First build advice

[Lemon357]

I'm looking to "build" a new bike to use to get two and from work which is about a 4 mile round trip with only hill but sadly its a pretty steep hill. Right now I'm getting by with a Amazon special bike but I seriously question how long this 400 dollar Chinese marvel of engineering will last lol.

The build I have spec'd out right now would be:

This Gravity Deadeye 27 Plus single speed bike would be the donor

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Mountain Bikes - MTB - NEW Gravity DeadEye 27PLUS CrMo Bladed Forks, Disc Brake Mountain Bikes w/SINGLE SPEED Drivetrain and Hydroform ALU

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And for the motor I would use this BBS02 kit from Luna and a battery from EM3ev

Bafang BBS02 Mid Drive eBike KIT

Get the Bafang BBS02 for only $525 and transform any bicycle into an electric beast. Do up to 30mph and use the gears of your bike to shift into low and climb big hills.

lunacycle.com

EM3ev Super Shark 48V (13S4P) Ebike Battery | EM3ev

EM3ev Super Shark, 48V, 13S4P Frame Ebike Battery. Safe by design, with CNC cell holders, cell level fusing and an Advanced Smart Programmable BMS with Bluetooth. The Shark Pack that we are proud to offer!

em3ev.com

I have seen 2 similar build to, being they use a mid drive motor on this same frame but they don't have much discussion on them. I know the main perk of a mid drive is using the bikes gears but I much prefer the simplicity of not having to worry about shifting or dropping the beans on IGH or some type of automatic shifting. Is this worth doing for the simplicity and ease of maintenance or should I just go with something like the Roadster V2 which is slight cheaper but has a hub motor which has way less power?

Thanks

 

[Hummina Shadeeba]

Another perk of mid-drive being lighter. I can’t imagine any drawbacks to using that mid drive with a single speed

 

[E-HP]

This Gravity Deadeye 27 Plus single speed bike would be the donor

Save up to 60% off new Mountain Bikes - MTB -NEW Gravity DeadEye 27PLUS CrMo Bladed Forks, Disc Brake Mountain Bikes w/SINGLE SPEED Drivetrain and Hydroform ALU

Mountain Bikes - MTB - NEW Gravity DeadEye 27PLUS CrMo Bladed Forks, Disc Brake Mountain Bikes w/SINGLE SPEED Drivetrain and Hydroform ALU

www.bikesdirect.com

Can’t tell for sure by the pics, but I would measure for chainring clearance before pulling the trigger on the bike purchase.

EDIT:
You can print the template out, but it's no good without the frame in hand, but judging by the pics, looking by the chainstay and rear tire area, it looks like chainstays widen out just past the 32T stock ring. You need to pay attention to the chainline as well.

BBS02 & BBSHD Motor Fitment Templates | BafangUSAdirect Help Center

BBS02 & BBSHD Motor Fitment Templates

intercom.help

Single speed on a mid drive Bafang is a non starter, literally.

 

[Hummina Shadeeba]

With a single speed there would be only the ability to pedal as like 3mph. Beyond that it would just be a motorcycle and need a hand throttle but maybe works for you. I don’t have a bafang specifically but do have a single speed mid drive and I like it a lot.
It’s in the background. I’m selling it for 1200$.

 

[Chalo]

Another perk of mid-drive being lighter. I can’t imagine any drawbacks to using that mid drive with a single speed

Then you haven't lived with a mid drive. Those things munch up bike parts better than they do anything else.

There is no good reason to use a mid drive on a single speed, rather than a hub motor. You'll just spend more on the motor system, much more on bike maintenance, and suffer a lot more downtime and show stoppers.

There are hub motors in the whole range from 1kg and weak, to bigger and more powerful than you can handle. Any one of them would be a far better option for a single speed bike, than a mid drive would be.

 

[Hummina Shadeeba]

I’ve had a couple single-speed hubs all of which I sold to make these single-speed mid drives (made three and have two more I’m making). Better acceleration. More efficient. Much lighter. There’s more maintenance and for some that might be the decider but replacing an 8-speed chain is cheap and easy and all I’ve had to do so far. I will have to replace bearings soon and they’re getting noisy.

More so on a full size motorcycle a hub makes more sense to me and won’t be trying to lift it. My mid-drive bikes I carry up and down stairs often. When u have to fix a flat, which is maybe the most common maintenance, a hub is more work.

 

[Chalo]

I’ve had a couple single-speed hubs all of which I sold to make these single-speed mid drives (made three and have two more I’m making). Better acceleration. More efficient. Much lighter.

No. You can only feed so many amps into a mid drive, but so much more current into a decent sized hub motor that it wins every performance contest every time. You want performance, hubs win. You want efficiency, hubs win. Low maintenance, hubs win. Longevity, hubs win. Reliability, hubs win. Redundancy, hubs win.

Mid drives win in terms of capabilities when you strictly limit power. But hubs make it so much cheaper and easier to add as much power as you need. More controller and enough battery to feed it.

