Sunday, May 12, 2013

Bike Review: P2SL Road Build

I described in a below post my use of parts pulled from the Gunnar, together with a few newbies (WTB saddle, FSA compact drop bars and stem, Ultegra FD from the set I bought for the Gunnar, used here instead because it is a braze-on) to turn the P2SL frame hanging in my basement into a road bike.  My design was to create a semi-light, fairly aero, comfortable, and inexpensive bike for racing purposes.

It's something of a goofy-looking rig.  At their best, time trial frames are not pretty, when compared with the elegance of (metal) road frames.  When combined with drop bars the bike looks like an ugly mutt.  And I accented it with white and blue just to be sure nobody missed it.  (Picture in the sidebar on the right.)

As I first built it, the bike was _steep_!  In my first ride I felt like I was holding onto my knees.  I could find the aero position, but it wasn't comfortable.  This would not serve for a 24-hour race!  I turned the stem over, gaining perhaps 17 mm in stack.  I then rode a comfortable 68 miles on Sunday, up the Monon Trail from downtown Indianapolis to the northern suburb of Carmel, then north and west on farm roads through Westfield to Sheridan, and back.  

A few notes rom that ride:

It was a windy day.  Aero is an interesting concept for a bike.  Of course, I did not get a chance to compare the alternative, but despite teardrop tubing and Hed deep-dish wheels, plowing into the wind was just that -- plowing.  In other words, the bike may cut the air like a knife, but it needs me to move, and I seem to catch far more of the wind than the bike.

The torpedo bottle in the stubby aero-bars is less than ideal.  There just is not enough room to handle the bars with the bottle there.  This is different from full aerobars, on which I can grab the bars past the end of the bottle.  I may experiment with the positioning before removing it entirely.

The WTB Rocket V saddle is so far a winner.  (I had used one on Sam's Kestrel in California in March as well.)  I am sufficiently sold that I just ordered the top-end, the Rocket V SLT (leather covering) from Amazon for the Gunnar.  This saddle has a slightly wider seat than my prior favorite, the Selle San Marco Concor Light, and I'm pleased to find it comfortable even though I am still smarting from 260 miles one week ago.  

I was worried about a funny cable routing problem on the front derailleur.  No issues with that, so far as I can tell.  Tuning is good but for trouble accessing the smallest cog.  The compact crankset with 12-27 cassette is a workable setup (though a little out of place riding in Indianapolis!).

I am running Vittoria Open Corsa CX in 23c on the Hed wheels.  I dropped the pressure after reading the tire research in Bicycle Quarterly -- 100 rear, 90 front -- and I found the ride passably comfortable. I cannot profess the excitement about the ride that I felt based on the Grand Bois 28c with latex tubes (400K ride report).  The next step may be to go with latex tubes here as well.

In the final analysis, I am riding this bike because I had parts that were worth next to nothing if sold.  Given the maybe $500 opportunity cost, it is a winner.


Unknown said...

I may be wrong about this, but as I understand it, riding a tri bike with road bars will be less aerodynamic than either a road bike or a tri bike.

Why it's less aero than a tri bike: for obvious reasons. A tri bike is built around aerobar geometry, flatter back, lower, etc.

Why it's less aero than a road bike: because of the phenomenon you observed. A tri bike forces you to ride steep, i.e., it pushes your hips forward. Unless you simultaneously move the front end forward and drop it pretty aggressively, the effect is that it forces you to sit up like a beach cruiser. Given that the rider represents 80-90% of total drag, and the fact that the P2SL's conservatively bladed frame probably is only offers a few percentage points less drag than a road frame, it may be a net loss. A road frame would set you back further, allowing you to get a flatter back and more aerodynamic position both when riding in the road position and when riding in shorty aerobars.

Just my two cents! Something tells me that, after 15 hours in the saddle, aerodynamics will be the last thing on your mind. Chamois cream will be the first.

Max said...

Good points. I mitigated the effect by turning the seat post head around and setting the saddle back in the clamps, but it is still probably a 74-75 degree seattube, rather than the appropriate 73 or so. In truth, this frame s a place-holder. Sometime soon I hope to replace it and simply shift all the peripherals straight over. Maybe a Kestrel Talon or that Felt AR2.