112 Miles at 15 mph - Ironman Bike Split and Cutoff

Triathlon finish time from three paces and two transitions

An Olympic-distance race at 2:00 per 100 yd, 18 mph and 9:00 miles ends at 2:56:35 with five minutes of transitions, and almost half of that clock belongs to the bike. This triathlon calculator turns your swim pace, average bike speed and run pace into a finish time for a super sprint, sprint, Olympic, Ironman 70.3, full Ironman or a course you type in yourself. It works in US units (per 100 yd, mph, per mile) or metric, gives every split and the elapsed time after each leg, and for the two Ironman distances checks the result against the standard cutoffs.

Quick start. Pick Ironman 70.3 and US units, then type a swim pace of 2:10 per 100 yd, 17 mph on the bike, a 10:30 mile and transitions of 6 and 4 minutes. The result is 6:31:04: swim 45:46, bike 3:17:39, run 2:17:39, and 24:14 of room under the 1:10 swim cutoff.

Seven boxes between the start line and the finish

Units - US units take the swim pace per 100 yd, the bike in mph and the run per mile. Metric takes per 100 m, km/h and per kilometer. The result repeats every pace in the other system.
Race distance - super sprint, sprint, Olympic, Ironman 70.3 or full Ironman, with the legs filled in for you. Choose Custom distance when a local race lists its own swim, bike and run.
Custom legs - only for Custom distance: the swim in yards or meters, the bike and the run in miles or kilometers, copied from the race website.
Swim pace - minutes and seconds per 100, for example 2:05 as 2 and 5. Open water usually costs a few seconds per 100 against the pool, because there are no walls to push off.
Bike speed - the average you hold on a similar course in race position, not the number from a group ride with drafting.
Run pace - minutes and seconds per mile or per kilometer. Take it from a brick run off the bike rather than from a fresh 10K.
T1 and T2 - optional minutes for the two transitions, decimals allowed (2.5 is two and a half minutes). Then read the finish time, the splits table and the cutoff check.

Eight race plans, and the finish each one gives

A first sprint

Situation: sprint, 2:30 /100 yd, 14 mph, 11:00 /mi, T1 4, T2 3
Result: 1:54:57. Swim 20:30, bike 53:16, run 34:11.

Seven minutes of transitions are 6% of this race. A beginner who practices one dry run of T1 at home usually finds two of them.

Olympic distance at steady training paces

Situation: Olympic, 2:00 /100 yd, 18 mph, 9:00 /mi, T1 3, T2 2
Result: 2:56:35, with the bike at 1:22:51 or 46.9% of the total.

The same course, raced in metric

Situation: Olympic, 1:55 /100 m, 32 km/h, 4:50 /km, T1 2, T2 1.5
Result: 2:35:35. The tiles also show 1:45.2 per 100 yd, 19.9 mph and 7:46.7 per mile.

A 70.3 debut

Situation: 70.3, 2:10 /100 yd, 17 mph, 10:30 /mi, T1 6, T2 4
Result: 6:31:04, inside every standard cutoff. One more mph on the bike gives 6:20:05.

Eleven minutes from 1 mph over 56 miles, against three and a half from swimming 10 seconds faster per 100 yd. Training time usually buys more on the bike.

A slow swimmer on a half

Situation: 70.3, 3:40 /100 yd, 15 mph, 12:00 /mi, T1 8, T2 5
Result: 7:51:45 on paper, but the swim takes 1:17:26 against a 1:10:00 limit, 7:26 too slow.

The finish would beat 8:30, yet the race ends in the water. The cutoff check shows the first limit that fails, not only the last one.

A full Ironman that just fits

Situation: Ironman, 2:30 /100 yd, 15 mph, 12:00 /mi, T1 10, T2 8
Result: 14:46:14, off the bike at 9:31:36 elapsed, with 34:24 to spare at the swim.

A full Ironman that misses the bike cutoff

Situation: Ironman, 2:50 /100 yd, 13 mph, 14:00 /mi, T1 12, T2 8
Result: swim, T1 and bike add up to 10:48:36, which is 18:36 past the 10:30:00 limit.

At 14 mph the same day reaches T2 at 10:11:41 and goes on to the run. That one mph is the whole race.

