carrefour

Dynamo hubs are used these days to power anything from lights, GPS, MP3 players, mobile phones. I was thinking it would be great to be able to power some kind of heating pads for the gloves/shoes with the power from the hub. This might be harder for the feet as the wiring would be more complex than for the hands.

Good thing is that this should be possible directly with the AC provided by the dynamo without any rectification to DC or smoothing out. Free heat on the downhills when the heat is most needed .

Has anyone tried anything like this? Looking forward to your ideas or working solutions.

carrefour

I guess I'm too geeky for this forum?

AEO

could look up electric socks...

those ran on regular DC batteries, so it shouldn't be too hard to hook them up to a DC dynohub.

2_i 

You already have heat sources in your hands and feet. Better insulation is a more efficient solution. However, you are free to solve problems that do not need to be solved and, for that matter, are not very interesting. I will not be coming along for the ride.

Wilbur Bud

You would likely get more useful replies in the total geekiness thread. Since I lay down to ride, I know sometimes my back ices up on the seat by the time I get to work if there's a really strong headwind (which adds time) and temps are below about 10F-15F, so I might find benefit to re-route some watts from legs to seatback.

AEO

or have a better sweat wicking layer

2_i 

Idle human body produces in my memory of the order of 200W of heat. Let us say that during a leisurely riding this rises to 350W. (The mechanical efficiency of the human body is of the order of 25%.) What is then the power of a hub dynamo of 3W compared to 350W that the body produces??

carrefour

Thank you everyone for your replies.

I agree that the body produces a lot of heat and that insulation/staying dry is the best way to keep warm. But that is easier done when riding in flat terrain than in the mountains (downhill). I live in Geneva-Switzerland and even in winter I love to venture higher up. I have very few issues keeping warm when riding up. However, when going downhill it is about impossible to stay comfortable. There is the added chill factor from the riding wind, the lack of physical effort and the need for finger control on the handlebar and brakes limiting the maximum size of gloves. A typical winter descent would be between 6 and 13 miles long, rolling down at an average speed around 30mph.
Considering that extra drag would be no problem on those descents and the fact that dynamo hubs can output more than 3 watts at higher speeds I was thinking that something would be possible here. After all it is possible to charge fairly strong battery packs with a dynamo hub...the type of batteries that would power the commercially available heated foot soles and other heating gadgets.

Again, I understand that this is not something that 99,5% of cyclists would consider a problem needing a solution. But that is what we have the internet for. So if anyone has some more ideas on this, I would love to hear them.

Keep warm!

2_i 

I doubt you go as high up and go down as fast as skiers do. What about mountain climbers in winter? They have no problem keeping themselves warm with their own heat in much rougher conditions than you can have.

Most of my own problems in winter are with keeping the temperature right. As you deal with more insulation, it gets easy to overheat. Regarding the extremities, the body works in somewhat unexpected ways. If you keep the core quite warm, the extremities can take quite low temperatures with limited insulation. Myself, I never put any different socks in winter than in summer. My shoes differ only in the fact that they cover ankles, as I do not like to get snow in. I wear regular leather gloves down to -12C and thereafter switch to moderate ski gloves. The necessary coverage may differ for different people, but will achieve more and with less effort than the meager 3W of a dynamo that you still need to split between individual feet and hands.

mudpuppy

I disagree with the naysayers. The only way to see if this gives you the results you want is to give it a try. It sounds like you may have some requirements, due to your long descents, which differ from what most of us deal with. Granted, you have a limited power budget, but heated socks don't draw much power either. You also have the option of targeting specific areas that give problems. For example, I have particular trouble with my thumbs getting cold, regardless of type of glove or mitten.

It should be fairly easy to whip up a prototype to check your idea out. I would go with having the majority of wiring in your clothing, with a single power lead at around belt level to plug in to the generator. You may be able to re-purpose things like headed socks if their resistance is appropriate. You also need to do some calculations regarding the output voltage of your generator and the maximum power that you can safely draw from it.

There is no guarantee that your efforts will not be a dismal failure, but I say 'shame on you' to those who would discourage some experimentation.

mikewille

How about re-purposing some xxx-large electric socks into electric pogies?
That way you avoid wiring in your clothing.

Impractical idea that I like anyway: Electric footwarmer that draws power through the cleat/sole.

carrefour

This is exactly what I was hoping for...some support and thinking along. For the moment all of this is nothing more than an idea of "why not". To be completely honest, I don't even own a dynamo hub yet. But as I love touring combined with stealth camping I have been thinking of charging a GPS through a dynamo hub. And of course the next logical step is to start thinking about LED lights and charging NiMH batteries for camera etc. So when my hands were getting cold again on my ride on Wednesday I got this latest crazy idea.

So far the (easy) way to go would be to start with a pair of electric socks and turn the "heated toes" part into a pad that can be stuffed in the gloves (my hands are my weak spot). I suspect that trying to heat both feet and hands would most likely be pushing the limits of the low power output of the dynamo. My personal experience is that I can bike with heavier boots and thicker socks, but my hands need to stay in control, so there is the problem of skiing gloves.

