Sunup eco DS (spoke mounted) rear wheel generator

History of how I heard of this generator

I first heard of the Sunup eco spoke mounted generator via Dosun whom I had contacted to ask if they would consider making a dynamo version of the D1. At the time (ca. Oct. 2010) I wrote:

Similar principle of attachment to the FER spoke dynamo it seems. Will be impossible to attach to some types of wheel, esp. those with brake disc, rollerbrake or drum brake. A demonstration by Dosun (who is/was distributing it under the Dosun name) showed/claimed it was more efficient than the DH-3N80 according to someone who visited their stand on Interbike...

I was supposed to get one (that I wanted to buy direct from Dosun) ca. end of November 2010, but there were delays...

Ca. nov. 2011 I also wrote: This Sunup dynamo may be similar in principle to the Lightspin. If you make the dynamo go round without load it will simply keep spinning freely for a while. There's another dynamo that keeps going round for a while without a load, the Go go shine dynamo (they say on that page the wires aren't wound around steel but plastic (and what's the efficiency?)).

Sunup Eco: Taipei cycle show (16-19 March 2011)

More on Sunup eco's DS generator: This was supposed to be available in November 2010 under the Dosun name, but it was delayed. Sunup want to make sure in particular that the voltage overprotection is correctly working, as the dynamo is not of the same design as other dynamos and dynamo hubs (it's a 3 phase generator whereas standard dynamo designs are claw-pole generators which are current-limited to about 0.50 A (well, at least with a true resistive load)). From their documentation the weight of this generator is ca. 650 g - 720 g (not sure which was the earlier version) and in the Sunup pictures it is shown in various colours. Sunup eco, from what I heard could be putting more effort into marketing these generators themselves.

This could be a good idea as Dosun doesn't seem to get how to advertise and get 'their' products known and 'out there'. I'm no longer interested in their stuff in particular due to disparaging remarks by someone from Dosun about reviewers such as myself (as if I want to get stuff for free; well, I actually said in an email that I wanted to buy their generator and headlamp...) No wonder the headlamps they introduced on interbike are still nowhere to be found, and not many people know about them (or are interested in them)...

Pictures/information from the Taipei cycle show (16-19 March 2011) website: Sunup DS

Interestingly, the Sunup version shown there has a rear lamp in the dynamo... (the text says the Dosun version is the one with the lamp, but the picture shows 'Dosun' on the one without a lamp). On this point I would like to say: I have seen someone ride a bike with Reelight type lighting, mounted at axle height, and this was very bad for visibility, as you're not looking that low which means automatically less attention goes there (unless it's insanely bright, to give an example), so I'm not keen on rear lamps that are mounted very low. Also, a rear lamp at axle height on the left hand side of the bicycle is not very visible from the right hand side, which is not often a problem, at least in countries where you ride on the right hand side of the road, but it can be a possible problem such as in the case when a car comes from your right (on an intersection), in which case the driver won't see much of that rear lamp.

Now to my experiences with the Sunup generator, which I got from Sunup:

Specifications (pre production model, but the one I got is the same as the production model):

Mass: 665 g, 769 g with all mounting hardware.
Size: The generator itself has a diameter of 75 mm,
Price: ca. $120,- / € 100,-



Originally the Eco DS I got was considered still not final, but it performed in Sunup's tests as desired and thus though I got it as being possibly not the final version to be produced in numbers, it was actually the production version because nothing was changed....

At first the idea was to just give a general impression and not a proper critical review, but Sunup was ok with a proper review even though it was still considered a pre-production model. This also meant I could discuss any flaws, should I find them. The idea was also that if I did find any, they intended to work on fixing them. During my review the generator was already considered stable, and any ideas/suggestions/problems I found may be implemented/fixed in a next generation of the generator.

It seems to work for hubs with shell diameter outside the flange of up to ca. 34 mm. Alternatively, it could be fitted if the distance from the hub shell where it is wider than 34 mm is more than 26 mm away from the axle end (I mean the start of where the threaded axle comes out).

Mounting on a front hub (normal or dynamo hub) doesn't work on all the ones I tried as you you need at least ca. 26 mm from the hub/flange to the axle. It's not what the generator was designed for of course! (But I was curious).
Mounting on a rear wheel with drum or roller brakes doesn't work.
Mounting on a rear wheel for brakes disc with 6 bolts (IS) doesn't work (needs more than 26 mm to the threaded axle).
Mounting on a front wheel or rear wheel with hub for centre lock brake disc doesn't work as it doesn't fit over the centre lock section (about 36mm diameter, this is just slightly too large! That's a shame). The centre lock ridges are also sharp, and could damage the rubber if I were to try to install (force) it anyway...

I was told the people from Sunup have considered making the generator work on disc brake rear hubs (in a different way than what I suggested below), but that they couldn't do this at the moment (without a huge effort into redesign I presume).

