Do quad piston brakes work better than dual piston? I asked an experienced good mechanic

Wheels of Happiness

Rizal Philippines

4.08.2021

Slideshare on Mt Bike disc brakes

For every 20mm increase in diameter, there is 20% increase in brake power,  Hence. the maximum increase can be had for 203 rotor size (from n 160 mm) - 40%

During the last two weeks, my mind was struggling to continue with my planned purchase of P3k ish quad piston brake.  (Its review though has been bad)

Some literature even mentions that larger gains can be made by increasing  the diameter of the disc rotor say up to 203 or 180.   where gains of 30 - 40 can be had.

So I asked a good and experienced mechanics (he grew up in Cuatro Cantos) and he pronounced that if ever it works, ever so slightly compared to two piston brakes.   It is difficult to bleed.  Some literature mentions that longer pads tend to flex more and result in chatter and brake material separation from backing.  This is consistent with  a vlogger report for its disappointing performance  (Not dramatic stopping power)   The gain in quad piston brake is only 10%.   Maybe this can be judged from length of brake pad which is roughly that much only:   4 cm single vs 5 cm for quad. 

Increasing braking power by increasing rotor size

Yes, it’s just the ratio, assuming the same calipers.

A hand-waving calculation would be:

Deceleration = braking force x (rotor diameter / wheel diameter)

The braking force is constant (same caliper), the wheel diameter is the same, so if you increase rotor size you increase the deceleration.

So save your PHP.  Invest only in larger disc (may be only in front)  better material for the brake pads.

If you dont do downhill, or free fall rides, be content with your 140 mm, 160 mm set up double piston.

Controlling impulse buying of parts - upgraditis

Wheels of Happiness

Rizal Philippines

4.05,2021

                                                              Aspiration

Sometimes we get the sudden urge to buy a part because we read that this is good, this will up the performance of the bike by that much.   

And so uncontrolled, this urge makes have a stable of bikes that we can we dont use daily or that is beyond the level of our own physical fitness.   We have Pinarellos, Specialized Bianchi bike, and we can hardly pedal 20kph on them

Lately I had the urge to buy a 4 piston MTB brake.  It is cheap albeit from an unknown brand.  However reviews suggest that this does not work well;  there are complaints that the  brake power is lost (due to a failed piston O ring) to one that totally does not work -  ie failing to stop forcefully and on time.   So I changed my mind, although I told the vendor of this defect, he did not come back with a  good answer. 

There are literature that says that a quad piston brakes gain is very marginal -  only 10 to 15%

I will settle with my XT which has worked well for several years.

It is better to upgrade the brake disc to to 180 to 203 mm size (7 to 8 inches)  However, ,there no adapters available.   But the gains from this upgrade is awesome up to 30 - 40%...!!!

However conversing with some MTB riders, I got the idea that unless you do hard downhill or FR, (free ride) there is no reason to spend more on brakes.  If you just ride on the road;   think more on how you can ride faster higher.   Those who brake often, a bike champ said, never win races.  

However there is the other side that says, with a stronger brake, you dont have to bike often.  You can brake later or not all knowing fully well that you are equipped with a strong brake.   

Planned improvements(upgrades) on my MTB

Wheels of Happiness

Rizal Philippines

4.03.2021

This post plans to sell one of the MTBs and focus on the TI bike to improve its capability:

    1.  Purchase a new pedal about 1k in a e commerce platform;

    2.  Invest in hydraulic brake bleeder set (all that I lack is the cup where you put the mineral oil.  )

    3.   Invest in a 180mm or 203 mm  rotor disk (the problem is with the adaptor)  This will according to a post, increase breaking torque between 20 to 30%.  and make you go faster.  You can go latebreaking) and say have more confidence in negotiating steep hills and dexcents.   

    4. Invest in a quad braking system that will boost your ability to modulate your braking.  Its heavier though by about 40 grams.    I plan to do it later because published prices was at P15k plus.   There are fakes I think (or Malaysia version of Shimano of about  P6 to 9K.  But I saw one that costs only P3K

(However tests showed that this set up had problems).   

I would like to say that I did not really pay attention to the MTB through all these years because of the job pressure and pre occupation with high end RB, the S and P bikes that cost me 7 numbers.

The improvement in bike is not really a sickness but a journey to knowing more things about biking 

and the equipment.    You test the videos and articles you have seen, and that generates a sense of achievement, excitement and growth

That makes biking, MTB or RB more fulfilling.  

However on my bike ride yesterday, after talking to a grizzled MTB rider, I was advised that investing in bigger disk or quad bike is not advised if you are not hardcore trail rider.   For most purposes an MT200 hydro brakes and 160 mm disc rotor is sufficient.