Spinup F12W front wheel generator for lighting + USB output

Overview

Spinup is the new brand name of Sunup for their bicycle dynamos. The F12W-pro is a front wheel spoke mounted dynamo, quite a bit lighter than the original Sunup Eco DS, and more power output. To see more go to https://www.spinup.life/. There are some concerns or issues as I described on the Sunup Eco DS page where I briefly analysed the data presented by Sunup on the Maxidyn/R12W and F12W-pro.

At the moment I'm not planning to review this dynamo but I will give some information about it. 2020-6-7: Sunup emailed me a few days ago whether I wanted to review one. Of course that would be interesting as it's a different concept, so I will do that. I made suggestions on price/warranty some time ago, but we will see what they are going to do after my review. If you have suggestions/comments in this respect, send me a mail... Addition: They later mentioned a warranty change to in the region of 3-5 years. I will discuss this with them in more detail after my initial review.

I felt originally (ca. end of 2019) that a review would be mainly of interest to have it as a comparison to other dynamos for readers, and that as I have enough dynamos and if needed I have my own USB power converter, there is not much need for my own use and this is why I didn't intend to buy one. In the end Spinup thought it would be good to have me review it, so see that after the following section which answered some of the questions I asked them several months ago.

From the website it was quite unclear how much power the F12W and R12W dynamos could provide, there were some contradictions. So I emailed them and about the F12W I was told:

The answers are not complete but complete enough I suppose, i.e. they mean that USB power output should at normal speeds (say 15 km/h) always remain at ca. 5W even with lighting on. To get more specific data I would need to test one.

The power for lighting will be as with the Sunup Eco DS, 6V DC. Note that normally all StVZO (the requirements for Germany) dynamo lighting will work on 6V DC as well as 6V AC-dynamo, because StVZO dynamo lighting is required to run on DC too. This is implicitly stated in the technical rules TA (which are not public, which is silly but I mentioned this about the issues with rules elsewhere on my site), though since about mid 2017 along with the revised StVZO par. 67, there also came into effect (via non-published technical rules that went beyond the published TA) the possibility to have bicycle lamps approved as DC-only (pedelec/e-bike), or AC-only so compatibility may become an issue. Note that the incompatibility of the Luxos U with the Eco DS is related to the USB power output, which does not fall under the rules of TA...

For me that you don't need to build a new wheel is not much of a factor in favour of this setup compared to a dynamo hub because I build my own wheels since after the DH-3N80, and I re-use rims/spokes if a dynamo hub fails so there is not much extra cost involved, mostly new spokes if their length is different from the length of spokes that I have [ I usually buy boxes with 100 spokes so plenty of spares or to build more wheels with dynamos with the same flange diameter ].

Review in progress (since 2020-6-15)

Specifications:

Mass: 370 g for the dynamo, about 10g or so more for mounting bolts + small plates that go over the spokes, and about 120g for the USB/light power converter box

User serviceable?: For warranty do not open it up as they will have a hard time then deciding whether some issue might be caused by a product failure or the user who opened it up. In practice I think it will come to what is the problem and what to look for as you don't want to send in a product to Taiwan for a minor issue that you can fix yourself... I will open up the dynamo soon to see what it is like inside, and whether DIY fixes are feasible should there be an issue as I had long ago with the Eco DS and a dry running bearing.

Price: $500 for the dynamo + power converter. But for esp. the EU there is import duty and VAT to consider. For NL/BE/DE this adds about 19-24% (for other countries you need to search what the rates in your country are). This means for NL/BE about $620,- which is about EUR 550,-. More on this further on.

Pictures:

To come.

Impressions unpacking

It looks good, the dynamo ring is heavier going than that of the Eco DS...

Mounting

There is a paper measurement tool you can print out to make sure it fits on your bike before ordering one, of course that doesn't apply to my situation, I will just use a wheel on which it fits...

I checked whether it would fit on the Shimano XT T8000 dynamo hub and the Renak hub, just for testing both hubs at the same time, but no. The plastic tool with brass insert is clipped on the dynamo ring that's mounted on the spokes, to then centre it with the quick release. Clever solution...

I mounted it on the wrong side, as otherwise the dynamo would be held against the ends of the fender stays. It should work fine this way, going in reverse. So this way it's on the disc brake side, but at the other side of the fork from where the disc brakes are normally mounted (the bike uses rim brakes but disc brakes can be installed as the mounts are there).

