Ironman Lake Tahoe 2013: Full Results and Analysis

All I knew about Lake Tahoe prior to the weekend was that the bike featured a lot of climbing and was at altitude – it was likely to be tough. With new races at unfamiliar locations I’m reliant on forums to fill in a venue’s back story. I hadn’t anticipated that a tough course would also meet such cold conditions. The results are unsurprising and Ironman Lake Tahoe looks to have a claim to the title of slowest race on the Ironman Circuit.

DNS and DNF Rates at Ironman Lake Tahoe 2013
Bib List Athlete Tracker
Competitors 2650 2265
Swim Finishers 2148 2148
Swim DNF/DNS Rate 18.9 5.2
Bike Finishers 1899 1899
Bike DNF Rate 9.4 11
Run Finishers 1717 1717
Run DNF Rate 6.9 8
Total Finishers 1717 1717
Total DNF/DNS Rate 35.2 24.2

Whenever a race proves tougher than expected there is a jump in its DNF rate over the Ironman average of around 5%. The figure I’ve seen quoted for Lake Tahoe is 35%, but as I’ve discussed previously DNF numbers are often inflated by DNS numbers. The table above shows the DNF rates based on the number of age group athletes who signed up to the event (bib list) and the number registered to start (Athlete Tracker). Based on the bib list we do get a DNF total of 35%, but 385 athletes (14.5%) weren’t even present on race day. Using figures from Athlete Tracker gives us a closer estimate of the DNF rate based on those registered to start – it will still include those who chose not to race on the morning. This yields a figure of 25%; Ironman St George 2012 is the only other recent race to have a clean DNF rate over 20%, Los Cabos is also close at around 20%.

Distribution of Finisher Splits at Ironman Lake Tahoe 2013
Distribution of Finisher Splits for All 2012 North American Ironman Races
Distribution of Finisher Splits at Ironman St George 2012

Knowing that a higher than normal percent of athletes didn’t finish we can also see in the distribution above that those that did were slower. Not so much in the swim, but bike, run and overall splits are all strongly skewed; the difference to the typical North American distribution is quite distinct. That the Lake Tahoe run splits lack much weight over 7 hours reflects the fact that athletes running that pace likely missed the cut off after an equally slow bike. Using Ironman St George for comparison again it’s apparent that, aside from the swim, Lake Tahoe was a slower event than the 2012 edition of St George. Cold conditions, altitude, plenty of climbing – this is not a fast race.

Median Splits by Age Division at Ironman Lake Tahoe 2013
Median Splits for All 2012 North American Ironman Races
Median Splits by Age Division at Ironman St George 2012

The median splits for each age group provide further confirmation. Swim times are comparable with the North American median and run times aren’t too far off, but bike splits are much slower than the average. Even the pro field was significantly slower on the bike at Lake Tahoe. Comparing to Ironman St George bike and run are broadly similar, but the swim is faster. Pro splits suggest Lake Tahoe may have been the faster race, but we can see among the age groups, particularly the older women, there are some distinctly slower times at Lake Tahoe. There are certainly a lot of parallels between the two events, but the split distributions point towards Lake Tahoe being the slower.

Predicted Kona Slot Allocation for Ironman Lake Tahoe 2013
  Number of Athletes Number of Slots
F18-24 4 1
F25-29 43 2
F30-34 106 3
F35-39 104 2
F40-44 143 3
F45-49 85 2
F50-54 71 2
F55-59 32 1
F60-64 8 1
F65-69 3 1
M18-24 15 1
M25-29 82 2
M30-34 220 4
M35-39 263 5
M40-44 359 6
M45-49 281 5
M50-54 156 3
M55-59 80 2
M60-64 37 2
M65-69 10 1
M70-74 1 1
Total 2103 50

The above slots are estimated based on the number of athletes completing the swim in the Athlete Tracker (not those in the original bib list), actual figures will vary based on start numbers. However the table provides a rough guide to the allocation and enables us to look at the times required to qualify.

Top 20 Male Age Grouper Performances and Kona Qualification at Ironman Lake Tahoe 2013
Top 20 Female Age Grouper Performances and Kona Qualification at Ironman Lake Tahoe 2013

Unsurprisingly the top 20 in each age group post slower times than we’d normally expect at an Ironman. The drop off in performance between first and tenth is also much faster than we usually see in competition for Kona slots. For a real indication of how much slower this race was it should also be noted that one solitary age grouper in the M40-44 division broke 10 hours. Qualification was less a matter of speed than strength and consistency in the face of a tough course and conditions.

Ironman Lake Tahoe is the slowest race I’ve analysed this year, certainly on the Ironman Calendar at the moment. Of course with only 1 year of data it’s impossible to know if this will prove to be the norm for the race or a slow extreme. Clearly though it’s always going to be a challenging course.

