Causes/prevention of Go SwissDrive torque sensor failure?

bombadero

Member
If anyone has any engineering insight into this, it would be greatly appreciated. I recently had the torque sensor fail on my GSD motor. Since GSD is out of business and my warranty runs out in a month, if it happens again I'll be on the hook for $1,400 for a replacement from HP Velotechnik, as this is for a Scorpion FS20. I'm wondering what might cause torque sensor failure and if there are any riding habits that might prevent it from happening.
 

JRA

Well-Known Member
There are many GSD systems out on Specialized Turbo S bikes, 500 on the Google campus alone, so perhaps focus your research on that brand?

Torque sensors are basically just a strain gauge and they are a pretty simple component. It may be that the controller and how it interprets the signal from it is at fault. Internal controllers like the GSD and other proprietary system hubs use have been known to fail but hard to diagnose easily without hub disassembly.
 

JRA

Well-Known Member
@JRA thanks, I've got a bit of an update about this that I posted on the general "GSD is gone" thread.
I saw that, glad you got the warranty. I would think it worth peeling back the onion on the one you have though and see if it can't be resuscitated. At least figuring out the problem would perhaps help prevent it happening again and maybe even be fixable.
 

bombadero

Member
Unfortunately, it had to be shipped back as part of the warranty replacement. I think they will probably diagnose it, refurbish it, and re-sell it to one of their many corporate clients in Europe that maintain fleets of e-bikes with Go SwissDrive units. Although they are dead officially as of the end of this year, under EU laws they have to continue providing service and replacement parts for 5 years after that.
 
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bombadero

Member
So the saga continues. I got the warranty replacement, and had an adventure with my car, a 2001 TDI Beetle on the way. I lost all of my oil on the trip to Alameda, which is an island, and the expense of towing back to San Francisco would have been quite high, so I had to leave the car behind to get repaired in Alameda. The oil supply line for the turbo failed. Apparently it had never been replaced, even though we had the turbo replaced not long ago. Fortunately my usual mechanic warranties their own work 3 years/36k miles, so they are going to reimburse me for it.

Then, when I got home, I munged the job of putting the wheel on. I had replaced the stock Schwalbe Marathon Plus tire with the Schwalbe Marathon GT 365 I like to run, thrown a disc rotor on to temporarily plug the rotor holes from moisture until I can get plastic caps to do the job, and installed a new cassette. I was torquing the drive side axle and sheared the axle right off. Talking to my mechanic, I guess it's better to tighten the non-drive side first, which has the torque arm, because the extra wiggle can introduce extra torsion into the axle and shear it.

So now my options are $750/7 weeks to round trip it to and from Germany again for repair, or $1,000/1 week for another new wheel at retail cost. Doh!