The rule applied by most road TT specialist is :
for your average speed, and average favorite RPM, try to have the chain straight.
So, adjust the front big ring size to make use of the 5th smaller speed in the cassette (out of 11, generally 15t).
Knowing your usual speed, and your favorite RPM, and your cassette, you calculate your front big ring accordingly.
This is why top TT guys use 58 or 60 front rings. Not to go 60 or 58x11, except for short distances or downhill.

For track TT specialist, no chain line issue, the rule is :
get bigger, as the efficiency of 16 is better than 15, better than 14, better than 13, ...

But if you go 50x15 (for exemple), it is good enough on this efficiency point of view.

Hmmmm, I'll bite. You're averaging 26mph and you need help with chainring selection.

I recommend you go with a 42t front and a 10-42 cassette.

hi check picture , wahoo element and etap data

70.3 buenos aires 4/11/2018
https://drive.google.com/...GQy/view?usp=sharing
https://www.strava.com/activities/1946275667

olimpic triathlon
27/10/2018
https://drive.google.com/...b3-/view?usp=sharing
https://www.strava.com/activities/1930286408

I'm a pretty new cyclist.
I started a triathlon one year and 8 months ago.
In my country it is very small.
Uruguay
And entering this forum I learned how little I know.
I do not have people in my country who can teach me.
That is why I come to you.
I am one of those who prefer big.
But in Buenos Aires, I spoke with experienced triathletes, and some told me big chainring, other chainring guy.
and the worst thing is that they came first and second. I mean the two ran your chainring

Thanks and sorry my english
Rafael

hi
very thanks
If what I always did, is what I saw there, try to keep the line of the chain
54/15/16 is right
But my coach says that if you go ahead with a very big chainring, muscle spending is greater
and I can not find data about if this is real
Thank you
Rafael

 
For 26 mph
95 RPM
11/25 11 speed cassette

Optimal will be 52 x 15

May be your coach says if you go bigger ring (54 already too big) :
you will tend to spin less : greater strain on muscles ?
you will move 17t to compensate : you chain not straight at all, more losses at chain level, for sure

For me, 54 already a bit too big

very very thanks
I'm going to look at ebay :)
to buy, 52 do not know if there are 130, I think it's only for compact 110
but I'm going to look
Thanks
Rafael

this was very informative. thank you. I will have to think about this for the flat courses we have near me; Eagleman, Pineman, etc.

looking at your data, you aren't keeping the cadence as high as you say.

54x15 to ride average of 20mph= cadence of 71 that is fairly low in my view

Hi
As I am new to the subject I do not understand much what it says.
I only see that he did not answer on the real issue.
I do not believe that someone enters to put data to spend money without sense.
keep the line of the consultation is healthier for all and not detract from the query.
In my country many days it is very windy, like yesterday, I almost died to make 160k wind and very strong wind back.
now I leave a few links of several training specimens that touched me for 70.3
I do not know if they are good or bad, I trust 100% in the coach.
Greetings and thanks for looking at the tred


Link
https://drive.google.com/...mDd_PBVx?usp=sharing


the lowest cadence you will see is 89 and the highest 94 in the middle cadences.
in various works to rhythm
and the speed
38 km / h the minimum and the maximum 43, on average

thanks
Rafael

You are not running out of gearing. You were only averaging 39kph.

You don’t need different gears to say it simply.

Thanks Now buy 2 chainring 1 round 54 sram and 1 qring 52
I used your information a lot
Thanks