This blog post is /actually/ a work in progress. Sign will be removed when completed.

This blog post is actually a work in progress. Sign will be removed when completed. Most recent update was mode on 8/1/2025.

Executive Summary

If you are willing to do some hacking this can be an effective e-bike alternative. I can't imagine running this device out of the box on the regular. I made it work for my short commute over the summer. I should be honest here, it made my summer commute happen so ultimately I'm happy with my purchase. But this doesn't mean it will be the right choice for you.

This review will be somewhat disjointed due to all the possible use cases, many of which I probably didn't consider. I'm also not doing a full unboxing/install overview so you may first wish to read a much more comprehensive review. I will share my mods below but a shout out to this pedal assist system which spurred my imagination.

To save you time here are some scenarios where you should just move on. This device is not for you if,

My use case

My son goes to summer camp about 1.5 miles away from our house. Every summer I've managed to commute via bike trailer. As he's gotten bigger and I've gotten older its been a bit rough on my knees. My thought was if I had something that gave me just a little boost to help out with the 60 lbs I was towing I could continue pedaling.

Elevation profile of my 1.4 mile ride to camp. At the beginning you can see a short climb with an average (max) grade of 10 % (15 %).

I was really close to going all in on upgrading a Yuba Kombi to an e-bike or maybe just outright buying the Kombi E5. But I had a few bikes sitting around and felt it could be a nice project to try out an e-bike conversion kit. (But man, I still really want a Yuba Kombi).

I thought about doing a true e-bike conversion (either mid-drive or hub) but felt it was overkill. All I needed was a bit of a boost on some hills. Even 50 Watts over a mile or two could do. Hmm, how much thrust could my leaf blower provide?

I started looking at some friction devices, but could not deal with how ugly they were. And yes, aesthetics absolutely matters to me (and to you as well, even if you won't admit it). And then I saw the QIROLL. Compact, sleek, minimalist. I was sold.

My full experience is below. I can say that I managed to successfully commute with my son to camp for all six weeks. This would not have been possible otherwise. I'll have to see what is in store for the future. I'm thinking grocery runs. And there is always next summer. That is, if my son allows me to trailer him again. At some point he will simply be too big (emotionally and physically) for that.

Full Review

I purchased a new QR-E MUTE-Plus +B60*1 133Wh Ebike Kit for $256 and $12 for shipping. The device was installed and tested on a trek 3700 with brand new Kenda Kwest 26-inch tires. The bike + kit weighed in at 40lbs. I weigh about 180 for a total weight of 220 lbs ≈ 100kg. I have to say, the motor itself is beautifully crafted. It's compact, minimalist, sleek and clean. It was really this aspect that sold me. Looks pretty cool installed on the bike. But the well thought-out design of the motor is where the engineers/designers decided to stop. It's unfortunate because with a few modifications this could have been an awesome device.

I had some buyer's remorse after my first trip around the block which starts off with a short but steep (10 % grade) hill. At low speeds you just don't get the boost you really hoped for, in particular when you are slogging up a hill. And if during your climb you drop below about 5 mph the device starts to slip and you hear the clutch repeatedly engage/disengage. While you do get some boost at these lower speeds--assuming the roller isn't slipping--you still have to work hard. It took me a while to accept the fact that I'm only getting a little help on the hills. But any help is better than no help.

At higher speeds (say >10 mph) the device really shines. There was no slipping at these speeds and the device gave you a nice push, akin to having the wind on your back. I likened it to saving a gear.

The controls as they came are really annoying. The throttle is only active when you press and hold a button. The problem is there is a quite a bit of drag when it's inactive. In practice I found myself holding the button for the entire trip aside from braking. The drag from the device when inactive isn't as noticeable at high speeds, but very noticeable when you’re approaching that 7 mph range. My guess is that most users will be holding the button down for a majority of time.

Finally I come to the perennial problem with friction drives--riding in the rain. As expected this device has zero traction in the rain. But you also need to keep in mind that slipping will occur any time the tire gets even a tad bit wet. Riding through some early morning dew or hitting a patch of wet pavement from a neighbor's sprinkler isn't a big deal as the tire will dry off quick enough. Although it can be rather annoying if this happens when you are slogging up a hill. But even the day after a rain when the ground is still damp with that slightly darker color (I'm not talking about puddling) you slip the entire time. If there are leaves on the ground, you slip. So I really don't know well this will fare in the north east fall/winter/spring where the ground is damp most of the time. I will update.

What improvements I would suggest.

My mod version 1

The controller that my QIROLL came with had two buttons (see image here). What I'll call button one (B1) activated the assist. For the friction drive to supply power it has to be moving and B1 has to be pressed. At any time that B1 is not being pressed no power is delivered. The second button (B2) has two functions. When the bike is at rest it toggles between Sport mode and ECO mode. When moving you press and hold B2 to activate the regenerative braking.

My mod moved button B2, which I always hit by accident, out of the way into part 1 in my image above. I then rewired things to have a toggle switch for the throttle, part 2 in my image. When the toggle switch is up the bike will accelerate unless you are already at a full stop. This is of course a problem when braking, so I added a cut off switch to my left hand brake (labeled 3 and 4). All of the wired connections were soldered onto a small breadboard located in the box labeled 1.

Roll-out test

At a flat location I took a few pedal strokes to get the bike rolling at 2-5 mph. At that point I stopped pedaling and let the motor take over (in sports mode). I let the bike accelerate for around 2/10ths of a mile. I did six runs (3 in each direction) for consistency. Here are the results. Plot of velocity versus time. The data points show the recorded values. The curves are a fit to a roll-out model which includes rolling resistance and aerodynamic drag. From this model the estimated power output is shown below. The largest uncertainty is the coefficient of rolling resistance. I took a broad range from 0.002 to 0.005 in order to demonstrate the sensitivity to this unknown. Plot of power versus velocity. What this tells me, and what my experience has also shown, is that you don't really see the full benefits until you reach speeds of at least 10 mph. The website claims that for the QR-E Mute I should expect 250W at 23 mph. While I didn't test it at that high of speed the trend is in the right direction, so I have no reason to doubt this claim.