What tire do I want to use for a computrainer TT race? Is the conti home trainer tire terrible? I assume max pressure regardless of weight since it’s a smooth roller? Do latex tubes give a similar advantage as they would “on the streets”? Is a wider tire better for lower Crr? Does it even matter?
Any other tips for going faster while not actually moving?
What is the purpose of this TT? Is it a test to set training zones or something else?
It is a race, so to cover the virtual 10kms ASAP.
Your tire will make no difference…the rolldown test eliminates the effect of rolling resistance so that the CT effectively measures watts at the hub.
If you want to win this CT TT in Boston, make sure you do the rolldown test with a really hard press on force and get a number like 3.5. Then you should go and unscrew the roller a half turn when no one is looking (this is effectively the same as cutting the course or drafting at IM Florida…). Now you will be MEGA STUDLY. Your FTP should climb around 20-40W :-). The CT will move your image down the course as if you are generating 40 extra watts.
All kidding aside, make sure you do a really hard warmup to heat up your tire, because if your tire heats up more DURING the race, your actual watts and your displayed watts will diverge and you’ll likely end up with a slower time than your actual effort.
Your tire will make no difference…the rolldown test eliminates the effect of rolling resistance so that the CT effectively measures watts at the hub.
If you want to win this CT TT in Boston, make sure you do the rolldown test with a really hard press on force and get a number like 3.5. Then you should go and unscrew the roller a half turn when no one is looking (this is effectively the same as cutting the course or drafting at IM Florida…). Now you will be MEGA STUDLY. Your FTP should climb around 20-40W :-). The CT will move your image down the course as if you are generating 40 extra watts.
All kidding aside, make sure you do a really hard warmup to heat up your tire, because if your tire heats up more DURING the race, your actual watts and your displayed watts will diverge and you’ll likely end up with a slower time than your actual effort.
Is this actually true? I ask because I’ve had my CT for about 2 years now…and for a looooong time I wasn’t calibrating every time I rode. I would screw it in and just leave it.
I wasn’t really using power and going mostly by HR and RPE since that’s all I was going to have on the course. But I never really understood true impact of that calibration.
Thx Dev, I don’t think even an extra 40 watts would help me win one of these given the uber-studs who show up. If anyone is interested though, the one I was thinking of is up in Portsmouth, NH:
(The added bonus is you have a chance to win a free entry to the Pumpkinman Sprint or HIM in Sept)
I would think that a Continental, Tacx, or Vittoria trainer tire would all pay dividends regardless of whether you are on a CT, Tacx, or manual stationary trainer. As for air pressure, I cant say for certain about the CT, but for the Tacx Fortius - 120 psi with 3 to 3 1/2 turns on the knob that adds pressure between the tire and the roller. For the absolute highest level of precission, due to practice runs on the CT with a power meter equipped bike to ensure that the CT’s calibration is in agreement with the power meter.
If you care about the watts be accurate, then you should do the roll down test on EVERY ride AND have a fan blowing air at the tire to keep temp constant so that your rolling resistance stays constant.
If you are just going by perceived exertion and heart rate and don’t care about what the watts say, then what you are doing is fine.
The entire point of the rolldown test is to eliminate the rolling resistance contribution from one tire vs another or the same tire at different pressures…but once you have done the rolldown test you want to keep temperature constant…if not, Gay Lussac’s law comes into effect as temperature changes for a fixed volume (P1/T1 = P2/T2)…here is the entire explanation of what is going on in your tire as it heats up:
Your tire will make no difference…the rolldown test eliminates the effect of rolling resistance so that the CT effectively measures watts at the hub.
If you want to win this CT TT in Boston, make sure you do the rolldown test with a really hard press on force and get a number like 3.5. Then you should go and unscrew the roller a half turn when no one is looking (this is effectively the same as cutting the course or drafting at IM Florida…). Now you will be MEGA STUDLY. Your FTP should climb around 20-40W :-). The CT will move your image down the course as if you are generating 40 extra watts.
All kidding aside, make sure you do a really hard warmup to heat up your tire, because if your tire heats up more DURING the race, your actual watts and your displayed watts will diverge and you’ll likely end up with a slower time than your actual effort.
Is this actually true? I ask because I’ve had my CT for about 2 years now…and for a looooong time I wasn’t calibrating every time I rode. I would screw it in and just leave it.
I wasn’t really using power and going mostly by HR and RPE since that’s all I was going to have on the course. But I never really understood true impact of that calibration.
It does make a difference. I think the manual states that each .01 of force equals about 1/2 watt.
But I think another poster had it backwards. If I calibrate at the beginning and the resistance is 3.0 cold, and then I warm it up and calibrate again it may be 2.0. If I never do that second calibration, the CT “thinks” that I’m pushing 50 watts more than I actually am. When I switch the setting from 3.0 to 2.0 after the tire is warm, it gets noticeably harder for the same recorded watts.
