FAO Yeehaa

YeehaaMcgee

bennett_346 wrote:

Yeah, tyres will have an effect on braking performance, but i'd wager that it's minimal. You can still play with pressures remember.

I assure you that they can and will make a huge difference. On the hill I had in mind, for example, You'd struggle to come to a stop with Kenda Nevegal DTCs, and if it's been raining in the last day or two, then it's highly unlikely I'd be able to stop at all with Halo Twinrails, whereas Continental mountain kings will work quite well.

bennett_346

YeehaaMcgee wrote:

bennett_346 wrote:

Yeah, tyres will have an effect on braking performance, but i'd wager that it's minimal. You can still play with pressures remember.

I assure you that they can and will make a huge difference. On the hill I had in mind, for example, You'd struggle to come to a stop with Kenda Nevegal DTCs, and if it's been raining in the last day or two, then it's highly unlikely I'd be able to stop at all with Halo Twinrails, whereas Continental mountain kings will work quite well.

You're still converting the exact same amount of kinetic energy into heat whatever tyre you use from a given speed to zero, and where some will be used to deform the tyre and the tread will have an effect on this, the biggest effect on the energy used to deform the tyre will be the tyre pressure itself.

YeehaaMcgee

bennett_346 wrote:

You're still converting the exact same amount of kinetic energy into heat whatever tyre you use from a given speed to zero, and where some will be used to deform the tyre and the tread will have an effect on this, the biggest effect on the energy used to deform the tyre will be the tyre pressure itself.

Like I said, i assure you that with some tyres, you will not be able to come to a stop, because there will not be enough traction.
That means that less energy is being dissipated by the brake, since it's not actually shedding all of your kinetic energy.

bennett_346

That's more related to the length of the hill really, you could stop on them if the hill was long enough to modulate the brake effectively and slowly come to a stop, the only difference being theyd have more time to dissipate heat before the bottom.

YeehaaMcgee

bennett_346 wrote:

That's more related to the length of the hill really, you could stop on them if the hill was long enough to modulate the brake effectively and slowly come to a stop, the only difference being theyd have more time to dissipate heat before the bottom.

The hill has a finite length. At the end there's a very sharp right hand bend. The hill is often slimy. You either stop, or crash into the wall, or aim for the driveway near the corner.
Think about driving a car on ice, the brakes cannot possibly work as hard as on dry tarmac.

bennett_346

I'm not disputing that. I'm just disputing the point raised that it would invalidate any results you got.

Ghostt

Basically, whenever you perform any sort of scientific investigations, you are usually trying to measure one variable, and so need to keep every other variable, which could affect the end results, the same for all the tests in order to say 'this happened because of x'. If you want to see if you can get a disc brake over 200c by riding down a hill then great, ride down and see.

Trouble is, there are too many variables to just say 'well, I rode my bike down a hill and the brakes didn't get to over 200c, therefore disc brakes can't get hotter than 200c'. There are too many variables: the brake system, the pads, the rotors, the tyres, the tyre pressure, bike weight, rider weight, ambient temperature and weather will all affect the results to some extent.

If you wanted to find out if a disc brake could go over 200c at all, then a more controlled environment is needed, such as a bench rig. However, I would be interested to see how hot you can get the brakes, I certainly know they get hot enough to leave a lovely rotor pattered burn mark!

steelie600

Of course you can get em over 200*c on a test rig. What I said was in normal use they will get over 200*c. Hence the big steep hill with a stop or die corner! This should simulate a downhill run, we can also use say LLandegla black runs and have a temp monkey at the bottom and a loony tick thats gonna come down at a billion miles an hour. (Anyone got Peatys number?)

Oh and that Traxxarse temp sender is no good as its a contact one, and about as accurate as hitting the moon with a spud gun. I also race nitro Rallyx buggies. Came 2nd in the Northern regionals once!

YeehaaMcgee

Llandegla blacks aren't anywhere near steep enough to stress brakes to breaking point, unless you're a chickensh*t numpty. Peaty would barely touch his brakes.

steelie600

Fair does, Fort William it is then!! ROAD TRIP!!!!!

Raymondavalon

steelie600 wrote:

I also race nitro Rallyx buggies. Came 2nd in the Northern regionals once!

