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Discussion Starter · #1 ·
I have some non series Shimano hydro disks on my 29er HT. I think there M5775's or something like that.

I love the modulation, they are super reliable however the stopping power is a bit less than I would like at times. I realize these are not XTR's, but would changing from something other than the stock pads or rotors help the stopping power at all?

I thought something as simple as a higher performance pad would help, but will it? I know it can with a car, but I'm not a bike disk brake guru. Would diffrent rotors help with trying to get a little more chomp?

OR is fiddling with any of this stuff a waste of money, and should I just save up for better brakes to get a little more bite?

Suggestions?
 

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What type of pads are you using? I actually can't recall whether organic or sintered metallic pads have more friction (how helpful I am lol), but we should know.

What is your rotor size? If all other things remain the same, a larger rotor provides more stopping power because it increases the torque the brake produces on the wheel. If you change your rotor size you'll also need a new mounting bracket for your caliper.

Also, when you're considering rotors, the more area the rotor has between the pads means there is more friction. But a balance must be stuck between rotor area and cooling ability if you want it to resist fade. Sintered pads are also better at resisting fade.

Also, have they been bled recently? Air in the line will compress and absorb the force you apply to the lever, which reduces power as well.
 

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I have some non series Shimano hydro disks on my 29er HT. I think there M5775's or something like that.

I love the modulation, they are super reliable however the stopping power is a bit less than I would like at times. I realize these are not XTR's, but would changing from something other than the stock pads or rotors help the stopping power at all?

I thought something as simple as a higher performance pad would help, but will it? I know it can with a car, but I'm not a bike disk brake guru. Would diffrent rotors help with trying to get a little more chomp?

OR is fiddling with any of this stuff a waste of money, and should I just save up for better brakes to get a little more bite?

Suggestions?
You can try different pads I can definately notice differences...

Try a clean and bake on the existing pads...

Wash and Rinse brakes...

Take off pads bake with an old fry pan at med heat till the stop smoking 10 mins...

Lightly sand...

Pinch the rotor with some sand paper and rotate the wheel for a minute or so...

Re-install...

Ride down a hill hard and brake hard several times...

If you don't like the performance after that then try some new pads.
 

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tips to improve stopping power?
same brake same rider.
Metalic pads
Bigger rotors
Most important proper technique load your tires, properly weight the bike fore/aft to get max load and traction.
Also, before you commit to buy any new parts you can do the following to check the integrity of your current setup:

1. Change your brake fluid if more than two years old.

2. If you have to pump your brake lever before it gets firm then you may have air in the system and it should be bled.

and if you have a caliper and/or a micrometer:

3. With a micrometer check the thickness of your rotors. The min. thickness will be labeled on the rotors. Only check the portion of the rotor that the pad actually comes in contact with.

4. With a caliper check the thickness of your brake pad friction material. Not including the backing plate you should have at least 1mm of friction material.

ALSO, some cleaners out there will reduce the stopping power of your pads. If you use any kind of cleaner/degreaser on your bike make sure it doesnt get on your rotor or caliper. If you have then that may be the source of your problem. Over time your braking power will come back but it will never be the same.
 

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Discussion Starter · #7 ·
The brakes are only 5 - 6 months old, and only been used this season. I don't feel any air in them, so I don't think they need to be bled. It's not that the brakes don't work as advertised, I'm just looking for a little more. I may try a bigger rotor up front, and switching to Metallic pads as some have suggested. Thanks for the tips guys!
 

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The brakes are only 5 - 6 months old, and only been used this season. I don't feel any air in them, so I don't think they need to be bled. It's not that the brakes don't work as advertised, I'm just looking for a little more. I may try a bigger rotor up front, and switching to Metallic pads as some have suggested. Thanks for the tips guys!
A bigger rotor up front for sure. But use caution in changing pads. Check your rotors first! Some lower end Shimano brakes come with rotors that are suitable for organic pads only! To check this look at the rotor closely. If they are designed for organic only pads it will imprinted on the rotor. While using metalic pads on these rotors won't kill them immediately, it will wear the rotors out in very short order. So double check this before going to metalic pads. If there is no marking on the rotor about organic pads only, then you're good to go. Otherwise it would be advisable to replace both rotors before running metalics.

Good Dirt
 

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Never heard of pad specific rotors atleast on standard normal brakes, you can get crazy light ones but even then don't think it matters.

Rotor Size Rotor Size and Rotor size, is pretty much all there is to it.

