I use a p7 torch on my helmet for my commuter duties (on a bike!), it's attached with some $3 mount from dealextreme and it works for me. Certainly gets you noticed by drivers when looking over your shoulder and the like, not that I guess that's much of consideration in the night rollerskiing game.....although I have to admit this is the first time I have become aware of night rollerskiing, so I'm guessing 🙂

Cheap but effective. Plenty of light.
1hr 10mins on full. Less than 1 min to swap cells.
2hrs plus if run on 1/3 or 2/3 power for climbing etc.

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[url= http://www.flickr.com/photos/takisawa2/5094447195/ ]IMG_0871[/url] by [url= http://www.flickr.com/people/takisawa2/ ]pten2106[/url], on Flickr

[url= http://www.dealextreme.com/details.dx/sku.12060 ]Torch,[/url] [url= http://www.dealextreme.com/details.dx/sku.5790 ]cells,[/url] [url= http://www.dealextreme.com/details.dx/sku.1251 ]charger.[/url]
[url= http://www.dealextreme.com/details.dx/sku.12000 ]mount[/url]
£31.41

I've got one of those but prefer this [url= http://www.dealextreme.com/details.dx/sku.16092 ]one[/url], but what ever you decide if it's a P7 900-lumen unit, it'll be ace.
Though I'd not recommend any of the 2 mode units, the low on those is rubbish (a decent low is useful on the road, the medium will extend you batteries life on the boring bits) and it's not difficult to count the clicks to get the '5-Modes' past the flicker settings.

I have the magicshine which I've always run on the bars till last week when I stuck it on my lid and it was really good. Didn't bother with the mount as I can just strap it straight onto a vent ridge on my Hex with the o ring. Zero fuss, brilliant, and they'll do about 3 hours+ on full.

If ultimate brightness isn't a factor then maybe also consider an XRE or XPG based torch too. They're cheaper (about £9-15), have longer runtimes off the same single 18650 battery and some of them weigh a lot less.

To be honest, what I did was buy the batteries, charger and mount. Then bought 3 torches to try as they don't really seem that expensive and I figured someone would have them off me.
This one's arrived:
http://www.dealextreme.com/details.dx/sku.15335 and is great, but maybe a little too tight a spot. It's very light, small and gets long runtimes.
The other 2 to arrive are these:
http://www.dealextreme.com/details.dx/sku.12060 (same as takisawa2 above)
http://www.dealextreme.com/details.dx/sku.33550 (XPG - maybe a little heavy to justify itself against the P7, but we'll see).

I'm using mine in conjunction with a bar P7 so my needs are a bit different to yours - a reasonably tight spot is desirable for me.

alexsimon... how do you like the tight spot light with your bar mounted P7 - does it offer a significant difference?

reason i ask is that i use a few year old led headtorch that is quite dim by p7 standards (it was fine with a 10/15w halogen combo!!) and doe'snt really stand out when i have the p7 on full blast so was considering getting a new torch for the helmet that would give me a better spot up the trail out of the wide beam of the p7.

I use two P7s - one on bars and another on head. Latter has a more spot type beam to pick out trail further ahead. Works very well, except the head spot is a bit big and heavy to be comfortable. Planning on getting something a bit lighter - probably XP-G as suggested above. Less than $15 from DX.

gavtheoldskater - well, what I've decided to do is point it higher and higher each time I've been out (3 rides). So it's actually a fairly large spot, but a fair distance away. Probably about 3 times the distance I set my main Magicshine P7 to.

I initially pointed the headtorch (the 230 lumen XRE) just slightly beyond the main beam of the P7, but I found the spot too bright and small.

f ultimate brightness isn't a factor then maybe also consider an XRE or XPG based torch too.

Ultrafire wf108 is C $20 or £14. P7 emitter and a tight spot, looking at a user posted vid on DX website. I have just ordered one to test. Might need a small amount of work with some thermal grease as they get warm on full chat.

singletrackmind - I can't find that model - did you mean the WF-501B WF-502?

Yes clicky link
http://www.dealextreme.com/details.dx/sku.36356

I just ordered a pair snd some 2500mah batteries .

For the cash it seems a good level of light .

On CPF there is a thread with a triple p7 emitter torch , frikken awesome light levels, like the Troute light.

It seems like some people get a really good bright torch (but runs hot) and some get a really low current sent to it which makes it less bright than an XRE. Hope you get a good one!

Just thought I'd update with some info on the new light which turned up:
UniqueFire L2 Cree XPG-R5
http://www.dealextreme.com/details.dx/sku.33550

It's definitely brighter than the TR-801 and a slighly larger, more blended spot. But it's also more blue and not as large a spot as I was hoping for. The halo is smaller and brighter though which I think is good. On the TR-801 the halo is so much in contrast to the spot that it's hard to see.

With the battery in it it's 157g (compared to 115g for the TR-801), so it's a little heavy on my currently slightly loose helmet. I'm sure it wouldn't be a problem for someone with a good roclock type system.

I only had a quick play but so far it seems pretty even between small+light+bright enough - versus - bigger+heavier+brighter