Thursday, 18 October 2012

Shimano DH-3N20 Review

Shimano DH-3N20 Review - Overview

The Shimano DH-3N20 is a budget, entry level hub dynamo. Which is available in a variety of flavours, 6V 3W or 6V 2.4W, with a quick release and a bolted variety. This review deals with the 6V 3W nutted axle variety.

Shimano DH-3N20 Review - Price

A top of the range bottle dynamo will cost you more than this hub, and you should go for the  DH-3N20 for sure, it is silent. With a bottle dynamo wirring away you will not enjoy rides in the country anymore.

I paid £29.99 for mine from JE James Cycles, I think they are normally £35 so still affordable. Of course the biggest challenge is building the dynamo in to you wheel! But don't let this put you off, wheel building is surprising forgiving.

Shimano DH-3N20 Review - Build in to Wheel

You may notice from the above  picture that the spokes are twisted together to make a butterfly spoke pattern, this not because I am an expert wheel builder . . .far from it it is because the spokes I had were too long, and rather than send them back I twisted them around each other to make them effectively shorter. They are 10 years old and have been used twice before, and came off a rear dished wheel, so I was using two different lengths . . . . all I am saying is that with all of these cr@ppy influences the wheel performs just fine. SO have a go you may be surprised.

Shimano DH-3N20 Review - Performance

 The DH-3N20 will light my LED lights at a slow walking speed. However, the front light a Lumotec Lyt Senso Plus will flicker at these low speeds, however, it is almost impossible to ride this slow, and a slow pace of the bike will result in full illumination of the front light. The rear light a Busch and Muller ToplightPlus lights fully at walking pace and is a very good light.

Shimano DH-3N20 Review -Conclusion

If you are looking to move away from  bottle dynamo then this will do the trick, studies (vintage bicycle quarterly) have shown that the DH-3N20 compares well to some expensive hub dynamos, so you are getting a bargain! If you can build you own wheel then you can do it very cheaply.

More on wheel building.

Environmental Permitting

Desktop Study

Sustainability Consultants

Shimano DH-3N20
Reviewed by Kermit Green on Oct 18 2012
Rating: 5.0


  1. hi friend, i've just by one, and readyng the manual i found that I'll need the SM-DH10 overvoltage protector, this is necesary? do you use that?

  2. Hi when I bought mine it came with a SM-DH10 overvoltage protector.

    BUT I never installed it and used it with a B&M LED light for serval months with ni problems with no over vaultage protector.

    I supose the smaller the wheel the faster the DH-3N20 turns, and so the more likley you will need overvault protection.

    I used 26" wheel (559), and no problems bigger than this probably OK, smaller then this I don't know. I used B&M Lumotec Lyt Senso Plus with no problems.

  3. I have the same dynamo.
    I got mine already built into a wheel from dutch bike bits.
    I had to slightly enlarge the slot in my axle to take the dynamos axle (which was a slightly larger size).
    fabulous bit of kit.
    I didn't bother with the over-voltage protection, and it was fine.
    the connecting clip piece that attaches the wire to the dynamo looked a bit dubious, so I taped it on with a bit of insulating tape to to be sure.

  4. Being these are the cheapest hub dynamo you can get (pretty much) I can't see the benefit in spending more, other than for a disc variant perhaps.

    Very good hub dynamo, bit heavy but who cares.

  5. Could you use it to hook up some kind of phone charger ?

    1. You can indeed. Two or three front headlamps I know of come with a USB socket so you can charge stuff whilst on the go. Check out "AXA Luxx 70 with USB" and "B + M USB-Werk power supply and charger" if you just want to charge stuff without lights. Also: