JT! Posted October 5, 2007 Report Share Posted October 5, 2007 (edited) Just wondering really, what makes the hope mono trial a trials brake? How does only having one piston make it more suitable for trials when more pistons make the brake more powerful.And, how does having more pistons increase the power? Becuase surely the power on a two piston system is halved for each one? What are the pros and cons over a floating rotor against a normal rotor? Edited October 5, 2007 by JT! Quote Link to comment Share on other sites More sharing options...
Shaun H Posted October 5, 2007 Report Share Posted October 5, 2007 Just wondering really, what makes the hope mono trial a trials brake? How does only having one piston make it more suitable for trials when more pistons make the brake more powerful.And, how does having more pistons increase the power? Becuase surely the power on a two piston system is halved for each one? What are the pros and cons over a floating rotor against a normal rotor?The Mono trials has 2 fapping great pistons because it gives a high leverage ratio i.e. small lever piston:giant calliper pistonsThis increases the power of the brake making it more suitable for trials. However it does cause a noticeable amount of flex in the calliper.More pistons increases the power so long as they produce a higher leverage ratio. So if you replace 2 massive pistons with 4 pistons of equal surface area then they will produce the same power. However more pistons usually gives a more progressive feeling brake.Floating rotors are good at dealing with heat and can be lighter than the full stainless equivalent. However I'm not sure how they alloy spider would deal with the forces in trials. It may well be that they're fine but there's no telling without trying. Quote Link to comment Share on other sites More sharing options...
AdamR28 Posted October 5, 2007 Report Share Posted October 5, 2007 It may well be that they're fine but there's no telling without trying.The issues is that the alloy carrier deforms slightly, causing the rivets to come loose, then you get a wobbly rotor Nothing really to add to what's been said above other than only a small increase in piston diameter causes a massive difference in power increase: A Mono Mini has 20mm piston but Mono Trial has 25mm piston, when you do the maths it gives 54% more leverage! Quote Link to comment Share on other sites More sharing options...
Elliot Posted October 5, 2007 Report Share Posted October 5, 2007 ...>Elliot jumping in on an interesting topic<So why does a hope have a reservoir while a maggie makes do without? whats the benefit of a reservoir? Quote Link to comment Share on other sites More sharing options...
AdamR28 Posted October 5, 2007 Report Share Posted October 5, 2007 So why does a hope have a reservoir while a maggie makes do without? whats the benefit of a reservoir?It's to do with the type of system - 'open' or 'closed'.Simplified, open brakes self adjust with pad wear and closed do not. Open systems are better at coping with heat than closed (theres MUCH more heat in a disc brake than a rim brake!) because the reservoir (there's a rubber diaphragm in there) can contract and expand with the brake fluid. Quote Link to comment Share on other sites More sharing options...
eskimo Posted October 5, 2007 Report Share Posted October 5, 2007 I have no idea what that means really, apart from the fact it 'works better' So what is the choice with disk brakes then? I see the Formula things on your site Adam but no other brands, are there not any other good choices about then?I really like Hope Mono Trial's. The fancy rotor, the fact it works, braided hoses, top service from Hope... Quote Link to comment Share on other sites More sharing options...
JT! Posted October 5, 2007 Author Report Share Posted October 5, 2007 More pistons increases the power so long as they produce a higher leverage ratio. So if you replace 2 massive pistons with 4 pistons of equal surface area then they will produce the same power. However more pistons usually gives a more progressive feeling brake.So why do some brakes have like 3 pistons either side, why not just have 1 like the mono trial? Quote Link to comment Share on other sites More sharing options...
Gavyn. Posted October 5, 2007 Report Share Posted October 5, 2007 (edited) I think the larger surface area of the pad distributes the heat better over all 6 pots rather than 2 so this makes the brake much less likely to fade. They also have a better lever feel and more modulation rather than lock and bite. Edited October 5, 2007 by Gavyn L Quote Link to comment Share on other sites More sharing options...
2sixstreet Posted October 6, 2007 Report Share Posted October 6, 2007 So why do some brakes have like 3 pistons either side, why not just have 1 like the mono trial?The pistons are of different sizes on multi-piston brakes. Following the rule of the least path of resistance, the bigger area'd piston will contact the rotor first (feathering the brake) and when this can go no further and you keep braking the smaller pistons act. This gives a more progressive feel with light braking and stupid amounts of power when right on it. Quote Link to comment Share on other sites More sharing options...
Shaun H Posted October 6, 2007 Report Share Posted October 6, 2007 So why do some brakes have like 3 pistons either side, why not just have 1 like the mono trial?As I said earlier, and 2sixstreet explained, with more pistons there is a more progressive feel as the pistons are different sizes.I think the larger surface area of the pad distributes the heat better over all 6 pots rather than 2 so this makes the brake much less likely to fade.I'm not 100% on the explanation given but larger pads do indeed help with heat dissipation although I can't imagine it makes a huge difference. Quote Link to comment Share on other sites More sharing options...
JT! Posted October 6, 2007 Author Report Share Posted October 6, 2007 As I said earlier, and 2sixstreet explained, with more pistons there is a more progressive feel as the pistons are different sizes.I'm not 100% on the explanation given but larger pads do indeed help with heat dissipation although I can't imagine it makes a huge difference.Okies. So is the idea that more pistons has more power just a myth, it just alters the characteristics?Also, will having more pistons spread out the force along the actual brake so it'll flex less - making it more powerful? Quote Link to comment Share on other sites More sharing options...
