MDcatV

what gearing are you TT guys running on your rigs?

I did my 1st TT this past weekend as part of a stage race. On road bike w/ no aerobars and in fact no aero gear at all except my skinsuit and shoecovers that I normally wear for crits. I was in 53x12 and to the point where my cadence was too high to maintain FTP (not spun out, just outside optimal zone).

So, if I'm going to put some time and $ into a TT set up, what gearing do you recommend? Think ubiquitously, for a guy who doesnt want to change out cranks and chainrings and TTs on rolling to flat terrain.

UT_Dude

I usually use pretty standard gearing... Standard 53/39 chainrings and an 11-23 cassette. I like having the 53 as the big ring, because with the 23 in the back, you can still grind up most hills in the big ring that you'll find on a TT course. I have to hit ~40 to spin out the 53-11, so that's never really been a problem either.

ElJamoquio

In my opinion, if you're really spinning out a 53x12, you're better off coasting. Many on the board disagree with me.

MDcatV

this course was on long gradual grades. wasnt "spinning out" I was just at a cadence that was outside my comfort zone to sustain the effort at threshold power, and *think* I would have been more comfortable pushing a taller gear.

UT_Dude

Like I said, having the 11 over the 12 should solve a lot of your problems.

waterrockets 

On TT pacing, here's a new paper on the subject. I haven't checked it out yet though. Looks pretty thorough. ELJ, I'd be interested in your thoughts:

https://groups.google.com/group/watta...ba9c8913f77ebb

transplant

before i dedicate an entire new thread asking for a critique of my latest TT performance:

are negative splits always faster? carmichael was on versus (and i've heard elsewhere) that your effort is best spent going harder on the "hard" sections, for lack of a better description...

again, before getting an entire thread about this, my numbers:
1st half - AP 354w / NP 357w @ 24.9mph
2nd half - AP 328w / NP 330w @ 27.9mph

pjcampbell

It depends completely on the course. I would look more into Allen Lim's video

https://www.saris.com/powertour.aspx
Pacing During a Time Trial

king-tony

No. It is course dependent. Assuming this was an out and back you were either going uphill on the outbound leg or into the wind which means that you spent more time at 357w then you did at 328w. How long was this course?

transplant

it was out and back. outbound was into the wind, for the most part. the thing i didn't anticipate was how hard the crosswinds were going to be.

from the results. i had a 9:15am start, and the winds were somewhat more gentle at that time.
"The weather at noon was 79° Fahrenheit, sunny, with winds out of the west at 15-20mph, with gusts well above 25mph.
This made for some very high return speeds coming east. There were 65 racers. Exact event distance was 36.70 kilometers (22.81 miles)"

patentcad

>>No delusions of grandeur<<

Nobody told me this.

skinnyone

Duh just remembered that I should prob have posted here instead of a new thread.

Anecdotal info on aerodynamics with relation to a TT or tri bike.

https://www.triathletemag.com/Assets/...Dec19_2006.mp3

milliWatts

This is truly an excellent thread and the OP sounds very experienced.

I'm hoping to get into TTing so I'm going to print the OP and hang it.

Just one question, though - should I start HARD?

fly:yes/land:no

so... i don't plan on doing any tt's. i just thought you guys might be able to explain the significance of base bar position. it was my impression that the base bars are pretty mugh insignificant, as you spend 95%+ in the extensions. you are really on the drops only when you are braking and sprinting, right? the only reason i ask is the lengths to which lim is going to get cvv's base bar equal to the oval concepts base bar from last year:

https://www.cyclingnews.com/tech.php?...ar_new_profile

king-tony

I think they are trying to shield the tire with the base bar..... I have no idea how anyone could ride in that position. The pads are below the top of the head tube.

marcelinyc

What about training?
When is a good time to start TT intervals?

ElJamoquio

FYI, the OP is one of the better amateurs in the country.

AlexTaylor

Are these the shoe covers in question?

https://www.wiggle.co.uk/p/Cycle/7/Pe...er/5360038025/

carlfreddy

Maybe I'm smokin' something, but I seem to remember a link floating around that had wind-tunnel data from a couple different TT bikes.

Anyone remember this? I can't find it.

mollusk

Yesterday I went out to do a personal 8 mile TT on my road bike (essentially a 20 minute or so interval) in the cold for us weather (44 F). I noticed a significant decrease in speed speed versus doing the same kind of ride in the heat of summer. At first I thought that I might have lost a bit of FTP as I have lost a significant amount of weight, but the Kreuzotter calculator gave me very comparable power numbers between the two types of rides I'm guessing that the increased air density (and hence drag force) made the difference. Any of you TT guys with power meters have good data on how air temperature changes your times? Is it only changes in drag? Is there any benefit to the increased concentration of oxygen due to being cold like with IC engines, i.e. more oxygen intake per breath?

mollusk

I think that I have at least a qualitative answer. Yesterday I did an ITT and didn't suffer anywhere near as much and rode faster. It was also about 25 F warmer.

TheKillerPenguin

So, we all know the natural tendency one has on a TT bike is to scoot forward on the seat. I'm setting up my position...should I measure my leg extension from where on the saddle I'll be sitting when going hard, or for where I'll be when I'm crusing? I assume that if I set it up for when I'm on the rivet, it'll just cause me to scoot even farther forward to compensate.

Thoughts?

mollusk

Hey, KP, if you ever get this figured out let me know. I'm a total noob at this stuff, so I can't help you out.

Today I rode for the first time ever with aerobars. I had a set just lying around because they came with a bike that I bought on Flea-Bay (Profile Design, Airstryke, and F-19 are on the things - I have no idea whether these things are good or not) so I thought that I would give them a whirl.

First thought was "Holy crap, does this make the bike twitchy. I'll never be able to ride in these things." After a while getting used to them and practicing transitioning from the "normal" bar positions to the aerobar position it wasn't so bad. My second thought was "Holy crap, you can go one hell of a whole lot faster with these things."

A couple of questions for those in the know. First, are dedicated TT bikes just as twitchy as road bikes with clip-on aerobars? I don't plan on buying a dedicated TT bike soon (although the shop that sponsors my racing team sells Felt and I might be able to score a killer deal on one), but damn the bike handling of a road bike with clip-on aerobars it is a major distraction.

The second question is how can I get my position lower? I have no spacers on my bike that I'm using as a TT bike (2002 Lemond Zurich - these have a pretty short headtube BTW) and I have my stem flipped down and I even rotated the aerobars down about 10 degrees from that and I still feel like I could get lower/more aero. I even started out with the aerobars inserted to their minimum amounts. I'm looking for a CHEAP solution here, not a $10K bike purchase solution.

king-tony

I've thought about this one for a while and I think the answer would be to set the seat up so that you are in your most aerodynamic position the way you would ride on the rivet. Obviously this would change a little based on the length of TT, but if you mainly do 20k's that is where I would set it.

mikearena

1. Told ya so.

2. It's my understanding that the slacker head tube of most time trial bikes will help smooth out the handling a little bit, but it'll never be quite as smooth as you're probably used to. I used to ride around on the track bike with aerobars (75* headtube) and that made for some close calls at times.

3. Some aerobars let you attach the extensions underneath the bars. I'm using the Profile t2+ bars, and it required some rearrangement of the attachment hardware, but I've got them set up so they attach under the bars and get me about another inch or so lower. You could also just buy a really tiny bike for dirt cheap and set that up for time trials if you wanted a separate bike solution. But really, you should just pick up a Felt DA because I want to see one in person.