Alun Goch Posted March 28, 2006 Report Share Posted March 28, 2006 Ok, I'll explain this best I can, apologies if it's hard to make out:Anyway, the larger the diameter of your wheel, the more leverage available from the rim. True?So effectively, there are greater forces landing on ledges etc with a larger wheel. True?With a rim brake, this is compensated for, as the brake also has more leverage. True?Therefore in theory, as diskbrakes work on rotors of a certain diameter, would they perform better on a smaller rim?I think it would because there is the exact same amount of power available from a disk brake, on whatever wheel its on, but a larger wheel would have more leverage to work against the brake.Am I making sense?Anyone with opinions or greater knowledge please could you learn me!Thanks beforehand, Alun Quote Link to comment Share on other sites More sharing options...
tipsy Jock Posted March 28, 2006 Report Share Posted March 28, 2006 I think i get what you mean, A disk brake will work better on a smaller wheel becuase there's less force being applied to it. Also shorter spokes mean that theres less wobble in the brake. Quote Link to comment Share on other sites More sharing options...
Alun Goch Posted March 28, 2006 Author Report Share Posted March 28, 2006 I think i get what you mean, A disk brake will work better on a smaller wheel becuase there's less force being applied to it. Also shorter spokes mean that theres less wobble in the brake.Yes, thats what I mean.So does it have any effect? Or is it negligable?Alun Quote Link to comment Share on other sites More sharing options...
bikerdude2006fr Posted March 28, 2006 Report Share Posted March 28, 2006 Yeah it has an effect, thats why most people will reccomend a 160mm disc for a mod and a 180mm dosc for a stock to compensate for the extra forces needed with the bigger wheels Quote Link to comment Share on other sites More sharing options...
tipsy Jock Posted March 28, 2006 Report Share Posted March 28, 2006 Yes, thats what I mean.So does it have any effect? Or is it negligable?AlunDefinately has an effect i think, i used to have an avid as a rear brake (on a stock) and it used to slip a lot, i like my maggie much more Although on a disc specific frame such as richs leeson or a Kot i think it might be less of an issue as the mounts are designed strictly for trials. Quote Link to comment Share on other sites More sharing options...
011001000110010101110010 Posted March 28, 2006 Report Share Posted March 28, 2006 I beg to differ, I run a 165mm rotor on my 24. Hope mini originial if you'd like to know. And it is simply the best disc brake I have ridden. A mate of mine has a 205mm and his is no where near as good as mine. Alot of people will vouch for this. Larger does not always mean better. Quote Link to comment Share on other sites More sharing options...
Will Arnold Posted March 28, 2006 Report Share Posted March 28, 2006 I beg to differ, I run a 165mm rotor on my 24. Hope mini originial if you'd like to know. And it is simply the best disc brake I have ridden. A mate of mine has a 205mm and his is no where near as good as mine. Alot of people will vouch for this. Larger does not always mean better.technically, it does.his could have been contaminated/badly set-up etc...lots of variables. Quote Link to comment Share on other sites More sharing options...
CurtisRider Posted March 28, 2006 Report Share Posted March 28, 2006 wills right, my first mini was f**kin superb, best brake ive ever owned, but my second one had nothing on it...both same size, same pads, same rotors....weird! seems to be luck of the draw with some brakes Quote Link to comment Share on other sites More sharing options...
deanie-b Posted March 28, 2006 Report Share Posted March 28, 2006 Variables IndeedHave to compensate for Frame flex,Heat dissapation, there is too many factors, to say simply that one is better than another. Quote Link to comment Share on other sites More sharing options...
011001000110010101110010 Posted March 28, 2006 Report Share Posted March 28, 2006 Ok both brakes from cold, first use mine is better.Pads are both hope standard.Frame flex? Quote Link to comment Share on other sites More sharing options...
hardcore_raver Posted March 29, 2006 Report Share Posted March 29, 2006 (edited) technically, it does.his could have been contaminated/badly set-up etc...lots of variables.correct, a larger disc means providing the brake has the same amount of power (from lever) theoretically the larger disc will stop quicker than the smaller one due to basic laws of physics.its all to do with momentum and speed; a larger disc has a higher speed (mesured on perimiter of disk) but less momentum which means that the same amount of power through the lever will actually produce the same amount of pressure, but because of the momentum being minimised by using a larger disc, it means that the wheel will stop quicker."So effectively, there are greater forces landing on ledges etc with a larger wheel. True?"FALSEwheel size is a similar matter although strength comparisons are hard to make as more money is put into research in 26" wheels than 20", not to say that there arent good 20" wheels on the market today.there are a lot of variants in these things but careful concideration and reviews can help. Edited March 29, 2006 by hardcore_raver Quote Link to comment Share on other sites More sharing options...
dave33 Posted March 29, 2006 Report Share Posted March 29, 2006 the mini will feel better almost like it has more 'snap' because its got a smaller rotor but it will take a later force to move the wheel with the bigger rotorthe best way to explain this is in terms of car brakes, you would think if a car with normal rotor skids when trying to stop fast then if bigger discs are fitted the car will just skit sooner, but this is not the case the bigger disc sloow the car faster than the smaller disc and they stop it from skidding as soon when under hard braking Quote Link to comment Share on other sites More sharing options...
