Has anyone ever blown a IGH hub?

Discussions related to motors other than hub motors.
This includes R/C motors, botttom bracket, roller and geared drives.
Post Reply
nukezero   10 kW

10 kW
Posts: 556
Joined: Jul 02 2013 5:00pm
Location: Los Angeles, CA

Has anyone ever blown a IGH hub?

Post by nukezero » Sep 23 2015 10:42pm

I was just wondering if anyone ever blown a IGH hub (shimano nexus or similar) by applying too much power?

1. if so, what are the symptoms, and over a course of how long, distance? etc.
2. when blown, can they be rebuilt?


just curious

User avatar
amberwolf   100 GW

100 GW
Posts: 27386
Joined: Aug 17 2009 6:43am
Location: Phoenix, AZ, USA, Earth, Sol, Local Bubble, Orion Arm, Milky Way, Local Group
Contact:

Re: Has anyone ever blown a IGH hub?

Post by amberwolf » Sep 24 2015 4:08pm

There's a thread (or post) showing a blown 3-speed Sturmey Archer hub, a few years back, and discusses rebuild though don't remmeber if they actually did or just replaced it. Conclusion was gear lash and shock to gear tooth roots was cause of failure.

nukezero   10 kW

10 kW
Posts: 556
Joined: Jul 02 2013 5:00pm
Location: Los Angeles, CA

Re: Has anyone ever blown a IGH hub?

Post by nukezero » Sep 24 2015 4:55pm

amberwolf wrote:There's a thread (or post) showing a blown 3-speed Sturmey Archer hub, a few years back, and discusses rebuild though don't remmeber if they actually did or just replaced it. Conclusion was gear lash and shock to gear tooth roots was cause of failure.
Last night, I forgot the source, but I thought I read somewhere that the nexus has a built-in safety to prevent over-torque and will do something in the event too much torque is applied. ??

User avatar
amberwolf   100 GW

100 GW
Posts: 27386
Joined: Aug 17 2009 6:43am
Location: Phoenix, AZ, USA, Earth, Sol, Local Bubble, Orion Arm, Milky Way, Local Group
Contact:

Re: Has anyone ever blown a IGH hub?

Post by amberwolf » Sep 24 2015 7:44pm

I dunno...I have a feeling that usually the issue isn't too much torque, exactly, but too sudden an application of the torque, without first taking up any lash in the gears.

User avatar
spinningmagnets   100 GW

100 GW
Posts: 11195
Joined: Dec 21 2007 10:27pm
Location: Ft Riley, NE Kansas

Re: Has anyone ever blown a IGH hub?

Post by spinningmagnets » Sep 24 2015 7:48pm

The $1500 Rohloff has a "shear pin" that is designed to break before the teeth in the gears. I think its about $60 to get the pin replaced by a factory authorised tech.

A lot of IGH's have been broken around here, I think the N171 is supposed to be pretty stout. Since it uses friction-balls, I assumed it would slip instead of break. https://hubstripping.wordpress.com/atc-nuvinci/

User avatar
Chalo   100 GW

100 GW
Posts: 7961
Joined: Apr 29 2009 11:29pm
Location: Austin, Texas

Re: Has anyone ever blown a IGH hub?

Post by Chalo » Sep 25 2015 1:14am

nukezero wrote:I was just wondering if anyone ever blown a IGH hub (shimano nexus or similar) by applying too much power?
I've screwed up two correctly adjusted and maintained Sachs Spectro 7 hubs by pedal power alone. I used that model because it was considered generally stronger than Shimano Nexus 7.

As far as symptoms, there are three that tend to indicate total failure:

1) nasty noises, often followed by

2) freewheeling in both directions and/or

3) pedal lockup

Most gearhubs aren't even rated for tandem use, so using motor assist through the gears is asking for trouble. As far as I know, the Rohloff is rated for 2500W gross power, the NuVinci N171 is rated for 5000W, and the NuVinci N360 is rated for 2000W. All the others are rated for one person's leg power, as long as the one person doesn't exceed their weight limit.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

nukezero   10 kW

10 kW
Posts: 556
Joined: Jul 02 2013 5:00pm
Location: Los Angeles, CA

Re: Has anyone ever blown a IGH hub?

