Issues with front hub motor on aluminum shocks.

General Discussion about electric bicycles.
Post Reply
jcool3   100 mW

100 mW
Posts: 38
Joined: Jun 18 2017 12:15pm
Location: san francisco

Issues with front hub motor on aluminum shocks.

Post by jcool3 » Aug 31 2019 10:36am

Are there issues with mounting a front hub motor on aluminum bike with suntour shocks. Would regular torque arm work?
The bike is a Specialized step-thru. My other bike has a rear hub motor and it is such a complete hassle to change flats!
suntourweb.jpg
suntourweb.jpg (42.13 KiB) Viewed 1027 times

User avatar
Drunkskunk   100 GW

100 GW
Posts: 7167
Joined: Apr 14 2007 11:37am
Location: Dallas, Texas. U.S.A.

Re: Issues with front hub motor on aluminum shocks.

Post by Drunkskunk » Aug 31 2019 3:30pm

If I had a dollar for everyone who has asked this question, been told it's a bad idea, decided to try it anyway, and then come back to post how they had broken their fork, I'd be be able to buy a Zero FXS.
If I had a dollar for everyone who's asked, been told No don't do it, decided to try it anyway, and then never returned to post anything again, I be buying the Zero with blood money.


It's a bad idea. Sometimes it works fine. With a low powered motor and getting the install right every time to remove the wheel, it will work without problems. Get things a little wrong, and most motors have enough power to twist in the dropouts. Aluminum, especially the cast aluminum used in cheap suspension forks tends to crack and break off when that happens, leaving you very suddenly with no front wheel. Losing your front wheel is a very painful way to crash.
Buy the ticket, take the ride.
Monster Bike:http://endless-sphere.com/forums/viewto ... =6&t=38667

User avatar
MadRhino   100 GW

100 GW
Posts: 6037
Joined: Sep 03 2010 5:28pm
Location: Montreal QC Canada

Re: Issues with front hub motor on aluminum shocks.

Post by MadRhino » Aug 31 2019 7:31pm

The trick when breaking a fork, is to keep the eyes on your front wheel. It will end up behind so you will roll to your ass, instead of digging the trail with your face.

Just in case you persist with the idea, and to make sure you can come back to tell us. :wink:
Make it fool-proof, and I will make a better fool.
Current bikes
Street: https://s20.postimg.org/ewrvugywt/Session_04_2015.jpg
Dirt: https://s20.postimg.org/lbqwr55ml/IMG_0157.jpg

Benjamin Wassink   1 mW

1 mW
Posts: 11
Joined: Apr 21 2018 3:17pm

Re: Issues with front hub motor on aluminum shocks.

Post by Benjamin Wassink » Sep 01 2019 4:50am

jcool3 wrote:
Aug 31 2019 10:36am
My other bike has a rear hub motor and it is such a complete hassle to change flats!
Learn to repair a flat with the wheel inside the frame! :wink:

Yeah i understand that for a new tube you need the wheel to come out the frame...

jcool3   100 mW

100 mW
Posts: 38
Joined: Jun 18 2017 12:15pm
Location: san francisco

Re: Issues with front hub motor on aluminum shocks.

Post by jcool3 » Sep 01 2019 7:53pm

Benjamin Wassink wrote:
Sep 01 2019 4:50am
jcool3 wrote:
Aug 31 2019 10:36am
My other bike has a rear hub motor and it is such a complete hassle to change flats!
Learn to repair a flat with the wheel inside the frame! :wink:

Yeah i understand that for a new tube you need the wheel to come out the frame...
have done that, still a major hassle ....

Stu Summer   10 W

10 W
Posts: 95
Joined: Apr 27 2016 8:01pm
Location: Hillsdale, NY

Re: Issues with front hub motor on aluminum shocks.

