Share the Wisdom Wednesday (but on a Thursday)

I don't remember the last time I posted a StWWboaT, but perhaps I've learned nothing worth sharing since my last post.  Mebbe, based on everything I read on Twitter, everybody knows everything about everything already, so why even bother?

Well, something happened the other day that I realized had happened to me before, and I then pondered, I'm probably not alone... so why not go ahead and let everyone (who reads this) learn from my mistakes?  Well, not necessarily a "mistake," so much as my continual and ignorant oversight. 

Oversight... a word that as I type it, I'm not sure it's what I actually mean because the less frequently I write, the more I doubt myself....

So it means what I meant and also something that seems something quite ass-opposite, but such is the English language.

Obvs I'm working with definition 1.

Here's the tl;dr part (as if it's not already).

I recently installed a set of new (to me) XTR four pot brakes on my Epic EVO SS.  Not that I've had issues with the two pot XTs that were on there, or the XTR Trail two pots that have been on the Vertigo and Vassago (Meatplows V.7 & V.9) for oodles of years.  It's just that I realize old things will work until they don't, so why not give something new a try?  I mean, I was a pretty devoted Hayes brake guy until I tried something new, and now I'm a Shimano guy through and through.  It's like I was a corn on the cob guy until I tried Brussel sprouts for the first time.  Keep your mind like a 7-Eleven, always open.

Go through the "hassle" of swapping perfectly good brakes for something else for some reason.

At least the hydro hose bit is on the proper side that the frame was designed for and not the previous outboard (why Shimano?) location.  Pretty much the main reason this bike was selected for the "upgrade" over the other two mountain bike sport cycles.

I mounted them up on a rainy Friday afternoon, did a full bleed on the rear brake since I left the line in the frame and reused it, replaced the stock pads with TruckerCo semi-metallic pads (the only pads I use), and then hung the bike up on a hook after centering the calipers and setting the brake levers in the correct (but actually wrong, doh) position. 

Dr Mike and I decided to ride urban style over to an open-after-Ian trail Saturday morning... and that's when I remembered that I hadn't gone through the process of bedding the new pads in properly.*  It was raining when I got done putting everything all back together, and no amount of GoreTex or beer was going to get me outside in a tropical storm to do it properly.  On the ride to Dr Mike's house, I did what I could to bed the pads in, dragging my brake with increasing force multiple times on every descent from my house to his.  It was not enough IMHOMO... or something else was wrong.

The ride commenced, and while the terrain was a wee bit punchy at Southwest District Park, the brakes never felt quite right.  

Meh.

Did I contaminate the rotor or the pads while piddling around with the caliper/lever swap or mebbe the bleed?

Mebbe I purchased used brakes that were being unloaded for a reason?

Shitty bleed... even though it felt great in the stand, and I wasn't seeing any bubbles when I finished?

Figure it out when I get home.  Plan on checking the pads... sanding with some high grit paper... do the rotors too... all with alcohol... both kinds.

Get everything ready, pull the pads, and duh.

I forgot about this.  Kinda.

My pal Jerry had told me about rotors "cupping" after lots of use.  I'd never really given it much thought, although I bought some cheap calipers to measure rotor width awhile back, but they can't measure the part that is "cupped."  Essentially, the part of the rotor with holes in it wears faster than the part that has more (or continuous) contact.  Since I run rotors with plenty of big holes, they wear down faster than rotors with more material.

Bear with me and my shitty MS Paint skills:

The red line shows where the pad will make constant contact, the green slightly less, and the yellow (where the rotor is "holiest"), the least amount of surface contact.  I do realize (post-MS Painting) that red = bad, yellow = better, green = best woulda made more sense.  Spend ten minutes using MS Paint trying to make perfect circles and get back to me about whether or not you woulda started over.

So why do I use the holiest of holy rotors then?

The Ashima rotors I run are stupid light, wear stupid fast, but are also super cheap.  I like them.  You don't have to.  I get a decent life out of them, and with the TruckerCo pads that I use, I've never been disappoint.

I guess the point of all this is that if you do a pad swap and think your brakes feel like dog turds, before you start going down too many rabbit holes (mebbe you touched your rotors or pads with pizza grease fingers or just looked at them wrong, have some air in the system, need a full bleed, have a sticky piston, etc), mebbe take a quick look at your pads first.  It might be time for new rotors... 

or you can do what I do.** 

I ride it out.  At least for awhile.  The rotors that are on the Epic EVO aren't really that old, I haven't ridden the bike in nasty conditions at all, and I'd not even used up one set of pads on the bike since last August, so the cupping has to be minimal.  

BUT...

It is enough to affect the braking performance until they get all mated up and happy with each other.  I'm fairly confident that after one DECENT ride, I'll be all buenos.

I got a lot going on this weekend, so expect... something(s) next week.



*This is some nifty reading from an article on B.R.A.I.N. about two new shop tools to bed in brakes properly:

"Mikolayunas learned that bed-in is actually a two-step process. The first step is the bedding, which increases the surface contact area between the pads and the rotor.

“The initial surface area contact of a new brake pad on a new rotor is relatively small,” he wrote in a product document he shared with BRAIN. “The amount of surface contact is known as ‘percentage bedding’ and the goal is to maximize this percentage before moving to the second process. 

 “A small percentage gain occurs almost immediately as, under initial clamping pressure, the piston, seal, pad and rotor come into alignment and square with one another,” he wrote. 

 More surface area contact is created as the pad compound conforms to the shape of the rotor. 

Once there is sufficient surface contact percentage, the next step is the burnishing, the transfer of material from pad to the rotor."

** I'm positive that somebodies are gonna tell me I'm full of shit... but that said, I think too many people don't consider rotors as a wear item as much as they need to.  This is just my "change the oil in your car, check your bike chain, wash your gloves after you sweat them all up, floss your teeth" kinda warning post... except it's about brakes.