Dynamo hubs

The charging is via a USB cable to the rear derailleur. Probably you can do it from a dynamo but the wiring wouldn't be ideal

Shimano had a patent for dynamo jockey wheels a few years ago

https://www.bikeradar.com/features/shimano-electronic-gears-could-soon-charge-themselves/

woah

It’s deliberately disabled according to the docs.

Hopefully a simple question... will a 2.4 W dynamo hub sufficiently power a front light?

Specifically, I'm looking at pairing this cheapy Shimano hub (https://www.ebay.co.uk/itm/392281228871) with a B&M IQ-XS. No intention to run a rear light as I only feel comfortable using blinking rear lights (except in group rides).

Motivation is an approx £80 hub+light setup vs the £300 or so SON I'd planned. £220 would be nice not to spend. Google has led to some real rabbit holes so any help would be grand.

Yes. Modern shimano hubs are only rated at 1.5 W these days. 2.4W are absoultely fine. Dep on the light the flickering that some show at low speed may happen at a faintly higher speed, but we're talking 3mph instead of 2mph.

Basically the 2.4W rating is something to do with German regs, basically they're likely to be nearer 3W but that can't be assured, or something.

Yes, 2.4w will be fine for modern led lights (even if you add a rear) but not so great if you’re wanted to add additional load eg for battery charging.

Yes that's it, what @C4r1s implied .. the 2.4W dynos were meant to play well with halogen lights with a front light used only, and the 3W were intended for front and rear. Now we all run LED, this is immaterial.

BTW that cheapy hub is defintely the win for non-disc dynos right now. I bought half a dozen for The Future.

Banging, thanks both - had a feeling it was some regulatory weirdness behind the additional SKU. Ordered now - had nothing but good experiences with Shimano dynamos and like @Skülly says worth laying in spares too - already discovered that 135mm rim brake silver rear hubs are thin on the ground so it's clear the end times are coming :(((

Would recommend a rear light as well, you can always supplement with a blinky if you wish.

already discovered that 135mm rim brake silver rear hubs are thin on the ground

I find this so depressing. I will only move to thru-axle when it is obselete, not before.

Just use a QR 135mm disc hub without a disc :)

I think the 2.4W standard for front light only/3W for front and rear related to using incandescent bulbs (of which halogen achieves much better brightness). LEDs are much more efficient, although I wonder to what extent modern lights are still developed with a 2.4-3w standard in mind?

Has anyone ever seen a hub properly dragging when the lights are on, as in noticeably? Got this SP PD-8 that is definitely not right, whereas I've never really felt the couple of watts or so lost to the magnets.

Yeah, I had an old alfine dyno that felt like I’d gone up a gear as soon as it turned on (ie I’d have to drop down one gear on the cassette to a lower one to maintain the same feel of cadence and effort). It then shortly went pop, so it may have been related!

Anyone got a dynamo front wheel going spare/recommendations? Just upgraded to discs and need to replace my existing set. Thanks

Yes, I have a shimano hub on a Dt Swiss rim, will post details this evening

Re my message above, I’ve asked my LBS who seems to say SP hubs out of their two year warranty period might as well go straight to the bin.

SP hub in not working shocker.

Not quite true? I’ve had very old SP hubs def out of warranty sent back for repair (replacement) at Ison, cost me £25 or thereabouts

2.4 was good for a strong B&M light, which would also give light on very steep and slow stuff. One thing though, I find shimano hubs quite notchy. I thought my cheap 2.4W one was to blame, but an Alfine I recently installed feels just as rough.

SP PD-8 feels fine, and I'm never sure if I actually feel the difference between on/off. Shimano deore LX with 2.4W I can feel rattling in the bars as soon as I go over 25kph. I installed an Alfine recently but haven't ridden it yet. I can feel it vibrate through the bike on the stand, though.

I saw some people recommend going at the bearings in shimano hubs, is this actually advisable?

Anyone got any recommended approach for testing if there's too much resistance in ny SP Dynamo hub? Been suggested there might be an issue but keen to avoid disassembling wheel if possible and sending off for repair if i can avoid

Re SP, I just noticed that my hub is making a low rattling noise at very low climbing speed, especially when I tilt the bike to one side. Which I guess means it's the bearings? Hub has, I think, under 5000km, so that's a bit of a bummer. Still works, and I don't hear it while riding regular speeds, but this sounds like the beginning of the end.

Mine was making a weird noise, took the wheel out, rotated the axle a bit and put it back in, clamped it up and all good.

That was 4 years ago.