Ritterview

Yeah. I started out with the Avid 203 mm, but needed more heat capacity because I am in Northern California, where steep and twisty descents abound, and because my stoker is preternaturally terrified of descending. I have to use my brakes to slow us way down, or find a new stoker. This stoker terror is a real demand on the brakes. For example, on the Death Ride our average 28 mph descent of West Monitor rendered my stoker visibly shaken. According to Strava, of 364 cyclists having descended West Monitor, the median speed is 35 mph, and our 28 mph was 344th (95th percentile). And it still was *too fast*. So, I need brakes.

On this thread, PMK tipped me as to the Formula 220mm (8.7") rotor, which was discontinued in 2009, but still available.





I thought it might fit within the chainstay, but it would not. This is with the 220 mm rotor. Too tight.




Accordingly, I took the bike to Calfee when we did a ride in Santa Cruz. They did a chainstay modification (and took these photo's as well).



This got the 220 mm to fit.



They did a carbon repair.



So, now the 220mm rotor fits fine, and the chainstay doesn't look any different.



The Avid 203 mm and the Formula 220 mm weigh 190 and 217 grams respectively, an increase in 27 grams (14%). The diameter and circumference are 8.7% larger, and the surface area 17% larger. The aluminum spider may help in heat conductance and dispersion (and the different color and pattern break up what can look like a manhole cover with a large disc).

I'll report how it has worked out in a later post.