Best wheel size for TSDZ2 mid-drive?

[CatfishMan]

So I am considering using either a 29" or 27.5" mountain bike. Which is ideal for a TSDZ2 mid-drive if range is my #1 priority? I don't care much about speed (as long as I can go 20mph with some pedaling I'm completely happy). I will be doing mostly gravel riding with some road as well. Pretty much all smooth riding. I'm leaning the 27.5" just because I feel like that will give me better control.

Also, what is the drag like on a TSDZ2 when the motor is disabled? I like to do long rides (50+ miles) so I realize to get that kind of range I will be pedaling without assistance a lot. Mostly want the motor for going up long hills (there are a lot where I live).

 

[jimmyfergus]

So I am considering using either a 29" or 27.5" mountain bike. Which is ideal for a TSDZ2 mid-drive if range is my #1 priority? I don't care much about speed (as long as I can go 20mph with some pedaling I'm completely happy). I will be doing mostly gravel riding with some road as well. Pretty much all smooth riding. I'm leaning the 27.5" just because I feel like that will give me better control.

Also, what is the drag like on a TSDZ2 when the motor is disabled? I like to do long rides (50+ miles) so I realize to get that kind of range I will be pedaling without assistance a lot. Mostly want the motor for going up long hills (there are a lot where I live).

I don't think it will make significant difference between the ~5% wheel size difference. That's around half the difference than between having an 11t vs 12t smallest cog on the cassette. A 20" wheel would be more of an issue because for those bikes the 42t chainring is very small - folders etc. usually have a 52t chainring or so.

I have tried riding with the engine off as an experiment and it felt like quite a bit of drag to me, but I'm not sure if it was just my perception compared to having assist. Someone else should chime in.

 

[CatfishMan]

I don't think it will make significant difference between the ~5% wheel size difference. That's around half the difference than between having an 11t vs 12t smallest cog on the cassette. A 20" wheel would be more of an issue because for those bikes the 42t chainring is very small - folders etc. usually have a 52t chainring or so.

I have tried riding with the engine off as an experiment and it felt like quite a bit of drag to me, but I'm not sure if it was just my perception compared to having assist. Someone else should chime in.

Thanks for the feedback. I ended up going with the 27.5".

So is the stock 42t ring good for for an 11-42t 10 speed rear cassette?

What battery are you running with your TSDZ2?

 

[jimmyfergus]

That would be plenty of range and top end - 28-106 gear inches.

I have a minimal battery - 52V 300Wh mini-cube, 3.1lb that fits in a small saddle bag. I get a solid 20 miles out of it on the road, could stretch to 30 if I charge and discharge 100%, which you don't want to do regularly. The battery works well for me for stealth and my urban utility riding, but is limiting for recreational riding.

I would recommend something bigger in general. It's easy to burn through the miles with assist, and off-road you'll use more than my ~10Wh/mile.