I agree that the wiring needs some careful thinking too. Mudpuppy's idea of connecting at the belt level sounds good. Straigth to the hands would be impractical and straight to the feet would be impossible. Mikeville, I like your idea of drawing power through the cleat/sole. Doesn't seem feasible today, but never say never. Most of the things we take for granted today were looked upon as crazy before they were invented.

Fissile

I tried battery powered hunting socks years ago, they suck -- produce very little heat using heavy D cell batteries.

Considering that only 3 watts are available from the typical dyno-hub at cruising speed -- 15 mph - you won't be able to generate very much heat. It's the laws of physics. The only practical thing I've found for warming feet is is well insulated socks and shoes/boots. The only practical thing that I found of warming hands, aside from good gloves, are the flameless hand warmers sold at camping/hunting stores. See here: https://www.safetycentral.com/jonhanwarac.html

electrik

Pack some better insulating layers for the descent. Anything you get to take down(heavy heater coils and a larger dynamo hub) has to be hauled up the mountain... Most cyclist rely on chemical packs to generate heat for cold feet... those get expensive. The only thing you might be able todo is installed heated pogies, but really with pogies one doesn't need further heat. Other than that i don't think being wired up to the bike without a quick-release option is wise.

jack002

Not to derail the thread at all, but have you looked into something like this?

https://www.amazon.com/Zippo-Warmer-B.../dp/B001RDFDD8

I like the idea of powering hand and foot warmers with a hub, but I'd not heard of doing that.

Arcanum

Using a dynamo hub to power hand warmers might not be very productive, but what about a heating element for a rear hub? Maybe it would avoid the problems some people have with it not engaging when they pedal after coasting?

carrefour

I'm sure the zippo warmer would be pretty effective keeping hands and feet warm. The only disadvantage would be that it is a slightly bulkier solution to put in shoes/gloves.

Heating the internal gear hub? Why not? You would have to work with some kind of sliding contacts though.
For a Rohloff hub it would be a matter of keeping the oil slightly warmer. But then many would logically claim that it is smarter and easier to change the oil to a thinner type at the start of winter.
As far as I know SRAM, Shimano and SA hubs are greased so there heating might help as long as we can produce enough heat from our dynamo hubs. We'll only know if someone tries it ;-)

1962Ford

carrefour,

I agree too many negative/naysayer responses here. My .02 cents would be to look at motorcycle heated grips like those that are used on touring motorcycles, BMW's etc. Companies like https://www.hotgrips.com/ and others make aftermarket solutions for many different configurations. Not sure what type of handlebars your are riding, but if it is MTB type then you might find something that works.

It looks like as a pair they draw 24W on low and 36W on high. This means some type of battery backup would be in order, but I would think that a water bottle battery such as is used with the headlight kits out there would be able to handle the draw during the descents with you charging it up on the ascents. It should work for the length of time you are on the downhills.

All of this is hypothesizing and of course may be cost prohibitive as all get out, but I think it could be done. It's just a matter of how much you want to do it. Hope that helps. I like it when people think about solutions to problems that may or may not even be there. That's how innovations work!

chrisb71

For the feet the obvious solution would be to run wires from the hips down your legs, you'd only have to connect it to the hips. some sort of quick-release or breakaway connector would be required for emergency dismounting. Same goes for the hands., in fact they both could be connected at your hip, that way you wouldn't have wires running up to your wrists potentially causing an accident if you can't move your hands the way you want.

carrefour

Interesting point on the heated grips. Officially a dynamo hub delivers 6V 3W so this would be far from enough. But the LED light experts have figured out that hubs can deliver up to around 10W at higher speeds when powering 5+ powerleds. I'm afraid this would still not be enough for cozy heated grips. But I believe that this indicates that it should be possible to draw a decent amount of heat out of a dynohub when we use the heat right in the gloves at the fingers (my weakest cold spot).

So my theoretic setup would start with good electric heated gloves, with individual fingers or max 2x2 fingers paired (lobsters)-if these exist-and to power them from the dynohub, rather than from batteries. Electrical wires and breakaway connectors would run over the saddle/hip region for free hand movement. Sorry, nothing for the feet for lack of electrical power I'm afraid and as some have suggested, adding socks and bigger boots are not too much of a problem. I want to believe that this would make a difference on a longer decent at high speeds.

I don't have a dynohub yet, but this project is on my list. I will update this when I have results. Thanks to everyone for their feedback and ideas. All of your comments (can be done or no way) have helped me understand what I would now call "my theory". Only a real life test will tell if this understanding is worth something or just plain nonsense :-).

electrik

Here ya go... Heated MTB style grips.

Wanderer

I have electric gloves and socks for motorcycle use. At 13V, they draw around 10 Amps, each pair. Made by Gerbing in Washington State.

They will keep you warm - but I have an alternator cranking out way more electricity than I need......

electrik

Yeah, that site is sparse on details, esp current requirements.... either the heated area is very small or they don‘t get very warm... cyclists just don‘t produce enough horsepower.

carrefour

More ideas? Keep them coming please. I'm interested for any feedback ideas and I thank everyone for their past/future contributions.

bbaker22

How about something like a B&M E-werk coupled with 12v gloves? Or maybe the PedalPower+ in conjunction with appropriately spec'd gloves?

I think the idea of using excess energy during descent for hand-warming is interesting.

baker