Any question answered...

There must be at least as many Watts absorbed from your motive power as are output as electricity. If there aren't, I'm getting a front dynohub to power a rear wheel motor for perpetual motion :-)

I just put a Velogical rim dynamo on my tourer, which is pretty great for weight and not needing to rebuild a wheel, but I've not been able to compare it to a hub. Has the advantage of being able to totally disengage when not in use.

Has the advantage of being able to totally disengage when not in use.

The no-load drag of the good dynohubs is probably less than the added aero drag of your rim dynamo :-)

Most modern lights will use 3W and with 60% efficiency that's 5W draw.

Using [1] at my usual plodding pace 160W gets me 26.6kph. 155W gets me 26.3kph.

I'll take a 0.3kph speed loss for the sake of not having to worry about batteries. You'll lose more than that through low tyre pressure.

1. http://www.kreuzotter.de/english/espeed.htm
   

I'm thinking the cheaper end of things so a shimano dynamo hub(or maybe just shopping in all the wrong places).

Reading online I should be able to power a rear light and charge some sort of battery pack which will output usb ports for charging but all the solutions for that seem to be diy and I'm not too keen on diy lipo packs.

B&M eWerk allows you to connect a hub dynamo and output USB, you'd then use whatever USB storage battery you want (get one from Portapow or similar). But with this you can't have a light attached at the same time.

http://www.rosebikes.co.uk/search/find/?q=B+%2B+M+E-Werk+power+supply+and+charger

For a front light too you could get a B&M IQ2 Luxos U that has a separate USB output (along with a switch to put it in high power mode).

http://www.rosebikes.co.uk/article/b--m-lumotec-iq2-luxos-u-senso-plus--front-headlamp-with-usb-connection/aid:620049

Personally I'd prefer a separate switch to the USB port as USB ports aren't weatherproof. Either you have the 'full beam' switch on the handlebars and risk plugging a USB plug in in the rain, or you bury it a bag (so it's away from water) but can't switch between full/dip beam. Mind you, the concept of 'full beam' is a bit unnecessary on a front light. If it's positioned/angled correctly you shouldn't need to dip anything.

Can't see if either of those will also power the back light for you at the same time.

Reminds me, I have an old IQ Fly lying around that I should put on my commuter, just need a cheap Shimano Dynohub front wheel (Rose Bikes do them cheap too).

His bike is the Time Machine. It probably doesn't care about any daft laws of thermodynamics.

@Greenbank I was thinking I would stick with the cree xml up front and then have the dynamo do the rear light and charge stuff. Not going to ditch the cree anytime soon as I'm sure it's sun on handlebars style light puts drivers off pulling out across me and shouting smidsy.

Next time I'm buying wheels not much in it between dynamo and non dynamo so will end up with some I think.

18650 rechargeable batteries: are some better than others, or will ebay cheapies be as good as anything?

Correct link this time
http://www.torchythebatteryboy.com/p/18650-batteries-chargers.html

Hmmm. Not exactly sure what those graphs are showing me!

42t 130mm narrow-wide chainrings.
Anything out there except RaceFace and Wolftooth?
And maybe a bit cheaper?

Absoluteblack?

http://absoluteblack.cc/cx-rings.html

I don't know how much the RaceFace and Wolftooth ones are, but these are £60.

Ah yes, just found these.
RaceFace are still cheaper though.

I've never used these guys before, but was doing some searching for a friend and this company looked okay.

http://blackberrycars.com/

Cheers

The environmentalist snow priecer.

Where can I test ride a genesis volare?

If it can wait...

I have their 104bcd ring and it works just peachy.

backstory:

we have a storage boiler than runs from 2am to 7am every night, up until 3 weeks ago it was fine, since then we can only shower in it in the morning if you turn the mixer tap up to full (so its pure hot water, no cold and even then its not exactly hot, its just warm), we cant do dishes in the evening with anything more than luke warm water (even if we dont use a drop of hot water that day)

However if we use the 'boost' setting on the boiler in the evening, we get good (normal) hot water, suggesting that the boiler does work to an extent.

landlord sent (cheapest guy they could find) round, he tested the thermostats (using a volt meter tthingy) and said they seemed fine and his response was 'it might just be because the waters cold outside now so its not getting hot enough'. He also said that 5 hours should be more than enough for it to heat the water up.

my landlord now thinks that we're just being picky and doesnt seem to want to do anything else, even though boiler man suggested the elements may need replacing.

Replacing the elements im not sure is the problem because the boost works, but boiler man didnt seem to have an answer to that.

Anyone got any ideas?

awesome.
why isn't this more widely used?

why isn't this more widely used?

Large hysteresis and scrubbing losses in the rubber drive tyre makes a big dent in the overall efficiency.

That's awesome thanks, yes it can wait!

we have a storage boiler than runs from 2am to 7am every night [...]

Do you mean an immersion heater? (Boiler=white box sitting on the wall, water and gas pipes in, flames inside. May heat water on use (in which case you wouldn't have the timer) or heat water that is stored in a separate tank. Immersion heater=giant kettle element in the water tank itself, water pipes to tank, power cable to end of heater.)

However if we use the 'boost' setting on the boiler in the evening, we get good (normal) hot water

It is fairly normal for immersion heaters to be set up with two elements, one long one that reaches most of the way down the tank and heats the whole thing, and one short one that only heats the top third or so. It's also fairly normal for it to be set up that normal, day-to-day heating uses the long element so you've got enough water for showers, baths etc, and for the boost switch to use the short element to give you enough water for the washing up fairly quickly.

[internet diagnosis]
You're probably there already - without seeing the thing, I'm suggesting you have two elements, and one has failed ... They do, you see, especially if they're ancient and in a hard water area ...

Did your landlord's cheapie chappie do anything like a continuity test on the element(s)? If one has failed, it'll probably have gone open circuit.

This'll give you an idea what the top of an immersion heater looks like - they're not exactly pricy. Biggest danger with replacing them is ripping the tank copper, especially if the old one's been in place for a while.

Anybody know where I can get a busch muller 470h bracket for mounting my headlamp? It looks like this

I can find it on ebay but dont fancy paying circa £15 for it. The shorter version can be had for about £4 but doesn't put the lamp high enough to clear the tyre properly. The original fitting with the light fouls the headset or mudguard and can't be used.