Second official attempt of 2009 at the Charlie Baker Time Trial. I lowered the handlebars on the death bike by removing a 10mm spacer and also angled my forearms down ever so slightly, but otherwise my setup was identical to last week. These small changes made the bike feel more stretched out which really seemed to improve my comfort. I was hoping that lowering the handlebars would make me a little bit more slippery as well.
I rode up to the race from my office in Wellesley, registered, and got three 2-minute efforts in at 70-90% of target average power. There was wind coming out of the south that would make coming back on Monument St. a little slow. When I got to the start line I had about a 4 minute wait. It was a pretty ideal warmup. My legs were a little tight from doing intervals on Tuesday, but I don’t think it had a huge impact on my performance.
My goal for the race was to improve my pacing by starting off at a pace that I would perceive to be extra easy for the first 5 minutes. With the headwind on the back side of the course it may have been ideal to save even more for the later half, but I’m not good enough at pacing yet to pull that off.
Within 0.1 seconds of my start time, a car came through the 4-way stop and pulled off to the side of the road with his flashers on. I had literally taken no more than 2 pedal strokes when this happened. In the racer’s meeting the promoter said never ever pass a car on the left, so with that in mind I pretty much just sat there and yelled “PLEASE GO!” The car did move before too much time was lost, but my average power for the first 5 seconds was a whopping 73 watts.
After the shaky start I settled into an unusually good rhythm for me, especially for riding the evil torture bike. 5 minutes into the race I felt just a hint of warm lactic acid building up, and I only spiked my heart rate by 2bpm or less.
Unfortunately the traffic was not so good. I was pinned against the side of the road and I don’t think I could have hit more potholes if I tried. Shortly before Carlisle Center the traffic may have played slightly to my advantage. I was passed by a School Bus and then a UPS truck. After passing me they stayed only about 100-200 feet in front of me. It could have been this or it could have just been the wind from the south, but I was going faster than usual for this part of the course.
Carlisle Center was a disaster. Traffic was backed up by at least 10 cars and some were extremely close to the side of the road. This forced me to soft pedal at less than 100W while I made a few very sweet cross moves off the side of the road.
After turning onto Monument Street I really began to suffer, but I was able to maintain a pretty decent power output unlike last week. I felt as if I was just crawling along, and my average speed really wasn’t good at all. I figured it was just the wind coming out of the south, but when I got overtaken by Lou Salemy who started 2 minutes behind me, it was really crushing. That guy was going so much faster than me, especially on the last two downhills of the course.
My official finish time was 24:05, and I felt good overall about the effort. My average power was 11 watts higher than last week, but with my handlebars lowered by a centimeter I was hoping for a faster time, maybe in the 23:35 range. Traffic slowed me down a little, but I can’t imagine it cost me more than 10 seconds total. My next thought was that the wind could have accounted for the remaining 20 seconds, but looking at the results I don’t think many other people were slowed down that significantly. Average power was a step in the right direction, but that was mostly due to better pacing. I’d still like to pick up 12-20 watts.
My CBTT model estimates my average CdA to be 0.279, up from an estimated 0.268 last week (updated 5-15). If anything this probably should have been lower due to my handlebars position change, so the difference is most likely due to the wind. I don’t account for wind in my model because wind speed is not constant, the effect is difficult to predict with certain parts of the course more sheltered than others, and the direction likely varies somewhat over the course of the race. Wind or no wind it didn’t appear that dropping the handlebars by 1cm had a big impact on my aeroness. I’d like to try moving my aero bars closer together to see if that has much of an impact. That will probably be the equipment change that I will make for next week. I still haven’t used my race wheels, mostly because I don’t like taking the time to put on the disc cover (which means taking off my cassette).
I rode up to the race from my office in Wellesley, registered, and got three 2-minute efforts in at 70-90% of target average power. There was wind coming out of the south that would make coming back on Monument St. a little slow. When I got to the start line I had about a 4 minute wait. It was a pretty ideal warmup. My legs were a little tight from doing intervals on Tuesday, but I don’t think it had a huge impact on my performance.
My goal for the race was to improve my pacing by starting off at a pace that I would perceive to be extra easy for the first 5 minutes. With the headwind on the back side of the course it may have been ideal to save even more for the later half, but I’m not good enough at pacing yet to pull that off.
Within 0.1 seconds of my start time, a car came through the 4-way stop and pulled off to the side of the road with his flashers on. I had literally taken no more than 2 pedal strokes when this happened. In the racer’s meeting the promoter said never ever pass a car on the left, so with that in mind I pretty much just sat there and yelled “PLEASE GO!” The car did move before too much time was lost, but my average power for the first 5 seconds was a whopping 73 watts.
After the shaky start I settled into an unusually good rhythm for me, especially for riding the evil torture bike. 5 minutes into the race I felt just a hint of warm lactic acid building up, and I only spiked my heart rate by 2bpm or less.
Unfortunately the traffic was not so good. I was pinned against the side of the road and I don’t think I could have hit more potholes if I tried. Shortly before Carlisle Center the traffic may have played slightly to my advantage. I was passed by a School Bus and then a UPS truck. After passing me they stayed only about 100-200 feet in front of me. It could have been this or it could have just been the wind from the south, but I was going faster than usual for this part of the course.
Carlisle Center was a disaster. Traffic was backed up by at least 10 cars and some were extremely close to the side of the road. This forced me to soft pedal at less than 100W while I made a few very sweet cross moves off the side of the road.
After turning onto Monument Street I really began to suffer, but I was able to maintain a pretty decent power output unlike last week. I felt as if I was just crawling along, and my average speed really wasn’t good at all. I figured it was just the wind coming out of the south, but when I got overtaken by Lou Salemy who started 2 minutes behind me, it was really crushing. That guy was going so much faster than me, especially on the last two downhills of the course.