2021-1-20, with update 2021-7-6: Note about mounting of the Spinup F12W-pro on the left hand side of the fork: There is a small drainage hole that will not point as much downwards as possible if you mount on the left hand side as I did. This is of course not how it is supposed to be, so consider my way to mount the dynamo as a non-optimal solution to the problem of fender stays being in the way, not a proper solution... I was aware of this but forgot to note it and Spinup asked me to mention this, and yes, that is needed!

2021-7-6: In more detail: There are 4 ways to mount it, I will add details on what the mostly minor issues are with each one:

  1. Right hand side, with the dynamo pointing towards you (on the rear of the front fork).This is how it was designed to be mounted.
  2. Right hand side, with the dynamo away from you (on the front of the front fork).
  3. Left hand side, with the dynamo pointing towards you (on the rear of the front fork). This cannot be done with disc brakes...
  4. Left hand side, with the dynamo away from you (on the front of the front fork). This cannot be done with disc brakes... This is how I mounted it. This way the rubber on the dynamo connects to the fork just as in situation 1 and it is away from the fender stays.

In use

Note that I am testing the dynamo on a Cannondale touring with headshok, and 50x559mm tyres. I will probably test it on another bike with standard steel fork and 37x622mm tyres soon to see about vibrations there.

Day 1 (2020-6-15): First ride was without lighting connected. I rode about 10 km with a trailer, at a moderate 20 km/h and the phone connected to the USB output (with a good USB cable, the quality of USB cables makes a significant difference to charge power from power banks and from USB power supplies) was not doing anything, had a charge of 64% at the start and 89% at the end. Charging started at around 6W (a bit more than 5V and about 1.16A), varying from 5.8W to 6.2W, then it went down a bit to around 5W getting back up occasionally. When the S5's battery was getting to around 80%, charge speed was going down, but the USB power increased when I switched on the screen. Clearly the S5 reduces charge speed for the LiIon battery, but takes more power if it's available to directly send to the screen. The ride was about 2.5 km within a city, with several traffic lights where I stopped. The internal battery kept charging the S5 with about 4W during those stops.

From this it's clear that phone battery anxiety related to using the phone to navigate is no longer needed, this will keep it topped up, but I will see what happens with lights on + navigation (Osmand) on + screen on, all the time, on the next 10km test ride.

The noise from the dynamo is a slight humm, a little louder than normal (not knobbly) tyres, so not annoying.

I can feel the dynamo when pushing the bike at very low speed, it's hard to describe how/what this feeling is like, but it's a bit similar I think to a product where you can feel the bearings running dry. This is not what is going on, but the mechanical situation gives a feel that makes me think of such issues in other devices. In use I didn't feel it though my first ride was with a bike trailer with lots of stuff in it.


Day 2 (2020-6-16): Test ride 12 km with lights on (Spanniga Axendo 40 + Duxo) + Samsung S5 phone connected running navigation (Osmand) + screen on all the time at maximum intensity, riding at 18 km/h on the straights, about 5 km of that is within a city: Phone start at 52%, charge power: around 6W but then varies drops to 5.66W. At the end of the ride outside the city (ca. 7.5km) the phone is at 57%. Within the city it drops a bit to 56%. On slow sections in the city the phone gets 4.45W from the battery. I noticed here that there is an issue with the phone not getting maximum power, namely charge power stays at ca. 4.45 W unless I switch off the screen then on again. In use I can actually feel some sort of vibrations, but high frequency, far higher than with dynamo hubs. It starts in my bike with headshok front suspension fork at about 16-17 km/h up to a bit more than 20 km/h. I didn't notice this last time I think because of the trailer but also I was riding mostly a little faster than 20 km/h, but perhaps it was caused by running with no lights attached and thus less power that needed to be generated by the dynamo. I will check that next time by switching the lighting on/off while riding. When dropping the speed to about 13 km/h the power output dropped to ca. 4.45W which is about what the system supplies via the internal battery. A bit faster and you get ca. 5.5W if before that you were charging at ca. 6W.

The ride back gave a strange result. The same settings on the phone, but charge started at 30% and yet while cycling through the city for about 2.5km I already charged the phone to ca. 40% and at the end of the ride (another 7.5km) the phone was at 57%. However, due to the stops, the charge speed was low and the whole ride back it was mostly low (ca. 4.45W), lower on average than on the first ride, because on certain steep sections and tight roads I was riding slowly due to my panniers being loaded with a lot of heavy stuff.

