Today's route took me over two of the climbs in the previous post so I collected a little more data. More importantly perhaps, the environmental conditions were exactly the opposite of what they were on my 1/3 ride so rather than a 28 MPH headwind on the Crabapple climb I had a tailwind of similar velocity. It wasn't a full-on tailwind, the steep part of the climb runs toward the SW and the wind was out of the WNW so the North bit helped, the West bit didn't.
So before I add some follow on thoughts, here's the data with the most recent in red. First the Palo Alto climb:
And then the Crabapple:
The Palo Alto data is in line with previous efforts so not much to talk about there. Faster than all but 2 rides on the Crumpton.
The Crabapple climb is a bit more intereting. As I said, bit of help on the climb, highest wattage and fastest time of the three outings. It is interesting that the S40 was nearly as fast on fewer watts but it could well be the wind accounted for the difference because as I said in the previous post, the winds were mild on the 16th.
As a wise man once said:
The speed at which you climb on a bicycle is determined mostly by the following factors:
- Power, measured in Watts.
- How much weight in the total package (bike plus rider).
- Aerodynamics.
- Drivetrain efficiency.
As can be seen from the data, my power output is similar on both the Cruzbike and the Crumpton. Maybe a small amount lower on the Cruzbike but that might have more to do with measurement than reality. I have Asioma power pedals on the Crumpton and a PowerTap hub on the Cruzbike and it's definitely the case that the farther you get away from the source of the power (your feet) the less accurate it is so this could account for the difference. So let's call it a wash.
I've not done a weigh-off between the two bikes but I'd say that as ridden the Cruzbike is about 8 lbs heavier than the Crumpton. However, the weight of the rider (me) dominates and the difference in bike weight only amounts to about 3%.
At the speeds I'm going, especially on the steeper climb, aerodynamics isn't really a factor. I'd expect an aero advantage to start showing up above 15 MPH and I'm going considerably slower than that.
The drivetrains are essentially identical. The Cruzbike has a very efficient drivetrain unlike a Long Wheelbase (LWB) recumbent like a Bacchetta.
So the bottom line is there's absolutely no reason for the Cruzbike to be a slower climber than the Crumpton.
If that's the case then why was I convinced it didn't climb as well?
As I said in my previous post, I think it's all down to perception and how your brain processes and interprets motion. On a DF, you're looking down and the ground is rushing by. On a recumbent you're looking essentially straight off into the distance so you gain ground on a reference point e.g., a tree, the top of the hill, etc., much more slowly therefore it "feels like" you're going slower.
There's one other factor: control. The stall speed on a DF is essentially 0 (track stand) whereas below about 5 MPH on the Cruzbike I'm struggling to hold a line. Coincidentally, on both the DF and Cruzbike when I look at my bike computer at the steepest part of the climb I'm going (wait for it): 4.5 MPH. No issues of control on the Crumpton whereas the slightest tug on the bars on the Cruzbike and I'm over in the other lane.
So the conclusion is this: they're roughly equivalent climbers, they're equally suitable for doing brevets and it's entirely possible the aerodynamic advantage of the Cruzbike would win out on all but the hilliest routes where the extra weight penalty might make a difference.
Based on all that, it's likely that I'll do one or more brevets this year on the Cruzbike. My longest ride to date has been 53 miles so I have some work to do to build endurance on it but there's time.
Stay tuned!
