Yeah i know doing that is definitely ideal, but im wondering is the scenario i presented possible?amberwolf wrote: ↑Dec 31, 2017 10:25 pmYOu'd want to make torque plates or clamping dropouts that bolt to or clamp to the frame.
See the Torque Arm Picture Thread for a few ideas, or search on
There's at least one thread in the for sale section for versions of them, I think by Miguerillart.
You can also look at the build threads for the various frames like that, wherever they've used their frame name in the thread title or first post to make it easy to search.
Alot of them have rear 12mm through axle no? Meaning the hub axle should still be able to thread on that side, Then on the right side with the dropout adapter you just push that side in like normal?amberwolf wrote: ↑Jan 01, 2018 3:29 amIf the DH bike is a 20mm thru axle type, then your hubmotor axle, which is probably anything from 12mm to 15mm, will just be floating in the hole, unsupported.
So every bump, lean, acceleration, and regen braking you do will bend and twist the axle end that is actually mounted into the slotted dropout.
At some point, sooner or later, you'll get this:
at the stress riser where the axle becomes flat past the shoulder.
Mine was from a different cause, with less stress on that axle than what you're talking about doing, but it still broke. It's happened to others for reasons similar to the stresses you'd be putting on it.
It's not really too hard to make a torque plate to solve the problem, so I dont' know why you wouldn't want to, unless you have a really small low-torque motor. (though even that can still break the axle from the bumps and leaning flexure).
If you don't have power tools you can hacksaw a thick (5mm+) piece of steel so it's Y-shaped in a way that lets you use U-bolts to clamp it to your chainstay and seatstay if that's how your bike is shaped (or a single bar if you only have chainstays), . Then on the rear-pointing part, you can hacksaw a V into it and then file that V out into a rectangle that fits your axle flats, then file the inside end of that round to fit the rounded part of the axle, so it's all snug. See the Torque Arm Picture thread and others for more stuff like that.
If it's a 12mm axle, and a 12mm hole, then the axle will at least be supported and centered, so it won't have the flexing problem at the other end from the bumps and leaning.
Yeah.. well not many hub motors have a 14mm or 15mm axle atleast to my knowledgeamberwolf wrote: ↑Jan 01, 2018 5:42 amIf it's a 12mm axle, and a 12mm hole, then the axle will at least be supported and centered, so it won't have the flexing problem at the other end from the bumps and leaning.
But it will still have the twisting forces from acceleration and regen braking (if you use that) countered at only one end. That's where at least a torque arm would help.
If it is a 14 or 15mm axle, it won't fit in the 12mm hole, and the frame will have to be modified, filing material from it (or drilling it), which may weaken that side, depending on how it's made. That's also where a torque plate would help (or at least a torque arm).
If it is a 20mm hole, and a smaller axle, it'd have to have something to hold the axle centered in the hole.
There's a number of them out there; they're not uncommon. At least some versions of the MAC (and probably BMC) geared hubs have 14mm axles. Crystalyte H40xx series, probably the 35xx, etc. I think the Leaf motors are 14.
The theory build i had in mind was the giant dh glory frame, which has 12mm rears, and 3000w qs hub motor with 12mm axlesamberwolf wrote: ↑Jan 01, 2018 6:50 amThere's a number of them out there; they're not uncommon. At least some versions of the MAC (and probably BMC) geared hubs have 14mm axles. Crystalyte H40xx series, probably the 35xx, etc. I think the Leaf motors are 14.
I know at least three of mine are larger than 12mm (probably more of them). Both of the MXUS 3Ks, and the HSR3548. I think my Fusin "1000w" geared hub is also bigger than 12, and maybe the Ezee (would have to go measure them). Possibly even my old 9C/MXUS generics (28xx types).
Only ones I know for sure that I've got that are 12mm are the old small Fusin geared hubs, and a TongXin roller-geared hub.
A quick search of ES for 14mm axle* finds a number of posts, though I havent' looked thru them to see how many different motors come up
https://endless-sphere.com/forums/searc ... mit=Search
Haven't checked for 15mm.
FWIW, I think there are some DH forks that use 15mm thru axles, not sure about rear dropouts.
I don't know about the frame you are talking about. But I don't think you'll find anybody here who would not urge you to have two robust torque plates or clamps (maybe not arms) if you are going to be using a 3000w hub motor - pretty much regardless of the frame. So if you think the frame dropouts may be less robust than typical, you REALLY need to be thinking about how to reinforce the mounts.
If it's a 3kw motor, and you run it with a controller capable of using it well, it's likely to have a lot of torque.