Cam MTB - the Cambridge Mountain Bikers' Forum

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  • Wear a helmet. Despite recent advances in medical science, brains still cannot be mended nor replaced.
  • Wear gloves or mitts. Hands often hit the ground first. Cuts and grazes invite infection and a hospital visit.
  • Wear eye protection, it only takes a twig or thorn to lose an eye. Crud catchers are a good idea in mucky weather.
  • When downhilling, for your own protection, allow plenty of space behind the rider in front.
  • Bring a bare minimum emergency tool kit and a spare inner tube.
  • Breakdowns are a bore. Plan not to have any by ensuring your bike is in perfect working order.
  • Punctures are also tedious. You can minimise them by fitting latex tubes, slime tubes or running tubeless tyres.

Photo: CAMMTB Winter 2022-23 rides have been posted up - please click on the Runs List link..

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Introduction, query about building better nightlights

Dear all, (new here!!)

I must say I notice your sort of group describes the sort of thing I go/do myself, being somebody who basically uses a well-maintained hardtail MTB as a hybrid, basically, town bike, distance, and offroad tracks.

I've been down that (gets muddy!!) offroad from Newton to Foxton quite a few times now. I've been to various other sites from Cambridge, Gogg magog hills / the roman road, down to Whittlesford, up to Ely, Across to Huntingdon, etc.

Its' possible I may be here until 26th, next ride out, etc. could at least say hello before I go away most of the Summer! As below i possibly could do with temporary use of a light, if this happens.

I notice what you say about lights -- myself, I really seem to have some night vision going and don't find myself needing amazingly bright lights, typical nicer cateyes etc. work for me (though one of mine is in need of a new nimh pack)! I definitely find LEDs with their higher CCT much better definition than halogens, myself.

I would be interested to know, as something I can do this summer, -- What do you do to build a really decent modern led bikelight? I recall some of the caving people like reusing older housings and just installing a modern heatsink/led-chip with the right switchmode driver? Curious how you do these things... =).

Simon Iremonger
Wolfson College, Cambridge.

Re: Introduction, query about building better nightlights

I built my own LED lights...

I'm running 4 x Seoul P4 (3.5W) driven in series from a 1A Buckpuck controller.

I use two 3300mAh 9.6V NiMh battery packs wired in series to give the headroom for the LEDs.

The LEDs are mounted inside a 1" diameter tube that has a section of 7/8" bar hammered into it to act as a heat sink. The LEDs are mounted on star boards and glued on to the heat sink with thermal epoxy. I have two LEDs with wide angle lenses and two with spots.

I configured the controller to have 3 settings - off, 330mA and 1A, and can switch the spots off separately - like dipping a car headlamp.

On full power with wide and spots on I get just over 3hrs run time. With only the 2 wide angle LEDs on low I get 24hrs.

Hope this helps,