When u have to fix a flat, which is maybe the most common maintenance, a hub is more work.

Just wait until you have to replace a clutch, nylon gear, bearing, or pedal sensor on a mid drive and then tell me hubs are more work. That's aside from all the chains, cassettes/freewheels, chainrings, wheel speed sensors, and taxi rides that mid drives will cost you, that hubs won't.

 

[gromike]

If you gear your mid-drive low enough for a steep hill you will be limited to slow speeds all the time. I would never put a mid-drive on a single speed bike unless all my travels were pretty much on the level. I have a BBS02 in a 8 speed and it is a very capable ebike. On a single speed, a hub motor is the obvious choice.

 

[Hummina Shadeeba]

If trying to climb a steep hill on a hub from a slow speed or a stop it might not even go up. my mid-drive with 10:1 gear ratio and 26” wheels crushes the 1500watt hub motor with 20” wheels and I hit 35mph without any field weakening. For sure u can get both torque and speed with a single speed and a hub is the same. It just comes down to weight in my mind.

Just wait until you have to replace a clutch, nylon gear, bearing, or pedal sensor on a mid drive and then tell me hubs are more work. That's aside from all the chains, cassettes/freewheels, chainrings, wheel speed sensors, and taxi rides that mid drives will cost you, that hubs won't.

With a single speed you don’t have most of those parts.

For me a big advantage of the mid-drive, even with a single speed, is the ability to convert speed to torque and ultimately get a lot more power out of a motor and therefore can use a smaller/lighter motor. the “illegal bike” here in ES for example, he could’ve just put the hub in the wheel but instead made it mid-drive for the performance benefits. In my experience with the same contoller a mid drive far out performs.

 

[E-HP]

If trying to climb a steep hill on a hub from a slow speed or a stop it might not even go up. my mid-drive with 10:1 gear ratio and 26” wheels crushes the 1500watt hub motor with 20” wheels and I hit 35mph without any field weakening. For sure u can get both torque and speed with a single speed and a hub is the same. It just comes down to weight in my mind.

Just to calibrate, which steep hill (street or trail name)? long and lat will do.

 

[Hummina Shadeeba]

Just to calibrate, which steep hill (street or trail name)? long and lat will do.

I don’t know what ur asking for sure but I live up Napa street in Sausalito and with hubs I need a running start. There’s a lot of steep hills here

 

[fill]

While i have no direct experience with mid drive motors, afaik the main benefit especially when it comes to hill climbing is the ability to use the bikes gears.

You might get better VFM with the amazon special, replacing its minimum spec controller and display with a 9x mosfet or 12xmosfet dual voltage controller allowing you to use a 48v battery to get an instant 30% more power from your motor for the hill.

 

[E-HP]

I don’t know what ur asking for sure but I live up Napa street in Sausalito and with hubs I need a running start. There’s a lot of steep hills here

Yup that's steep, but only the last 200 feet is really steep, above that set of apartments. Starting at Caledonia, I think I'd be somewhere over 40 at Bonita, as long someone was watching the cross street near the top for cars/people/dogs. Even at that grade, you'd be hard on the brakes between Bonita and Filbert, especially with that curve. Starting at those apartments though, I don't think I'd even hit 15-20 because it would be too hard not to wheelie starting on that grade with a hub (24" wheels).

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Interestingly, Filbert in SF has the same grade for about the same distance.

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[Chalo]

With a single speed you don’t have most of those parts.

You have a chain. You have a freewheel or freehub. You have a wheel speed sensor if it's a crank drive like the OP is discussing. And when the chain or freewheel breaks on such a system, you're walking. So... you have every single one of those things I named.

For me a big advantage of the mid-drive, even with a single speed, is the ability to convert speed to torque and ultimately get a lot more power out of a motor and therefore can use a smaller/lighter motor.

You're conflating a frame mounted motor driving a dedicated sprocket, with a mid drive that uses the bike's gears. They both have tradeoffs, but the one the OP and I are discussing is the one that uses the bike's gears.

 

[offGridDownUnder]

Napa street in Sausalito and with hubs I need a running start.

Long time ago, but I don't think the hills have gotten much lower since I was there. Take this seriously.

 

[offGridDownUnder]

I would want the hub drive for the braking ability with those hills.

 

[offGridDownUnder]

When u have to fix a flat, which is maybe the most common maintenance, a hub is more work

So, get one that is designed properly so it's not?
GMAC - Grin Kits - Product Info

1. Detach cable
2. Loosen torque arm fixing screw (leave attached)
3. All the rest the same as a wheel without a motor.
4. Reverse when fixed

 

[Hummina Shadeeba]

Yup that's steep, but only the last 200 feet is really steep, above that set of apartments. Starting at Caledonia, I think I'd be somewhere over 40 at Bonita, as long someone was watching the cross street near the top for cars/people/dogs. Even at that grade, you'd be hard on the brakes between Bonita and Filbert, especially with that curve. Starting at those apartments though, I don't think I'd even hit 15-20 because it would be too hard not to wheelie starting on that grade with a hub (24" wheels).

