Conversion Solution for Blue Ridge Parkway (hill assist)

Hey all, I'm looking for some advice for converting my Surly Disk Trucker to electric assist. Grin and others who only sell hub motors seem to think mid-drive systems are not good. However I can't get over the advantages of a mid-drive so I have a hard time ruling them out.
Here's my situation:
- 2019 all steel Surly Disk Trucker as is weighs in at 32.4 lbs. My weight is 180 lbs.
- Assuming hub or mid + battery will put bike @ 50 lbs. (+/- 2), so total e-bike and rider weight is 230 lbs.
- Triple in front 48-36-26 and 10 speed cassette 11-36...so plenty of gears.
- Prefer to keep as light as possible since I want to use as much human power as possible.
- Don't need any assistance on flats, mostly looking assistance for 5-7% grades that can be from 2-8 miles.
- I plan to contribute 120 watts of human power when climbing hills.
- Would like 60 mile range. Keep in mind any given ride would have 50% up and 50% down.

What is the best solution for Motor:
Mid drive 750 watt motor looks to give best weight to power ratio and should have plenty of power/hear dissipation.
Hub drive, looking at the Grin line up:
G310/G311 Bafang seems under power for long inclines.
Shengyi SX, not sure.
eZee, GMAC Grin All Axel, probably OK, but not sure if they would be better than the Bafang BBS02 mid-drive.

Controller: Which would give the best automated solution to only giving assistance on hills?
Eggrider - for Mid-drive - could be programmed to only kick in during lower RPM's. This assumes cadence would slow down as I started to climb. iPhone app is very appealing. Might not work with some hub motors systems.
Grin Cycle Analyst - With hub motor and torque sensor it could be programmed to only kick in after I exceed 120 watts human power.

I'm not expecting answers to all questions, but chime in on anything you have experience with. Thanks

Go to your local bike store or ebikes store and ride a mid-drive then try it it's free ride and a rear hub motor try it it's free.

You may be making this more complicated than necessary in some ways. Which is part of the fun. Good job nailing down the parameters, like weight and grades etc.

Any of those will work, really. The G310? Sure, if you keep pushing 120W and pull the throttle back to 1/3 power, the motor will more than double your power and do it all day long on that 7% grade (until the battery runs down anyway.) Whether you could configure a pedal assist system to do exactly what you'd want, without a throttle, I don't know ... probably close. Throttle is more direct control, though. The common style of controller has what Grin's motor simulator calls a "voltage" type throttle, so very approximately you tell it let's go 20mph, and if you're pedaling 20mph, the motor will idle. When you slack off, the motor picks up, and you keep going 20mph. Voltage controls speed (and often there's a "cruise control".) The Base/Phaserunner controllers are different.

Want regen on the way back down? OK, if you can count on managing battery reserve, and if you want to go with the Grin Phaserunner controller family, that can be configured to put in a steady dribble of power that balances the drag from a direct drive, so it pedals like a geared hub but can do regen. Usually that's as much because people like that braking ability on long descents, as opposed to just the extra watts. And then there's the superior direct drive heat dissipation. Just by way of suggesting that even the options you aren't considering, would be fine.

Yeah, I'm pretty sure I'm making this more complicated than it needs to be. Believe it or not that's why I've left off the regen braking. :lol: If I could get a system that had it, great, but for now it's not a hard requirement. I had an old Bionx system with regen braking and it didn't really make that much difference...but I also wasn't on the BRP with it. I did loved it for braking.

My wife has a bike with a 750 watt hub motor and it will climb hills all day long...or until the battery runs out. So I know by just going to the higher power system it will give me a motor that won't overheat. I guess I was trying to see if I could get a system that weighed less than 18 lbs. This requirement is both for riding weight and for the actual lifting of the bike. I have to pick it up to put it in my van to get to the Parkway. My wife's 68 lb. 750 watt bike is a killer for me at my age. The lightest system I thought might work would be the G310/11 hub motor, but the simulations I've run don't look promising.
Take a look at the attached motor simulations. Maybe I'm doing something wrong, but it looks like the G310 with 125W human power on a 5% grade would overheat in 15 minutes. The Grin craps out in 31 minutes.

