improving the braking power of hydraulic disc brakes

[emaayan]

so now i'm using tektro rear disc-brake from ilia and magura mt2 for the front, but it still feels the stopping power is not enough

the rear rotor is 165 mm cause the guy who installed it said that 203 mm may cause deformation in the frame but i'm still gonna try http://www.jensonusa.com/Shimano-SM-RT81-XT-Ice-Tech-Rotor (i have alfine 11) see if that helps

i'm also gonna try to switch pads http://www.jensonusa.com/Magura-MT-Performance-71-Brake-Pads i'm not sure what will go with the tektro, so i'll try this http://www.jensonusa.com/Brake-Pads/Swiss-Stop-Sintered-Shimano-Disc-Pads

the reason i wanted a magura in the front was becouse it also uses the same mineral oil as the tektro, as tektro is only hydraulic e-brake available aside from hygia which not only can't exactly be found but also uses mineral oil (as opposed to some claims here about dot oil) , i can't even be sure about which mineral oil , because i understand that for example shimano's mineral oil won't be good for magura as it's not the same viscosity.

another option i read here was to use this, but it seems it also needs mineral (probably the same type as magura itself uses)

http://www.hibike.com/shop/product/pd897c030ae9484fb91d5aea4278c224f/Magura-pressure-switch-for-E-bike-for-all-rim-and-disc-brakes-Schliesser.html

 

[amberwolf]

Can you skid the tire when you brake? If so, that's the maximum stopping power you can get.

If that's still not good enough, then you don't need better brakes, you need more contact patch and/or better-gripping tires. (then if it won't skid anymore when you use max braking, *then* you could get better brakes).

 

[Drunkskunk]

Yep. Braking power is a attribute of the tires. If the brake can skid the tire, it is getting the maximum braking power possable. if it can't skid the tire, throw it away.

But I'm going to take a wild guess here, that your problem isn't skidding the wheel, but how hard you have to grip the rear brake to make the tektro do that?

The problem is that you have a Tektro brake. replace it with a Magura and it will solve most of the trouble. Using a larger rotor will give you better mechanical advantage and help some more.

That Shimano rotor looks cool, but it's only advantage would come if you're overheating your brakes. otherwise, it will do nothing or worse.

The nonsense about the larger rotor warping the frame has come from someone who mistakenly believes larger brakes give more stopping force. But there is absolutely nothing in the brake system that can make the tire grip the ground harder than it does at the point of a skid. larger brakes are just for better cooling and lower brake line pressures due to mechanical advantage.

 

[emaayan]

I cant skid the tires,but the tektro is the only hydraulic ebrake i could find. Other then getting that magura adapter,which seems rather complex to install.

 

[Tench]

The actual force applied to the frame by the brake caliper may actually be reduced by fitting a larger disc. Put longer handles on your wheel barrow and you can carry more weight with less effort. Seems your advice guy didn't have 203 discs in stock so advised what he had was the best! he needs swerving in future!

 

[ferret]

Most of the stopping is done by the front brake, so if you need stronger braking it's better to upgrade the front rotor rather than the rear. When changing rotor size (front or rear) you will need a suitable caliper adapter bracket:

http://www.discobrakes.com/?s=0&t=4&c=56&

 

[emaayan]

thanks i've already upgraded both my brakes to 203 mm rotors.

 

[Drunkskunk]

As bad as Tektro are, they should skid the tire, even if you have to grip the lever with all 4 fingers and crush it with your hand.
If they won't, it may be an alignment issue on the pads, or an air bubble in the line.
Start with loosening the brake caliper slightly. just a couple turns on the bolts. then ride it a short distance and try the brakes. If it will stop better, it's an alignment issue and the brakes just need some adjustment. if not, bleed them.

 

[emaayan]

but those things have already been bled a weeks ago. i'm a little worried bleeding them myself even though i have the tektro kit, i don't have any clear instructions on how to do it..

 

[brumbrum]

Two syringes 100 ml each or slightly smaller
Clear tubing that will snugly fit over calliper nipple, say 30cm's.
Zip tie
Cloth
Correct fluid. Usually dot 4 or 5.1 . Do not mix the two together.


Fill one syringe with new fluid. Fit tubing to syringe and snugly sit other end of tube over the caliper nipple (loosen nipple first). Use a zip tie to tighten on tubing to the nipple.
Put a rag all around the area, you don't want brake fluid on the disc or your pads.
Put brake lever reservoir level and undo cap to get to the fluid.

Pull out some fluid from the reservoir with the other syringe.
Now push some in from the caliper end making sure it does not over flow the reservoir. Look out for bubbles in the reservoir and pull out with syringe. Keep repeating process until no more air bubbles appear.



make sure the reservoir is brimmed full before replacing cap.

It needs a bit of patience.