Post by nukezero » Sep 25 2015 1:25am

Chalo wrote:
nukezero wrote:I was just wondering if anyone ever blown a IGH hub (shimano nexus or similar) by applying too much power?
I've screwed up two correctly adjusted and maintained Sachs Spectro 7 hubs by pedal power alone. I used that model because it was considered generally stronger than Shimano Nexus 7.

As far as symptoms, there are three that tend to indicate total failure:

1) nasty noises, often followed by

2) freewheeling in both directions and/or

3) pedal lockup

Most gearhubs aren't even rated for tandem use, so using motor assist through the gears is asking for trouble. As far as I know, the Rohloff is rated for 2500W gross power, the NuVinci N171 is rated for 5000W, and the NuVinci N360 is rated for 2000W. All the others are rated for one person's leg power, as long as the one person doesn't exceed their weight limit.
So I would suppose applying 750W or (500w reduced) mid-drive to a Nexus 8spd is probably going to blow it up sooner or later?

I am searching for threads on the internet to find people who've blown up the 8spd nexus and can't seem to find any. I did see people screw up their Nuvinci though.

Warren   100 kW

100 kW
Posts: 1324
Joined: Oct 05 2010 11:35am

Re: Has anyone ever blown a IGH hub?

Post by Warren » Sep 25 2015 8:23am

My personal experience as a bike mechanic, and everything I have read, aligns with what Chalo said.

I am a huge fan of derailleur systems. I really wish Shimano or SRAM would make a heavy duty, 4 speed rear derailleur system for 1000-2000 watt mid-drives...14-42, 4 speed, industrial grade, 1/8" wide sprockets and chain.

User avatar
Chalo   100 GW

100 GW
Posts: 7961
Joined: Apr 29 2009 11:29pm
Location: Austin, Texas

Re: Has anyone ever blown a IGH hub?

Post by Chalo » Sep 25 2015 9:10am

nukezero wrote:So I would suppose applying 750W or (500w reduced) mid-drive to a Nexus 8spd is probably going to blow it up sooner or later?
If that's the only source of power, then I doubt it would have to break things. A healthy person can put out more than that much power for a short time, and pedal power comes in pulses, with higher torque peaks to sustain a given average.

There are two factors that will cause a gearhub to break when used with a motor. The first is stacking motor power with leg power, thus exceeding maximum design forces. The second is instantaneous, insensitive delivery of motor power, which some motor systems manage to avoid by means of gradual onset.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

Triketech   1 kW

1 kW
Posts: 332
Joined: Mar 31 2015 6:50pm

Re: Has anyone ever blown a IGH hub?

Post by Triketech » Sep 25 2015 9:24am

spinningmagnets wrote:Since it uses friction-balls, I assumed it would slip instead of break. https://hubstripping.wordpress.com/atc-nuvinci/
I shared that assumption as well. After 4000 miles of pedal power only but geared much lower then recommended (26T granny, 22T N360) the were two issues that came up. First was the freewheel pawls failed. Second was just enough torque induced distortion that allowed seals to leak the semi-fluid over about 1000 miles.

I shipped the wheel back to Fallbrook Technologies, and informed them of my out of spec gearing. They didn't care, rebuilt my wheel for free and return shipped at their cost.

Acceptable torque limit on the N360 is about 1000 inch-lbs.

Currently using SRAM Dual Drive DD3 pedal only with a 26T Granny & 36-11 cassette, no power. The anti-rotation washers on the DD3 have slipped a bit internally which wallowed out the flats on the soft washers. I doubled the toothed washers and haven't had issues since then. Will later install a BBS02 I have to test. Rob Camp has been using a DD3 with a BBS02 (500 watt) for several months now, no problems so far (ICE Trike). Myrtle the Turtle used a DD2 for about 7000 miles with a 750 watt Mid Drive when it failed (HPV FS20).

Alfine 11's tend to fail regularly among aggressive Mtn Bikers who usually gear them too low, and appears to have a higher failure frequency then the Nexus 8.

Rohloff is about as stout and lightweight as it gets. What annoys me about Rohloff is some of dyno comparisons of the Rohloff were run with the lubricant replaced with a low fill of WD40 to reduce pumping losses to give better numbers then it really has.

nukezero   10 kW

10 kW
Posts: 556
Joined: Jul 02 2013 5:00pm
Location: Los Angeles, CA

Re: Has anyone ever blown a IGH hub?