So this is what lead me to Mid-drive vs hub. Seems like for a 500-750 watt system the mid-drive is a better choice...but like I said, places like Grin are really down on mid-drives. The only downside I can see it they don't have torque sensors. I also lose the granny gears in front, but I figure between the 10 in back and the assist, it would be OK.

I guess I don't understand the simulations with the torque throttle. It's set at 0, and you're pulling 721W? Same here, and when I adjust things ... not getting it.

Whatever. If you try a 25A normal controller with a voltage throttle, see if you "never" overheat at 14 mph up that 5% grade. The key is that you're willing to put the 125W in at the pedals. Without that, or if you had to keep up with motor vehicles, you'd need a bigger, heavier motor. There must be a way to get similarly thrifty usage with a torque throttle.

The other popular crank drive, TS something or other, uses torque sensors, if you really need that. They have a reputation here for fragility, I guess to some extent all the lower end crank drives do, but at the moderate level you're talking about that all should be no problem at all.

Williemakeit said:

So this is what lead me to Mid-drive vs hub. Seems like for a 500-750 watt system the mid-drive is a better choice...

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If you're trying to maximize performance with a limited amount of power, mid drive is your hookup. Also if you're trying to do as much repair and maintenance as possible. Mid drives are hard on bike parts. That's why I let mine go.

There is no way on God's green earth I would attempt that ride on a bicycle, e-bike or no. Everyone, or the vast majority at least, are rubber necking, taking in the scenery as much as possible. That leaves just the absolute minimum attention available for paying attention to what's actually in front of them. That leaves you an accident looking for a place to happen.

Are bikes even legal on the Blue Ridge? Those narrow lane winding uppy and downy roads are challenging enough in a decent handling car. Now enter the thought of a motor home making it's way through there..... and you on an e-bike?

I hate to break it to you, but the BRP is much safer than almost all other roads on North Carolina. Most of the time there are very few cars. Most traffic in NC is around Ashville, but there are also more bikers in that area so I've never had a problem. I have the Garmin Varia rear view radar to alerts me when cars are coming from behind. The bigger problem I've found is cars will give you room when they pass, but will also pass on hills and blind curves, so on-coming cars are more of a problem for them. Down hills you are typically going as fast or faster than traffic.

Middrives can be great--the three issues I know of with them (relative to hubmotors) are:

--there are a lot more parts between the motor and the road, so there are a lot more things that can go wrong, and a lot more stuff that wears out, and that stuff wears out faster.

--some of those parts are *also* your pedal drivetrain (in most commercial middrives), so if the middrive breaks those, you are now walking.

--Many of the middrive systems don't really react to your pedal control inputs the way the bike itself does without a drive, and can either take a bit of relearning, or may require working around how the middrive reacts in various situations (some of them emergency events). Some are programmable in ways that let you fix this, many aren't. Some can operate entirely by throttle, which will also mitigate the problems, but not all can.


But if none of that is a problem for your use case, or youc an work with it or around it, then a middrive with the right gearing, that also lets you change gears normally like for pedalling, can use less power to do the same kind of thing, by keeping the motor in it's more efficient RPM range--but like with pedalling, you do have to change gears at appropriate times to make this work, and some people don't end up doing that, making the system not a whole lot more efficient than a good hubmotor system for much of their usage.

Myself, I went hubmotor because I had too many problems with being stuck roadside due to middrive failures that took out the pedal drivetrain, too. However, since I ended up going higher power, the bikes were heavier, and harder to pedal without power, and got bigger to let me put more battery on there to compensate, and so on until i began having problems with quality of axles and such, increasing the problems with the hubmotors to where I would get stuck roadside for different reasons. So it can be a six-of-one / half-dozen-of-the-other thing depending on your specific use case, as to which is better for your needs.


So it depends on which is more important for your use case: reliability / lower maintenance / redundancy, etc., or potentially better range / lighter weight / etc.

How the drive works with you to move and control the bike or stop it also make a difference, depending on the specific use case.

Williemakeit said:

This requirement is both for riding weight and for the actual lifting of the bike. I have to pick it up to put it in my van to get to the Parkway. My wife's 68 lb. 750 watt bike is a killer for me at my age.

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I am familiar with that problem. I tried to lift my grocery getter up on a Park Bicycle Service Rack ... not happening ... not until I stripped some of the weight off.