A local race with odd distances

Situation: custom 500 yd / 15 mi / 3.1 mi, 2:15 /100 yd, 16 mph, 10:00 /mi, T1 3, T2 2
Result: 1:43:30. Pool sprints often list the swim in yards, and none of the standard rows fit them.

Race distances in miles, yards and kilometers

The calculator uses these legs. The three short formats follow World Triathlon, and the two Ironman formats are set in miles, so their metric figures are not round numbers. The cutoffs are the standard IRONMAN limits, counted from your own start in a rolling start.

Distance	Swim	Bike	Run	Standard cutoffs
Super sprint	400 m (437 yd)	10 km (6.2 mi)	2.5 km (1.6 mi)	set by the race
Sprint	750 m (820 yd)	20 km (12.4 mi)	5 km (3.1 mi)	set by the race
Olympic (standard)	1,500 m (1,640 yd)	40 km (24.9 mi)	10 km (6.2 mi)	set by the race
Ironman 70.3	1.2 mi (2,112 yd)	56 mi (90.12 km)	13.1 mi (21.1 km)	swim 1:10, bike 5:30, finish 8:30
Ironman	2.4 mi (4,224 yd)	112 mi (180.25 km)	26.2 mi (42.2 km)	swim 2:20, bike 10:30, finish 17:00

The bike cutoff is not the time on the bike. It is the elapsed time when you reach T2, swim and T1 included. A 1:45 Ironman swim with a 10-minute T1 leaves 8:35 for 112 miles, which is an average of about 13 mph before stops.

What a small gain in each sport is worth on race day

Every row below changes one number and keeps the rest. The gain grows with the distance, but not evenly: on long courses the bike leg dwarfs the other two, so the same effort in training pays back differently.

Distance	Swim 2:10 to 2:00 /100 yd	Bike 16 to 17 mph	Run 10:30 to 10:00 /mi
Super sprint	0:44	1:22	0:47
Sprint	1:22	2:44	1:33
Olympic	2:44	5:29	3:07
Ironman 70.3	3:32	12:21	6:33
Ironman	7:02	24:42	13:07

A faster swim helps most where the cutoff is the problem, as in the slow-swimmer example above. Otherwise the bike column is where minutes are cheapest, and part of that comes from position and pacing rather than fitness. The calculator assumes even paces, so it cannot show the cost of riding too hard and walking the run. That part is up to you.

Finish time questions before race week

How accurate is a predicted triathlon finish time?

As accurate as the three paces you enter. The arithmetic is exact: each leg is distance times pace, rounded to the second, plus the transitions. The error comes from the inputs, so use paces from race-like efforts: an open-water swim, a ride in race position, and a run straight off the bike. Courses also measure long or short by a few hundred yards.

Should I use my pool pace for an open-water swim?

Add something. A pool gives you a push-off every 25 yd and a black line to follow, and open water gives you neither. Many coaches add a few seconds per 100 for that. A wetsuit works the other way, so two swims in the lake before race day tell you more than any rule.

Do the Ironman cutoffs start at the gun or at my own start?

In a rolling start they are counted from the moment you cross the timing mat into the water, so the result checks your own elapsed times: swim 2:20, swim plus T1 plus bike 10:30 and finish 17:00 for a full, and 1:10, 5:30 and 8:30 for a 70.3. Some races use other limits, and the athlete guide always wins.

How long are T1 and T2 usually?

It depends on the transition area more than on the athlete: a long run up from the beach or a change tent adds minutes that a compact sprint layout never asks for. Most race results list T1 and T2 for every finisher, so last year's results of your own race are the best guide. Leave the boxes empty to see the race without them.

Why do the splits add up exactly, and my watch does not?

Each leg is rounded to the second before it is added, so the elapsed column and the finish always match the splits above them. A watch often stops a leg a few seconds late or counts the run from the mat at the tent, and the official results draw the line at the timing mats.

What run pace should I enter for the marathon of an Ironman?

Not your stand-alone marathon pace. After 112 miles on the bike most age groupers run well slower than in a fresh marathon, and many walk the aid stations. If you have no race to compare with, take the pace of your long brick runs and add a margin. The tables of the VDOT calculator describe a fresh runner, so treat them as the ceiling.

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Swim Pace Calculator

Your pace per 100 yd or 100 m from a pool swim, and CSS from a 400 and 200 test - See the calculator

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How long is 112 miles at 15 mph on an Ironman bike leg?

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