Nevertheless, I suggested making the diameter of the dynamo's drive wheel slightly larger so it could fit over centre lock and IS 6 bolt brake disc hubs, using switchable inserts to mount the dynamo to that brake disc mount. This could even eliminate the need to mount it on the spokes, at least when fixing using the brake disc mount. Another option is to let the generator get driven by an IS 6 bolt hub with an insert around it but in between spokes and brake disc. The generator should fit between the brake disc blade and the spokes, at least in the hubs I've seen.

Such a rear wheel brake disc mount fixed generator is almost what I wished for on these webpages since I started them in 2008, i.e. a cassette type dynamo for the rear wheel...

I mounted it on an old rear wheel for derailleur, and turned it by hand, and the wheel with dynamo kept going for about 7 seconds with just a very slow push.

Installation on rear wheel for cassette (hub for derailleur and rim brakes)

sunup eco DS installation sunup eco DS installation sunup eco DS installation sunup eco DS installation

For installation you use 3 or 4 aluminium plates which keep the generator securely fixed to the rear wheel. For 36 spoke wheels (18 spokes per side) you can use 3 mounting plates while keeping symmetry. I.e. the next plate will be mounted on the end of the next 6 spokes which are 120° further. For 32 spoke wheels you will need to use 4 plates and mount the next plate at the end of the next 4 spokes. For 28 spoke wheels (14 spokes per side, which is of course not divisible by 3 or 4) you could use 2 mounting plates I suppose but the generator may get to sit not equidistant from the hub at all positions. So using 3 or 4 and just mounting them as best you can near to 90° or 120° from the previous plate is probably better.

Experiences running a Philips SLD & Edelux dynamo lamp

I don't notice the dynamo in use at all, which is how it should be (what a relief after years of annoyance by vibrations in the handlebar from dynamo hubs). Of course it can't slip like a sidewall dynamo, and I don't hear any noise either. This is actually a pretty cool dynamo. A version for use on brake disc hubs would be a fantastic alternative to a dynamo hub. What I did notice is that the hub doesn't give much power at low speed, this isn't bad most times except for people who have some very steep hills close by and regularly ride at about 7 km/h on uphill sections. I will check the exact speed at which light output is so low that the lamp switches to standlight.

The output from the Sunup is actually DC. This is also why running an Edelux only works in one of the 2 possible wiring options (it's not due to a short-circuit as there is no electrical connection between the bike's frame and the generator; note that the Edelux has an earth connection...). The Philips SLD works whichever way you wire it up.

Running the dynamo without load the multimeter shows 14V at relatively low speeds, so I will check and ask about the voltage limiter etc.

Power output and test results from Sunup including lux measurements of various headlamps (they have also put this on their new website)

             (km/h)       5    10    15    20    25    30
             (26"-rpm)   40    80   120   161   201   241
             (gen-rpm)  241   482   723   964  1205  1446

Cyo          (V)       3.57  5.31  7.04  8.24  8.77   --
             (mA)        26    96   140   174   335   --
             (W)       0.09  0.51  0.99  1.43  2.94   --
             (Lux)      2.3    16    26    35    55   --

E3-pro-StVZO (V)       3.41  5.23  5.56  5.86  6.02  6.01
             (mA)        28   106   215   360   456   459
             (W)       0.10  0.55  1.20  2.11  2.75  2.76
             (Lux)      1.2     8    18  27.7    32    33

Edelux       (V)      3.54  4.80  6.15  7.31  7.98   8.12
             (mA)       30   114   196   247   396    455
             (W)      0.11  0.55  1.21  1.81  3.16   3.69
             (Lux)       4  15.5   29   41.5    63   68.8

Philip SLD   (V)      3.83  5.63  6.35  6.63  7.01   6.76
             (mA)       26    98   186   313   462    457
             (W)      0.10  0.55  1.18  2.08  3.24   3.09
             (Lux)       2    10    23    42    60     60

Measurements of the Cyo at 30 km/h were not done because of concerns about the voltage, if I remember correctly. I know nothing about 3-phase to DC conversion nor about the power limiter Sunup uses/makes, but I will try to find out...

2011-11-11: I've done power output measurements with 1,2 and 3 XM-L LEDs in series. Measuring resistor = 0.05 Ohm.

Sunup eco DS power output measurement

Power output measurements with 1,2 and 3 XM-L LEDs in series
Speed VR Vtotal Power
5 km/h 1.7 mV 2.60V 0.09W
10 km/h 9.0 mV 2.76V 0.50W
15 km/h 20 mV 2.87V 1.15W
20 km/h 22.4 mV 2.89V 1.29W
25 km/h 22.4 mV 2.89V 1.29W
30 km/h 22.4 mV 2.89V 1.29W
Light starts at about 4 km/h, below that almost nothing.
XML EZ E7 (6V, 2 cores parallel, 2 series):
Speed VR Vtotal Power
5 km/h 1.0 mV 5.00V 0.10W
10 km/h 4.8 mV 5.47V 0.53W
15 km/h 10 mV 5.64V 1.13W
20 km/h 18.5 mV 5.78V 2.14W
25 km/h 21.9 mV 5.82V 2.55W
30 km/h 21.9 mV 5.82V 2.55W
Light starts at about 5 km/h, below that almost nothing.
XML (T6, 1A) x 3 in series:
Speed VR Vtotal Power
5 km/h -- mV -- --
10 km/h -- mV -- --
15 km/h -- mV -- --
20 km/h 10.0 mV 8.33V 2.66W
25 km/h 22.0 mV 8.56V 3.76W
30 km/h 22.0 mV 8.56V 3.76W
Light starts at about 15 km/h, below that almost nothing.