Be sure to get a removable battery either down tube or rack mount. That way you can remove from 7 to 12 pounds depending on the battery. Also think about this ... a front hub drive wheel is also fairly easy and quick to remove. You would need to check the brakes every time you put the wheel back on the bike.

A simple thumb throttle is the easiest way to control when you want assist and when you do not. With a geared hub motor there is little to no addital drag when using pedal only.

A ramp might be the answer for getting your heavy bikes into the van. Also a receiver mounted rack on the van that carries the bike by the wheels can be easier. You lift the bike onto the rack one wheel at a time.

Not sure what hub motor your wifes bike has, but a lighter geared hub motor would be a good choice. 7% not hard for a motor that weighs about 8 or 9 pounds. Typical direct drive bike hub motors weigh more like 15 pounds. Keep the total weight under 300 pounds, or not much over for the geared motors.

60 miles range up and down the hills will take a lot more weight in batteries. As much as 30 pounds. But that can be in the panniers, or triangle bag, removing it to load and unload. A good quality 15 pound battery, 750-800 watt hours in size, such as 48v 15 ah, can definitely get you 40 miles. 20 miles of it uphill. You pedal a lot for that of course, but climb the hills at about 15 mph, using only enough motor power to go 15 mph..

The BEST way to achieve longer range is a throttle, but it takes time to learn not to squander the power riding up the hill at 17 mph. PAS has improved a LOT, but no computer is smarter than you are. Simply putting a 15 mph speed limiter on the controller can work good too, such as you can do with a cycle analyst and a grin setup.

But,,, if you want to haul more weight than 300 pounds up any of those hills someday, then you want the powerful mid drive. Then you can grind up the hills slower, resulting in your 120w being more of the total it takes to get up it.

All thanks for the input. Based on comments it seems that setting up the throttle to assist during hill climb might be an option. Here are the options I'm now considering for hill climbing assistance:

1. Torque sensors with hub drive (haven't found add-on mid drive with torque sensors).
Pros:
- In theory I could set motor to kick in after I have reached say 120 human watts. This would typically happen as I started to climb.
- Mostly automatic and wouldn't need to do anything to kick motor on.
Cons:
- Might get tired and un-able to continue threshold human power to keep motor engaged...however with trial and error I think a sweet spot could be found.

2. Use Cadence to kick motor in (Hub or Mid Drive).
Pros:
- In theory I could set motor to kick in after I drop below 70-75 rpm's.
- This would also assist getting up to speed.
Cons:
- May be times when I want assistance above 70 rpm's. Eggrider could handle with since it has 1 bike profiles.

3. Manual Throttle Control (Hub or Mid Drive).
Pros:
- Simple and can be used as needed. Just set the throttle % by feel and kick it on when you need it.
Cons:
- Would have to hold throttle on long hill that can take 1 plus hours to climb. Typically have 2-3 hours climbing time on 60 mile ride.

Williemakeit said:

3. Manual Throttle Control (Hub or Mid Drive).
Pros:
- Simple and can be used as needed. Just set the throttle % by feel and kick it on when you need it.
Cons:
- Would have to hold throttle on long hill that can take 1 plus hours to climb. Typically have 2-3 hours climbing time on 60 mile ride.

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I think I mentioned, my controller has a "cruise control" feature, and I think that's fairly common. I just need to hold the throttle steady for a few seconds (3? don't know, it goes pretty fast anyway) and then I can let it go. It makes a big difference on grades that go on for more than a few hundred feet. I can switch between 3 throttle control settings, but that isn't very interesting - if I wanted to restrict speed or maybe get a little more low speed sensitivity, I could set it on 70%, etc., but in practice I can't easily tell the difference. So ... not sure what you mean by "set the throttle % by feel", but I don't think you'll really need that feature.

I can't say how realistic your ideas are about the various pedal assist systems, never tried any, they seem highly dependent on configuration options. But relative to throttles - it appears to me that the two pedal controls to some extent may match the two throttle controls we've been looking at.

