(Sellers of recumbent bikes will differ in the same way Pope Urban VIII differed with Galileo in the 17th century about whether or not the sun revolved around the earth. So be it.)
All things being equal (bike weight, cyclist weight and fitness) physics favors DF bikes in climbing.
DF cyclists are advantaged over recumbent cyclists in climbing for one simple reason: they can get out of the saddle, drop (dead weight plus gravity) their entire weight on each pedal stroke, pull up on the handlebar. This allows them to gain wattage / power at less physical cost.
Recumbent cyclists are disadvantaged over DF cyclists in climbing because they can't drop dead weight onto the pedal. All forward motion is generated exclusively by physical muscle, with no help from gravity.
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On the `right' course a recumbent cyclist would be able to sustain continuous muscle power on a climb for a short enough time so that depletion, exhaustion and fatigue do not fully occur.
On the `right' course the steep climbs (5% +) are short in distance. (Without the advantage of dropping dead weight on a pedal the steeper the climb the slower the recumbent: fact).
On the `right' course the steep descents (6% +) are short enough so that simple aerodynamics don't favor recumbents, i.e., a skilled DF rider can descend as fast (or, almost as fast) as a recumbent. (The steeper the descent the more the recumbent is advantaged by simple aerodynamics).
On the `right' course there are limited `flat' miles where the aerodynamic advantage of recumbents is unquestioned. (`Unquestioned,' at least by those who are not 17th century `faith-based' cyclists or sellers of recumbent bikes).
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This is the `almost' perfect course for DF / recumbent competition:
The Skull Valley Loop Challenge
But I doubt that there will ever be an apples to apples DF / recumbent competition on this course.
Why?
- Because recumbent cyclists don't train for fast competition on hills.
- Because DF cyclists do train for fast competition on hills.
Why do I say `almost?'
- Because ... DF cyclists are advantaged over recumbent cyclists for one simple reason. (See above).
I disagree about why DF riders have an advantage. You don't get something for nothing when you "use gravity" as they have to lift themselves back up.
ReplyDeleteWhat they do get is a change in which muscles are being used and possibly a change from mostly an aerobic workout to a muscular one. This change is more difficult to get on a 'bent.
Another point is that many 'bents don't have well supported bottom brackets. Flex in the frame is a source of power loss and that can show up the most in climbing.
From a subscriber to the Bacchetta List:
ReplyDelete"Standing on the pedal does indeed recruit body weight to assist in pushing it down, but when it gets to the bottom of the stroke, we need to use our muscles to lift our body back up for the next stroke. The amount of work we expend will be the same as if we remained seated. Now what does make a difference, is that a DF rider can move positions, sitting, standing, and adopt different pedalling techniques such as pulling the bars to recruit upper body strength. This means that different muscle groups are engaged, allowing others to rest and recover. This, we can't do (as much, anyway) on a recumbent."
I think he's on the mark. I would make this exception:
"DF riders lift their leg weight, not their entire body weight. Leg moves up, accesses the rest of the body weight when dropping on the pedal."