Originally Posted by
zatopek
I ride both round and oval chain rings on my various road bikes. After many years and lots of miles on both, here are the differences I have detected. After really long rides, 80 miles or more, I find my knees feel a bit less achy on oval rings. Toward the end of those same rides, I think my legs feel a bit less zapped with oval rings. I have never detected a speed, sprinting or climbing difference based on which rings I ride.
Originally Posted by
DrIsotope
^^^ This mirrors my experience. I also think there's something to the notion of "recruiting different muscles" through somewhat different pedal strokes. I just know that at least to my perception (feel) I am fresher after multiple back-to-back days when switching back and forth between the oval-ringed bike and the round-ringed bike. So as a rider not obsessed with seconds off of a TT time, and more about enjoying ride 5 of the week just as much as ride 1, less fatigue is worth the price of admission.
But I've never used oval with a front derailleur, so there might be something to that. Bike shifts exactly the same as it ever did. If I had to time my shifts on my front rings like an old diesel tractor, I would likely feel differently.
Ditto. It's not so much a consistent, measurable difference in speed, power, etc., but in feeling less fatigued. As I mentioned above, the non-round, not-quite-oval Biopace rings encourage me to slow my cadence without losing speed, which definitely lowers my heart rate compared with spinning. While I'm more comfortable spinning around 90 rpm -- mostly because it just seems to mesh with my natural internal rhythms -- it'll peg my heart rate quicker on climbs. When I consciously keep my cadence a bit slower, push slightly harder gears, and watch my heart rate, I tend to feel less exhausted after my usual workout rides on the same route.
And the last time I consciously tried to push my limits on the old Trek 5900 with Biopace -- mashing harder gears and pushing my heart rate to the max sustainable limit -- I set my fastest times along a 35 mile roller coaster route, on a warm night with neutral wind, just a slight breeze.
Reminds me, I gotta fix the headset on that bike (old Chris King headset, appears to be titanium, finally needs new bearings after 27 years and zero maintenance). It's not radically different from my Ironman, but about 5 lbs lighter and possibly even better on chattery chipseal for comfort. It was just a pleasure to ride, with those 170 cranks and Biopace rings. I sorta prefer the Ironman as a casual cruiser, with 50/38 or 50/39 round rings and 13-25 or 13-28 freewheel. I can't get much top end speed on fast downhills without spinning out, but that bike is a joy to cruise all day at 15 mph and for casual group rides.