• the "torque throttle" in your Baserunner simulation would make a lot of sense in a torque sensor pedal control
• the voltage throttle like mine makes sense with a cadence system. I've heard the cadence system described as "if you pedal harder, the battery watts go down", which is what happens with a voltage throttle. (Conversely, if your input stays constant and the load goes up, like on a hill, the watts of course go up. So the object is to have the throttle where it draws 0 watts on the flat, and starts pulling on the hills - though there's an efficiency issue here between the ideal voltage speed and actual forward speed.) The assist level options would equate to throttle settings, I guess.

Have ridden much of the BRP in Virginia on a bicycle, some on e-assist. Great road to ride. Have driven the entire BRP in our Bolt. Once down into NC people were driving like idiots. Went from tourists to racer wannabes. Everybody imagined they were hauling moonshine in that 1950's classic movie. With the much tighter curves, and many long dark tunnels in NC, you are dead meat on a bicycle.

I usually ride in the mornings, maybe they don't start running moonshine until later in the day. :lol:

AHicks said:

God's green earth

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Well you got that part right :wink:

AHicks said:

There is no way on God's green earth I would attempt that ride on a bicycle, e-bike or no. Everyone, or the vast majority at least, are rubber necking, taking in the scenery as much as possible. That leaves just the absolute minimum attention available for paying attention to what's actually in front of them. That leaves you an accident looking for a place to happen.

Are bikes even legal on the Blue Ridge? Those narrow lane winding uppy and downy roads are challenging enough in a decent handling car. Now enter the thought of a motor home making it's way through there..... and you on an e-bike?

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I’m assuming you’ve never been there. There’s tons of cyclist on the Blue Ridge Parkway. I visit the parkway frequently multiple times a year. The speed limit is 35 mph and most people are doing barely that in their cars. It’s not that unsafe for people to ride their bikes on the Greenway. Now there’s sections that are more crowded than others but a lot safer than trying to ride through any big city.

Here’s a picture I took a few weeks back on a hiking Adventure off the Blue Ridge.

donn said:

3. Manual Throttle Control (Hub or Mid Drive).

I can't say how realistic your ideas are about the various pedal assist systems, never tried any, they seem highly dependent on configuration options. But relative to throttles - it appears to me that the two pedal controls to some extent may match the two throttle controls we've been looking at.

[/list]

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At this point I'm ready to admit, you'll probably right about these ideas perhaps not being realistic. The fact that nobody has chimed in to say anything about using torque settings for cadence says it may not be worth worrying about. In the end it may just be a simple case of finding good assistance percentages for each level, then using those levels as required. I'm not giving up on the other ideas, but definitely giving this part of the system choice a lower priority.

Today I rode a Cannondale Topstone with a 250W Bosch mid-drive (85Nm torque). Level 2 assist (Tour) was enough to give me the help I need on a long steep hill. By comparison, rode a Orbea Vibe with 250W Ebikemotion X35 Plus 20mph hub drive (40Nm torque). I had to go the the Top level of assist and it wasn't enough. I'm guessing this motor is pretty close to the G310 Bafang I have modeled in the motor comparison from my earlier post. I would say the motor simulator is pretty close to reality.

I know both Shimano and Bosch have some well refined mid-drive systems. However it looks like all are meant for special built frames...bummer.

Williemakeit said:

Today I rode a Cannondale Topstone with a 250W Bosch mid-drive (85Nm torque). Level 2 assist (Tour) was enough to give me the help I need on a long steep hill. By comparison, rode a Orbea Vibe with 250W Ebikemotion X35 Plus 20mph hub drive (40Nm torque). I had to go the the Top level of assist and it wasn't enough.

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The displays didn't show the watts you were drawing? It's pretty hard to get much insight out of those rides, without some idea what was under the hood and how hot it was running.

donn said:

The displays didn't show the watts you were drawing? It's pretty hard to get much insight out of those rides, without some idea what was under the hood and how hot it was running.

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Both bike had a minimalist setup. Orbea doesn't even have a display. Amber, green and red lights for power levels. I can tell you the pull they had by comparison were relative to the torque ratings. I guess what I learned was a 250W hub motor with 40Nm of torque didn't do what I needed, which was to provide a minimal level of assistance up a 5-7% grade. (I was in a gear I would have used with no assistance peddling about 80 rpms, about 8-10 mph). I believe it would have failed within minutes if I would have continued. The hill I tested it on was barely over 1/4 mile and the assistance was hard to detect for the first half and non-existent for the second half. Neither had a throttle, the Cannondale would have crawled up with throttle, but Orbea would not have.

