So we’re drinking our post ride carbs and the question comes up ‘Would it be easier to run 10 k then ride 25 miles or the other, 25mb/10k run?’ Consensus was run/bike would be easier but no one had tried it so theories were idle prattling but we’re good at that. Anyway I wonder if anyone else has theories on this question.
There is a series of sprint tris near here that are swim/run/bike (600m/6km/25km), I’ve done a couple of them and it definitely feels easier than the usual swim/bike/run, can’t really compare it timewise though. I find I could just blast the run without worring about the bike leg and then go all out on the bike. Works ok for a sprint and helps split the pack up on the bike (its a hilly course so drafting wouldn’t be much of a problem anyway), not sure how well it would work with a longer distance.
http://www.hillingdontriathletes.co.uk/Races_Folder/triduseries.htm
There’s a 1mile swim/6.4 mile run/21 mile bike in Boerne, Texas (near where Buffalo Springs is held I think). It looks like a fun race. My sense is there are some strength issues with running off the bike which don’t arise when biking after the bike, more than just overcoming that ‘brick’ feeling after running. No deep insights here I guess but hmmm interesting sort of thing.
I really would have to say run/bike, though I bet if you practiced at it you’d find a small difference either way.
If heat is an issue, and it seems like it usually is, then run/bike would be easier than bike/run (assuming the race starts in the morning). From a participant perspective, run/bike seems to make more sense for hot races, though there is some danger doing the bike when you’re more tired. I assume the biggest reason that most races are bike/run (apart from tradition) is that it’s too expensive to keep the bike course closed or patrolled for so long.
There is an annual 5k run/12mile bike/1/4 mile swim here is Naples. After observing this race for 20 years, I would say it favors runners.
" I assume the biggest reason that most races are bike/run (apart from tradition) is that it’s too expensive to keep the bike course closed or patrolled for so long."
That may well be the case, but from a safety point of view a lot of tired runners coming into transition in a shorter spread of time than after a long bike would produce great knots of tired cyclists making all sorts of mistakes due to mounting fatigue. People would get hurt, especially in a longer, or more heavily populated race.
Oh and if the bike were at the end of an IM - the body count on the course would be particularly acute at the finish - imagine all us tired MOPers hammering for a sprint finish - might as well install whirling blades at the end…j
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Maybe I am missing your point about “great knots” of cyclists coming out of T1. Sure they’d be more tired in a run/bike format, but they’d be a lot more spread out after doing both the swim/run.
There’s plenty of people doing run/bike but it’s usually run/bike/run. Granted they’re not as tired after 2mi than after 6/13/26, nevertheless they manage. My feeling is there’s not many swim/run/bike races mainly because it’s just not the way it’s done. My question in the OP was why does it seem harder (I’m assuming that’s the consensus) to run off the bike rather than the other way round? My guess is there’s strength issues coming off the bike that affect the run (hip flexors weaker off the bike? I dunno). Admittedly not that insightful but just wanted to get opions from ST corporate brain trust. Swim/run/bike probably makes for some wild finishes.
There’s a 1mile swim/6.4 mile run/21 mile bike in Boerne, Texas (near where Buffalo Springs is held I think).
Boerne, TX is probably 375 to 400 miles away from Lake Buffalo Springs. Boerne is outside San Antonio while Buffalo Springs is outside Lubbock. Two very different worlds.
Hmmm, I shoulda known that, I was thinking Lake Buchanan…doh! Lubbock and San Antonio, quite different indeed.
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Oh and if the bike were at the end of an IM - the body count on the course would be particularly acute at the finish - imagine all us tired MOPers hammering for a sprint finish - might as well install whirling blades at the end…j
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Could you see all those people, picking up there kids / dogs/ and grandparents putting them on the handle bars and riding across the finish. 
…or pet fish…!
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Oh and if the bike were at the end of an IM - the body count on the course would be particularly acute at the finish - imagine all us tired MOPers hammering for a sprint finish - might as well install whirling blades at the end…j
/
Could you see all those people, picking up there kids / dogs/ and grandparents putting them on the handle bars and riding across the finish.