"The 33"-Road Bike Racing - Time Trials and cadence

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View Full Version : Time Trials and cadence


bidaci
11-02-07, 06:58 AM
I have read different views regarding a fast cadence and a slow cadence for optimal efficiency over time. But for a short TT (15KM) where optimum power output for a short period of time is desired is it better to have a slower cadence pushing a higher gear than a high cadence?

What cadence do you usually find using in your TT position and how does it compare to your road position?

Wondering if during the off season, I should spin harder or faster on the trainer.


waterrockets
11-02-07, 07:10 AM
I'm about the same cadence in both positions and race types. I don't modify my cadence for event duration, although it does seem like dropping 5-10 rpm for a short TT might make some sense.

Nothing beats testing -- everything else is speculation. If I were you, I would go out for like 4x 7-minute intervals, alternating between, say 92rpm and 100rpm. See what happens to your average speed, and report back. If you have a power meter, all the better...

cat4ever
11-02-07, 07:18 AM
Lower cadence on the TT bike. That's just the way it works out for me.


kukusz
11-02-07, 07:33 AM
You might want to check this out:

http://www.pezcyclingnews.com/?pg=fullstory&id=4011

There is a couple studies in there on cadence.

jrennie
11-02-07, 09:07 AM
97 seems to be my magic average. I jump around 90-100+ but it always seems to be a 97 average no matter the distance.

curiouskid55
11-02-07, 10:16 AM
I try to keep my cadence between 105 and 110, But also constantly monitor my HR to make sure I am working hard enough.

carpediemracing
11-02-07, 10:23 AM
See if you can't do a test on something which allows you to vary power regardless of rpms. I think the Tacx power trainer does this, I know there's some exercise bike thing that does it also - know anyone or a gym that has one? When I tested on such a device I found my rpms rose until I was doing a steady 111 rpms for about 150 watts worth of incremental increases. I didn't keep an eye on cadence, just tried to keep going, so I wasn't trying to "adjust" my cadence consciously. Then I blew sky high.

Such a test will help you find your optimal cadence at that moment using that equipment (particularly crank length). Change something you'll have to repeat the test to see how you changed.

hope this helps,
cdr

DrWJODonnell
11-02-07, 10:26 AM
Personally, I always TT at an average of 100+ for cadence. My best power output (per HR) is at around 80. My problem is twofold. At a low cadence I don't adapt to slight changes in resistance (Grade and wind) and I am much more likely to cross teh redline and need to recover for a loss of a few seconds. The other thing is that Lower cadence wears me down quickly and I find once I drop cadence I cannot raise it efficiently.

So, being the non TT guru I am, I have found that what works the best for me over all TTs is to start at a higher cadence and slowly 'bog down' over the course of the TT. I typically start at 105+, but for the last few miles I will be around 90.

However, this is what works for me. You have to find what words for you though experience. Good luck.

San Rensho
11-02-07, 10:54 AM
For what its worth, the ultimate TT, the hour record, was set at a cadence of around 104.

waterrockets
11-02-07, 11:43 AM
For what its worth, the ultimate TT, the hour record, was set at a cadence of around 104.

That brings up a question I've had recently: what's the aerodynamic impact of a higher cadence? The top foot is going proportionally faster through the wind in the pedal stroke, as cadence increases.

tfro
11-02-07, 12:18 PM
That brings up a question I've had recently: what's the aerodynamic impact of a higher cadence? The top foot is going proportionally faster through the wind in the pedal stroke, as cadence increases.

http://biketechreview.com/phpBB2/viewtopic.php?t=1048&highlight=cadence

Cliff notes seems to be that pedal movement isn't fast/big enough compared to the rest of the system to really matter.

waterrockets
11-02-07, 12:36 PM
http://biketechreview.com/phpBB2/viewtopic.php?t=1048&highlight=cadence

Cliff notes seems to be that pedal movement isn't fast/big enough compared to the rest of the system to really matter.

Yeah, I guess that with 175mm cranks at 100rpm, your foot is moving at 4.1mph. So, at 26mph, your foot is doing 30mph on top and 22mph on the bottom. Adding 5% to that cadence isn't going to amount to much.

I guess there's also no lack of results for time trialists winning w/out shoe covers in major TTs.

recneps
11-03-07, 08:43 PM
Honestly, for me low cadence vs fast doesnt make a difference especially in TTs. Theres only a certain amount of power you can put out whether it is at 110rpms or 90. and as far as I am concerned aerobic power vs anarobic, its all aerobic for a TT.

Basically its preferance.

San Rensho
11-04-07, 09:48 AM
Honestly, for me low cadence vs fast doesnt make a difference especially in TTs. Theres only a certain amount of power you can put out whether it is at 110rpms or 90. and as far as I am concerned aerobic power vs anarobic, its all aerobic for a TT.

Basically its preferance.

I really don't consider 90 to be a low cadence or 110 to be a high cadence, just the upper and lower limits of normal cadence. To me, low cadence is around 70 and high cadence is 120+

asmallsol
11-04-07, 09:50 AM
Training, racing, TT, whatever, I always feel comfortable at a high cadence around 105-118, so therefore I keep it there.

ratebeer
11-05-07, 01:55 AM
* Generally, the higher your LT, the higher your optimal cadence
* Higher than "normal" cadence relies aerobic power
* Lower than "normal" cadence relies more on muscular power
* Lower cadences can have more of a detrimental effect at the beginning of a race than at the end

seppomadness
11-05-07, 05:17 AM
Personally, I always TT at an average of 100+ for cadence. My best power output (per HR) is at around 80. My problem is twofold. At a low cadence I don't adapt to slight changes in resistance (Grade and wind) and I am much more likely to cross teh redline and need to recover for a loss of a few seconds. The other thing is that Lower cadence wears me down quickly and I find once I drop cadence I cannot raise it efficiently.

So, being the non TT guru I am, I have found that what works the best for me over all TTs is to start at a higher cadence and slowly 'bog down' over the course of the TT. I typically start at 105+, but for the last few miles I will be around 90.

However, this is what works for me. You have to find what words for you though experience. Good luck.

God that is scary I could of written that myself word for word. I seem to rev up around 115-120rpm fairly comfortably for some reason. I suck bad though.