Eastwood said:

AHicks said:

God's green earth

Click to expand...

Well you got that part right :wink:

AHicks said:

There is no way on God's green earth I would attempt that ride on a bicycle, e-bike or no. Everyone, or the vast majority at least, are rubber necking, taking in the scenery as much as possible. That leaves just the absolute minimum attention available for paying attention to what's actually in front of them. That leaves you an accident looking for a place to happen.

Are bikes even legal on the Blue Ridge? Those narrow lane winding uppy and downy roads are challenging enough in a decent handling car. Now enter the thought of a motor home making it's way through there..... and you on an e-bike?

Click to expand...

I’m assuming you’ve never been there. There’s tons of cyclist on the Blue Ridge Parkway. I visit the parkway frequently multiple times a year. The speed limit is 35 mph and most people are doing barely that in their cars. It’s not that unsafe for people to ride their bikes on the Greenway. Now there’s sections that are more crowded than others but a lot safer than trying to ride through any big city.

Here’s a picture I took a few weeks back on a hiking Adventure off the Blue Ridge.

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Yes, I've been there, which is exactly why I believe what I wrote. We can agree it's a wonderful drive if nothing else. Maybe I was just on one of the "busier" sections you mention, because I never saw anyone brave enough to try it on a bike.

Williemakeit said:

I guess what I learned was a 250W hub motor with 40Nm of torque didn't do what I needed, which was to provide a minimal level of assistance up a 5-7% grade. (I was in a gear I would have used with no assistance peddling about 80 rpms, about 8-10 mph).

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Yet the G310 appears to have a similar torque output, as you noticed, but will go up 5% grade all day at 13mph, at 2/3 throttle, delivering 258W motor power on top of your 125W pedal input. So either 1) the simulator is wrong, 2) the parameters weren't the same, like maybe you weren't pedaling or it was really a 10% grade, or 3) that isn't really a comparable motor. I like the idea of trying things out in the field, but I'm not sure the Orbea motor tells you anything about the G310.

donn said:

Yet the G310 appears to have a similar torque output, as you noticed, but will go up 5% grade all day at 13mph, at 2/3 throttle, delivering 258W motor power on top of your 125W pedal input. So either 1) the simulator is wrong, 2) the parameters weren't the same, like maybe you weren't pedaling or it was really a 10% grade, or 3) that isn't really a comparable motor. I like the idea of trying things out in the field, but I'm not sure the Orbea motor tells you anything about the G310.

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Yep, the G10 simulator shows it to be fine under those parameters. However it overheats in 27 minutes if you change the 5% to 7%. As I stated I was peddling about 80 rpm’s, if I wasn’t I would have stopped since there was no throttle. I appreciate the feedback, but I don’t agree there wasn’t anything learned. Certainly it’s not a conclusive comparison either but I don’t have everything required for a better comparison at my disposal. I was hoping someone on this forum might have some experience with various lighter weight motor on hills that could help fill in the blanks.

Williemakeit said:

Yep, the G10 simulator shows it to be fine under those parameters. However it overheats in 27 minutes if you change the 5% to 7%.

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OK, so you go slower - a little over half throttle to 10mph, and you're back to "never." 10% grade, 1/3 throttle. Etc.

Maybe this is all wrong, there's some giant error that makes these simulator outcomes invalid? Possible, but I just don't think that Orbea experience with an unknown motor proves it.

Eastwood said:

The speed limit is 35 mph and most people are doing barely that in their cars.

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Interesting. When I drove it two years ago, it was mostly 45 mph, and people were passing me on blind curves while I was going that speed.

https://www.visitroanokeva.com/things-to-do/blue-ridge-parkway/tips/#:~:text=Speed%20Limit%3A%2045%20mph,and%20less%20in%20certain%20spots.

Are you sure you are not talking about the Skyline Drive? That has a 35 mph speed limit the entire way.

When I had a motorcycle and was more interested in such things, I had the impression someone had made business of photographing motorcyclists taking the curves at death defying speed, somewhere on that particular route. Maybe hiking in the area is a better way to experience it.