Conversion Solution for Blue Ridge Parkway (hill assist)

[Williemakeit]

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.

I think it proves there would be little to no factor of safety. At this point I'd rather have an extra 2 lbs. if it means I can avoid a potential problem.

 

[Williemakeit]

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

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.

How about we get back to the subject mater. :thumb:

 

[ilu]

I have a full suspension mtb with TSDZ2 mid drive motor, which goes up to 800W of power and a hardtail mtb with Bafang G310 rear hub motor. I use the G310 with 36V battery and 20A limited controller, so the max power is also about 800W.

I don't have any long steep hills nearby, but riding both bikes from time to time, I can say that the hill climbing ability of the G310 is quite close but not as good as the mid drive, as can be expected. And if the speed drops below 10 km/h, the hub drive doesn't feel to put up significant power anymore.

The TSDZ2 has torque sensor and can be configured really well with an open source firmware upgrade, but I cannot really recommend the motor because of it's several constructional weaknesses. If you go with a light geared hub motor, be sure that with the system you can monitor the motor temperature, so you don't have to be worrying about it when riding the bike uphill. I don't have a temp sensor in mine so I wouldn't use full power for more than 10-15 minutes.

 

[Williemakeit]

The TSDZ2 has torque sensor and can be configured really well with an open source firmware upgrade, but I cannot really recommend the motor because of it's several constructional weaknesses. If you go with a light geared hub motor, be sure that with the system you can monitor the motor temperature, so you don't have to be worrying about it when riding the bike uphill. I don't have a temp sensor in mine so I wouldn't use full power for more than 10-15 minutes.

Thanks for the input! The TSDZ2 seems like a great idea but I've read mixed reviews and it seems the bad speaks louder than the good. It's always hard to tell if the product is weak, or the operator contributed to the problem.

It makes sense the G310 hub would not contribute as well at low speed since it has less torque.

How do you like the response of the TSDZ2 (torque based) vs the hub motor being cadence based. Big deal, or not?

 

[ilu]

When riding offroad, the torque sensing is absolutely better. It's much more natural feeling and the assist starts almost immediately when pushing on the pedals, whereas with G310 it can take up to 1-2 seconds especially in higher speeds. But it took a lot of tweaking to achive it, I had to mechanically calibrate the sensor and try a lot of different settings in the firmware.

Mostly I drive the hardtail on the streets though, and then the assist mode doesn't matter so much. I had another TSDZ2 fitted on that bike before, but it was too much trouble trying to maintain both of them, so I changed it to hub motor instead and I have been satisfied with the G310. Battery lasts longer (80-100km with 600Wh), but it's probably because the assist is limited to 30 km/h so with more speed I don't use the motor.

If you're not going to do any singletrack type of riding, I would recommend a hub motor for the reliability. But if you don't mind doing a lot of customization and maintenance work, then TSDZ2 can be a good choice as well You might be lucky and get a motor that works without problems, but there are several design flaws and durability issues that make it a hit or miss kind of thing.

 

[Williemakeit]

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.

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.

I've been struggling to figure out the lightest geared hub motor I can get that will not overheat on 5-10 mile hill climbs (5-7%). I'm not convinced there are any kit motors rated at 250-350 watts that are up to the task. From what I've been able to find the 250-350 motors weigh in at around 5.3 to 6.6 lbs. Next step up are the 500-750 watt range motors that weigh in around 8.5-9.3 lbs.

I'm not so much stuck on the weight difference as I am concerned about the lighter motors not being up to the task. On one hand it think the 250W motors should be up to the task, so why get the heavier one if they are. However, when I run the Grin motor simulator, there appears to be a fine line between success and failure. For example you plug in the G310 std motor with 36V, 242# total weight, 125W human power, 5% grade and it's fine if you keep the throttle @ 33%. However as soon as you go past 34% it starts to overheat.

So I"m trying to separate this calculator outcome from real life. Any feedback with 250 watt caliber geared hub motors would be welcomed.