Remember a 160mm rotor on a 29er will have the same breaking force as a 144mm rotor on a 26er, thats why your power likely isn't great, even a 180mm is only really a 162mm area.

I prefer full sintered pads to, organics just don't work for me they just glaze over and do nothing at all but make a weird noise.
 

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lol, those are my rotors, so I guess I'll be needing new ones
Oh yes, if you look at your pads you'll likely see there very shiney and well glazed over.

I remember advising someone not to use those rotors for this reason years back and got flamed for it, I guess we can consider them wrong yet again :)

I don't like Stock Shimano or Avid pads either, hayes pads are fine, Tektro's are amazing.
 

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Can you explain the physics behind this? From an energy solution standpoint, I don't see that this is true, i.e. for a given rider mass and speed, all the kinetic energy of the rider must be converted to heat in the pads/rotors to stop. True that the angular velocity of the 29er rotor is a bit slower than the 26er as the wheels are not turning as fast at a given speed; could that be it - energy dissipation is related to speed of the rotor through the pads?

Chris

Never heard of pad specific rotors atleast on standard normal brakes, you can get crazy light ones but even then don't think it matters.

Rotor Size Rotor Size and Rotor size, is pretty much all there is to it.

Remember a 160mm rotor on a 29er will have the same breaking force as a 144mm rotor on a 26er, thats why your power likely isn't great, even a 180mm is only really a 162mm area.

I prefer full sintered pads to, organics just don't work for me they just glaze over and do nothing at all but make a weird noise.
 

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wider tires would help as well wouldn't they? maybe not in overall power, but definitely braking performance in general
Along with making changes to the brakes themselves there are a few other things to look at for improving braking performance.:)

With powerful brakes you only ever use a small percentage of the maximum braking force available, it's just that you don't have to squeeze the brake lever as hard as you would with a weaker brake to slow at the same rate. In general the theoretical maximum braking force that even a basic disc brake can produce in the dry (if you squeeze the brake lever really hard) is above the level that you can safely use. In practice the wheels will lock, or you'll flip the bike, before reaching the theoretical maximum deceleration achieved in testing. The maximum real world deceleration you see achieved by the same rider and bike will remain similar, even if the bike's brakes are upgraded with different ones. The limitations on braking being tyre grip and weight transfer.:)

When you see people asking for more stopping power what they're really thinking of is either a disc brake which produces more braking force at a lower hand pressure, or one that stays at a constant level of performance without fading on extended descents.

Tyre grip is one of the main limiting factors for slowing a mountain bike. If the braking force you apply exceeds the available grip from your tyres then you'll lock a wheel and skid. If you can increase the amount of tyre grip by choosing a tyre with a soft compound, a larger contact patch and a tread pattern that works well on the surface you're riding on then it's possible to generate a higher braking force before the tyre loses grip and skids. Up to a point you can increase the contact patch, and increase the amount of tyre grip, by running lower tyre pressures also. At too low pressures the tyre will deform or even rotate on the rim under heavy braking which isn't ideal. You can generate a higher braking force on a hard surface (such as tarmac) than it's possible to do on a loose surface offroad.

The other limiting factor is weight transfer. The centre of gravity on a mountain bike is quite high which affects how hard you can brake. When you brake hard on a surface with plenty of grip the majority of braking is done by the front brake. As the front wheel slows it wants to stop rotating, whilst your body and the rest of the bike wants to continue to rotate forwards around the front hub. The weight of your body and the bike resists this rotation and keeps the rear wheel from lifting off the ground. If your braking force becomes high enough, and your weight is in the wrong place, then the bike will flip over sending you over the handlebars. This youtube video shows how too much front brake will flip even a heavy bike.:)


By shifting your weight rearwards to counteract this weight transfer you can brake harder than if your weight remains positioned further forwards on the bike. Stiffening the front suspension fork will also help braking performance by reducing brake dive which throws your weight forwards.

A useful technique to work on when braking hard is to remember to move your weight rearwards, but also try to lower your entire upper body at the same time, in order to lower your overall centre of gravity slightly. This picture of Fabian Giger (Rabobank-Giant) is a good example.:)
 

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energy dissipation is related to speed of the rotor through the pads?

Chris
Correct, friction increases ofcourse as more rotor passes through the pads, but that level of power is relevant to the actual speed your traveling, on a 29er the rotor is turning 10% ish slower for the same speed rider wise.

29" or 26" wheels, given the same weight the kinetic energy is identical and by the laws of conservation energy can't be lost merely converted so the same amount of heat is generated.
 
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