I had another opportunity last week to climb to Glen Cove. But with dark clouds in every direction, I turned around at 3000 ft after seeing a lightning strike in the Devil’s Playground. Nevertheless, the descent was consistent with the previous ride as I dropped the vertical in one fell swoop hoping to reach the car before the snow/rain/hail reached me.
I did some rough math on the energy required to hold back my 200 lbs of ballast (rider,bike,gear) over 1500 of vertical across 9 minutes. Anyone with a thermodynamics background can correct me, and I am leaving out tire rolling resistance and wind, but given the rate at which the bike accelerates from Glen Cove under pure gravitational pull, I have to believe these are marginal. My calculus has Power = Work Done / Time to do the Work. Word Done is lbs * ft so 200 * 1500 = 300,000 ft-lbs divided by 540 seconds is 555 watts. I belive the metal pads do a better job of conducting those 550 watts from the braking surface to the air thus keeping the surface temperature lower.
No topic draws as much heat and light in the Mountain Bike forums as the subject disc brakes and how to remedy them so I gingerly offer my opinion to the other early adopters of disc road bikes:
1. Road bikes have far less mass and dampening ability than mountain bikes. A noisy or inconsistent MTB brake is annoying but greatly dampened by the mass of the frame, front and rear suspension, and the greater rotational mass of the MTB tires (about 700g vs 200gm). Road bike disc brakes need to be near perfect to make them enjoyable.
2. If you plan on riding in the mountains you might consider requesting Metal pads over fiber for the thermal performance and longevity. As of this writing (5/10/2015) the pads still don’t show up in the US so ask your LBS.
3. Don’t assume even tens of thousands of vertical in urban settings will translate to performance in a mountain descent.
We have had a very wet week with a couple feet of new snow on the peak in the past days. While thwarting many rides the moisture is welcomed compared to the alternatives of wildfire and water restrictions. While Glen Cove tends to remain accessible in the spring, the next section to consistently open will be the the next 1500 feet between Glen Cove and the Devil’s Playground as pictured here from last year as I round the switchback in the distance. I’ll post more on the road disc brake performance as I get further up the mountain. I am looking forward to the full 7000+ foot descent from the 14,110 foot summit of Pikes Peak to Cascade.
Road Disc 