TLDR – The Enviolo hub in my Cube Cargo bike failed. The hub was slipping in low hears, on a bike trip up some steep hills. Took it to the shop and it was a simple fix – a loose control cable.
My Cube Cargo bike does not have a standard sprocket cassette and derailer on the rear wheel to change gears. Instead, the rear wheel hub is an Enviolo Continuously variable planetary transmission all of the gear changes are internal to the hub. The Failure happened under Maximum load with three girls upfront in the lowest gear on a 30-40 degree inclined hill; Read, much big steep hill. About halfway up the hill, we stopped for the girls to get out and follow on foot up the hill, pedaling up the hill did not feel right to me; figured it had to do with not feeling 100%. At the top of the hill, the girls got back in and we carried on until the next hill when the Enviolo hub was slipping continuously in low gear. It felt like a sprocket with rounded teeth allowing the chain to slip. The Girls got out again and I tried to ride up the hill without success. – The hub was in complete failure mode in low gear unable to transfer any torque to the wheel.
The hub is sealed, without special tools, there is not much I can do here to look at it. Sadly due to the failure, we had to call the trip and head home. Riding back home the overdrive gear, the one with the gear ratio less than 1:1, was not slipping at all. The slipping appeared to be limited to the low hill climb gears which would apply maximum torque to the balls inside of the Enviolo. The Enviolo works by moving a traveler inside of the hub side to side tilting balls changing the area of the ball resting on the input disc and the output disc. – See diagram below. – The tilted ball will have a different diameter at a different angle creating a different gear ratio between the input and output discs.- Youtube video by Manufacturer for more
Dropping the Bike off
The next day after the failure we loaded my other Ebike into the cargo bike and Maddex and I set off to Cycle SuperStore to drop off the Cargo bike for repairs. We stopped by Marley park on the way. Maddex and I had about 30 minutes to play in the playground without any other people – Brilliant! We dropped the bike off without issue. The repair tech said he would contact Cube to ask what to do with the hub, as he was not familiar with this brand. He knew the Shimano hubs. When I looked up the issue before calling the shop I found little information online. Most failures of this kind described at all resulted in a warrantied hub – My expectation was a few weeks without a bike while we waited for a warranty replacement.
Upon arrival at the bike shop, we pushed the bikes into the shop to drop the cargo bike off. Before heading home we unloaded the other e-bike, put both wheels back on, and rode to a subway for lunch. WOW the old bike feels so strange, Like the middle of the bike is missing; the front wheel is so close to me. It’s like I am in some odd short clown car or something – So odd. My body hates how this feels for about the first 20 minutes of the ride. Maddex and I had lunch in the Laffy taffy park as the kids call it, Bellgrade park is what normal people call it. My phone battery was running low on the ride home. I turned my phone off and let Maddex perform all of the navigation – we made home without issue.
One Day later – All Fixed
Marc at Cycle SuperStore emailed me to let me know the cargo bike is fixed already. He explains the cables which control the Enviolo were loose causing the issue. They tightened the cables and there is no longer any slipage. I’m skeptical this fixes the issue, but defer to the experts. My response to Marc is below where I try to logic out how the cable could cause the issue
Loose cable was it? That caused the hub to skip/hold no torque in the hill climb gears? Ridding up a hill in the hill climb gears there was no torque at all applied to the rear wheel. – I guess if there is no tension on the idler in the hub due to loose cable the idler could move side to side changing the ball geometry causing a loss of traction. Along that same logic, the overdrive gear ratio would not apply enough toque, and have enough contact to matter.
Seems WAY too simple – it felt like there was something broken in the hub ridding – but the logic seems to work. Maybe the odd feeling was the idler moving a bit. Thanks for fixing it !! I’ll be by monday to pick it up.
Loose cable as the solution sounds brilliant to me if it works. The fix was covered as part of the included in the price of the bike 6-week checkup which they also performed while the bike was in the shop. As part of the checkup the Bosch drive software was updated – Hope that does not turn into a mess with another 90 minutes ridding in circles.
A few more days later – Picking up the bike
A few more days later on a Monday, I rode the normal Cube E-bike to the shop to pick up the fixed Cargo bike. Being short on time I accepted the bike was fixed with little question, loaded my other bike in the Cargo bike to created Bike-ception and headed home. Shockingly, I was unable to slip the Enviolo on the ride home. Bonus shifting is smoother than it ever has been before. The Bike still has a bit of a shimmy at about 32km+ but everything else is great. The Shimmy will be the next project; I’m thinking of a race motorcycle-style stabilizer.