Dynamo Lighting [was: LEL FAQs]

[Greenbank]

When you turn Solidlights off it still draws some power (i.e. applies a small resistance) in order to keep the voltage down to protect the delicate electronics inside and (I think) to keep the standlight accumulator topped up.

With little or no resistance a dynohub can go over 50V on an open circuit.

An E6 is just a bulb in a circuit. It doesn't need equivalent protection as the voltage will be drawn down to a safe level by the time the filament has heated up, so the temporary over-voltage surge is dealt with safely.

In other words, there's no difference between lights off and hub disconnected with an E6 (or two), but there is a difference between lights off and hub disconnected with Solidlights.

Lights off on a Solidlight is not the same as lights off on an E6.

[border-rider]

I can't tell the difference with a  Solidlights, connected or not.  I'm pretty convinced that any difference it makes is entirely negligable compared to other loss mechanisms, as Vorsp said.  The sheer lack of faffage makes it a clear winner for me on rides involving night.

[Mr Larrington]

Wot MV said.  If I'm riding the Speedmachine I tend to leave the Solidlight on all the time coz I can't reach it from a seated position to turn it off

[mike]

+1. 

I used to think the solidlight & SON was slowing me down till I bought a battery light and tried that instead - it's not the hub, it's riding in the darkI'm scared of the wheeliebins.  

But I didnt know that about unplugging it.. I'll try that next time!

[Chris S]

A couple of times I've ridden with the Solidlights plugged in during the day and I've looked down and thought "Sod it, it's plugged in."

Next time I stopped, I unplugged it. The difference? Bugger all.

[Chris N]

You might not physically notice unplugging the light/switching them off/not using a dynohub, but it will make a difference - whether it's actual or a placebo doesn't matter.  Lots of small differences = one big difference.

[LEL]

Word form route checkers is tht the route around Eskdalemuir has a significant number of potholes.

Advise a wide spread ligth beam around here.

[Greenbank]

You might not physically notice unplugging the light/switching them off/not using a dynohub, but it will make a difference - whether it's actual or a placebo doesn't matter.  Lots of small differences = one big difference.

Exactly. I always try and remember to unplug mine for the daylight ours. I'll plug it back in if it's going to start to get dark on the next section. Lights on all the time = 1400m extra climbing over the LEL distance. It's an extra 0.25 AAA for an AAA rated 300km ride.

Tomorrow I'll ride to the start of the Elenith with Solidlights on and then unplug them at the hall (I'll also try and remember to swap to sunglasses at this point!). If I'm as slow as last year I can then plug the Solidlights back in, and swap to normal glasses at Rhayader.

[Panoramix]

SON's load is about 6W at 20kph rising to about 8W at 40kph (see DYNOTEST )

If cyclist + bike = 90kg
speed@20km/h : 20/3.6 = 5.6m/s
gravity 9.8 N/kg
incline 1% = 1m climbed for every 100m travelled

90 x 5.6 x 0.01 x 9.8 = 49W

so to climb a 1% incline at 20km/h you need 49w on top of the power necessary to cycle on the flat at 20km/h

6/49 = 0.12.

So having the Dynohub equals climbing a 0.12% slope. 1400 x 0.0012 That is an extra 1680 m of climbing on LEL assuming you have it on all the time. If you do 10% night riding, that is 168m!

I wish I had a SON!

[border-rider]

I wonder if you lose more time in the plugging/unplugging than you gain in not having the tiny extra amount of drag...

[Greenbank]

I wonder if you lose more time in the plugging/unplugging than you gain in not having the tiny extra amount of drag...

Possibly. To look at it another way:-

2 * B&M Ixon + 2 sets of 4xAA lithiums would easily cover all the night riding on LEL that I expect to do. One light on low power for most night riding. One light on high power for faster bits, both on high power for tricky descents. I doubt you'd have to even change the batteries. Cheapo blinky LED for visibility.

That setup is probably 100g lighter than Solidlights 1203D, let alone the extra weight and increased rolling resistance of the SON hub. No matter how good the SON is, it won't beat a decent non-generator hub.

Don't get me wrong, I love my SON + Solidlights and will continue to use them for Audaxing and commuting long into the future but, for LEL, for me, for riding plan, it makes more sense to use battery lights.

[LittleWheelsandBig]

I wonder if you lose more time in the plugging/unplugging than you gain in not having the tiny extra amount of drag...

Jan Heine suggests that the drag of a SON hub is worth about 1.5% of the overall riding time of a brevet.  Check out www.cyclosmontagnards.org where some USA-ians have decided to recognise various average brevet speeds.

The interesting part that pertains to this discussion is "Battery powered headlights are considered "outside assistance." They are allowed but we add a penalty of 1.5% to the time of riders who use battery-powered headlights. This levels the playing field compared to the most efficient generator hub systems available today."

[border-rider]

it makes more sense to use battery lights.