 

[Punx0r]

I fitted a front Avid Juicy 3 and found it just couldn't endo the bike no matter how hard I squeezed the lever. I tried everything I could think of from bleeding to degreasing the pads and disc and then roughening them with sandpaper. In the end I binned the new "organic" pads and fitted some metallic ones and the brakes were immediately transformed to single-digit operation...

 

[biohazardman]

I have the stock entry level Hayes mechanical MX4 brakes with the 203 mm rotors on my Giant and they put me up on the front wheel or skid the back whenever I choose for it to be so. If your brake levers get a good solid feel and stop before they hit near the bottom then I would look at the pads first as someone else mentioned. From what I have read here and there the Tektro is an entry level unit but werqs OK. There was mention of other brands being a bit better but nothing saying they had serious deficiencies.

 

[emaayan]

so semi metallic is better then sintered?

 

[brumbrum]

Simtered are good, better than organic, but they may squeal a little

 

[emaayan]

I thought there only 2 types of pads.

 

[Punx0r]

Sorry, metallic = sintered

I don't know if the organic pads I had were defective or something, but they were poop. There may well be organic pads that work just fine, I just suggest making sure the pads aren't at fault when trying to fix the problem you're having with your brakes

 

[emaayan]

i can never be sure which pads are better, i recall that pads that wear out faster actually brake better.

 

[brumbrum]

Rear brake is just for control. The front brake is most important for stopping power. At the end of the day you are using budget hydraulic brakes (no offence meant) so you can only expect so much. I had clark's hydraulic brakes which are fairly budget, i ended up selling them on ebay as my avid bb7 cable disc brakes were ten times better. No bleeding, fit nicely with a motor and are easy to adjust. I still use them on my commuting bike. I highly recommend the AVID BB7 calipers, you can buy them on their own with pads but without the rest of the kit. So you can use any brake cable and your own levers.

 

[Ch00paKabrA]

Rear brake is just for control. The front brake is most important for stopping power. At the end of the day you are using budget hydraulic brakes (no offence meant) so you can only expect so much. I had clark's hydraulic brakes which are fairly budget, i ended up selling them on ebay as my avid bb7 cable disc brakes were ten times better. No bleeding, fit nicely with a motor and are easy to adjust. I still use them on my commuting bike. I highly recommend the AVID BB7 calipers, you can buy them on their own with pads but without the rest of the kit. So you can use any brake cable and your own levers.

I'd like to chime in here regarding "budget disc brakes". As long as two criteria are met, there should be no problems locking up the brakes using hydraulic disc brakes. 1. No air in the lines. 2. No oil/grease on either the rotor or contaminating the pads or possibly alignment. I checked my brakes earlier and the alignment was lousy but I can still lock up the brakes.

As far as the rear brake being for control, I don't know what you mean by that. Brakes are for stopping. While it is true that in a car the front brakes do most of the stopping, it is more balanced on a motorcycle and in this case, a bicycle. I tend to stop mostly with the rear brake and only hit the front if I need to. using the front brake on a bike with a suspension tends to make the bike want to dive. I don't know about you, but I use the rear brake to stop not "control". One thing you learn quickly is that you let the rear of the bike go all over the place, even in a skid, just keep the front wheel pointed where you want to go and you will be fine.

For those that follow motor sports, particularly motorcycle racing, there have been huge advances in power delivery, handling and fuel management but there has been very little advance made in reducing stopping distances in the past few decades. the issue is that at a certain point either the wheels lock up of the bike endos. I have a set of Avid DB1 hydraulic brakes on one of my bikes. There is no braking system that can be considered more "budget" since front and rear with 2 rotors costs less than $100.00. I can lock up a 3 inch wide front and rear tire with 2 fingers. The fact that the OP can not lock up the wheels on his bike probably speaks to contamination of some sort rather than not enough money spent. If the lever feels spongy then it is probably air contamination, if it is firm then it is probably contaminated pads.

A trick we racers (yes I still have my motorcycle racing license) use for a nice firm lever is that after you bleed the brakes, take a long piece of string and tightly wind it round and round the grip and the lever and leave it over night. What many people don't realize is that carbon dioxide and oxygen are actually dissolved into the brake fluid and under high heat and high/low pressure situations they can turn from a liquid to a gas robbing you of lever firmness, by doing this, the gasses will separate and escape through the seals.

If you don't believe me, then while you have the syringe hooked up to the brakes and you have dispelled all of the air, pull back on the syringe hard causing negative pressure (it works that way too) and you will see bubbles form. These are comprised of the dissolved gasses.

Good Luck to the OP. I hope you can figure it out. My first choice would be to clean the rotor with brake cleaner and change the pads.

 

[brumbrum]

What was meant is that you control your braking with the rear and then complete the stopping with the front.