48 Volt Rear Hub Build

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EbikeAus   100 W

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48 Volt Rear Hub Build

Post by EbikeAus » Feb 05 2018 4:42am

Hi all,

This is my first post, have been wanting to join your great forum for a while now.

I couldn't find an introduction section so here's a bit about myself.
I live in Melbourne, Australia.

Currently have a Bafang 36 volt 250 watt Giant Roam conversion which I love getting out on!

Now that I have the ebike bug I feel the need for more power. I have an Apollo Gauntlet MTB (will add photos soon) which is in need of a rear hub motor.

I was looking to get this one

https://www.ebay.com.au/itm/Electric-Bi ... SeZMH9i6eA

I sent the seller a message regarding it being suitable with mechanical disc brakes, which they said is fine. But they say it is not supported for a mountain bike??

Do you guys see any reason this would not work on a 26'' rim MTB?

Any other recommendations for a rear hub motor would be most appreciated

Thanks in advance :)
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Chalo   100 GW

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Re: 48 Volt Rear Hub Build

Post by Chalo » Feb 05 2018 2:21pm

It will fit, no problem. The seller is probably aware that the operating speed range and torque of the motor are appropriate for street use, but not for off-roading. Too much full throttle power demand at low speed results in overheating.
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EbikeAus   100 W

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Re: 48 Volt Rear Hub Build

Post by EbikeAus » Feb 05 2018 3:07pm

Thanks for the response Chalo! I thought that could be it
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Re: 48 Volt Rear Hub Build

Post by EbikeAus » Feb 06 2018 5:15am

Ok. Kit ordered. Better get a battery sorted.

14s 4p of 30Q goodness

30Q 14s pack https://imgur.com/a/ejkCt

Haven't quite got adding photos worked out yet
Last edited by EbikeAus on Feb 08 2018 12:06am, edited 1 time in total.
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Re: 48 Volt Rear Hub Build

Post by EbikeAus » Feb 07 2018 1:10am

Here's a pic of the bike for this project.
I found it on hard rubbish! It's virtually brand new

Apollo Gauntlet https://imgur.com/a/fqP3g
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Wolfeman   100 W

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Re: 48 Volt Rear Hub Build

Post by Wolfeman » Feb 07 2018 10:21am

That'll be a cool build. I love my hub motor hardtail.
FullSizeRender-2.jpg
FullSizeRender-2.jpg (116.13 KiB) Viewed 2211 times
Keep posting updates, it's a great way to document your build and share what you learn along the way.
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https://endless-sphere.com/forums/viewt ... =3&t=96873
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EbikeAus   100 W

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Re: 48 Volt Rear Hub Build

Post by EbikeAus » Feb 07 2018 10:16pm

The kit should be here today or tomorrow
Hoping to get the battery soldered up soon. So hot here at the moment. Its about 35 deg C in the shed at the moment.
Opposite problem to what some of you guys have at the moment. I heard on the radio it was minus 19 in Minneapolis the other day :shock:
Thanks Wolfeman! Off to check out your build thread
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dogman dan   100 GW

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Re: 48 Volt Rear Hub Build

Post by dogman dan » Feb 08 2018 7:14am

They might have thought you wanted the front kit. if so, that is why they said not good for an MTB. The forks may not have room for the motor, and if they do, the motor may crack the alloy forks if they do not get a good pair of torque arms.

Excellent bike for a rear kit. You still need torque arms, really need them if the frame is aluminum alloy. With rear motor, it will off road, but overheating can happen if the grades are too steep, without any downhill cooling time. Not a problem unless you ride steep uphill continuous for miles. You can climb indefinitely if you keep up the speed, like not less than 20 kph.


On my off road direct drive motors, I like to drill a few tiny 1-2 mm holes in the cover. It does not cool it, or let in big sand. But I can then smell when the motor is getting too hot when I stop. Drying varnish smell ok, burning varnish smell time to stop.

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Re: 48 Volt Rear Hub Build

Post by EbikeAus » Feb 09 2018 4:21am

Thanks for the heads ups Dan
I didnt know what torque arms were but a quick look around the forum and web tells me that yes I will need them, it makes sense as well.
I think I might get the engineering shop down the road to make some. Or are there any good pre made options on ebay or amazon? Shipping to AU might get a bit too much.
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dogman dan   100 GW

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Re: 48 Volt Rear Hub Build

Post by dogman dan » Feb 09 2018 8:05am

Pretty easy actually, to make your own TA. If you can access a grinder, or even just a hacksaw, a drill, and a round file.

But sometimes the stock front TA works great, if your bike has a large flat area around the dropout.
Flat space around the rear dropouts.jpg
Flat space around the rear dropouts.jpg (145.82 KiB) Viewed 2124 times
The other pic is one example of a home made TA. It requires a second piece, that comes off the stock front torque arms you can get. Make this if the stock front one won't fit.
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EbikeAus   100 W

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Re: 48 Volt Rear Hub Build

Post by EbikeAus » Feb 09 2018 6:42pm

That doesn't look too hard to make. Thanks :)
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Re: 48 Volt Rear Hub Build

Post by EbikeAus » Feb 11 2018 12:37am

Hi guys
I received the kit late last week and first impessions are it looks pretty good for the money.
I seem to have hit a couple of issues though.
I have a few questions about the install if I may.