Your tire will make no difference…the rolldown test eliminates the effect of rolling resistance so that the CT effectively measures watts at the hub.
If you want to win this CT TT in Boston, make sure you do the rolldown test with a really hard press on force and get a number like 3.5. Then you should go and unscrew the roller a half turn when no one is looking (this is effectively the same as cutting the course or drafting at IM Florida…). Now you will be MEGA STUDLY. Your FTP should climb around 20-40W :-). The CT will move your image down the course as if you are generating 40 extra watts.
All kidding aside, make sure you do a really hard warmup to heat up your tire, because if your tire heats up more DURING the race, your actual watts and your displayed watts will diverge and you’ll likely end up with a slower time than your actual effort.
Is this actually true? I ask because I’ve had my CT for about 2 years now…and for a looooong time I wasn’t calibrating every time I rode. I would screw it in and just leave it.
I wasn’t really using power and going mostly by HR and RPE since that’s all I was going to have on the course. But I never really understood true impact of that calibration.
The calibration is HUGE.
It is a race, so to cover the virtual 10kms ASAP.
10km. Yum - that’s about my distance all right … maybe 13:30 on a flattish course with zero overall elevation change?
Wow.
I knew calibration would make a difference I just guess I never thought it would be that significant. 30-40 watts is HUGE.
I am going to try that tonight…with a 30-40 watt difference I should be able to see a speed difference as well, right? So if I have everything calibrated correctly at 3.0 (or so) and pick a gear and RPM that gives me 250 watts…If I then loosen it up and ride that same gear and RPM I should see a higher wattage and speed, right? I realize that is not a very accurate way to do it…but with a 30-40 watt gap I should be able to eye-ball that.
I am training with power now. But up until a few weeks ago I still didn’t calibrate with every ride.
Although I do have fans blowing all over…so I was doing something right!!
Just when I think I can’t get any dumber…
it’s in 'da manual eh? 0.01 lbf~=1/2 W —> 1.00 lbf ~=50W
I prefer learning things the hard way. that way the lesson is never forgotten.
When I was a kid I got leggos and/or transformers. Do you think I read the manuals then? Of course not. did I break some…youbetchya.
Why would I use the manual now when I buy a new toy? I’m still just a big kid.
I’d rather show the world how stupid I am by posting my stupid crap on ST…which I seem to do on a regular basis.
Hell…just yesterday I posted that I held 130% of ftp for 5 min…until people were like “wow, that’s pretty damn good”. I thought to myself that it wasn’t that hard, what’s the big deal? Well it wasn’t that hard because 330w isnt 130% of 300w which is my ftp (298 actually). Stupid me. There is a pretty big difference between 110% and 130%.
That mistake won’t be made again because as is normal for me…I looked like an idiot.
hey this forum features such erudite posters as Mr. F.Day so don’t be too hard on yourself 
!!
Check out the Minoura Dualist. Touted as an indoor/outdoor tire. Pretty sticky on CT climbs - less slipping than TACX or Conti, but tough enough that you can ride it outside on those nice weather days.
I suggested calibrating at 3.5 and then unrolling back so you end up around 2 and not slip (but ride as if at 3.5). What I can do on my next ride is do this exact thing and then ride with my SRM in parallel and see what the divergence is
Your tire will make no difference…the rolldown test eliminates the effect of rolling resistance so that the CT effectively measures watts at the hub.
If you want to win this CT TT in Boston, make sure you do the rolldown test with a really hard press on force and get a number like 3.5. Then you should go and unscrew the roller a half turn when no one is looking (this is effectively the same as cutting the course or drafting at IM Florida…). Now you will be MEGA STUDLY. Your FTP should climb around 20-40W :-). The CT will move your image down the course as if you are generating 40 extra watts.
All kidding aside, make sure you do a really hard warmup to heat up your tire, because if your tire heats up more DURING the race, your actual watts and your displayed watts will diverge and you’ll likely end up with a slower time than your actual effort.
Is this actually true? I ask because I’ve had my CT for about 2 years now…and for a looooong time I wasn’t calibrating every time I rode. I would screw it in and just leave it.
I wasn’t really using power and going mostly by HR and RPE since that’s all I was going to have on the course. But I never really understood true impact of that calibration.
It does make a difference. I think the manual states that each .01 of force equals about 1/2 watt.
But I think another poster had it backwards. If I calibrate at the beginning and the resistance is 3.0 cold, and then I warm it up and calibrate again it may be 2.0. If I never do that second calibration, the CT “thinks” that I’m pushing 50 watts more than I actually am. When I switch the setting from 3.0 to 2.0 after the tire is warm, it gets noticeably harder for the same recorded watts.
Thanks for that note on .01 = 1/2 watt. I forgot to calibrate during an erg workout today. I was supposed to be riding tempo at 240w (calibrated at 2.0). By the end I was spent and when I did a rolldown I realized the real number was 2.44. I was guessing that I was pushing about 260w in reality and I think you just confirmed that.