PaRtZ Posted March 29, 2006 Report Share Posted March 29, 2006 So if Im getting this right, providing all variables are equal (and er...not varied) a magura on a stock bike will work better than a magura on a mod bike?Im using the "opening-a-farmers-gate" principal in my mind, its easier to control the further away from the fulcrum......Hmm I think this is going to be a thread similar to the plane on a converyor belt one.... Quote Link to comment Share on other sites More sharing options...
Greetings Posted March 29, 2006 Report Share Posted March 29, 2006 (edited) 26" wheels: Rotor size 160mm - 0,242 180mm - 0,272 185mm - 0,280 203mm - 0,307 24" wheels: Rotor size 160mm - 0,262 180mm - 0,295 185mm - 0,303 203mm - 0,332 20" wheels: Rotor size 160mm - 0,314 180mm - 0,354 185mm - 0,364 203mm - 0,399 With these numbers it is easy to realize that a 203mm rotor on a 26" wheel will be less effective than a 160mm rotor on a 20" wheel. The larger the number, the more power the disc will deliver. More accurate calculations are dependant on the size of disc race and the shape of the pads. This however requires calculus and I'm not yet quite familiar with using it.edit: of course I'm not taking the power of the caliper and grip of the pads etc under consideration, after all we're only talking about disc sizes here Edited March 29, 2006 by Inur Quote Link to comment Share on other sites More sharing options...
Alun Goch Posted March 30, 2006 Author Report Share Posted March 30, 2006 So if Im getting this right, providing all variables are equal (and er...not varied) a magura on a stock bike will work better than a magura on a mod bike?Im using the "opening-a-farmers-gate" principal in my mind, its easier to control the further away from the fulcrum......Hmm I think this is going to be a thread similar to the plane on a converyor belt one.... Well, technically, they have a better lock, but because of the larger diameter, the forces from ledges etc. are also greater, so I suppose this makes no difference.Inur, what are the figures measured in?Alun Quote Link to comment Share on other sites More sharing options...
dave85 Posted March 30, 2006 Report Share Posted March 30, 2006 Those are ratios, dimensionless numbers. The magura will work better on a stock bike in theory, in practice its just closer to the ground and pics up more crap hehe Quote Link to comment Share on other sites More sharing options...
Si-man Posted March 30, 2006 Report Share Posted March 30, 2006 Yeah it has an effect, thats why most people will reccomend a 160mm disc for a mod and a 180mm dosc for a stock to compensate for the extra forces needed with the bigger wheels f**k that rule, 180mm hope trial on a mod, is a f**king beast!! Quote Link to comment Share on other sites More sharing options...
Zordon Posted March 30, 2006 Report Share Posted March 30, 2006 So if Im getting this right, providing all variables are equal (and er...not varied) a magura on a stock bike will work better than a magura on a mod bike? I think you're right, cause rim brake surface diameter/wheel diameter ratio is higher in stock wheels (even using the same height tyres). Quote Link to comment Share on other sites More sharing options...
011001000110010101110010 Posted March 30, 2006 Report Share Posted March 30, 2006 Its all about the moment, a moment is a turning effect. Moment = force x perpendicular distance from the pivotThe pivot being the axel. Quote Link to comment Share on other sites More sharing options...
Greetings Posted March 30, 2006 Report Share Posted March 30, 2006 Well, technically, they have a better lock, but because of the larger diameter, the forces from ledges etc. are also greater, so I suppose this makes no difference. Inur, what are the figures measured in? Alun the figures are not measured in anything its the disc size to wheel ratio. these figures are merely to be compared between each other. someone might want to put that up into FAQ for future reference. f**k that rule, 180mm hope trial on a mod, is a f**king beast!! getting a setup like that tomorrow, i'm not sure if it will not be too powerful. yet i probably won't need to bed the brake in for it to work well Quote Link to comment Share on other sites More sharing options...
Dan Clark Posted March 31, 2006 Report Share Posted March 31, 2006 Weight of the bike would also come in into it, mods usually being lighter would require less force to stop. Quote Link to comment Share on other sites More sharing options...
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