2sixstreet Posted October 7, 2007 Report Share Posted October 7, 2007 Okies. So is the idea that more pistons has more power just a myth, it just alters the characteristics?Also, will having more pistons spread out the force along the actual brake so it'll flex less - making it more powerful?I cant quite explain why more pistons WILL give more power as surface area is independant of friction, friction (drag) being the driving factor (pad contact on rotor). With more pistons you increase the surface area of the pistons being driven which will give you more force. SO, even though the area of the pad doesnt come into the equation, the more pistons you have, the greater amount of power you can apply to that pad.Another way of thinking of it is running a 6" rotor and then an 8" rotor on the same wheel. You will expereince greater 'power' with the larger rotor due to a bigger radius away from the centre of the wheel. You could probably achieve the same power from a single piston system at 8" as a dual piston system at 6". This is from the greater force that can be applied to the pad, not because you have more pad area.Hope that makes some sense. Please feel free to correct me if you think i'm talking out my chocolate starfish. Quote Link to comment Share on other sites More sharing options...
JT! Posted October 7, 2007 Author Report Share Posted October 7, 2007 (edited) Well i understand that greater surface area of the pad doesn't increase the power becuase you have the same initial force from the brake which is spread over a greater area. It's for that same reason i can't get my head around why more pistons would give you more power, unless it has to do with less brake fade like mentioned above. Edited October 7, 2007 by JT! Quote Link to comment Share on other sites More sharing options...
Gavyn. Posted October 7, 2007 Report Share Posted October 7, 2007 I asked at hope at the worlds in fort william, why such brakes are needed for downhill and the guy I spoke to said the brake doesn't fade as quickly as something like the mini mono or the trials brake because it handles the heat better. Quote Link to comment Share on other sites More sharing options...
2sixstreet Posted October 7, 2007 Report Share Posted October 7, 2007 Well i understand that greater surface area of the pad doesn't increase the power becuase you have the same initial force from the brake which is spread over a greater area. It's for that same reason i can't get my head around why more pistons would give you more power, unless it has to do with less brake fade like mentioned above.Yes, you have the same initial force at the lever but since hydraulic fluid is incompressible this translates to the SAME force in however many pistons you are running, not spread over them. It wont be an average of the lever force at each piston it will be an addition, therefore more power. The more pistons you add the bigger the fluid reservoir required and the greater lever travel which then becomes a limiting factor.Pretty much whatever pressure is available at the lever will be available at however many pistons you have. Quote Link to comment Share on other sites More sharing options...
JT! Posted October 8, 2007 Author Report Share Posted October 8, 2007 Yes, you have the same initial force at the lever but since hydraulic fluid is incompressible this translates to the SAME force in however many pistons you are running, not spread over them. It wont be an average of the lever force at each piston it will be an addition, therefore more power. The more pistons you add the bigger the fluid reservoir required and the greater lever travel which then becomes a limiting factor.Pretty much whatever pressure is available at the lever will be available at however many pistons you have.But it's not the same force per piston. On a one piston brake (one either side) what ever power from the lever is halfed to each piston.If you have 3 pistons either side, the power is divided by 6. But becuase all the pistons are attacted to the pad, it all the original power gets added back up onto the pad. Making it the same as a one piston brake.At least that's my way of thinking anyway. Quote Link to comment Share on other sites More sharing options...
Tomm Posted October 8, 2007 Report Share Posted October 8, 2007 But it's not the same force per piston. On a one piston brake (one either side) what ever power from the lever is halfed to each piston.If you have 3 pistons either side, the power is divided by 6. But becuase all the pistons are attacted to the pad, it all the original power gets added back up onto the pad. Making it the same as a one piston brake.At least that's my way of thinking anyway.You're right, but I think other factors such as friction coefficients and heat dissipation are important on discs, especially when used for DH etc. Quote Link to comment Share on other sites More sharing options...
2sixstreet Posted October 8, 2007 Report Share Posted October 8, 2007 You're right, but I think other factors such as friction coefficients and heat dissipation are important on discs, especially when used for DH etc.I dont totally agree but cant for now back it up with hard evidence so will shut up. My basis is from experience with hydraulic equipment and several operator controls running on the same system. The same pressure was always available at each point, even if the system was open. Similar principle to what is being discussed. Quote Link to comment Share on other sites More sharing options...
Tomm Posted October 8, 2007 Report Share Posted October 8, 2007 I dont totally agree but cant for now back it up with hard evidence so will shut up. My basis is from experience with hydraulic equipment and several operator controls running on the same system. The same pressure was always available at each point, even if the system was open. Similar principle to what is being discussed.I'm not saying it's anything to do with one brake exerting more 'pressure' or anything to do with open systems either. But there is obviously a reason why DH brakes can be 6 or 8 pot, whereas the best brakes for trials are more like 1 or 2. Quote Link to comment Share on other sites More sharing options...
2sixstreet Posted October 8, 2007 Report Share Posted October 8, 2007 I'm not saying it's anything to do with one brake exerting more 'pressure' or anything to do with open systems either. But there is obviously a reason why DH brakes can be 6 or 8 pot, whereas the best brakes for trials are more like 1 or 2.A lot to do with the speed you're trying to bring the bike to rest from and as you have said heat dissipation etc. You dont put Porsche brakes on a peugeot 106 for the same reason - its just not necessary. Quote Link to comment Share on other sites More sharing options...
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