Post by Stu Summer » Sep 01 2019 9:34pm

I had a cheap, cast aluminum suspension fork break with a rear hub motor. Wasn't even going fast. Just not strong.
2013 DB Haanjo Commuter with BBSHD and Zzipper fairing
Marin Rift Zone FS with BBSHD
Kysmo "lab" bike with 350w hub motor
Ryan Vanguard recumbent LWB with a 36v Cyclone 350w middrive and a 56v MAC 5t in the front hub.

User avatar
wturber   10 MW

10 MW
Posts: 2111
Joined: Aug 23 2017 8:52pm
Location: Fountain Hills,AZ
Contact:

Re: Issues with front hub motor on aluminum shocks.

Post by wturber » Sep 01 2019 11:28pm

jcool3 wrote:
Sep 01 2019 7:53pm

have done that, still a major hassle ....
Yep. That's why I've made my rear tire more puncture resistant. Given that I already have a rear hub motor, that seemed to be the simplest and least expensive approach.
"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

John in CR   100 GW

100 GW
Posts: 13956
Joined: May 20 2008 12:58am
Location: Paradise

Re: Issues with front hub motor on aluminum shocks.

Post by John in CR » Sep 02 2019 8:11am

I snapped both AL fork dropouts in the first meter of my first hubmotor ride. Luckily my dual torque arms kept the wheel on the bike and avoided the face plant.

Flats are a pain on a hubmotor whether on the rear or not, so I switched to moto tires a decade ago and would never go back.

Voltron   10 MW

10 MW
Posts: 2148
Joined: May 02 2013 4:53pm
Location: Santa Barbara CA

Re: Issues with front hub motor on aluminum shocks.

Post by Voltron » Sep 02 2019 11:13am

a0bbyp.jpg
a0bbyp.jpg (424.17 KiB) Viewed 902 times
brokenfork.jpg
brokenfork.jpg (46.67 KiB) Viewed 902 times
Here's 2000 words worth of pictures...

jcool3   100 mW

100 mW
Posts: 38
Joined: Jun 18 2017 12:15pm
Location: san francisco

Re: Issues with front hub motor on aluminum shocks.

Post by jcool3 » Sep 02 2019 2:10pm

Voltron wrote:
Sep 02 2019 11:13am
a0bbyp.jpg
brokenfork.jpg

Here's 2000 words worth of pictures...
Did these have torque arms?

jcool3   100 mW

100 mW
Posts: 38
Joined: Jun 18 2017 12:15pm
Location: san francisco

Re: Issues with front hub motor on aluminum shocks.

Post by jcool3 » Sep 02 2019 2:13pm

wturber wrote:
Sep 01 2019 11:28pm
jcool3 wrote:
Sep 01 2019 7:53pm

have done that, still a major hassle ....
Yep. That's why I've made my rear tire more puncture resistant. Given that I already have a rear hub motor, that seemed to be the simplest and least expensive approach.
Unfortunately I went thru an episode with 3 flats within a week on my rear hub motor wheel. Finally figuring out that the xlm thorn resistant tubes were defective .... the presta valves were leaking at the base which was impossible to fix.

Voltron   10 MW

10 MW
Posts: 2148
Joined: May 02 2013 4:53pm
Location: Santa Barbara CA

Re: Issues with front hub motor on aluminum shocks.

Post by Voltron » Sep 02 2019 2:58pm

Re torque arm, not sure, but many I've heard of had them, and still broke off the dropout tips, but at least had the wheel stay semi attached to the fork.
I've had bad luck with extra thick Prestas, the stem attachment area is so small it rips off easily, esp if the air is a little low to where the tire creeps around the rim during hard braking. Maybe drill your rim for Schrader valve if the rim is wide enough?

User avatar
MadRhino   100 GW

100 GW
Posts: 6037
Joined: Sep 03 2010 5:28pm
Location: Montreal QC Canada

Re: Issues with front hub motor on aluminum shocks.

Post by MadRhino » Sep 02 2019 4:10pm

When you build a bike, the tires and puncture proofing are way lower in the priority list, than making a rear wheel mount that is planned for quick servicing.