Q1. There seems to be around 3-4mm between the disk calliper and hub motor, is this ok?

https://imgur.com/NtLRUiX

Q2. The derailleur is touching the hub and I haven't tightened down the bolt yet and is already touching.

https://imgur.com/a/ENMCF

Thanks in advance
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Chalo   100 GW

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Re: 48 Volt Rear Hub Build

Post by Chalo » Feb 11 2018 12:47pm

You may have enough lateral adjustment in your brake caliper to make it work. The mounting holes are slotted. You will have to adjust your cable tension and fixed pad position. If that's not enough, you can use washers in between the frame and the caliper adapter carefully remove a little bit of material from the side of the caliper adapter. [Edited to address the correct direction the caliper must move.]

It's hard to tell, but it looks like your derailleur hanger is bent inward. Bike shops have a tool for precisely aligning that, and it's a quick job.

There are professionals almost everywhere who have no problems correcting mechanical issues like these.
Last edited by Chalo on Feb 11 2018 3:04pm, edited 2 times in total.
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Re: 48 Volt Rear Hub Build

Post by wturber » Feb 11 2018 2:22pm

Looks almost identical to the issues I had with my install. I dealt with the disc brake spacing by making a spacer out of thin aluminum (1/16" or so). Once the disc was shifted, adjusting the brake body to match gave the extra clearance so there is no rubbing.

I dealt with the derailer by simply locking out the lowest gear with the derailer adjustment screw. Maybe my derailer is bent and there is a better fix as Chalo suggested. But I don't need the lowest gear, so I'm good with this simple "fix."

Also, I found it pretty simple to make my own custom torque arms. I used some of that 1/4" mild steel bar stock you can get at Home Depot. I used a hack saw to cut it, drill press to make the main holes and various files and sandpaper to finish the shape. Some people might be critical of using such a cheap and mild steel. But it is easy to work with and I have a hard time imagining that the motor has enough torque to rip through 1/2" inches of it and the aluminum dropouts to boot. If you make your own, be sure to make the slotted hole for the axle with a very tight tolerance fit. You want a very close fit across the entire face of the axle flat. I'm no engineer, but I think having a closed slot is probably better than an open slot and not quite as good as a clamping slot. Lots of good examples elsewhere in the thread.

https://endless-sphere.com/forums/viewt ... d#p1315521
"Commuter - DC Booster"
Iron Horse 3.0 hardtail - 48V / 1000W / 470rpm generic Chinese DD Hub motor (ebay)
8 x 36v 4.3ah 10s 2P battery packs - 1500W 30A DC Boost Converter delivers 54v and about 1000 watts peak
53T/42T Sakae Road cranks - 30mph+ on flats
viewtopic.php?f=2&t=90369

EbikeAus   100 W

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Re: 48 Volt Rear Hub Build

Post by EbikeAus » Feb 11 2018 4:55pm

Thanks so much chalo and wturber!

Thats given me plenty to work with, I appreciate it :)
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Re: 48 Volt Rear Hub Build

Post by EbikeAus » Feb 12 2018 6:35am

Thanks to you guys I've got things pretty much sorted with the hub/ clearance issues.
Just need to get the torque arms made. The battery is done, just waiting on the bms to arrive.

The kit has PAS but I'm thinking of not using it with this build. I've heard it isn't great with these cheaper kits.

What do you all think?

I should add that tbis bike is just for fun, no commute or anything like that.
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Re: 48 Volt Rear Hub Build

Post by wturber » Feb 12 2018 2:25pm

I also didn't install the PAS that came with mine. But after hearing many good things about the KT controller "torque simulation" PAS, I went ahead and installed it. I'm glad I did. I probably ride about 80% on PAS, adjusting the assist levels mostly between settings 2 & 3. I keep the throttle enabled and will use the manual throttle for when I want more power than the PAS is supplying such as short steep hills, the need for fast accelleration, etc.

I can't vouch for other systems, but the KT system works fine - so long as I also have the manual throttle option. But then, I'm using my bike for commuting and for medium-long rides where I wan't to manage power use carefully. I'm not sure it buys you much if you are just zippin' around for fun.
"Commuter - DC Booster"
Iron Horse 3.0 hardtail - 48V / 1000W / 470rpm generic Chinese DD Hub motor (ebay)
8 x 36v 4.3ah 10s 2P battery packs - 1500W 30A DC Boost Converter delivers 54v and about 1000 watts peak
53T/42T Sakae Road cranks - 30mph+ on flats
viewtopic.php?f=2&t=90369

EbikeAus   100 W

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Re: 48 Volt Rear Hub Build

Post by EbikeAus » Feb 13 2018 5:29am

Thanks wturber! I think i'll start without the PAS and see how it goes.
I have PAS on my bafang bike, so might be nice to try this bike without it.