What could explain this difference? The first ride was warm in the afternoon, the 2nd ride back was in the evening and it was a bit colder, could that affect charging? Perhaps, but I think it is more likely caused by the charge status being inaccurate on the S5 (charge goes up very fast at lower charge percentage). Further, is the fact that charge speed after a slow section stays at ca. 4.2-4.4 W even if I ride a lot faster after that for a while at which point I can force faster charging by switching the screen off and on again, caused by the USB converter's electronics/settings, or by the S5? What charge power is used is something you won't realise unless you run with a USB power analyser all the time, so something you won't normally do on long tours, thus you could be charging at higher power in many situations by forcing it to go back up with the screen trick I did. I will need to test with the Xperia XZ that I have, to see what the situation is like with that phone when running navigation while being charged + display on + lighting on.


Todo:
- Check on vibrations at ca. 16-20 km/h by switching the lighting on/off while riding.
- Run the phone test with an Xperia XZ.


Day 3 (2020-6-17): I was checking the dynamo, lifting the front wheel and rotating it and noticed that I could hear a very slight rattle of the phone mount, I will try to record that in a video as it shows exactly the frequency that I feel in the handle (far higher than with dynamo hubs and lower individual jolt strength, but noticeable). This is on my Cannondale touring bike with headshok. Then a testride with light on + Osmand on on the phone + screen on maximum brightness, of ca. 8 km mostly outside any city using the Xperia XZ: Charging starts at ca. 7.5W... (so this is in addition to the ca. 3W for the lights, I will measure the exact power going to the lighting later) When speed drops too low it goes to ca. 4.5W, that is at around 13-14 km/h. When I got there after 8 km the phone's battery indication dropped from ca. 48% to ca. 47%... This is despite an average of 5.5W being supplied over the ca. 25 minute ride. It looks like the XZ is using more power than the S5, the battery certainly doesn't last long in normal use compared to the S5 but that may be to deterioration (I got it from a relative who upgraded, I use it almost exclusively for navigation). Power went back up to 7.5W or some other value (not sure what causes the variation) all higher than the 4.5W standard for the internal battery level power and I tried switching the phone's screen off/on and this helped but here the charging seems to go to higher speed after a while after a slow down on a small hill or through a tight corner. So I wonder now, how exactly does the power indication work on the USB output (done with voltages on the status wires) as the available power varies, and how does the phone react to this? I don't have an indication of this on my USB power meter so I may buy another one that has this decoded automatically on a display as fairly recent USB power meters do.

On the way back it's a similar story. I tried switching the light off and a while back later on again and it seems to have almost no effect on charge speed, except perhaps at lower speeds such as ca. 13 km/h where I get the feeling it keeps supplying the phone with a higher power than with light on. But that needs longer term investigating riding at low speeds as the internal battery is a factor that makes the investigation more tricky. What I was thinking about is this: With low output USB power supply keeping the phone connected and charged means the screen won't come on each time charging starts/stops, but if you want maximum charge speed then re-negotiation or re-indication of charge power is possibly better, so perhaps disconnecting the USB power output at stops is better so that when you start riding the output can go at 6W+ quickly (at ca. 15 km/h), instead of relying on re-negotiation of the phone. I don't know how often the phone checks for what power is available, but with the XZ too switching the phone's screen off then on again makes charging quickly get to a higher level after being stuck for a bit on 4.5W (internal battery type charge speed). Getting back home the battery dropped to about 43% with a slightly lower ride speed and slightly lower average output of the F12W.

As to vibrations: I noticed them more strongly with the light on... This may be an issue that gets solved by tightening the tie wrap, which Spinup mentioned to me before I got it, I will check this.

Conclusion with the XZ: I still need to ride with a low battery and see if charge indication is not iffy with the XZ too but really if the charge indication goes down it means more power is used than supplied through the F12W, so you can't use the XZ with screen on all the time for navigation and keep the phone charged, you need to switch off the screen from time to time. This means a not quite as comfortable 'no battery worries' ride as with the S5.

So already this is a long story, it's a complex topic!


I need to test using power banks. I will start by riding with the ML-102 which I use for travelling, and I will try some different, shorter cables (I've been using good 2m long cables which allow a high charge speed but I have some shorter cables which are better but which I generally don't use at home nor when travelling).


