I’m aware courses are different, weather is different, all sorts of circumstances are different. But if we have:
What roughly does it take to get a 2:10h bike in a 70.3 race?
W/kg with an average CdA? Any personal experience with precise CdA numbers?
Any relevant input would be highly appreciated.
I think the best available model for those thype of things. Insert weight, gpx of course and weather, your power and you can model estimation. Some pros use is for ballpark figures and pacing.
You can play with power and CdA to check routes to your goal.
I’m well aware of the Best Bike Split. However, BBS requires a specific course to function, and I’m looking for general, non-event specific information.
Pretty hard to give you an answer for “non-event specific” results, since specificity requires details about the course. SO many factors play into this….wind, elevation, position, tire choice, etc.
What some can relay to you are specific results they have had, but which could be rather meaningless due to the above variables. A few years ago, I went 2:19 at IM Muncie 70.3….but in one leg of ~30 min, I was right about on the average speed you would need to go 2:10. I went 25.7mph on 213AP / 216NP. Course was dead flat and new, smooth asphalt. IIRC, there was a slight tailwind as well (which my return leg data seems to confirm as my avg speed went down but power remained consistent). I had my CDA tested the previous fall at ERO and it was .220, although I had since changed my kit and helmet. Both were almost assuredly faster than what I tested in, but I can’t say for sure and therefore I really have no idea what my specific CDA was that day. Zipp 808 front w/ Zipp disc, Shiv TT Nosecone bike.
But as noted, none of that means anything really outside of that day and those conditions.
Slightly better than 1000 w/m^2.
So 2:10 for 56 miles would be would be a speed of 25.8 mi/h (41.6 km/h)
Based on this Power to Speed Calculator, you can play around with Weight, CDA & power to achieve that speed.
As an example:
80kg, 0.225 CDA & 250w should get you pretty close (on a pan-flat course).
Personally, on a flat non technical course, I could ride a 2:10 with about 220-230w and a 2hr flat at around 280-300w.
I weigh 155. CDA per testing is sub .200
On a flat course, W/CDA > W/KG
Yes very much W/CDA > W/KG
Can play around with the weight slider in that calculator. Has very little effect.
This would have been my guess without any science. If you want to ride about 2 hours, push about 300w.
Yup…that lines up with my data above. We are about the same weight and similar CDA. Factoring in the slight tailwind from my Muncie bike leg, those numbers would be just about right.
@KlemenSj but really it is just so individual to rider CDA & stuff though.
At my local Tuesday night TT, I will often do the same speed as people putting out 80w more than me.
Take this 100mi TT from early in the year.
43.7 km/h so 2:03:44 for 56-mile speed
But off only 267w
Funnily enough just looked up the Strava file of a friend who I was fairly sure had gone about 2:10 in a 70.3. And yes, he did 253W for a 2:09:xx on a pretty much pan flat course with good tarmac, he weighs ~80kg and while I don’t think he’s ever tested his CDA I’d guess he’s in that ballpark. Decent triathlete position that is a good balance of aero, power, comfort and ability to run off the bike. And bike itself ticks off all the low hanging fruit - clean front end, good hydration positioning, deep front wheel, disc at the rear - without being a super bike.
I recently did a full IM distance bike leg with the below stats. I wasn’t kitted out (speed suit, shoe covers, etc…) and was staying in low tempo power. This is a flat course with no stops.
Good post. I’ve gone 2:10-2:13 several times on the Gulf Coast course in PCB and all are ~245-255 AP for someone 73.5in tall and 168lbs.
I’ve gone similar speeds on other courses, but call those out to agree with @Power13’s comment that it can be “day specific” as well. My slowest time on that course was 2:13:XX and it was actually my highest AP and NP as I got out of the swim really quickly and may have passed 4 people all ride - also a hellaciously windy day. Conversely, I went 2:10:XX on 246 AP, but the swim was like glass, so there were a ton more people able to swim quicker. I think I may have passed 20 people that day and sat in a legal “group” for the last 15 miles - this day also had no wind on the way out and tail on the way back. (Legal group called out bc a Marshall was with us the last 10 miles and I received 3 separate thumbs up when asked if we were legal).
Roughly 10% more than 1000 w/m^2, i.e., around 1100 w/m^2.
This thread makes me wish I still had my TT bike.
Thank you Ben, this link is extremely useful!
Out of curiosity: at what point in your career did you decide to switch from a road bike and invest in a TT bike?
1 year for me. Started TT/Tri’s in 2017, and got a TT bike at the start of the 2018 season.
Was only a pretty cheap 2nd hand one though.
Definitely worth clip-on aero bars on a road bike in between.
If set up well, can see a bigger gain from them. Than from clip-on aero bars to full TT bike.
That’s why I’m asking. I’m currently on a Giant TCR Advanced KOM 2022, fitted and with clip on aero bars.
My power is good, but definitely a lot of room for improvement.
Only recently I started looking into the aerodynamics aspect as well. I don’t want to leave large gains on the table simply because I’m neglecting an important factor of performance. I could push 3.5+ W/kg in my 70.3 races next year and I’m wondering if I’m at a point where I should start considering aero gains, starting with a TT bike.
185lb rider, 0.23cda, 220W That’s what bbs says for the Miami course. Are there flatter courses?
