First off, I’m just a middle of the pack age grouper, so I run second hand stuff as long as I can. With that background, earlier this year, I purchased a nice 2015 Shiv for a very reasonable price. I put my Reynolds AR80s on it and knew it was faster than anything I had ever ridden before. I just felt fast. And after I got it pretty well dialed in, it was fairly comfortable also. I fell in love with that bike. It was going to be my “forever” bike.
Then, about three months ago I ran across a 2011 Cervelo P2 that was being sold for parts. When I asked the seller why, she said she believed the CF handlebars were cracked. I picked it up on a lark, thinking I might just fix it and flip it. Turns out the bars weren’t cracked but I replaced them anyway, along with the front fork which had been cut down to the bare minimum for time trials, and then I put on a set of Reynolds AR41s.
Comparing these bikes, I just don’t get it. I have set them up as close to the same as possible. The stack and reach are within 1/2" of each other. Seat height is almost identical. The two big differences which I cannot alter without replacing parts or significant expense is that the P2 has 170mm crank arms to the Shiv 165mm, and I have one more inch of forward travel on the P2 seat post than on the Shiv.
Yet, despite the similarities, I am consistently able to maintain about 1mph faster average pace on the P2 over the Shiv. And it feels like I can do that on the P2 without putting as much energy into a ride as it takes with the Shiv. Every time I ride that P2, I catch myself saying, “Jesus, this bike is fast!” When we’re talking about an average pace of 18.Xmph on the Shiv and 19.Xmph on the P2, that 1mph is not insignificant. You figure over the course of an IM, that difference is roughly 15-20 minutes (provided I could maintain that over the full distance).
What is it that makes it easier to go faster on that P2 than on the Shiv?
I suspect that extra little bit of travel does play a role. Kind of hard to believe it would be that much, but I do prefer a more forward position on the bike.
I suppose weight could be a factor. I haven’t put both bikes on the scale to see where they are. Just guess though, I would say they’re within a pound of each other.
I was about to say the same. It is actually far from a trivial task to make positions on two bikes exactly the same. A half an inch difference here, another one there, etc, and you may end up having two very different positions, even if it sounds like they’d be “almost identical”.* For example, it doesn’t require large differences from the two positions for your head and shoulders to fall in a significantly more aero tuck on one position over the other. For example #2, since you don’t have a power meter, you don’t know if you just can produce e.g. 10 W more power on your p2 with the same effort.
Of course there can be something else going on as well (friction in chain, bottom bracket rtc, different tires ??..), but all in all, to me it sounds plausible that you have just “accidentally” found a more optimized position now on your p2, so congrats for that!
*In your case the situation is even more difficult due to the different crank lengths, so basically it is not even possible to match the positions perfectly.
You should probably be using 150mm or 155mm cranks.I’ve been told this. I tried 150s on another bike and absolutely hated them. I’m a masher, not a spinner.
too many differences: half an inch here, half an inch there, and you ride in a completely different position. also: same seat heigth on bikes with a 5mm different crank length means that either one has a 5mm too high seat or the other has it 5mm too low. given that one bike “feels” faster, I would set up the other in the same way, with tolerances within 2mm, not “half an inch”; I suspect that the “slow” bike is not intrinsically slower, but you’re not able to produce the same watts in the current position. I suggest also to swap wheels between bikes, and see how it goes
Highly likely position. 1 mph difference average on a well repeated course is a huge difference. More than small weight and small power will account for. Riders position is like 80-85 percent of the aero drag.
For me it’s almost the difference between aero bars in an aggressive position vs no aero bars on the same bike and wheels. Or using 88 deep aero wheels vs box no aero wheels.
As said before it’s very hard to mimic the same position exactly on 2 bikes.
And given you are leaving aero gains on the table if you can easily get 1 mph by switching bikes you now may want to consider trying out best aero helmets and aero tested Trisuits for more advantage. As you can see it’s not just for the super pointy end ultrafast folks.
See if the crank and jockey gears on rear derailleur turn freely on Shiv. I’ve had problem with both due to bearing going bad. You can’t tell unless you remove the chain and spin. P2 looks better than Shiv. I’ve never liked the Shiv design.
I’d suggest you get profile pictures of you on both bikes (wearing your helmet), then enlist the help of a neighborhood teenager who is familiar with ancient technology, and upload the pictures here.
Try and get pictures at the top and the bottom of the pedal stroke.
It’s position differences most likely. The shiv is a more aero frame than the P2 (roughly equivalent to the 2011 P3). Note: the 2015 shiv tri frame is the same one originally released in 2011, from an aero perspective. There was an update to the aerobar (safety recall), but same frame.
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And given you are leaving aero gains on the table if you can easily get 1 mph by switching bikes you now may want to consider trying out best aero helmets and aero tested Trisuits for more advantage. As you can see it’s not just for the super pointy end ultrafast folks.
In fact the time savings will often be greater the further back you go in the field and as importantly, the amount of energy saved by finishing the bike leg faster can make the difference between blowing up at mile 7 of the run or finishing the run without slowing much.
See if the crank and jockey gears on rear derailleur turn freely on Shiv. I’ve had problem with both due to bearing going bad. You can’t tell unless you remove the chain and spin. P2 looks better than Shiv. I’ve never liked the Shiv design.Already done. In fact, I double checked that before this ride specifically to make sure there was no obvious drivetrain drag.
I’d suggest you get profile pictures of you on both bikes (wearing your helmet), then enlist the help of a neighborhood teenager who is familiar with ancient technology, and upload the pictures here.
Try and get pictures at the top and the bottom of the pedal stroke.I will see if I can do this today.