Todo:
- Ride with the XZ while that has a low battery, say 20-30% and see if the charge drops then too (it should)
- Do the same tests as I've done with the phone, but instead using the ML-102 which charges an 18650.
- Check whether vibrations are influenced at all by how tight the tie wrap is that keeps it pressed to the front fork.
- Make a video of the slight rattle in the phone mount, then combine all videos I made and publish it.

Day 4 (2020-6-18): I made a shortish 5km ride. I did the same tests as I've done with the phone but using the ML-102 which charges an 18650: I had the same issues as with the phone. The ML-102 gets ca. 6.8W. When when you start riding slowly the USB power output drops to 4.2-4.5 W and then it stays in the range 4-5W for several km. I don't know if after a long time it would go back up. That's a test for a longer ride. With the XZ it took about 1 km in one test I did for the charge speed to go back up to more than 7W which is better than with the ML-102, so using the ML-102 18650 charger/powerbank as an intermediate won't improve matters... The interaction between the 2 USB devices is an issue in not getting maximal power output for the phone, and for the powerbank.

I checked whether vibrations are influenced by how tight the tie wrap is that keeps the dynamo pressed to the front fork. The answer is no, only switching the light on/off gives a big difference. I will see what happens with another headlamp than the Axendo 40. [ it could also be that the vibrations are only noticeable with the total power getting over a certain threshold, though my impression was that with no USB power and headlamp on I felt it more than with USB power only. I will check this again. ]

2020-6-20: Tested a bit with various cables, and low speed riding. Light output seems independent of the USB output, At about 10 km/h the Axendo 40 begins to flicker a bit and at about 9km/h and less there is almost no light. This is not enough for e.g. going up hills. Taking out the cable from the USB box, nothing changes and this is a case where power is available as the phone was being charged (I think the internal battery was empty from lots of low speed riding, but I will check again), but the light should be powered at a bit more power at the cost of the USB output (and even from the internal battery). I tried to get the vibration of the phone mount on video but instead, while riding I got a vibration in the fender also from the dynamo which happens at around 17 km/h (a bit more or less and there is no resonance) and made a video of this which may be good enough despite wind noise.

2020-6-22: My tests showed that the resonance varies (and note they are in a bike with headshok fork but in any case vibrations, if felt, will in any bike be at a far higher frequency than with gearless dynamo hubs), it can happen with only USB output or only light (but usually faint), but mostly with high power USB output combined with lightoutput, and the speed at which I notice vibrations is around 17 km/h.

Note that there are various things to determine the characteristics of this system, and thus to figure out why and when exactly things like vibrations happen: light output on/off, USB output on/off and power to USB is coupled with dynamo output and battery output (if there is enough charge in it), battery charging is based on whether the battery is full or not and what power the dynamo can provide at a given speed. This is why it takes a while to figure out all the numbers and dependencies.

I searched a bit for reviews and found one from Taiwan that gave some information on the settings: https://bikeexpress.com.tw/2020/spin-up-f12w-pro-bicycle-usb-charger-dynamo-from-sunup-eco-1/
I extracted the essence + added some comments:

More power output means stronger jolts from the dynamo and thus it is logical that I notice vibrations most of all with lights + high output USB, but there is possibly something else going on at the same time: The system as described in that article seems to have 4 strictly separate states. If the states give a different power output just at the end of one and the start of the other, then that could cause resonance too. I.e. suppose the system puts out 5+3W at 17.1km/h and 7.5+3W at 17.3 km/h then with varying speed in that region it is possible to get vibrations from that difference when hovering around the speed where the system changes states. That would likely be a quite low frequency resonance from your speed going over and under the threshold repeatedly. Ride at 17.1 km/h speed up slightly to 17.3 km/h, power output rises, which means if you keep your power output steady that your speed drops to below the 17.2 km/h threshold (see the general page for calculations how much speed drops from a few Watts of power), then the output of the dynamo lowers, and you speed up. Etc. [ 2020-6-28: This may have caused the fender rattle that I got near 17.0 km/h in a very small range around that speed. ]

2020-6-30: The main things to test are to put it on a bike with steel front fork (no suspension), and to try it on the rear wheel (why not? ;-) ). I've also thought more about the R12W (Maxidyn), which is heavier but if it has the same output in USB power as the F12W, then that would be a a really nice dynamo on a bike where you can mount it (i.e. no internal gear hubs and no disc brakes).