The power seems limited only by the current at about 0.44A (although apparently the power limiter is set to give a maximum of 0.50A, but when looking at Sunup's own measurements, the maximal current is quite close to what I measured!), power rises quickly from 10 km/h on, so I think if the power limiter/3 phase converter were less restricted you could use this system nicely for multiple LEDs and get much more power out of it. It would then need electronics for voltage conversion similar to a standard buck or boost LED driver so that you get some light at low speed with 3 LEDs, or perhaps current could be increased (out of the converter) and run LEDs parallel. Even with the current system, I suppose some form of buck converter could be used to extract the most power. I want to try that...

Running a Philips SLD from SP PD-8 dynamo hub + another Philips SLD from Sunup DS at the same time

On 22 Dec. I finally did the comparison test to show the difference in generated light at different speeds with both the Sunup and a regular dynamo hub. I made a mp4 movie of it but perhaps I will make a new one to better show the differences.


I made a slightly better movie on 31-12-2011: sld-sunup-pd8-2011-12-31 Note that the road on the right has a fence that's better visible than the green on the left, and the lamp aimed in that direction is the Saferide 60 attached to the PD-8. But this video does show reasonably that the Sunup provides less power at low speed. To be able to show this better I need a camera with much better low light capability...

The comparison test confirms the impression I had, which is that the main disadvantage of the Sunup DS is the low power output at low speed. If you ride a lot of hilly sections where you don't get above ca. 10 km/h a dynamo hub would be better. If you ride relatively fast (20 km/h and more) then this is about as good as a dynamo hub, at least to power a standard StVZO compliant headlamp.


This is a high quality generator, and I love how smoothly and vibration free it runs. It does have 2 downsides:

Sunup intends to increase power at lower speeds and give 3 W at 15 km/h instead of now at ca. 20 km/h. This would also increase power at really low speeds (5-7 km/h). This version will appear in 2012. More about these issues after my power tests of the current generator in which I will circumvent the built in limiter/converter...

Selfmade USB output

17-8-2013: I made a USB output for the DS1 which gave very good results. I used a 7805 linear regulator to get to 5V, then used resistors to indicate 2V on the D+ and D- data lines to indicate 0.5A charging capability, and this way I could charge my Galaxy Y phone by 17% in a 25 minute ride. This is better than the Luxos U which does about 14%-15% with a full buffer battery.

Maintenance to fix a dry running bearing

19-8-2013: After a few rides, with this USB output, I noticed a scraping sound, strangely only when riding with power off, and only on bad roads (vibrations, at each bump I heard this sound). I thought perhaps the magnets touched the coil but it turned out that the sound came from a bearing.

I opened it up and there was a little bit of corrosion inside, but the real problem was that the bearing of the middle cog was running dry. I lubricated it and put some grease on the gears as well, which made it run noticeably nicer, so perhaps after 2 years of use, people should disassemble the Sunup and check for such issues, or is the Sunup supposed to last without ever disassembling? I asked the manufacturer about this but haven't got an answer, yet.

There was not a clear point visible that was the entry point for water, but I suspect it doesn't matter where precisely it got from, as the moisture will not directly get to all the other stuff because it's all some distance away from the housing...

I suppose the moisture could have entered the top, and I would think that a weak point is the rubber at the top where the power cable leaves the housing, this should be at the bottom for this reason of it being an extra opening.

In any event, any water goes to the lowest point and there it has rusted the metal.

When reassembling I put some threadlock on the miniature inner hex bolts as stainless steel in aluminium gives a strong reaction from the aluminium (galvanic corrosion). Aluminium corrodes into white powder, which I already saw on the bolts. I removed the powder from the bolts but not from the threads in the aluminium. In other stuff on the bike, such as pedals, this has usually resulted in bolts getting stuck so hard that I needed to destroy the bolts (or heat up the aluminium quite a lot) to get them out. That would not be nice on the Sunup particularly as the 3 bolts around the dynamo part would be hard to get out and to find replacements bolts... So using some Loctite or similar is a good idea.

After this I did a testride and the problem was gone...

Future version

2012-1-30: Power output has doubled in the new version which provides a huge amount of power at high speed. The old version provides (or better: can provide) a lot of power above 30 km/h, the new one reaches a little over 3W at 15 km/h and more than 8W at 25 km/h. Efficiency is yet to be determined. Ditto for power loss at higher speeds, can it be used efficiently? (the original version produced 10W at 40 km/h, the new one should provide 20W at that speed, which is a huge amount, and not really needed.


It was not distributed at the time of my review, but some shops sell them by now. The recommended retail price by Sunup is $120,- which is about €100,- including VAT for EU. See Bicycle parts: Lighting.

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