I’ve had an old cervelo p2 that I’ve ridden for 10+ years now. I’m sufficiently fast on it, but very jarring to ride on chip seal roads on my 23/25mm tires. The bike can’t take wider tires.
I’m starting to look for a new bike for the sole reason of getting wider wheels to be more comfy. Still not sure it’s worth $6-8k, but maybe…
On my road bike I’ve been riding 32mm tires for years
As I’ve started my research, i was surprised to see the first couple TT bikes I looked at still having max tire clearance of 25 (or maybe 28 depending on wheel)
For racing I’m fine to deal w high psi / narrow but I hate riding it in training
Are most of the fast TT bikes still optimized for narrow tires?
If you are referring to new fast tt bikes, I think you’ll find they come standard with wheels designed for 25 or 28mm tires. Aftermarket wheels as well. My new Trek SC came with 28s.
The Felt IA 2.0, Factor Hanzo, Sworks TT, Speed Concept, Cube, Scott Plasma and Cadex tri all take 28mm tires and most pros are running a 28mm rear tire.
I was able to put my old Vision Merton SL55 with Conti 5000 28s on my old P2C. The clearance is very small, but it works, is smoother and faster. The difference is 17.7mph on the old Zip 404s with Conti 5000s 23cm versus 18.8mph on the same course and similar weather at 117 ave watts for both races. (I’m 64yo and relatively new to cycling, so I don’t have a lot of power.)
The fronts are the smallest clearance and I have to be careful that I put the wheel on straight. I got longer screws for the rear adjustment and it fits fine. Of course, I also had to adjust the brakes.
I would think a setup like this will work on the P2. But if you want to spend $6k for a newer bike, then go for it.
Fortunately, I’m only 165#s and still highly flexible - easily staying in the aero position for a couple of hours on olys and such short distances. In training I do 40-50 miles in aero without issue. The bike fits me very well. I’d love to get 50 more “z2” watts. Then I’d be somewhat competitive.
I think I edited and added a pic (still getting used to new forum - which I love)
I meant physically I wish I could average 167 in z2 instead of FTP around 167.
I know I could get more speed with a disc wheel, much better helmet, skin suit, etc. But I just wish I had a higher FTP.
But for a $700 bike I bought five years ago and good wheels I took off my R5 when I retired it, I’m pretty happy with the bike. If I could find a good used rim disc wheel for “cheap”, I’d probably start there.
My wahoo kickr also has my FTP around 165 and my Specialized SL6 with Rotor power meter says the same. So, while it may be off a little compared to three I have, they all say my FTP is around 165.
I don’t know enough to argue one way or the other. But that’s all I know. When I had the 23mm my speed at similar watts was around 17.5mph.
Here’s the same race last year. I don’t have the Garmin session, but here’s the TrainingPeaks. The only differences are the wheels/tires and I flattened the aero bars from pointing up around 30d to basically a flat 0d. average watts were 3 less, but speed was 1+mph slower. Everything else, including the kit, socks, shoes, helmet, etc. we’re the same.
Here’s the photo from last year (I noticed I didn’t have the rear bottle), and the TrainingPeaks. Notice even the HR is the same. Top speed and power were higher last year because I pushed power even downhill. This year I didn’t because I blew up on the run last year. Saving some energy and having a faster bike, I shaved around 10mins off my time (I was very happy about that).
I do recall I was running latex in the Zip 404s last year and TPU in the Visions this year, and I was the same weight. My practice rides were similar - much faster on the Visions, in the 18.5-19 mph for around 115-120 watts. Maybe the only thing I’m good at on the bike is being and staying aero. I do roll my shoulders in as much as possible, thinking that helps to be aero (I don’t know if it does).
How do you calculate rolling resistance and drivetrain efficiency? It’s an Ultegra from probably 2013ish timeframe 10sp, and I have no idea on the teeth count. The wheels are Conti 5000s clinchers with the TPU tubes.
What’s an impossible CdA? I’m guessing there’s some number that’s so low no human on the best bike can get there.
I’m not sure what the calculation is suppose to show me. I guess I could change the rolling resistance for the Zips (also Conti 5000s but 23mm with latex tubes) and slower mph and see a change in the CdA, but what would that tell us?
I found the power to speed calculator and changed everything but the CdA, rolling resistance and drivetrain efficiency. Came out to pretty much right on my average speed.
I think the point is that changing tire size (holding all else equal) doesn’t increase your speed by 1mph.
I’d guess the speed difference you saw was much more related to how fast you took the turns, weather (air density / humidity / wind), or position / gear. Maybe even psi in your tires
The roads I race on (State TT, in Hempstead, since you’re in TX) are almost perfectly smooth, and I’d guess tire size contributes nothing to speed. I’m closer to 30mph in a 40k, and looking for wider tires solely for comfort on crappy training roads
I agree that it’s not just getting wider tires. I think it’s more replacing the old Zip 404s with the Vision carbon wheels. I’m sure 55mm depth and the hub are better than the Zips.
I thought the question was how I could go 18.5+/- with only 115/120 watts. That’s the question I was addressing.
I’m out of Katy, so you may pass me on my Saturday morning long rides. “30mph average on a 40k TT”… Seems professional level to me. Impressive.
I didn’t notice it asked for the weight of everything. It may be even more than 85kg. The P2C isn’t a light bike compared to my R5 and SL6. I’ll have to weigh it one day.
18mph at 120w is around 0.250cda. It’s fine but not great.
Is also hard to compare between different days as weather conditions play a huge role. Aside from wind the temperature and barometric pressure have a big effect on air density, which in turn directly affects speed at any given power. Luckily since you have the dates, times, and locations you can lookup weather data and calculate the air density for each ride.
Other things you need to have to compare two separate rides accurately is road surface, tire pressure, braking and turn data, elevation changes, time out of aero tuck, just to make a few.
Yes, there’s really no way to directly compare two rides. My information, very generalized, was my Vision wheels, over many rides on the same roads and similar weather, seem faster than my Zip wheels.
Technically, a wind tunnel would be the only true way to measure how much different the wheels are (or even if they are different).
But I am glad to see that my current CdA isn’t “great”. Does this mean I can continue to get more gains by improving my position on the bike, or do I have to spend more money?
I wish I could average 167 in z2 instead of FTP around 167.
I do roll my shoulders in as much as possible, thinking that helps to be aero (I don’t know if it does).