I’ve uploaded a spreadsheet of the results and splits for Ironman Lake Tahoe 2013 to my Google Drive.

All Ironman Results and Statistics

A growing collection of results and statistics for the whole Ironman race calendar.

Find out what it takes to place in your age group or to qualify for the Ironman Worlds Championships in Kona.


  • This is great stuff. Thanks for the analysis.

  • J.L.

    This math professor likes your analysis. And, I’m also very glad that I chose Whistler as my first Ironman. I had my heart set on Tahoe…love the area. But after surviving Whistler, and knowing how depleted I was after the bike, I cannot imagine what these athletes went through. My hats off to all the finishers, but especially those who DNF’d. I hate to sound like a 12 year old, but it really is NOT fair. I have friends that are getting ready for their first…in Florida. So much more I could say, but I’m sure you understand it better than me. I know that for Whistler, I trained for the course map which said 4200 feet total elevation and then my garmin reads 6200. Doesn’t take a math major to figure out someone just simply isn’t paying attention when they ask people to pay $750 to do their race. I just feel really bad for the people who trained for a tough course but were given something so much harder.

  • Hardest IronMan in the world. Orthopedic Surgeon Dr. Mark Kwartowitz finished in just over 13 hours proving to our patients that he practices what he preaches…movement/motion is life.
    Amazing accomplishment to all the finishers of Lake Tahoe IronMan!

  • Always pleased when mathematicians and statisticians approve! Thanks for the comments.

    New races on the Ironman calendar are always a bit of an unknown. Seeing a California race I’d have automatically assumed hot and sunny without further knowledge. While I’d heard discussion of the potential difficulties of the course, I’d not anticipated that it would prove to be the slowest Ironman race I’ve analysed yet. Clearly a challenging day for those unfamiliar with the course and expecting a ‘typical’ Ironman race.


  • Jeff

    Not discussed much, but the wind was also a factor in the slow bike splits. It was a headwind in the valley going towards Truckee (the downhill part), so it was hard to make up time there, plus it got people even colder.

  • Marvin

    In regards to your comment, “DNF numbers are often inflated by DNS numbers”, I would say that in some cases, the DNS numbers are at least partially DNF. Not sure if it’s just the way they track things, or if WTC is trying to keep their DNF percentages lower. For 2012 SG, there were a number of us that were pulled from the swim, however the final “results” showed DNS. Some of them were updated later, but I’m not sure that they all got fixed. For Los Cabos, I had my chip come off in the swim, and ended up with “DNS” listed in the final results.

  • Marvin,

    There’s little real transparency with any of these numbers around Ironman. No explicit DNS, DNF or DQ numbers are published on; I have seen a few races that have published clear numbers on their own sites, but it’s increasingly rare as Ironman standardises web pages. So it’s probably fair to say that all DNS and DNF numbers are an estimate based on the information available. I don’t think the WTC deliberately alter the numbers, I think they just don’t manage the results consistently or well enough so lots of mistakes slip through and remain in place.

    Basically though – you’re right that we can’t be 100% sure on the numbers, at least not with the current way information is given.



  • Steven O’Connor

    Well I was excited about getting into IMLT until I started reading the reviews and numbers. I just finished IM MOO (second time) and was thinking it was pretty tough but sounds like IMLT will be a bit tougher. Oh well, a sign at IM MOO summed it up for me


    IMLT will be my 9th and really none of them have been easy. Thats why we love it.

  • Bruce English

    I learned from Mike Reilly (the “voice” of Ironman) at the IM Lake Tahoe wrap up and awards presentation this morning in Squaw Valley that 2139 athletes “hit the water” (as he put it), and the DNF rate for those starting the race was 20.7%. This was my fifth Ironman, and clearly the hardest challenge of them all.

  • Thanks Bruce,

    Interesting to have the official word. Although that number differs from the Athlete Tracker, that has swim times recorded for 2148 athletes! If 2148 started and finished the swim that’d give a DNF rate a little under 20.7%. Always hard to pin exact numbers down for races!


  • tim

    As a timer for another company, I will say it’s NOT hard to pin down exact numbers on how many DNF’d/DNS for each race (I actually send that info to the Race director of each race afterwards). We don’t actively publish those numbers either as it is sometimes daunting to see them, as you’ve shown above.

    Nice work though!

  • Kevin

    Do you have any data on Mont- tremblanc ?