Post by nukezero » Sep 25 2015 1:56pm

Ok, correct me if I'm wrong. If the Bafang BBS-02 applies 120nm of maximum torque, that is 88 ft-lbs.

I am currently 160lbs, and if I stand up and jump down on my pedal, I'm technically applying 160-ft-lbs of at that moment of down-stroke instantly. The subsequent stroke will be less of course.

So by technical logic, it seems the IGH is well within it's limits to handle the 88 ft-lb torque?

User avatar
Chalo   100 GW

100 GW
Posts: 7961
Joined: Apr 29 2009 11:29pm
Location: Austin, Texas

Re: Has anyone ever blown a IGH hub?

Post by Chalo » Sep 25 2015 5:33pm

nukezero wrote:Ok, correct me if I'm wrong. If the Bafang BBS-02 applies 120nm of maximum torque, that is 88 ft-lbs.

I am currently 160lbs, and if I stand up and jump down on my pedal, I'm technically applying 160-ft-lbs of at that moment of down-stroke instantly.
That's true only if you're using a crank a foot long, which isn't likely. Most cranks are less than seven inches long. So that's like 90 lbs-ft at the crank, but it could be more or a lot less at the wheel, depending on the gear being used.

However much torque you get from crank and motor drive, if you feed the motor's power through the gears, it adds to whatever you do with the pedals.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

bobc   10 kW

10 kW
Posts: 993
Joined: Jan 20 2011 5:08pm
Location: Knutsford England
Contact:

Re: Has anyone ever blown a IGH hub?

Post by bobc » Oct 06 2015 2:58pm

FYI we raced for many years in the greenpower electric car races using the nexus 7 and nexus 8 IGHs. Our power max was about a kilowatt but we were doing 35mph with 26 or 20inch wheels so torque was not so high. We found that the 8spd boxes lapped this up, no failures in thousands of miles. The 7 speeds, we actually broke 2 (before moving lock stock and barrel to the 8speeds)
The 7 speeds had another little peccadillo, when spinning VERY fast gears 6 and 7 just no longer exist (you stay in 5th). This is due to centrifugal action on some internal ratchet pawls. IIRC about 1000rpm are needed to do this, unlikely in a bike wheel
Bob

slowhands   100 W

100 W
Posts: 127
Joined: Aug 12 2015 1:53pm
Location: San Jose, CA

Re: Has anyone ever blown a IGH hub?

Post by slowhands » Oct 06 2015 7:07pm

Here is a NuVinci locking up under hard use, 2:35 into the video:
https://www.youtube.com/watch?v=5AMAXM5W2OU

Despite this failure, the NuVinci seems ideal for a mid drive, no worry about gear shift sensing. Smooooth.....

crazyebot   1 mW

1 mW
Posts: 17
Joined: Feb 15 2018 11:37pm

Re: Has anyone ever blown a IGH hub?

Post by crazyebot » Feb 20 2018 1:03am

I command thee thread - riiiiise!

I'm running a secondhand Cruzbike quest 451 with a Tongsheng 500w mid-drive.

Bike has 20" wheels and a SRAM Dual drive 2, that appears have a textured washer where I'd expect something with a lug. The wheels where rebuilt before the bike came my way, so I'm wondering if something got lost along the line.

Sourcing a replacement is proving... Problematic. I'm investigating my options. Does anyone think I'm going to strip my dropouts via a 40km daily commute before I find a solution? Asked another way, if I don't cycle like I'm trying to outrace the semi-trailer from that early Spielberg film, can I get away with not having a lug anti-rotation washer on one side of the wheel for a couple of weeks?

User avatar
amberwolf   100 GW

100 GW
Posts: 27386
Joined: Aug 17 2009 6:43am
Location: Phoenix, AZ, USA, Earth, Sol, Local Bubble, Orion Arm, Milky Way, Local Group
Contact:

Re: Has anyone ever blown a IGH hub?

Post by amberwolf » Feb 20 2018 1:25am

I guess it depends on how tight things are in the dropouts, and how strong the dropouts are at the flats of the IGH axle width, and how much torque is being applied to taht spot.


