I’ve had the GMAC system installed now for a few months. Bike Swift and Martin did a fantastic job, a clean install, and amazing to work with after the sale.
My wife and I have a rather unique install versus most, as we are riding a Ventana full suspension mountain tandem on mostly single track trails. Our loaded weight including the bike, GMAC system, us, and our gear ranges between 400-450 pounds. There’s a tremendous amount of abuse riding a bike like this the way we do. That being said I am impressed at the performance of the GMAC system.
Two things that were a must for a system on our tandem was a hub motor and regenerative braking. The reason for the hub motor requirements was when you’re on a tandem mountain bike there’s already a tremendous amount of strain put on the drivetrain and adding a mid drive motor system would just destroy the drive train because you would have too much power going trough it. The regen was a requirement because when you’ve got that much weight it only makes sense to turn it into electricity and help keep the brakes cool by taking some of the load (and of course extending the range).
Due to the gear hub configuration of the GMAC, there is the benefit of more torque when climbing slower (which we do a lot of). We did have to tune down the regenerative braking quite a bit and learn how to best use it when on the trail so we didn’t damage the motor. Again, the only concern for damaging the motor is because of the extreme abuse the bike is being put through. If you were to use this in any other situation I feel that it would be an almost bulletproof set up and you would probably not have to tune things down much if it all.
If you like to be able to customize things this system allows the most customization that I’ve seen in a system. On the flip side, if you would rather you can just leave it alone it works great to.
We are very happy with our purchase of the GMAC system from Bike Swift and highly recommend it.
