Question about dynohub with LED headlight
 

It's getting real dark in the morning and I am about ready to buy a dynohub. I saw a comment that LED lights flicker a lot with a DH. Can anyone substantiate this? The newer LED headlights have standlight circuitry. Would this not control the flicker?

Thanks

Gary

They don't flicker while you're riding. I have a homemade setup with a 4W bulb and a Sanyo hub, it stays steady on down to about 5MPH. Totally worth it.

I have a Shimano Alfine hub and Schmidt Edelux light. At walking speed it flickers. Above about 5 mph it's fine.

I have a Novatron dynohub, a Planet Bike LED dyno light and a Spanninga (?) taillight. I find a little flicker for about the first 100 yards and then it's Ok. The Planet bike people told me this was a feature of their light. Actually it stays in flash mode for that time, then steady on. Taillight is almost instant on.

The stand light on both of these lasts a while. I'd say about 5 minutes or more. Although obviously not as bright as when moving.

This tends to be a big problem at work because there's always someone grabbing me to warn me that I never turned my light off. :eek:

Like tsl said they tend to flicker at slow speeds. How slow depends on the dynohub and wheelsize. I have a Shimano dynohub on a 20" wheel, with a Lumotec CYO N Plus headlight. It flickers below about 3 mph but the dynohub is designed for a 700c wheel. The CYO has a stand-light, but it's a lower intensity than when powered. I think that's common for front standlights.

I love the setup, only wish it were on my commuter now with its 27" wheels instead of my rando bike (recumbent).

According to German standards, the lights should be flicker-free at walking pace (I think they walk quite quickly). My Shimano DH-3D71 with Lumotec IQ Fly senso flickers to about 3mph then goes solid. The standlight is a much lower level of illumination and it flicker up to the riding illumination.
When you spin a dynohub you feel some resistance and notchiness, it is just the resting position of the coil within the magnet and does not cause any drag when riding. The actual drag casued by power generation is hardly detectable.
Ive never found a modern dyno-hub user who was dissapointed with their setup or who wanted to revert to batteries.
German standards which are the highest and best national standard and you should make sure your system is compliant with StVZO regs.

Hi Gary:

No flicker at speed, some flicker at real low speed (i.e. walking the bike). If I may, I recommend going with a less expensive dynohub and more expensive light, um, like my set up--SRAM iLight hub, LightOn! dynolight. See BF thread, if interested. (After two full years of regular cyclocommuting use, I remain a happy user.)

Just down the road in Cary,
Erich

I looked at one of the SRAM dynamo hubs and the description stated road bike, my commuter is a MTB, is there a dynamo hub for MTBs?

The hub doesn't matter, unless you need one with disk brakes. The only dynohubs with disk mounts (that I know of) are the Shimano ones with Centerlok mounts. Other than that, any hub would work. Sanyos are probably the cheapest, I got mine for $40.

Schmidt makes disc hubs too; you can get them somewhat less pricily by ordering direct from Europe (starbike for instance)

Short answer: DO IT, you won't regret it.

I think the flicker issue has been addressed - I've noted the same thing - flicker at a slow walk, nothing beyond that.

I have an Alfine dynohub with a Supernova E3 Pro headlight and tail light. I've used both the symmetrical and asymmetric (German DOT compliant) models. The symmetrical throws a brighter, narrower beam farther down the road at the expense of broad lighting from 0-25 feet. The asymmetric is not quite as bright, but provides a phenomenal "carpet of light" from the front wheel to about 50 feet out, then rapidly dissipates farther out.

Also found Supernova makes an "Infinity" hub for 6-bolt disks... for $200+!! I'll stick to drum/rim brakes....

psssst: the Alfine dyno hub is 100 bucks and works great, and is disc compatible (centerloc) :thumb:

Not sure if the OP needs disks or not, but that's about the best price you're going to find for a disk dynohub.

I used to wire a capacitor into my homebrew LED lights to reduce the flashing, which worked fine, but I eventually gave up on that. The way the lights flicker at walking speed is annoying if you're trying to ignore it, but I don't want people ignoring me. Now I think of the flickering as a safety feature.

And yes, absolutely, go for it. Go with LED lights; incandescent and halogen aren't bright enough. Don't bother with a switch, just leave them on all the time; and don't worry about what dynamo hub you get. Any working dynamo hub is fine. I use 50+ year old Sturmey Archer dynohubs on a few of my bikes, and they're great. Newer ones are great too. It's all good.

I have a Shimano DH-3N72 hub ($100) and a Lumotec IQ Cyo with the standlight ($100). It is an exceedingly bright light and flicker is not an issue. I guess when I am coming to a stop, I might have noticed a slight flicker but, believe me, it is no big deal. Mine has a switch which is important to me because I don't want the light when I don't need it. Plus there is a slight amount of drag associated with the hub- turning the light off reduces the drag. I love the set up.

My understanding is the cadillac of dynohubs is SON, but they are expensive. Apparently, the main benefit of the SON is reduced drag. I have never experienced a SON, so at this point I am completely happy with my $100 Shimano.

Thanks to all. I am now illuminated (groan) on the subject. I was concerned that the flickering would be noticeable at my normal speeds (and drive me nuts). I had been steering myself toward the Sturmey Archer dynohub with drum brake but have been looking at the Shimano hubs though. No disk brakes for me - my current commuter is > 30 years old and the one that I am building up is > 40.

I am sensing from the responses that the issue with drag is nothing more than another silly thing for the fretters to worry about.

I was planning on mounting a Lumotec IQ CYO N Plus.

Gary

i own both a shimano DH-3n72 and a schmidt son28. I can't really feel any difference, if that matters. not to say there isn't a difference though...

I love the lumotec IQ CYO lights. I have the regular and find lighting the "nearfield" is of little importance.

+1

I have one bike with a Shimano Dynohub, and another with the Schmidt SON - the Schmidt has slightly less drag, and is much prettier. Unless concerned about racing and dropping every possible gram and bit of drag, or you are unusually concerned with aesthetics, there is not enough difference between the hubs to worry about.

With regards to the flickering, my bike with the SON uses a Supernova E3 - when taking the bike out of the garage, first thing in the morning, there is flicker when first starting out, but after having ridden 100 yards or so, if I slow to walking pace, the light is solid - it has a standlight feature so once charged up, it is very steady.

Stand-lights are adding a capacitor in the light circuit, so it stays on at stoplights.
it will also smooth out any pulses that may happening, be at very low speeds.
like walking..

The standlight cap doesn't smooth flickering at lower speeds. I've got an Edelux, a Supernova E3 and an IQ Cyo (all with standlight) used on both SON28 and 3N72 hubs and all flicker at speeds below 3mph, even if I've been riding for 30 solid minutes and the caps are fully charged.

Exactly.

My light has an ambient light sensor which turns itself on and off according to need. It turns itself on under bridges and such during the day. The only way I know it does so is the reflection on the fender. Otherwise, I can't tell. Same when it shuts itself back off.

on any given hill, I out-descend (in the falling rock sense) almost everyone I ride with, so I'm not particularly concerned about the drag in my dynohub. The reason I want a Son is that they have the SON XL version that conducts the power through the dropout, which is a big upgrade from loose wires. But I as of now have 3 Shimanos and no Schmidts.

Both Schmidt and Sturmey-Archer make dynohubs with ISO disk mounts.

Shimano does too, the DH-3D30.