Long Distance Competition/Ultracycling, Randonneuring and Endurance Cycling - Shimano Dynamo hub, reliability and bearing life

I posted this over in touring, but I thought it would maybe get some more traction here.

I've been using a shimano DH-3D71 dynamo hub for about a year, and I've been really happy with it. I'm trying to decide whether I should use it for my upcoming pan am tour. I'll be on the road for a year or so, going from Alaska to Argentina.

From what I understand the bearings on one side of the hub cannot be serviced, which concerns me. Is this correct? Should I be worried? Has anyone put 15,000 plus miles on one of these hubs?

I thought Shimano Dynohubs use Ultegra type bearings that could be serviced by any bike shop, unlike SON hubs that use better quality sealed bearings. I do not own one yet, but I am planning to get DH-3D80 later this year.

you can only service half of a Shimano dynohub. there are some small wires that run through a groove in the axle.

I had one these for about 5 years. In these 5 years I probably out about 40000 km on it without problems.
But last December it suddenly froze, I could not rotate the axle. I tried to fix it by opening the hub and service both bearings. If you are very careful and know what you are doing it is possible, but it is very easy to break the cable that runs through the axle.
When I put everything together, it still did not work, so I bought me a SON 20r.

I had one these for about 5 years. In these 5 years I probably out about 40000 km on it without problems.
But last December it suddenly froze, I could not rotate the axle. I tried to fix it by opening the hub and service both bearings. If you are very careful and know what you are doing it is possible, but it is very easy to break the cable that runs through the axle.
When I put everything together, it still did not work, so I bought me a SON 20r.

Thanks that is helpful. When you say it didn't work, do you mean that the axle still did not spin, or that it no longer powered the light?

The SO just had her front and rear wheels rebuilt after some 10,000 miles of riding... her dynohub was fine... unlike her Nexus hub which needed replacing.

Thanks that is helpful. When you say it didn't work, do you mean that the axle still did not spin, or that it no longer powered the light?

It would not spin. During the reassembly I also broke the cable.
The problem could have been caused by water inside the hub, the magnets inside were very rusty.

I have about 7000km of hard (some off road, all weather) riding on one, so far no problems, works great.

I just have got one of these in my hands.... it feels a bit notchy when I rotate it with my hands... but I think that's normal. If these have Ultegra bearings then I think it should definitely last long enough.

@paulkal - you broke the cable...but do you think its doable if done very carefully??? will be good if you can post pics of the axel.

Now I don't know whether I should go the DIY way.... (which in India can be a bit troublesome finding the parts)...but the brighter lights & building something it quite tempting or should buy something off the shelf... again through either Evans or Wiggle online & get things stuck at customs for months & get charged in the end.

I keep hearing from some & the great Peter that a simple B&M light is quite sufficient... is that really so. I've gone the dynamo way after my 300k experience in the dark where my cheap light was not only inefficient but got dimmer by the hr.. thanks to my luck that I was back on lit city roads... before becoming a Road Kill ;).... Any links of way forward from here will help.

I bought mine in 2001. I have no idea how many miles are on it but it's a lot! It's worked great, no problems. A friend of mine who bought his about the same time had a problem similar to Paulkal but he sent the wheel back to Peter White who fixed it. I don't remember what he said the problems was.

I have a Shimano dynohub on a Shimano wheel on Machka's new bike as a temporary fix until I can source the rims I need for the SON version. I bought it on eBay originally as a training wheel.

Anyway, it seems to be fine but some observations which aren't necessarily deal-breakers:

1) It has slightly higher rolling resistance compared to the SON on my bike. This is evident from the plain old "give it a spin off the ground and see how long it takes to stop" test. My SON rotates about twice as many revolutions (if not more). The SON has done some 40,000km of all sorts of riding.

2) Despite having much fewer spokes compared with my SON (18 v 36), the Shimano wheel is slightly heavier -- which is almost entirely attributable to the hub. However, I would say the weight difference in negligible for touring purposes.

3) My main concern would be broken spokes on such a low count. This wheel has quite heavy gauge spokes, and it is on the front, so the issue may not be significant.

4) You have to fiddle around with the connector. The B&M lights come with spade terminals, Shimano have a proprietory fitting, but it is dead easy to rig it on to the wires (this may have changed since the wheel I have was made).

I am a fan of the B&M Fly Senso. The light for my purposes is excellent with wide spread and good penetration ahead. Machka has one connected to the Shimano hub, and putting aside mounting issues that relate solely to the bike, she is also happy with the output and coverage.

FWIW, I have toured a lot with a dynohub and attached lighting, and it's great to know that I can keep riding after nightfall to get to me accommodation destination without fear of getting hit or being pulled over by the police.

I just have got one of these in my hands.... it feels a bit notchy when I rotate it with my hands... but I think that's normal. If these have Ultegra bearings then I think it should definitely last long enough.

@paulkal - you broke the cable...but do you think its doable if done very carefully??? will be good if you can post pics of the axel.


If you are carefull it is diable to overhaul the hub. I threw away the hub, so can not post pictures.
The hubs are indeed notchy because of the magnets in it, when cycling I did not notice it.
@Rowan, I prefer the Shimano connector to the SON, they are easier to remove. However the SIN is a bit lighter.

I still out-coast a lot of other riders with my Shimano dynohub. I have trouble paying twice as much for a Son, although I keep getting close to pulling the trigger on that.

Yes I was game for the SON but after looking at the, the price made me wonder!!!

Anyway I've got the 36hole variant... Are the Mavics 319s good enough for touring & PBP with these hubs???

I built mine Velocity Fusion wheel 32 spoke with Shimano DH-3D80 hub last month and I am impressed how light the wheel is. I did a fleche ride and a 300 brevet with the wheel and I could not tell the difference riding between dynohub or regular front wheel. I was saving for SON hub, but decided to go with Shimano for $$$ and so far I am very happy with Shimano and I still have money left to get other bike toys I want.