I have an old IGH (Shimano 333? or was it an old SA?) in the frame of SB Cruiser for the pedal drivetrain (can't be in the wheel cuz it's a hubmotor), and I don't think I have all the antirotation hardware; at first I didnt' have any and it just spun in the dropouts when trying to pedal. :lol:

(after I fixed that I sheared the bolts securing a drive sprocket to teh spoke flange, and went with welding the sprocket on instead--not an option for the axle stuff).

The hardware I have there now works, but it's not much surface area against the dropouts; I'd love to have more to ensure it can't spin, cuz the only time I *need* this to work is if the motors don't work. ;) Then pedalling at 1-2MPH (but high torque) is my only way home.

User avatar
Chalo   100 GW

100 GW
Posts: 7961
Joined: Apr 29 2009 11:29pm
Location: Austin, Texas

Re: Has anyone ever blown a IGH hub?

Post by Chalo » Feb 20 2018 2:05am

crazyebot wrote:
Feb 20 2018 1:03am
Bike has 20" wheels and a SRAM Dual drive 2, that appears have a textured washer where I'd expect something with a lug. The wheels where rebuilt before the bike came my way, so I'm wondering if something got lost along the line.
I think the Dual Drive came with serrated washers, but you can grab up some of the keyed washers that were used with T3, P5, and S7 hubs. SRAM seems to have exterminated the proud line of gearhubs they bought from Sachs, but there are still some parts around. Brompton folding bikes in particular represent both a large installed base of SRAM gearhubs and a group of zealous owners who demand parts support.

Image
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

crazyebot   1 mW

1 mW
Posts: 17
Joined: Feb 15 2018 11:37pm

Re: Has anyone ever blown a IGH hub?

Post by crazyebot » Feb 21 2018 12:05am

Thanks Amber and Chalo. : )

The Australian Distributor for SRAM (Monza Imports) hasn't replied to my enquiry for parts. I'll investigate Brompton.

A knowledgeable local guy also suggested I consider some Sturmey-Archer parts, specifically HMW494 or HMW155:
https://www.sheldonbrown.com/sturmey-ar ... tionwasher

... Which are also parts that don't appear to be readily available here in Perth. Thanks again for the lead, Chalo.

User avatar
Chalo   100 GW

100 GW
Posts: 7961
Joined: Apr 29 2009 11:29pm
Location: Austin, Texas

Re: Has anyone ever blown a IGH hub?

Post by Chalo » Feb 21 2018 12:41am

Take heed about Sturmey Archer parts: Sturmey gearhub axles are not the same size as Sachs/SRAM gearhub axles. As in 13/32"x 26tpi versus M10.5x1.0. (Unless it's M10.5x26tpi, which is dumb but not out of the question.) Anyway, the holes in the keyed washers might fit just peachy, or might not. I guess it's a cheap experiment to make.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

User avatar
Papa   1 kW

1 kW
Posts: 392
Joined: May 13 2008 1:06am
Location: NW

Re: Has anyone ever blown a IGH hub?

Post by Papa » Feb 21 2018 1:29am

crazyebot wrote:
Feb 20 2018 1:03am
Sourcing a replacement is proving... Problematic.
Contact Aaron's for replacement IGH parts:

http://www.rideyourbike.com/internalgears.shtml

Email: aaron@rideyourbike.com
~ Recycle... Ride your bike again ~

crazyebot   1 mW

1 mW
Posts: 17
Joined: Feb 15 2018 11:37pm

Re: Has anyone ever blown a IGH hub?

Post by crazyebot » Feb 21 2018 1:55am

Doh. I've just ordered some 155's and 494s via Ebay. It's the thought that counts though - thanks Papa.

User avatar
Chalo   100 GW

100 GW
Posts: 7961
Joined: Apr 29 2009 11:29pm
Location: Austin, Texas

Re: Has anyone ever blown a IGH hub?

Post by Chalo » Feb 21 2018 2:26am

Papa wrote:
Feb 21 2018 1:29am
crazyebot wrote:
Feb 20 2018 1:03am
Sourcing a replacement is proving... Problematic.
Contact Aaron's for replacement IGH parts:

http://www.rideyourbike.com/internalgears.shtml

Email: aaron@rideyourbike.com
Aaron Goss is a close friend of mine. He and I were in the same bicycle club in Seattle. We've taught each other a lot of things.

And yes, he's tops for maintaining a stock of gearhub parts. I got my supply of Sachs Torpedo 3 sliding keys from him. Just try to find them elsewhere.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

Post Reply