  • Kevin

    Spell check…Mont- tremblant

  • Love the data, we were hearing rumors of 1100 people DNFing from hotel staff and other finishers last night and this morning. It was a challenging day on many fronts – from freezing conditions at the start, to not feeling my toes for the first 2 hours of the bike, slightly insane climbing with super fast descending, only to be followed by a run that teases you with passing by the finishing line only to head out again, and of course as the light faded the temperature dropped like a rocket and the run course became a place to watch where you put your feet else you’d be off them quickly.

    Very happy and a little sore tonight.

    Thank you Lake Tahoe, you put on a hard, hard race but very rewarding to cross that finish line.

  • Beth goldsmith

    Lake Tahoe was my 5th Ironman. Since I completed the first year of St. George140.6 I figured Tahoe could not be any more difficult. Especially since they changed the St. George course after the first year due to the DNF rate. You may note how many flat tires occurred at Tahoe. I had 3 in the first 7 miles which set me back over an hour on the bike. Thought I could easily make up the time- but the hills seemed a lot hRder than St. George. Need up with a DNF in mile 18 of the run because I was just so tired of being SO cold. While I never imaged being a DNF’er, I can honestly say I don’t feel too bad about it. Tough course, tough conditions (my t- bag was literally covered in ice), unfortunate flats but incredibly gorgeous course. Extra medals should be given to the finishers on this race.

  • Tim,

    I should say that it’s hard to pin down exact DNF/DNS data from the results provides given the uncertainty of start numbers (athletes may or may not be listed on Athlete tracker whether they started the race or not, it varies). I’m sure timing companies will have accurate figures, just the way the data is provided in this instance makes things ambiguous. Certainly Ive used other timing systems, Challenge Roth’s for example, where DNS, DNF and DQ was very explicitly indicated in the results.



  • Kevin,

    I’ve looked at Mont-Tremblant here: . I’ve done an analysis on every WTC Ironman race since Kona 2012, you can find them all through this page here:


  • Andy Sweet

    Thanks for all the analysis, this is great info.
    I was an in-water support person on a kayak and there were clearly some who quit during the swim–I personally helped 3 people drop out. The water was cold but not terribly so, in the mid-60’s. The brutal cold was at the start of the bike, with air temp in the 30’s.
    I imagine there were some people who picked up their bibs on Friday and got daunted by the storm all day Saturday, and didn’t start. We were all lucky the race wasn’t on Sat.

  • Shane

    At 39 years old this was my 1st “Ironman” branded 140.6 miler, I had completed my 1st one 2 years ago in Sonoma County California that was “personable” & well organized. I attempted my second 140.6 miler last year (ironically enough also based out of Lake Tahoe on the Nevada side) which turned out to be an EPIC FAIL!!! on the organizers part (No safety or briefing, participants arrived before organizers at the swim, no lighting, not a single road hazard marked, small portion of gravel to traverse on a road bike, no electrolytes offered on the bike, cryptic directions to follow for both the bike & run written in chalk of all different colors, every distance was incorrectly short 2mile swim, 107 mile bike, etc).
    Tahoe was TOUGH!!! But what about this race was unexpected? The altitudes were given as well as accessible on any web search (if you disagreed). The routes had been published well in advance of registration. It took a little less than a day for the event to sell out (as opposed to minutes or hours) so many athletes did indeed think twice about the Endeavour. The water temp of Lake Tahoe was never expected to be warm. If the surface temperature of the lake cooled off 2-5 degrees (at most) over the weekend it is hardly an issue as it was always going to be a “wetsuit swim”. Safety in the water was ample with plenty of support, so no one should have felt “unwatched”. The only portion of the bike leg I heard any legitimate complaint on was the portion of road on “Carnelian Woods Ave” & the “no passing portion of trail” (150 yards long, again it was identified & thus labeled a “no passing zone”). However 98.5% of the bike route was beautifully paved, well marked, had well stocked aid stations & safe!! The run was exactly what had been advertised with well stocked aid stations and lights handed out for those of us that finished in the dark (took me a little over 15 hrs).
    Ultimately the only portion of this race that was unexpected was the weather. According to the weather forecast (at 5 days prior) this too was exactly what was projected. The community support was awe inspiring given the weather conditions & the cheering/support/costumes/& antics of the sidelines on those epic climbs reminded me of when I watch the “Tour de France” on television!! As an Inaugural event my family & I felt WTC/”IRONMAN” put on a great event in the most beautiful location I have ever competed in (as well as so iconic to be competing in the Olympic valley). They will plan for better heating/warming issues in the years to come…. Or then you can say they missed the mark, but as they “improve” on this race by bending to public demand to make it “easier”, no one will ever be able to say they had it as “tough” as we did on that Sunday!!! Nor will the utterance of “YOU ARE AN IRONMAN” feel as “powerful” of an accomplishment as it was for me Sunday evening!!!!