go down steep hills at high-ish speeds. That's why I want to build on a quality modern MTB. Robust frame, slack geometry. As for brakes, as mentioned previously, I have nice, high-end hydraulic MTB brakes. Hope Tech 4s, which are a four piston hydraulic brake, and Hope rotors, which are 203mm front and 180mm rear. I also have an 11sp XT drivetrain I can throw on it if I want, but for the sake of simplicity and reliability, my plan is a single speed drive train, if I don't need the gears. Ideally a thick, beefy BMX chain and cog would be used with the mid-drive if I go that route. I worked in a bike shop as a head mechanic. I'm well aware of how mid-drives eat chains and cassettes, and destroy derailleurs.

 

[Electric Earth]

If it’s paved, that would make it among the steepest paved streets in the world. Do you have google maps coordinates?

Oh, well it's certainly not that steep. I've biked much steeper roads in San Francisco. Google maps says it's ~

43°02'18.4"N 89°23'32.0"W​

Is there a way to see the angle of a hill by looking on google maps?

 

[E-HP]

but for the sake of simplicity and reliability, my plan is a single speed drive train, if I don't need the gears. Ideally a thick, beefy BMX chain and cog would be used with the mid-drive if I go that route. I worked in a bike shop as a head mechanic. I'm well aware of how mid-drives eat chains and cassettes, and destroy derailleurs.

Single speed mid drive makes no sense especially if you're geared for 35mph. It'll be basically like a direct drive hub, but noisier with more parts to break, and crap for hill climbing.

 

[neptronix]

Trying to look into the Grin All-Axle, but they don't seem to have it on their motor simulator. What is this thing capable of? Will it get me 35mph+ with good acceleration, and long term reliability? Will it climb a fairly steep, somewhat long hill?

Put ferrofluid into it and it will handle what you are asking.
It's on the simulator. Here's a link to what it would look like on a 5% continuous grade with ferrofluid ( statorade ) in it.
Motor Simulator - Tools

 

[neptronix]

Single speed mid drive makes no sense especially if you're geared for 35mph. It'll be basically like a direct drive hub, but noisier with more parts to break, and crap for hill climbing.

Exactly, all the downsides of the hub motor but without the bevy of power and regenerative braking ability. That and you're losing 50-10% of your power for the luxury.

Rear chain drive to a disc brake sprocket would be much better. Hub is the next best thing that doesn't cost a gazillion dollars.

 

[E-HP]

Oh, well it's certainly not that steep. I've biked much steeper roads in San Francisco. Google maps says it's ~

43°02'18.4"N 89°23'32.0"W​

Is there a way to see the angle of a hill by looking on google maps?

This is what is use for grades, both street and trail, since you can map out a whole route and get a good idea of what to expect. Odd, I looked up the coordinates on Google Maps and it shows Badger Street in Madison, WI. I don't see any hills going different directions from that spot (only some 3%-4% grades at most).

HeyWhatsThat Path Profiler

Compute elevation profile for an arbitrary path

www.heywhatsthat.com

 

[Electric Earth]

Put ferrofluid into it and it will handle what you are asking.
It's on the simulator. Here's a link to what it would look like on a 5% continuous grade with ferrofluid ( statorade ) in it.
Motor Simulator - Tools

Looking at that simulator with a 52v 13ah battery, it seems like the top speed isn't much more than the old $500 amazon rear wheel kit I had, which came with controller and throttle, plug and play. I ran that in Portland rainy weather doing bike delivery for a year, putting thousands of miles on it without issue. This motor alone is more than that kit. What makes the value in this? Am I missing something obvious?

 

[neptronix]

Yep, you could save a lot of money going to a bike with 135mm dropouts!

I like the all axle for it's low weight and ease of wheel changeout.. a lot.

 

[Electric Earth]

I do also have a 2006 Specialized Stumpjumper that I could easily convert, but it's not generally as suitable, I don't think. Older geometry with steeper head angle, thinner tubed Fox fork of that era, etc. But maybe that would be the route to take. Hmm...

The only aspect of that is that I'm changing directions to a slower bike, that I'd likely ride more like a traditional bike. Then I'd want torque sensing...

I feel like then I'm either building a different bike than originally planned(not necessarily a bad thing) for cheaper, or I'm back to a mid-drive so that I can get the performance I want out of this bike. What would one need in order to get a mid-drive that is capable of 35mph+ and decent climbing ability, without a geared drive-train? Or is that not something that really exists?

 

[bengxe]

52v won't be enough for the speeds you want, which is why several people mentioned 72v batteries. There are 2 winding options of the grin motor you can compare on the simulator, the fast one will probably be too much heat unless you drop the wheel diameter. Its an expensive motor because its lighter and better constructed than the 9c clones, but you also pay extra for it being the only option for a lot of modern bikes. A frame with replaceable dropouts and making your own torque plates is one way around that.

 

[Electric Earth]

Rear chain drive to a disc brake sprocket would be much better. Hub is the next best thing that doesn't cost a gazillion dollars.

Why a disc brake sprocket? Why not to the regualr chain cog on the rear wheel?

 

[bengxe]

Trying to look into the Grin All-Axle, but they don't seem to have it on their motor simulator. What is this thing capable of? Will it get me 35mph+ with good acceleration, and long term reliability? Will it climb a fairly steep, somewhat long hill?

As for the bike capabilities, as mentioned, it's a modern MTB geometry. It's designed with a slacker head angle and meant to go down steep hills at high-ish speeds. That's why I want to build on a quality modern MTB. Robust frame, slack geometry. As for brakes, as mentioned previously, I have nice, high-end hydraulic MTB brakes. Hope Tech 4s, which are a four piston hydraulic brake, and Hope rotors, which are 203mm front and 180mm rear. I also have an 11sp XT drivetrain I can throw on it if I want, but for the sake of simplicity and reliability, my plan is a single speed drive train, if I don't need the gears. Ideally a thick, beefy BMX chain and cog would be used with the mid-drive if I go that route. I worked in a bike shop as a head mechanic. I'm well aware of how mid-drives eat chains and cassettes, and destroy derailleurs.

My Banshee Rune is significantly slacker and more robust than that thing and I do not feel safe cornering hard on it beyond 35-40mph because of the frame and wheel flex. That's at about 200lbs with me on it.