2020-7-31: I took the dynamo's shell off, to try to get it to run more smoothly with some grease or oil. The shell is really light weight, that will be more fragile in case of say a fall than a dynamo hub. I noticed that the play that I could feel is not in the gears, but the the small gear wheel can move a little on the axis when keeping the dynamo fixed. This means I will try to open it up further and see if I can remove this play which may help remove vibrations.

Warranty, price

An issue with long distance service, even if you have warranty, is issues with posting stuff across customs boundaries. There is not just the high price of posting for you and for the company back to you once it's fixed, but you also need to indicate that something is a return for repair and the manufaturer needs to do the same otherwise you could get a customs bill. Furher, sending packages to Taiwan and back can take quite a bit of time. This is why I'd be interested in being able to fix any issues myself, rather than rely on the manufacturer.

For the initial sale of the F12W, customs and VAT cost in the EU will be high, unless customs lets the package go through. There is always this possiblity, but it's getting harder. In the late 1990s and early 2000s getting stuff from Amazon.com or sellers on ebay.com always came through here in NL without any customs issues but as more and more people ordered from outside the EU, packages are getting checked even if they are indicated to have a low value. So customs cost in NL for a bicycle dynamo for $500 (need to take the total incl. postage cost and insurance), is it seems about 3% so $15, then add 21% VAT (yes, on top of the customs value, which in a way makes sense however what doesn't make sense is that both are charged over the postage and insurance which are 'used up' in sending the item and most of the service's work done (posting in the country, transport on the aircraft) is outside the EU so any cost within the EU should be handled by the postal company as you pay in a country for a certain amount, and any work that company does in another country should be dealt with internally in volume, doing it in customs for customers on an individual basis is insane). So that gives from in total with postage of $500, an amount of $623. For Belgium it's about the same, for Germany a few percent less from the lower VAT, but I'm not sure about customs tariffs there. In Germany the chance that you need to pay is far higher, customs are more strict and will open most packages and will often want to see a bill to check the sale price.

Update several weeks later Oh, got post from TNT, I need to pay VAT/customs, total cost goes up from VAT/customs cost by 15 euro for 'their work'... Bill dated 18-6, payable by 25-6, arrived weeks after that. Eehh, yeah right, I'm not going to hurry to pay that. That reminds me: Customs/VAT bills are almost 100% certain when using a fast postage method such as TNT express, UPS, etc.

For the USA this is much less of an issue due to the far lower VAT which varies by state, I remember having seen rates of around 5-7%.

At the current exchange rate in NL/BE the price for the F12W without duty/VAT is about EUR 440,-, and including duty and VAT it is about EUR 550,-

Comparable costs in the EU for a dynamo hub based solution:
A good hub dynamo costs:
- SP PD-8: ca. EUR 100,-
- Shimano XT T8000: ca. EUR 95,-
- Renak: ca. EUR 140,-
- SON28: ca. EUR 230,-

Then to build it in a wheel:
- spokes ca. EUR 25,
- rim ca. EUR 25 for a standard rim,
- wheel building cost is ca. EUR 25,-

This gives a total of a good hub dynamo built into a wheel of ca. EUR 170 to EUR 305.

To get the equivalent of the F12W-pro you must add a USB converter. You also need to make a cable with a switch to switch between light and USB (or use the on/off switch on the headlamp, if there is one). A fairly cheap option is B&M's USB werk for ca. EUR 80,- which provides at most 5V 1A with a small battery, which is similar to how the F12W works (but at which speed do both supply 5V 1A?). Options such as forumslader are more expensive (I think it was about EUR 120,- several years ago, so likely more now), and may give a bit more power.

So the total price with these USB converter choices ranges from ca. EUR 250,- to EUR 430,- This is except for the SON28 based solution still a long way from the F12W pro (esp. when assuming it won't get through customs without having to pay VAT), but the Spinup solution gives more power, and gives light and USB output at the same time.

Warranty is in general in the EU 2 years, but Schmidt/SON gives 5 years. Sunup is thinking about the warranty, to make it in the region of 3-5 years. I think for the price that that is needed, otherwise at least lower the price.

Considerations on the choice of this dynamo/system or another

Advantages of the Spinup vs dynamo hubs:

Disadvantages:

Conclusion

Not yet finalised...