Street View · Google Maps

Explore a place in a more immersive way in Google Maps.

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View attachment 357998

Interestingly, Filbert in SF has the same grade for about the same distance.

Street View · Google Maps

Explore a place in a more immersive way in Google Maps.

www.google.com

So you’d be going 40mph up it with ur hub I guess. I dont doubt it’s possible with a hub if it’s big enough. It will have to be much bigger than a high geared mid drive and weigh more. That’s pretty much my only claim.

 

[Hummina Shadeeba]

You have a chain. You have a freewheel or freehub. You have a wheel speed sensor if it's a crank drive like the OP is discussing. And when the chain or freewheel breaks on such a system, you're walking. So... you have every single one of those things I named

I have no freewheel or free hub that the motor power goes through and it’s a fixed gear. That’s not everything u mentioned though:
“

replace a clutch, nylon gear, bearing, or pedal sensor on a mid drive and then tell me hubs are more work. That's aside from all the chains, cassettes/freewheels, chainrings, wheel speed sensors”

I would want the hub drive for the braking ability with those hills.

I use the mid drive for braking


I had that gmac motor as a single speed in a 20” wheel. It’s nice but it’s not as easy to fix a flat as a regular wheel.


To each their own and there’s trade-offs. I’ve become a big fan of mid drives on a single speed for low weight and performance and relative simplicity. If he were using a bicycle drivetrain with gears that’s more complex and more maintenance but he’s talking about a single speed. I don’t know if u can make it a fixed gear with that motor and do regen.

 

[E-HP]

So you’d be going 40mph up it with ur hub I guess. I dont doubt it’s possible with a hub if it’s big enough. It will have to be much bigger than a high geared mid drive and weigh more. That’s pretty much my only claim.

Yes. 1500W motor with a 24” wheel instead of 20”. 20” would be better on the 30% though.

 

[Hummina Shadeeba]

Yes. 1500W motor with a 24” wheel instead of 20”. 20” would be better on the 30% though.

my esc must have been the bottleneck and in my experience that hub without a good running start on a steep hill can be bogged down with my max settings on vesc6. If u come over here we can race up and compare. The hill on the other side of the library is consistently steep and safer to blast up.


Just finished this..single speed mid-drive with fixed gear.
I’m selling the exact same bike for 2400$. I’m into making these and a huge amount of time n no profit. This one I’m keeping.

 

[Chalo]

I have no freewheel or free hub that the motor power goes through and it’s a fixed gear. [...]

I use the mid drive for braking

The OP is talking about a bicycle with a mid drive. You're talking about a gimpy little motorcycle with a frame mounted motor. They're not the same thing at all, and using a Bafang BBSXX on a single speed bike is always a bad idea.

 

[Hummina Shadeeba]

The OP is talking about a bicycle with a mid drive. You're talking about a gimpy little motorcycle with a frame mounted motor. They're not the same thing at all, and using a Bafang BBSXX on a single speed bike is always a bad idea.

I was meaning this in the pic. The bbsxx seems pretty much the same except with a metal gear as apposed to belt for the first reduction. But the motorcycle is the same with a fixed gear single speed mid-drive and they have their advantages over hubs.
Why u think it’s a bad idea to use with a single speed? It will be less maintenance which was ur biggest complaint. Unless he wants to add to the power by pedaling I don’t see much value in multiple gears and more parts to maintain especially if he can fix the gear to the motor and regen brake.

 

[E-HP]

my esc must have been the bottleneck and in my experience that hub without a good running start on a steep hill can be bogged down with my max settings on vesc6.

You do need enough current to create torque without gearing. I had to look at the simulator to get comfortable with my estimates. On flat ground I hit 40 in 240 ft, per my testing. On the simulator, at 40, I still have 80nm+ available. After comparing acceleration on 0% vs 8%, I'd guesstimate I'd hit 40 by the end of the green line, right at the 31% section. Momentum plus 80nm will probably drop me just under 40 for the 100 feet up to Bonita. Then start coasting then brake about 50 ft. from the top. It would be scary with so many driveways and relatively narrow street. If you're riding up that at 35, hopefully you're wearing good protection.

Its a 42mile round trip for me, so I'd probably have to ride like a granny either on the way or back, to conserve, which is less fun. Somewhere in between would be better. Corta Madera has some steep roads, but most are curvy. Its going to be a couple months before my collar bone is healed and I'm back to riding though <sigh>.

Unless you want to add to the power by pedaling I don’t see much value in multiple gears and more parts to maintain especially if he can fix the gear to the motor and regen brake.

Note that based on the other bike the OP is considering (belt drive, single speed, small geared hub), it looks like he intends to pedal.