My official finish time was 24:05, and I felt good overall about the effort. My average power was 11 watts higher than last week, but with my handlebars lowered by a centimeter I was hoping for a faster time, maybe in the 23:35 range. Traffic slowed me down a little, but I can’t imagine it cost me more than 10 seconds total. My next thought was that the wind could have accounted for the remaining 20 seconds, but looking at the results I don’t think many other people were slowed down that significantly. Average power was a step in the right direction, but that was mostly due to better pacing. I’d still like to pick up 12-20 watts.
My CBTT model estimates my average CdA to be 0.279, up from an estimated 0.268 last week (updated 5-15). If anything this probably should have been lower due to my handlebars position change, so the difference is most likely due to the wind. I don’t account for wind in my model because wind speed is not constant, the effect is difficult to predict with certain parts of the course more sheltered than others, and the direction likely varies somewhat over the course of the race. Wind or no wind it didn’t appear that dropping the handlebars by 1cm had a big impact on my aeroness. I’d like to try moving my aero bars closer together to see if that has much of an impact. That will probably be the equipment change that I will make for next week. I still haven’t used my race wheels, mostly because I don’t like taking the time to put on the disc cover (which means taking off my cassette).
6 comments:
Jay - What kind of wheel cover do you own? The spreadsheet is interesting. Do you have a template that is already massaged for CBTT?
This week should be interesting. Dougie it threatening to come and ride cannibal. If the weather is good I'm guessing he will be in the low 22s.
http://www.wheelbuilder.com/store/product.php?productid=16265&cat=0&page=1
i ordered mine from here.
yeah i have a template for the cbtt. course data is based on a .gpx file from motionbased.com. i also have one for longsjo TT, but i don't have much data for that, and drag numbers aren't so interesting there. it takes me about 5 minutes to drop in the power data and run the model manually. i added wind to it, but toggling the wind values to get a better result can really take a lot longer.
haha nice! yeah i would think 22's for sure. low 22's would be in the course record range for cannibal, but i wouldn't doubt it. i guess the pressure is on now!
I just got one of those covers. The seal to my DT 1.1 rim is not as tight as I'd like, but I knew when I got it that they work better with a deep rim. I saw a guy at Stillwater in 2007 who had one on a 404 and it was pretty slick.
So what inputs does your spreadsheet take besides the course? Just weight and power? Are you taking an average for the entire event, or plotting numerous points on the course based on the speed, power, grade, wind at that point? That would be pretty interesting.
Wheelbuilder did a real nice job cutting mine out and it fits pretty much perfectly. I just wish it didn’t weigh so much. My Powertap wheel weighs in at 1000-1200g (I can’t remember) as it is. The cover adds another 400-500g (again I can’t remember). That’s a pretty heavy wheel! At least the price is right and I really don’t think it makes much of a difference for a race like the CBTT. I hate installing but again, it’s worth it to me to save the money.
My model uses the following inputs:
-Body weight
-equipment weight
-outside dry bulb temperature
-outside dew point temperature
-average elevation of course
-wind speed
-wind direction
-rolling resistance
-course length
-frontal area (drag coefficient)
-course data (direction heading, distance, gradient)
-powertap data (distance, time, power)
It breaks the CBTT course into 41 sections. I think that’s a little on the high side but the course does have a lot of rollers that I didn’t want to ignore. I calculate both the actual and theoretical times it takes for the rider to complete each section of the course. Theoretical times are calculated in a separate model with 1-second increments to account for momentum. Most inputs are known, so I mostly just toggle the frontal variable input until the theoretical time matches the actual time. On a windy day I may toggle the wind inputs a bit to make the “actual speed vs. theoretical speed” match up a little better. For example at Wed’s CBTT my theoretical speeds were too slow on the way out and too fast on the way back. Adding a little wind from the south helped even that out.
I can email you some files if you’re interested. The excel file is set up so that I can produce a semi-presentable .pdf summary. The excel model itself is a bit of a disaster and I can’t imagine too many people would enjoy sorting through it.
Tonight I’m testing it out on the final hill of the course while gliding. A friend recommended trying it without pedaling so I could take an input out of the equation (watts!) and potentially reduce error. I thought it was a good suggestion.
Coasting a downhill and finding your max speed is the old fashioned way of checking your setup... It sounds like you've covered most everything anyway, except stuff like passing UPS trucks.
Pedaling makes some difference, with most riders probably pulling forward picking their head up. I find holding my head in one spot difficult. I like to exaggerate adjustments to get an idea of what is happening. For example, lower your aerobars by 10 cm. Would you be able to pedal without your knees splaying outward? Probably not, and the same thing might happen (obviously to a lesser degree) when you lower them 1 cm.
Are you measuring your frontal area somehow or just deriving it from everything else?
Disc wheels generally weigh a lot anyway, unless you spend a fortune. 1600 grams with a PT is not that bad. My cover weighs 440g.
It is cut flush (by them) but it's not the kind of seal I saw when these covers were used on a 404, where it had tight contact with the rim itself, 2cm or so inside of the braking surface. In that case the cover is a smaller diameter and probably significantly lighter. The utility provided by such a combination, especially if you're going to use a PT hub, makes it a pretty good value. I would imagine it could come out on par with the weight of a low-medium end disc.
If my saddle sore heals I'll probably be at CBTT again this week. I'll look for you.
if you think of a way to account for the ups trucks, let me know.
i'll probably be in the latter half of the race. i'll keep an eye for ya.
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