Pedalcell Cadence X: high power rim generator with USB power outputs


Old introduction

I should be getting one soon (Feb. 2020? [ As of 2020-6-7 still delayed due to what's going on and I gather they are sending out samples first to people who already wanted to buy one which is logical ]) to review. I will link here to the site and I will add some thoughts about this dynamo later.


On their website you will find lots of information on the blog such as some of their own tests

Thoughts about rim dynamos and USB-only power output

I am interested in this probably with a different view than most people, not to use it as say a charger for phone + USB chargeable bike lights, but as an additional system to a dynamo hub, mainly to charge anything you may want to charge to stay self-sufficient on long tours, i.e. to charge a phone (navigation), tablet, electric shaver, powerbank. I consider a dynamo hub as an essential part of the bike and the cost is not that big of an issue if you take a SP series 8 or just about any from Shimano and build your own wheels.

Rim and sidewall dynamos give off quite a bit of noise usually, so for me that could be an issue in using such a dynamo on rides, esp. night time rides when there is less ambient noise. So my plan of how to use this Pedalcell dynamo is that if there is noticeable noise, to use a rim generator additionally during the day to charge up devices on tours, and at night use the lighting of a gearless dynamo hub. It will be interesting to see how much noise it actually makes in use...

Warranty and repairs, price point

I talked to the guys from pedalcell long ago to discuss various issues such as noise, efficiency, price point, and about price my point was that the price has to be such that is has to be palatable in one go. The price point of ca. $250 is fine for that (contrary to the other new USB power solution by Spinup, the F12W-pro, which is priced at $500, too much I think, however, Sunup/Spinup offered to send me one for testing and I will do that, that will be interesting also to compare to the Pedalcell).

Then to warranty, they originally envisioned 90 days [ which is a period I know is typical for various products in the USA but this duration is never seen in the EU. 1 year was the common duration in NL and Germany many years ago, but which changed (I think EU wide) to 2 years ] and you could buy an additional warranty for longer period. This was curious to me as in NL warranties were always 1 year minimum with implicit life-time duration warranty. E.g. if your washing machine breaks down within the warranty you pay nothing, if e.g. it breaks down after 4 years with a life expectancy of 8 years (I think it's around that duration), then you only need to pay half the repair cost (as you used up half the expected life of the device). I discussed this topic with them, and what they told me was interesting as it showed a different way to look at the issue of costs involved in warranties. In the end they decided, after more testing to better determine long term reliability, that they could offer 2 years at the original price. Nice :)

I still wonder about repairs, what sort of things could go wrong, what would repair prices be?


Mass is about 500g for the preproduction version with fixed cable to the USB box. Power output is up to 5V at 2.4A for output 1, and 5V 0.6A for output 2.

Experiences from 2020-9-17

I got a preliminary version on 2020-9-17. This has a 3D printed housing and the electronics may be fine-tuned for the final version. [ And they have been changed to provide more power ]

The dynamo has a lock that keeps the dynamo locked so that it won't accidentally engage, however, I don't like the way it's done with a knob, that must be turned a bit to make sure it fits again when trying to lock it. I will describe it later in more detail. The standard system as used on sidewall dynamos is just fine: Unlock to run on the rim by pressing a lever, locking could happen but is very unlikely and not a problem (I've never had this happen), accidental unlocking in which case the dynamo suddenly starts running on the rim or tyre while riding is extremely unlikely, almost impossible (I've never experienced it).

I couldn't fit it on the rear fork of my test bike as the Magura HS33 brakes are very clearly in the way on one side, and the frame lock also very clearly in the way on the other side, so I can't fit it on both the left- and right hand sides of the rear stay of the bike.

On the front fork I couldn't fit it on the right hand side due to the Magura rim brakes, and on the left hand side I needed to loosen one of the fender stays. To properly mount it I'd need new fender stays and bend them around the dynamo. However, a bigger problem is that the dynamo doesn't reach high enough, I can't get the rubber-like ring to run on the rim, due to the HS33 brakes, even though they are less in the way than on the other side. The mounting bracket is hindered in this position with the dynamo on the opposite side of the fork leg, such that I can't get the dynamo placed high enough.

It looks as if I need to modify the mount by removing some material from the top from the mount and from the 2 contact points with the fork, but I'm not sure that even with that modification that I can mount it properly then.

More to come

2020-9-18: Day 2 I ended up mounting it on the horizontal rear stay (non-drive side). This position or the seat stay are for me the preferred position for rim or sidewall dynamos, but the cable length of the USB box and its size meant that the horizontal stay is suboptimal in visibility of the output (for the USB power meter), I had to position it as far forward as possible and on the right side of the top tube so my legs wouldn't touch or hit it.

