seibaatgung

Anyone have a dynamo hub on both wheels? For reliability reasons, of course.

gnome

You are unlikely to do much touring with a rear dynamo hub. The only rear dynamo hubs that I'm aware of are the Sturmey-Archer AG three-speed and FG four-speed hubs from the 1940s - 1960s. Those hubs are a bit scarce to find these days and don't generate as much current as a modern front dynamo hub. You will likely be walking up a lot of hills if you use one.

The other possible way to have a dynamo hub front and rear would be somehow rig a fixed gear sprocket to the shell of a disc braked dynamo hub. Then you'd be down to a single speed. It may work depending on your terrain.

Modern dynamo hubs from Shimano, Shutter Precision and SON are generally very reliable.

veganbikes

I have yet to see any modern dynamo hubs at the rear gnome listed probably most of them and they are quite ancient at this point. I don't even think any BB based ones are still around. You can find bottle dynamos still but in the end a new SON hub is way better than anything else and if you are in need of more power you maybe want to consider alternative forms of power generation or better batteries. I think with a SON hub and a Cinq Plug V you will do pretty darn well and you probably could also run front and rear lights as well.

seibaatgung

Why, relative to a front dynamo hub?

gnome

The AG was a three speed internal gear hub with a dynamo. The FG was a four speed internal gear hub with a dynamo. They had a limited range and generally didn't allow you to set the gearing up low enough to climb steeper hills. If you could set the front chainring and sprocket up to have low enough gears to spin up a hill you would have a very low top gear for on the flat. Also as they are now very old internal gear hubs I wouldn't like to stand on the pedals when riding one as the additional torque generated may result in the pawls in the hub slipping.

A modern front dynamo hub allows you to use any gearing you like. If you have a modern internal gear hub you can probably get the gearing low enough for climbing and have a reasonable flat cruising gear. Modern internal gear hubs probably have a lower minimum front chainring to rear sprocket ratio as well. If you run derailleur gears you can run as low a gears as you like.

Trevtassie

If you were that worried by reliability it'd be easier to carry a spare front hub and a spoke key....

seibaatgung

Or just bring a solar panel

JaccoW

It's probably relatively easy to build a bike with a front dynamo hub and a Velogical rim dynamo and make it easy to switch between them using some SON coax connectors.
But generally speaking it's rarely the dynamo hub that fails.

The only other rear dynamo hub I know was a Shimano 4-speed automatic shifting unit. Incredibly rare though.

Tourist in MSN

I bought my first SP dynohub seven years ago. I have no reliability concerns, I see no reason for another dynohub. My last tour, for the last two or three weeks of it I was fully self supporting on electrical needs from the dynohub.

Quite frankly, if my dynohub was unreliable, it is the bearings that are more likely to go than the electrics from it.

If you are worried that much, pull a trailer that uses the same dynohub wheel as your bike front dynohub wheel. Check out the Extrawheel trailers.

SapInMyBlood

Smart 👌😎

Moe Zhoost

Or just pack a battery backup.

I've owned 3 dynohubs (SP, Shimano, and Sturmey) and found all of them to be completely reliable in generating electricity. The main lighting issue I've had is that sometimes the connectors need tweaked. Mechanically they are all good, though I did have to replace one of the cartridge bearings on my Sturmey (after 10,000 miles or so).

There's really nothing complicated about a dynohub. Basically it's a ring of permanent magnets that rotate (non touching) around a fixed stator. Worn bearings and physical damage are the only things you need to worry about. It's certainly a good idea to carry extra wiring and connectors on a tour, though.

Tourist in MSN

What do you bring on a tour that is specific to dynohub power system? I bring a roll of electrical tape and that is it.

tcs

Very gently, in a 'buy you a coffee' kind of way, this is a fool's errand.

That said, you can keep an eye out of Ebay for a discontinued Shimano Nexave Di2 FH-C810 low power magneto hub.

gnome

ooh that is an interesting hub. I didn't know it existed, even briefly. I may have to hunt for one to add to my obscure hub collection. You could use it to charge a powerbank to power your other electronic devices. Of course a front dynohub will produce more power and charge quicker.

seibaatgung

why is a front dynamo hub more efficient?

gnome

reading up on that obscure, obsolete Shimano hub it was rated at 4.1V and 1.2 watts.. A SON dynohub is rated at 6v and 3 watts. You'll have to ride twice as far or twice as fast to get the same charge from the Shimano rear hub as you would from the front dynohub.

Moe Zhoost

Tape is a good carry, but like I said, extra wiring and connectors are comforting to have. It's easy to imagine an event where something snags your wire at the hub knocking it into the spokes, which then damage the wire and fling the connector into the brush. I reckon if this happened to you, you'd likely figure out how to MacGyver it with just electrical tape.

Tourist in MSN

Two of my touring bikes and my rando bike have dynohubs, I used heavier gauge wire from the hub to the fork crown, used several zip ties to attach wire to the fork blade. It is not coming off. But, maybe for some others that might be an issue.

My heavier duty touring bike, I consider it to be my expedition bike, on a tour the dynohub is used solely to power my Sinewave USB charger for charging batteries, no other wiring on the bike. There is wiring on my other touring bike that has a dynohub for lighting, but if I lost my dyno powered lighting, it would not be a disaster, only an inconvenience.

Thanks for answering, that might be an issue for some other people. Maybe for bikepackers that don't have front panniers and might snag a wire on something.

If anyone is curious, I described at this other link how I wired up the lights and charger on my rando bike.
Wiring up a dyno powered lighting system with USB charger

Germany_chris

sure if your wiring looks like mine does right now but I don’t think anyone goes on the road like this

seibaatgung

Why rim brakes?

Germany_chris

Because it’s a Cross Check

JaccoW

How do you like those Pirelli Cinturato Gravel H tyres? They look interesting for a touring/rando bike.

Germany_chris

I’ve only put 100km or so on them but they do roll nice and install relatively easily.

that picture though is of my new cross check which replaced my touring bike as my commuter. The reason I’ve got the wires wrapped around the fork blade is I’m considering putting my local basket on the there and will need cable if I do that

seibaatgung

you say that like it's a bmw or a maine coon

softreset

How else do you respond to your question about "Why rim brakes?"