This is my preliminary view at this moment (2020-6-27): This systems gives you hassle free light + USB output (of ca. 4.5W minimum, up to 6.5-7.5W depending on the USB device attached to it) at the same time. It makes it possible to be mostly self sufficient on long tours where you may be camping in the wild at the end of each day. There are variations in power output with a given USB device attached caused by the fluctuating power and that USB power negotiation wasn't designed for this purpose of non-steady power supplies, but it will be enough to keep your phone going with a nearly full battery if you don't always have the screen on (and to have it on at full brightness). For longish day trips, of say 60 km to a city of ca. 30 km from where you live, then later that day back again, and where you want or need navigation, it is also nice in that you don't need to worry, don't need to take a charged powerbank with you which would otherwise be needed as the phone's battery is normally dead before a ride of ca. 60 km ride is over when using GPS based navigation when using the screen a lot (in NL you would like to have the screen on all the time due to mostly short sections of roads, not many long roads where you go 1 direction for say 5-10km that you follow without any need to navigate). The price is an issue, but Spinup made this choice I think because the development cost. And I can see that a lot of development went into this system. Despite my issue with vibrations, Spinup did try to make it nearly vibration free, but I suppose even for a 3 phase system that is hard because of various factors (any play in the gears could also have an effect). This dynamo is incomparable in quality to the old front wheel spoke dynamos such as from FER. For me the need to spoke in a hub dynamo is not much of an issue in favour of this dynamo, I like that it's no hassle all in one and USB + lights at the same time. The low light output at 10 km/h and slower is an issue. With a lot of load in your panniers going up steepish hills you can go that slow and if that is at night (as I did e.g. on my trip in 2013 in Germany) that's a problem.

One thing I've been thinking about is that I really need to test some more USB converters (which means either USB charging, or lights) and see how they would do with a USB powered light (that you could charge in the daytime, or even when riding with light on if the light allows that), and charging the phone. Such systems would need 2 USB outputs for a hasslefree system so that you don't need to unplug and plug in cables all the time... I have one USB dynamo running on the backwheel that a friend loaned me, I suppose it's time to try it out now...

Testing the F12W made me think more about the the R12W. I never got round to buying one to test it, but if the USB power output is similar to that of the F12W then it will be a pretty good deal, definitely worth the price of $230 for a guaranteed USB power source + lights at the same time. This is only an option if the R12W fits on your bike of course (so a bike with rear wheel with a cassette hub, and using a rim brake, internal gear hubs and disc brakes do not combine with the R12W nor with the original Eco DS).

Update 2020-7-31: I updated the table of downsides with a possible downside of being more fragile in case of accidents or in case of vandalism. Further my preliminary conclusion for travel bikes: As many people spends thousand of euros on travel bikes, a few hundred euro should not be a deciding factor on an essential part of long distance touring: Keeping phones and navigation stuff charged and for lighting in case of bad weather or even evening rides (though most long distance riders don't ride when it's dark). For those riders I can definitely recommend the F12W pro if you don't mind the low lightouput at/below 10 km/h. For anyone else the price is hard to swallow. I did get a customs/VAT bill in the mail after all, many weeks after the supposed send date of 18-6 and the 'pay before' date of 25-6-2020 (Yes, right, they want me to time travel to pay that bill!). So that's something to keep in mind.

Further, as I dismantled the dynamo I installed the wheel with Shimano T8000 again and with the same Axendo 40 + Duxo setup and light came on at 3 km/h or less, at 5km/h you have strong light, more than the Spinup at 10 km/h. This may be an issue for long ascents, and it can be annoying on paths where you can't ride fast, e.g. close to your house walking the bike, you don't see anything if there is no other lighting around (such as streetlighting).

Still to test on a bike with steel front fork, so that is yet to come...

Additional thoughts

For a setup where you might want 2 dynamos with one dedicated to say charging a power bank (and to have something to fall back on in case of long tours), as I did long ago on a long tour with the PD-8 and Eco DS, this doesn't combine with a dynamo hub, so a 2 dynamo option would be:

For any type of rear wheel (cassette or hub gears, rim or disc brake):

Only for a bike with rear wheel that has a cassette and uses a rim brake on that wheel:

An alternative to 2 dynamos would be a dynamo + light weight foldable solar panel, but only for sunny days, esp. tours in summer, to charge a power bank.

Note about buying an F12W-pro: Import costs could be a lot lower than I mentioned, email me or Spinup for details. Also, if you want to buy one after my review (for the high power output, which is the best I've seen so far of any device): I'd appreciate it if you let Spinup know you got to them via my review so they get feedback for the interest coming from my page.

Conclusion, 2021-4-28, CadenceX vs. the F12W pro and dynamo hubs

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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