Pinch dropouts are simple and safe, quick and easy.

Not applicable for all frames, bolt-on through axle dropouts are also very quick to service.
Make it fool-proof, and I will make a better fool.
Current bikes
Street: https://s20.postimg.org/ewrvugywt/Session_04_2015.jpg
Dirt: https://s20.postimg.org/lbqwr55ml/IMG_0157.jpg

User avatar
wturber   10 MW

10 MW
Posts: 2111
Joined: Aug 23 2017 8:52pm
Location: Fountain Hills,AZ
Contact:

Re: Issues with front hub motor on aluminum shocks.

Post by wturber » Sep 02 2019 7:08pm

jcool3 wrote:
Sep 02 2019 2:13pm

Unfortunately I went thru an episode with 3 flats within a week on my rear hub motor wheel. Finally figuring out that the xlm thorn resistant tubes were defective .... the presta valves were leaking at the base which was impossible to fix.
Yup. My most recent flat was a presta valve base failure. But that was on the front wheel. I'm at about 3500 miles without a flat on the rear now. I've had no rear flats since I went with the "tire inside a tire" scheme.
"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

jcool3   100 mW

100 mW
Posts: 38
Joined: Jun 18 2017 12:15pm
Location: san francisco

Re: Issues with front hub motor on aluminum shocks.

Post by jcool3 » Sep 02 2019 8:51pm

wturber wrote:
Sep 02 2019 7:08pm
jcool3 wrote:
Sep 02 2019 2:13pm

Unfortunately I went thru an episode with 3 flats within a week on my rear hub motor wheel. Finally figuring out that the xlm thorn resistant tubes were defective .... the presta valves were leaking at the base which was impossible to fix.
Yup. My most recent flat was a presta valve base failure. But that was on the front wheel. I'm at about 3500 miles without a flat on the rear now. I've had no rear flats since I went with the "tire inside a tire" scheme.
these were all presta valve. My first blow out, the presta valve was gone so I had no idea what was going on. The second leak occured during installation. I took off the wheel, put in a new presta valve tube and it started leaking immediately. The third
install I rode for a couple days and then flat .... leaking presta valve. Those were xlm thornproof tubes from Random Bike Parts.

Thinking of going to a mid motor instead of front or rear hub motors.
Last edited by jcool3 on Sep 03 2019 9:47pm, edited 1 time in total.

markz   100 GW

100 GW
Posts: 7769
Joined: Jan 09 2014 11:38pm
Location: Alberta Canada

Re: Issues with front hub motor on aluminum shocks.

Post by markz » Sep 02 2019 10:03pm

Justin rode across Canada with a front 500W hub.
https://youtu.be/oCvo6ffWRdE?t=272https ... WRdE?t=272

User avatar
wturber   10 MW

10 MW
Posts: 2111
Joined: Aug 23 2017 8:52pm
Location: Fountain Hills,AZ
Contact:

Re: Issues with front hub motor on aluminum shocks.

Post by wturber » Sep 02 2019 11:49pm

markz wrote:
Sep 02 2019 10:03pm
Justin rode across Canada with a front 500W hub.
https://youtu.be/oCvo6ffWRdE?t=272https ... WRdE?t=272
... and a non-suspension steel front fork. :^)
"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

User avatar
amberwolf   100 GW

100 GW
Posts: 28295
Joined: Aug 17 2009 6:43am
Location: Phoenix, AZ, USA, Earth, Sol, Local Bubble, Orion Arm, Milky Way, Local Group
Contact:

Re: Issues with front hub motor on aluminum shocks.

Post by amberwolf » Sep 03 2019 12:26am

jcool3 wrote:
Sep 02 2019 2:13pm
the presta valves were leaking at the base
Failure at the base of the stem usually means the pressure was too low, so the tube and tire was able to move around the rim, which tears the stem at the join with the tube.

