Dammit’s adventures in mountain biking

Ok, I bled the rear brake on the 4th of March, the lever was (fnar) rock hard at that point, and each day thereafter when I pulled the lever to test it (the bike was in the spare bedroom whilst I waited for the suspension bolt that I broke to arrive).

Yesterday I went to Swinley with Fenella, one hour forty eight moving time and the lever feel was great, nice and firm, bite point came in smoothly and powerfully.

However, I did notice that toward the end of the ride the outside two pistons were fully extended, the inner's not so much, and the pads were rubbing on the disc lightly - enough to make an embarrassing noise.

This morning I wanted to resolve the issue before heading out as the noise was not one that I wanted to accompany me around the Surrey Hills.

Bike in the stand, wheel out, pads pushed back, retaining pins out, pads out, loosened calliper, gave it a clean, wheel back in, centred it, pads back in, pin in, span the wheel and pulled the lever.

Outer side pistons moved in, to what looked to be the maximum extent that they'd comfortably move, inner pistons moved when the lever was operated but didn't auto-adjust and stayed in place.

The brake stopped the wheel, but the lever was travelling fully to the bar.

This didn't make any sense to me, so I took everything apart, grabbed the isopropyl and some clean towel and cleaned everything, worked the pistons in and out, but could not get the inner pistons to come out evenly with the external ones.

If I pushed all the pistons in, no pads, pulled the lever then the upper external piston moved but the other three stayed put.

Time was passing so I put everything back together, wheel in, and then rode the bike up and down before pulling the lever - success! Or something like it, bike point was very close to the bars, but it was there. Bike on roof, drove to Holmbury St Mary.

Bike off roof, set off - absolutely no brake. Fucksticks.

If I pumped the lever maybe 20 times I could get a little bite, but that vanished as soon as I stopped working the lever.

I rode for a while and then decided to call it as whilst I was fast I was unhappy with the balance when setting up for corners using only the front brake, which was leading to some interesting lines. I got seven PR's, Strava told me when I got home. I think that's tyres with lower rolling resistance rather than my "can't stop/won't stop" approach courtesy of Magura.

So! Place your bets:

1. The fluid has leaked away and there's practically nothing in there
   
2. Huge air bubble
   
3. Inner pistons stuck in their bores
   
4. Evil goblins
   
   

And if either 1 or 2 is your choice, where has the fluid gone/air got in?

I'll pick something nice from my parts bin as the prize for the person who comes up with the correct answer.