Oh I agree

If I were investing now from scratch in lights for audax, I'd look very hard at battery lights. 

[scottlington]

I wonder if you lose more time in the plugging/unplugging than you gain in not having the tiny extra amount of drag...

Jan Heine suggests that the drag of a SON hub is worth about 1.5% of the overall riding time of a brevet.  Check out www.cyclosmontagnards.org where some USA-ians have decided to recognise various average brevet speeds.

The interesting part that pertains to this discussion is "Battery powered headlights are considered "outside assistance." They are allowed but we add a penalty of 1.5% to the time of riders who use battery-powered headlights. This levels the playing field compared to the most efficient generator hub systems available today."

That's ridiculous.

[scottlington]

I wonder if you lose more time in the plugging/unplugging than you gain in not having the tiny extra amount of drag...

Possibly. To look at it another way:-

2 * B&M Ixon + 2 sets of 4xAA lithiums would easily cover all the night riding on LEL that I expect to do. One light on low power for most night riding. One light on high power for faster bits, both on high power for tricky descents. I doubt you'd have to even change the batteries. Cheapo blinky LED for visibility.

That setup is probably 100g lighter than Solidlights 1203D, let alone the extra weight and increased rolling resistance of the SON hub. No matter how good the SON is, it won't beat a decent non-generator hub.

Don't get me wrong, I love my SON + Solidlights and will continue to use them for Audaxing and commuting long into the future but, for LEL, for me, for riding plan, it makes more sense to use battery lights.

That makes a great deal of sense. A reasonable amount of night riding is spent riding along lit roads and the Ixxon IQ I think is way too bright even on low setting for that. A £5 Frog front is well worth it to save on battery life as much as possible. My set up for LEL will be (and currently is) 1 x Ixxon IQ and 1 x cheapy Frog. 2 may be cool but 1 of these lights on high setting is probably ample for my needs.

Mind you, what if it fails.... hmmm *thinks again*

[clarion]

I wonder if you lose more time in the plugging/unplugging than you gain in not having the tiny extra amount of drag...

Jan Heine suggests that the drag of a SON hub is worth about 1.5% of the overall riding time of a brevet.  Check out www.cyclosmontagnards.org where some USA-ians have decided to recognise various average brevet speeds.

The interesting part that pertains to this discussion is "Battery powered headlights are considered "outside assistance." They are allowed but we add a penalty of 1.5% to the time of riders who use battery-powered headlights. This levels the playing field compared to the most efficient generator hub systems available today."

That's ridiculous.

No, that's fair.  So long as they have built their bike themselves, including mining the ore...

[border-rider]

Actually, it's quite possible to ride LEL hardly using lights at all.

[red marley]

Actually, it's quite possible to ride LEL hardly using lights at all.

I'm not sure sure that's going to be possible for a large number of people this year. My start time is 2:00pm, so would probably not be able to build up enough time before dark on the first night. Also, with 600 riders all starting from London, I think there will be greater demand for sleeping space this time. Combined with Mel's recent announcement that we will have to provide our own sleeping stuff in our bag drop(s), I am expecting to have to do at least one, probably two, through the night sessions.

[border-rider]

Actually, it's quite possible to ride LEL hardly using lights at all.

I'm not sure sure that's going to be possible for a large number of people this year. My start time is 2:00pm

Fair enough

I did say "possible", and that is predicated on having a sensible start time

see also PBP and the benefits of the 84 hour group

[Panoramix]

Thinking a bit further:

Switched on SON = 3.6 extra kg on a 3% incline @ 20km/h. This sounds a lot if you see it this way as I would definitely not bolt 3.6kg dead weight on my bike!!!!

[Hummers]

I wish I had a SON!

You are not wrong there.

They are so much less complicated than daughters.

H

[Panoramix]

I wish I had a SON!

You are not wrong there.

They are so much less complicated than daughters.

H

thanks for the tip, it sounds very wise. I have two daughters and they can be a bit difficult to please. The 6months old version has the bad habit to whinge at 2am. If only I had known before that SJS was in this business my nights would be much more peaceful!

[frankly frankie]

I was going to use some LED  battery torches (TR801) on the elenith instead of lugging the SON + solidlight combo around. 
By the time i'd worked out how many batteries (industrial style 18650 li-ions) might potentially be required for the given number of possible hours on unlit roads (plus a spare back-up battery) along with a standby cat-eye 410 for town-use i decided not to bother. 

Actually, it's quite possible to ride LEL hardly using lights at all.

Come to that, its possible to ride the Elenith entirely in daylight ...

[border-rider]

Come to that, its possible to ride the Elenith entirely in daylight ...

Yeah, but that requires the rider to be somewhat swift.  LEL in daylight doesn't really - it just needs a bit of planning.

[rogerzilla]

I reckon the dynamo slows me down by 0.5mph.  I run it for about 80 miles of the Dun Run, which means I get to Dunwich a whole 8 minutes later.