You don't see the movement in a presta tube (cuz it's fixed to the rim by the nut), but you can easily see it in a typical schrader tube (the stem looks tilted in the valve hole).

User avatar
wturber   10 MW

10 MW
Posts: 2111
Joined: Aug 23 2017 8:52pm
Location: Fountain Hills,AZ
Contact:

Re: Issues with front hub motor on aluminum shocks.

Post by wturber » Sep 03 2019 1:41am

amberwolf wrote:
Sep 03 2019 12:26am
jcool3 wrote:
Sep 02 2019 2:13pm
the presta valves were leaking at the base
Failure at the base of the stem usually means the pressure was too low, so the tube and tire was able to move around the rim, which tears the stem at the join with the tube.

You don't see the movement in a presta tube (cuz it's fixed to the rim by the nut), but you can easily see it in a typical schrader tube (the stem looks tilted in the valve hole).
That's possibly what happened. I drilled the rim out and am now running Schrader on the front. It was dumb that I had presta on the front and Schrader on the back to begin with. Really dumb actually.
"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

User avatar
amberwolf   100 GW

100 GW
Posts: 28295
Joined: Aug 17 2009 6:43am
Location: Phoenix, AZ, USA, Earth, Sol, Local Bubble, Orion Arm, Milky Way, Local Group
Contact:

Re: Issues with front hub motor on aluminum shocks.

Post by amberwolf » Sep 03 2019 1:50am

Nothing really dumb about using two different types, though it means having to carry two kinds of spare tube (unless you carry two presta, or two schrader and a drill ;) ).



I haven't used presta in...forever (other than what came on that Trek), but I've had this happen with schrader valves numerous times, both in powered (from acceleration and braking) and unpowered wheels (from braking, mostly, sometimes on rear wheels hauling heavy loads, mostly back in pedal-only days).

So lots of observations to draw conclusions from, unfortunately. :(

User avatar
wturber   10 MW

10 MW
Posts: 2111
Joined: Aug 23 2017 8:52pm
Location: Fountain Hills,AZ
Contact:

Re: Issues with front hub motor on aluminum shocks.

Post by wturber » Sep 03 2019 11:50am

Yes, but I only had a spare Schrader tube. That was actually the dumb part.
"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

jcool3   100 mW

100 mW
Posts: 38
Joined: Jun 18 2017 12:15pm
Location: san francisco

Re: Issues with front hub motor on aluminum shocks.

Post by jcool3 » Sep 03 2019 9:52pm

wturber wrote:
Sep 02 2019 7:08pm
jcool3 wrote:
Sep 02 2019 2:13pm

Unfortunately I went thru an episode with 3 flats within a week on my rear hub motor wheel. Finally figuring out that the xlm thorn resistant tubes were defective .... the presta valves were leaking at the base which was impossible to fix.
Yup. My most recent flat was a presta valve base failure. But that was on the front wheel. I'm at about 3500 miles without a flat on the rear now. I've had no rear flats since I went with the "tire inside a tire" scheme.
what size tire do you have inside and out?

User avatar
wturber   10 MW

10 MW
Posts: 2111
Joined: Aug 23 2017 8:52pm
Location: Fountain Hills,AZ
Contact:

Re: Issues with front hub motor on aluminum shocks.

Post by wturber » Sep 06 2019 12:43am

jcool3 wrote:
Sep 03 2019 9:52pm

what size tire do you have inside and out?
Outside is a 26X 2.0 Bontrager. Inside is the tire that came with the ebike kit wheel. I'm not sure of the size. I think it was 1.95 or 1.85. Here's a couple of pictures of what I stuff into the Bontrager. The combo is a thicker than normal tube, an anti-flat tire liner,
and the old tire with the sidewalls cut off. I use rubber cement to glue the anti-flat liner to the tube. I just use one thin coat which is just enough to keep the liner in place as I stuff the three piece sandwich into the tire. The rubber cement is flexible enough to give and let everything expand as needed when the tube is inflated.

Image
Image
"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

Post Reply