Power: To come. I tested with charging the Samsung S5. I discussed the results with Pedallcell and the electronics will be changed to fix the problems/undesireable effects that I noticed [ related to renegotiation, but also voltage drop ].

Noise, vibrations: walking with he bike I feel vibrations in the saddle, but in use at speeds of say 15 km/h I notice very little. Noise is not annoying, lower in frequency and in loudness than other sidewall or rim dynamos that I've used. Far better than sidewall dynamos and than the Velogical rim dynamo.

2020-9-19: Day 3 I tested charging the Xperia XZ and a ML-102 powerbank with 18650, and both also have issues in the USB output not supplying the power that the dynamo can supply, to the USB devices. I don't think giving the exact results is very useful (not coming close to the spec for the high power output port, about 1.1A max), as the USB box will be changed with esp. a different USB IC and some different programming to fix the issues such as for power renegotiation (slowing down on my devices power will drop but not to USB 2 (5V 0.5A) level, but that seems to happen with some devices so then a renegotiation by disconnecting/connecting is in order, but there are other options to handle that than simply always renegotiate). I should get a final sample later and test that for how well it works and give the results then.

The mounting bracket is a problem in that mounting on the rear wheel I need to mount the USB box on the top tube to also read the USB power meter's output and that hinders a bit. It is also where for several reasons I put the bike computer, a Cateye Commuter (I commented in a video about the backlight not working and there are some reliability issues, but it's not dead yet. I will replace it with a wired one in the near future, possibly Cateye Velo 7), also there, close to the USB box. The USB box interferes with the signal from the speed sensor... For the rear bracket pedallcell will make a fix so the dynamo can be mounted higher on bikes such as mine with HS33 brakes. I should get that soon, then I will do some tests with both USB power outputs even though the high power output doesn't yet produce full power.

I suggested to pedalcell to make the USB box with inputs and outputs on the same side, so you could e.g. mount the box hanging down on the seatpost underneath the saddle and get to the USB outputs and the input cable not needing to go into a loop, but perhaps with the final version, which will have a thinner and more supple cable, that won't be an issue. I think for the front too it would be useful to hang the box upside down so that there is no ingress of rainwater.

Experiences with an iphone

I got an iphone SE on loan and charge speed was below expectations (ca. 0.70A) but all of that should be fixed with the final version. I didn't add the information of charge speed to this page earlier as I felt it was not so important due to the improved final version coming out soon, I will add more details soon, and update once I get the final version.

2022-4-17: A commenter on youtube asked me about the sideways pressure on the wheel by this rim dynamo.

He stated:

I was referring to the pressure the pedal cell puts on the rim. I went to a bike shop recently and an employee did not recommend these types of dynamos. The employee said that wheels were not purposely built for lateral pressure like that...he recommended hub dynamos.

To which I replied:

Don't worry about this pressure it is tiny. Much smaller than forces that are required when turning the bicycle, when going through corners at an angle or even going through corners slowly upright, the forces on the front wheel required to overcome the friction of the tyre to steer the bike are much greater (and exactly the same in direction) than these forces of any rim dynamos, and on the rear wheel you have similar sideways forces from the bike going through corners at an angle. Example: When using panniers on a front rack on a touring bike, the wheels are loaded so much that steering mean the whole wheel deforms while turning. This means that the resistance to overcome to go through a corner rather than to go straight, was so big that the spokes are bending. I noticed this myself on a tour because with these panniers (ca. 10-15 kg load) the front tyre was touching the fender while turning, which it didn't do normally. But have you ever heard a bike shop argue that front panniers are bad because the wheels are not designed to deal with such loads? Or that you should not go at an angle through corners? I haven't... So this is a non-issue with such dynamos. All wheels can stand the required small sideways loads easily.

Summary so far of the prototype, but also final because they don't reply to me for 1.5 years

Conclusion, 2021-4-28 + updated 2023-3-21: CadenceX vs. the F12W pro and dynamo hubs

Addition 2022-10-1: I still haven't got my hands on the final version, nor the mounting bracket addition to use on my Cannondale Touring. I've not seen replies to emails for a while. This means the following is about assumed power output from the final version of the cadence x, which I cannot verify at the moment. So beware, until I get a final version to test, also to see about whether or not it slips in the rain with a high power output.

Addition 2023-3-21: No response to any emails since 1.5 years means I won't recommend this dynamo.

After having used the CadenceX and the F12W-pro for quite a while, and taking the figures of higher power output of the final version of the CadenceX compared to the pre-production version into account, the following points are the essence of the differences:

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