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Effect of Turns on Overall Speed

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Effect of Turns on Overall Speed

Old 06-23-21, 09:38 PM
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Dthomp22
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Effect of Turns on Overall Speed

Hey all,

Im a total crit junkie. I just love really technical races (probably because it drops less experienced riders) and constantly ride on a crit course that I have that is basically a rectangle, one mile long, 4 90 right turns. Pretty simple. I have a question for those of you who double as crit riders and longer distance / TT. How much difference in overall speed do you think it makes to have to accelerate out of turns constantly, 4 times per mile, over, say 10 miles.

To throw some numbers in, lets say I get on that course alone and ride 10 miles at 200 Watts and that is equal to 22 mph average. Now I switch to a TT, straight out and back, same distance. Should I expect to go faster for the same Watts, or should I expect to be able to put out more Watts without the bursty efforts? Or a combo of both? Would I actually perform worse without the bursts of speed and instead, long consistent effort?

Thought it was an interesting question. Appreciate all thoughts!
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Old 06-24-21, 01:21 AM
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tempocyclist
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That is interesting! I

I'd be inclined to say you'd be faster for the same average power over the out-and-back TT course - or at least - I would be faster over the TT than the crit style course. Slowing for corners kills average speed and the big burst of sprint power four times every mile would drain the legs.

I think it might come down to what type of rider you are in a way.
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Old 06-24-21, 07:48 AM
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There's a lot at play. In TT your effort is so regulated that you can attain a higher AP. How tight are the corners? Are we talking you have to stop pedal for 5 seconds per turn and lose 2mph or you stop for longer and lose a lot more?

I'd be interest in rubiksoval chiming in. I've no idea on the crit part.

I ride in a hilly part of town with constant corners. It costs.

For the TT bike, I've gotten to the point I that if it is visually clear and I can own my whole lane and the whole next lane I can stay in the skis. That has taken a LOT of butt puckering practice to do. Easier for lefts than rights. Rights I'll slow it up more to avoid going over the center yellow. Lefts? If it is visually clear it's a full speed turn in the skis. Mind you these 90 degree turns are NOT the Euro city streets lined with barriers that pros must navigate and slow down for. But wider American streets/roads with the 90 degree turn. And pros enter a corner probably 3 to 4mph faster on a TT bike than I do. So they have to shed that speed.
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Old 06-24-21, 07:49 AM
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Sy Reene
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Originally Posted by Dthomp22 View Post
Hey all,

Im a total crit junkie. I just love really technical races (probably because it drops less experienced riders) and constantly ride on a crit course that I have that is basically a rectangle, one mile long, 4 90 right turns. Pretty simple. I have a question for those of you who double as crit riders and longer distance / TT. How much difference in overall speed do you think it makes to have to accelerate out of turns constantly, 4 times per mile, over, say 10 miles.
Why isn't this simply determined by looking at your ride data? What mph are you going at during the 1 mile straight stretches? Subtract from this the ride's overall average mph.
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Old 06-24-21, 08:23 AM
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Originally Posted by Sy Reene View Post
Why isn't this simply determined by looking at your ride data? What mph are you going at during the 1 mile straight stretches? Subtract from this the ride's overall average mph.
The whole loop is 1 mile. If I had to guess, its .3 on the long sides and .2 on the shorts in one rectangle. I suppose I could look at the data for those longer straights and see, the thing is that I spend so much time accelerating and decelerating for 90 turns (probably .1 miles per turn to be honest) so I was wondering how it factored in to a more straight effort without all those turns.
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Old 06-24-21, 08:25 AM
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[QUOTE=burnthesheep;22115542]There's a lot at play. In TT your effort is so regulated that you can attain a higher AP. How tight are the corners? Are we talking you have to stop pedal for 5 seconds per turn and lose 2mph or you stop for longer and lose a lot more?

Flat course, 90 turns and I stay in the right lane only because I cant see around corners though I do have the whole lane because it is never busy. I definitely have to stop pedaling, probably hit the flats at ~22 and take turns around 18 mph since theyre so tight.
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Old 06-24-21, 09:36 AM
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So, the important questions are: do you have to brake on approaching the turns (probably), how much speed do you lose from that, and how quickly do you accelerate when coming out of each turn. If you have to brake at all, that's energy that you don't recuperate. Track velodrome riders don't really lose speed in the turns (their wheel speed actually increases) but that's because the radius of the turns is large enough that they don't have to brake -- but 90 deg turns in a crit aren't like that. Even if you can coast through the turns, in a crit you have to accelerate out of each turn. Typically, the accelerations are way above FTP so even though they're short in duration there's a physiological cost (that's the idea underlying the normalized power algorithm). If you had a power meter on your bike we might be able to see what those braking decelerations and then accelerations out of the turns are "costing" you. Then we could probably figure out what your total energy expenditure was, and re-allocate that if there were no braking decelerations and turn accelerations to figure out the new speed on a straight course.
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Old 06-24-21, 06:51 PM
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It's going to vary a lot depending on the rider and how wide the entry & exit to the 90 degree turns are. Given enough road and solo you should be pedaling through a 90 at a similar speed to what most can sustain for 10 miles. If not pedaling at worst coasting for a couple pedal strokes. Crits turn into acceleration contests more because of accordion effect than the cornering capability of a bike.
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Old 06-25-21, 05:40 PM
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Interesting to read a thread where the answer was already known.
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