OMG, he came second, second.. in a regional RC race series, ZOMFG, what a man, no a god, am icon, Clark Kent has nothing on this guy, nothing I tell you...

Northwind

steelie600 wrote:

This should simulate a downhill run, we can also use say LLandegla black runs

How about using a downhill run? Fort William, and put the bike in the hands of a coward. I barely released the back brake on my first run, you could feel the heat pouring off it when I stopped without getting anywhere near touching it- like a cooker hub.

Stevo 666 wrote:

but what the fark is a sensible thread like this doing in the Crudcatcher?

Well I could move it to the Hub if you like, but nobody ever reads the Hub.

steelie600

It didnt start out sensible tho!! Its gone that way with a healthy injection of Jedi level geekiness and anorak wearing

YeehaaMcgee

Yeah, the plan so.far, is to get a fat guy, a fairly fat guy, and a twig, to ride down a steep slimy hill, near a pub, and try not to crash.
Sounds like a proper crudder plan to me.

steelie600

So im the fat guy, your the fairly fat guy, whos volunteering to be twiggy then??

YeehaaMcgee

Nobody yet.

Richie63

Just been reading this thread and if you want a twiggy (72Kg) rider who'll chuck themselves at a pub I'll do it
Could also bring a selection of bikes to the party.

This sounds a right laugh and possible Darwin Award material

WHEN?

steelie600

gonna be a few weeks yet kidda as im concentrating on building my bike. See my Univega thread on here.

But will be before the end of summer. Also its not so much a selection of bikes, more a selection of brakes. IE Cheap shimanos, ice techs, saint downhills. Avids Juicy, BB7, elixir, etc

YeehaaMcgee

Holy crap. How many? I've got a Shimano XT, and I guess I could probably try and set up an old Hope C2, and get my bike which has the old Saint single-calliper brakes back from my mate, and bleed them. Except he doesn't want me to bleed them, because he's already scared of how powerful they are.

How about we just bring our bikes with whatever brakes are on them, and we each ride each bike.

Richie63

Yup can do a selection of brakes, Formula, XTR, Elixir, SLX on different bikes.

YeehaaMcgee

Richie63 wrote:

Yup can do a selection of brakes, Formula, XTR, Elixir, SLX on different bikes.

You think any of us can afford XTR?

steelie600

I fecking cant!! Thats fer sure LOL!! My budget for brakes is about £60 ish LOL

Yehaa if your mate doesnt want them 2 pot saints ill buy em off ya!! Much cheapyness of course!

nicklouse

So who has been to the Alps?

Richie63

Me and back there in August

steelie600

nicklouse wrote:

So who has been to the Alps?

I want to go. My target is to do the Mega in 2014. Why you ask such heinous questions??

bennett_346

nicklouse wrote:

So who has been to the Alps?

Me. Never got faded brakes (Elixir) and i dragged down a fair few 15 minute descents.

YeehaaMcgee

steelie600 wrote:

Yehaa if your mate doesnt want them 2 pot saints ill buy em off ya!! Much cheapyness of course!

Steady on, they're actually my brakes, on my bike! He's just sort of borrowing it, long term.

nicklouse wrote:

So who has been to the Alps?

Oooh, many many people. I've been there twice this year, and three of my mates were on both trips. Why do you ask?

Twelly

Just thought I would resurrect this thread with something I just stumbled on

http://www.sicklines.com/2011/02/14/shi ... mark-test/

Testing results for the Shimano Ice Tech brake discs....

...including heat readings of way over 400 degrees for 'traditional rotors'

Case dismissed

YeehaaMcgee

TwellySmat wrote:

Just thought I would resurrect this thread with something I just stumbled on

http://www.sicklines.com/2011/02/14/shi ... mark-test/

Testing results for the Shimano Ice Tech brake discs....

...including heat readings of way over 400 degrees for 'traditional rotors'

Case dismissed

Erm, no it isn't. Not only do they not mention if they're using some mechanised test rig, in which case it would be easy to reach incredible temperatures, but they don't seem to mention any temperature readings at all. They measure in WATTS.
FAIL

cooldad

And every fule kno you measure temp in volts.