Spreading the disease

[dougnutz]

A friend of mine is considering building an ebike to commute on. His main concern is a 12-13% grade that he will have to climb. It’s about .4 miles long then it flattens considerably.
Personally it seems like a 9c 2808 or similar motor from ebikes would do the trick. I think he wants the bike to climb with little or no assist. I’ve also been considering recommending a mac 8t or similar as an alternative. I’m pretty sure either would do the job but I don’t have any experience with the mac so I thought I would ask for feedback before talking him into one or the other. I already know what Nept is going to recommend
Oh and another nice thing about the 2808 over the mac is that it’s readily available and practically local to me

 

[dogman dan]

If he wanted to pedal, or the hills was half that length, the 2808 on 48v would do it fine. He's just going to have to pedal some that half mile, unless he builds a John in CR style rig. Small wheel, big wattage. 5000w into a 20" wheel and he'll fly up that hill. And have an illegal in the USA vehicle.

But for sure, a 2808 will beat a 2807 on that hill. Chances are, if he runs the 2808 on a 30 or 35 amp controller he'll get up it, but toasty by the top.

Mac 10t shoud do it. 9c 2810 would too. Since I have several 2810's around, my approach would be a 2810 on 72v 20 amps. And a half mile of pedaling would be acceptable to get up it a tad faster. That would also be illegal, but less noticable than a 50 mph bike.

 

[neptronix]

Magic pie on external controller, or better ( crystalyte HT, 5304, 5403/5405, or the cromotor(tm) hubzilla(tm) ).

A MAC or 9C/MXUS sized motor will do it, but generate a good amount of heat and efficiency loss in the process. With a lot of pedaling, they'll make it, but they won't make it *with gusto*

 

[John in CR]

If he wanted to pedal, or the hills was half that length, the 2808 on 48v would do it fine. He's just going to have to pedal some that half mile, unless he builds a John in CR style rig. Small wheel, big wattage. 5000w into a 20" wheel and he'll fly up that hill. And have an illegal in the USA vehicle.

Just do the commute off road, then it's not illegal....or put some small wings on it and call it an ultralight aircraft, which doesn't have such a silly low power limit and should baffle a cop enough to get off....or just ignore such unjust ridiculous laws, which are made to be broken. Don't ride like an idiot and don't make yourself look like someone the cops want to mess with regardless of the 2 wheeler's legal status. Look at the preponderance of higher than legal powered ebikes on the forum, and I haven't heard of any problems resulting from being over the limit in terms of power. Slap a 750W sticker on it if he's worried about it.

 

[dougnutz]

Thanks for the input. Methods "wife kits" with a 2810 might be the right fit for him. I've also been looking at the area on mapmyride.com. There are some routes he could take that would add a mile to the commute but the hills are on the 9%range.

The next step is a battery. I'm tempted to recommend 10s lipo with methods boards. Though being a noob maybe a cell man a123 battery pack. His commute would only be about 4 miles round trip. It's going to take 20 or 30 amps to climb the hill but he doesn't need a lot of capacity. So presumably we are looking at 5c discharge.

 

[dogman dan]

One more mile is nothing to an ebike. Even the 2807 handles 10% grades with pedaling fine. So for that route the 2808 will be fine. Ignore those who love to hate the 9c motor. No, the 9c is not a 3000-5000w motor. But you can get up 9% fine on 1000w. Go for the wife kit only if you don't mind slow, or 72v to get the speed back up.