I don't want to wear out my welcome here but I have a question regarding my battery.
As I mentioned I'm building a 14s 4p from Samsung 30Q cells.

My battery knowledge comes from my other hobby, which is off grid solar. I have a 48 volt prismatic LiFePO4 battery system.

I've also made some batteries from 18650s.

With solar systems we usually regard 48 volt lithium as 14s, or 16s for LiFePO4.
Doing a bit of research, it looks like my 14s pack will be overvolting for this 48 volt kit. Do you guys think 14s will work, or will I destroy my controller?
I just opened one end of the controller case. Looks like there's 2 x 63v capacitors
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dogman dan   100 GW

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Re: 48 Volt Rear Hub Build

Post by dogman dan » Feb 13 2018 7:32am

63v should be your absolute max charged voltage, as you see on the caps inside. , so no problem with 58v 14s.

EbikeAus   100 W

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Re: 48 Volt Rear Hub Build

Post by EbikeAus » Feb 13 2018 2:06pm

Thanks Dan. Thats great to know!
I wasn't very excited about ripping my first pack apart.
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Re: 48 Volt Rear Hub Build

Post by EbikeAus » Feb 14 2018 11:58pm

Hey all,

I decided to get my local engineer shop to make some torque arms. I'm just too busy with work and getting ready to move house. Also they will laser cut them from stainless so will look so much better than anything I could do.

I have more questions please :)

Q1. What thickness stainless would you recommend for the TA's

Q2. Was thinking of a closed in section for the dropout and then a hole to bolt to the threaded hole already there? Would this give enough rigidity? The existing bolt hole looks to be around 6mm.

https://i.imgur.com/KIbbxrT.jpg

Q3. In the photo below there is no washer inside the dropout. This helps line the rear wheel up as you can see in second photo. Do I need a washer on the inside of dropout? Common sense tells me yes. Should I get a thin washer made to fit dropout as the one I have seems to push the wheel out of true.

https://i.imgur.com/80oChjj.jpg

https://i.imgur.com/ZKkvEWE.jpg
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Re: 48 Volt Rear Hub Build

Post by Raisedeyebrows » Feb 15 2018 12:35am

I have a set of basic hose clamp torque arms on my hubmotor bike currently but want to make a set of 1/4" thick stainless ones w/bolt hole like the ones pictured above in Dogman's photo. You're smart to invest in a nice pair, you won't have to worry about the hub spinning out and causing a wiring disaster.
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Re: 48 Volt Rear Hub Build

Post by EbikeAus » Feb 15 2018 5:50am

Raisedeyebrows wrote:
Feb 15 2018 12:35am
I have a set of basic hose clamp torque arms on my hubmotor bike currently but want to make a set of 1/4" thick stainless ones w/bolt hole like the ones pictured above in Dogman's photo. You're smart to invest in a nice pair, you won't have to worry about the hub spinning out and causing a wiring disaster.
Thanks! I nearly bought some of those hose clamp ones but from past experiences I've learned if at all possible, do it right first time :D
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dogman dan   100 GW

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Re: 48 Volt Rear Hub Build

Post by dogman dan » Feb 15 2018 7:18am

Bolt to the existing hole should be fine. At 1000w, just one should be enough. Two better of course. Get that hole made just slightly small, then file out by hand to a nice tight fit.

If your axle is 10mm flat by 14 mm round, deepen the dropout notch 2 mm. so the axle center is still in the center where it was for a 10mm round axle. Then make the TA to fit.

Best bet is not to drill that bolt hole till its actually on the bike. then mark and drill for the bolt. Use a hard bolt, not a soft one intended for a rear rack.

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Re: 48 Volt Rear Hub Build

Post by wturber » Feb 15 2018 12:39pm

EbikeAus wrote:
Feb 14 2018 11:58pm
Hey all,

I decided to get my local engineer shop to make some torque arms. I'm just too busy with work and getting ready to move house. Also they will laser cut them from stainless so will look so much better than anything I could do.

I have more questions please :)

Q1. What thickness stainless would you recommend for the TA's

Q2. Was thinking of a closed in section for the dropout and then a hole to bolt to the threaded hole already there? Would this give enough rigidity? The existing bolt hole looks to be around 6mm.

https://i.imgur.com/KIbbxrT.jpg
That scheme is working fine for me. My motor is currently set up to pull about 1100 watts max and I have two such torque arms made out of mild steel. After about 1700 miles, there is no sign of any compromise, wear, movement or distortion. My frame is also made of aluminum.
"Commuter - DC Booster"
Iron Horse 3.0 hardtail - 48V / 1000W / 470rpm generic Chinese DD Hub motor (ebay)
8 x 36v 4.3ah 10s 2P battery packs - 1500W 30A DC Boost Converter delivers 54v and about 1000 watts peak
53T/42T Sakae Road cranks - 30mph+ on flats
viewtopic.php?f=2&t=90369

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