First TT w/ PT (ride log)

frenchyge

Tonight was the last training TT of the season, and the first one since I've had my PT. I don't do many TTs, and feel that pacing has been a major weakness, so I was excited to use my PT to help with pacing.

The Course - 5.8 miles, mostly flat (route profile attached below, courtesy of RapDaddyo), out-and-back. Weather was 80's, slight (<5mph) variable breeze from the north.

Pacing Strategy - My previous PR for this course was 14:33 back in June. I estimated that I could hold ~340W for the 15 minutes it would take to complete the course. After evaluating the ride profile and weather forecast, I decided to use a variable pacing strategy. My goal was to use a 340W target to minimize overshoot during the initial portion, use 360W pushes through the slightly uphill middle portion of the outbound leg and immediately after the turnaround, and recover at ~300W during the slightly downhill portions of the course before pouring it on for the home stretch.

Warmup - ~20 minutes, with a few brisk pushes to get the body working. One issue I discover during this period is that my TT bike (/trainer bike) is built with an 8-speed triple, while my PT hub has a 9-spd cassette. That's a problem because the 8-spd chain is too wide for the cassette spacing. Result: the 4 big cogs work fine, the next 3 skip horribly since the chain won't settle in, and the 12T works fine. That'll make pacing a little more challenging.

The Ride - Fast out of the chute @590W for the first 15 seconds before settling down to an even pace. Still took too long to find the right rhythm, as the first minute averaged about 430W. From there, the outbound leg was paced pretty well, as I averaged 318W with a normalized power of 331W. The pushes went well, although the rests were a little weaker than target. My body was a little *too* happy to be getting that rest. Another brief 500W push at the turnaround, but now I'm starting to hurt. I'm only able to generate 325W after the turn instead of the ~360W push that I had planned to the top of the rise. From there I'm supposed to be resting, but I'm only able to hold ~250W instead of the ~300-320W that I had hoped. Gave everything for the last half-mile, and I'm done.

Results - 14:28, which is a PR and I'm probably less fit now than I was in June (just before my peak). Avg HR @ 175 was 4 beats higher than in June. Outbound Leg - 7:30, 318Wavg, 331WNP, 23.7mph. Return Leg - 7:00, 271Wavg, 278WNP, 24.6mph. Total - 14:28, 296Wavg, 307WNP, 24.2mph. 23rd place in open training TT.

Conclusions - 1) Even though the return leg hurt and I wasn't able to hold my target power, I still achieved a negative time split (which I certainly didn't do in June) and the pacing strategy was probably a good one. 2) Over-estimated my target power @340W, and was only able to achieve 307W NP. 3) At first glance, my ride seems to have the typical "start too fast, slack off in the middle, finish strong" profile of an amateur TT-er, but after thinking about it that was kinda my strategy because of the slightly uphill outbound leg. 4) Time to go buy a 9-speed chain for my trainer bike before winter hits.

Hope this was somehow helpful. If anyone knows how to upload an image of the power/speed profile, let me know. Cheers.

Attached Thumbnails

 

RapDaddyo

That's cool stuff. You can make an image file (e.g., jpg) out of the power/speed graph with a screen capture program (I use SnagIt - http://www.techsmith.com/products/snagit/default.asp). Or, if you have Adobe Acrobat (full product) you can print to Acrobat Distiller and then attach the pdf file. Either way, the resolution isn't great, but if you make a separate wko file of just the TT it won't be too many minutes and it won't be too bad. I want to take your wko file and overlay the course and wind and then work on some optimization pacing strategies subject to your FT (sounds like it was ~310w).

Cyclist14

You are very, very detailed.


Keep up the good work!!!

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ric_stern/RST

First off great result.

secondly, irrespective of the course profile, this is not an amateur mistake -- i have data from elite senior world male champions who make exactly the same 'mistake'.

ric

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RapDaddyo

Actually, I think your only "mistake" was in overestimating your sustainable power at 340w. Any TT is ridden with an explicit or implicit pacing strategy. Some pacing strategies are founded on inaccurate assumptions (e.g., constant power will result in fastest time) and some pacing strategies require competencies that the cyclist has not developed (e.g., a highly variable power pacing strategy of, say, 150w-500w). But, your pacing strategy was founded on sound principles (ride at higher power on uphill and upwind segments) and you had solid course and environment data (topography and wind). The only problem was that your pacing strategy assumed you could ride for the required duration at an NP of 340w, which was about 30w above your present fitness. Given that, it was predictable that you would ride the 1st leg too hard and wouldn't be able to maintain your target power on the 2nd leg. So, I don't fault your pacing "strategy." It just points out the importance of having very precise knowledge of one's sustainable NP for a given duration and the benefit of practicing variable power pacing. One more point. If I was a little uncertain of my sustainable NP for a given duration, I would probably take it out a little more conservatively and then gradually ramp it up if I found that I could go harder.

frenchyge

Agree, that was definitely an over-statement of my ability. That was based on a 5-min interval from 3 weeks ago where I held 361W, which I reduced based on being 15-min vs. 5-min. I've probably suffered some detraining in the last couple weeks as well - welcome to August.



That's a good idea, which I also considered, but when the outbound leg is uphill and/or against the wind there is little opportunity for that. You have to go hard from the start or you lose time. I guessed 340W, but I was riding at ~360W for most of the outbound leg because of the push, which compounds the problem. In the case where the outbound leg is your high-power leg, I'm guessing that you're better off to overshoot on the way out, and hold on to what you can on the way back. That's pretty much what happened to me and I still ran a negative split, so I'm okay with my pacing (aside from my poor assessment of 15-min power).

Were you planning to project what my time would have been if I'd just held a steady 310W for the entire time? It'd be interesting to see what the difference would be.