Pat Menzies wrote: A sprint Duathlon is about comparable to a 15km-half race in duration and intensity so the effort level you can sustain for that time is what you end up doing.
You can be a bit more reckless in the first run portion because there is some actual recovery time in the transition zone and most bike courses will offer areas where you can enhance your recovery on the bike. If you actually went "all out" you would be feeling like you just finished a 5km race.
As it turned out, I indavertently followed Pat's theory to a "T" this weekend ... First run (only 2K) was pretty well at my current 5K pace .. but, I ended up wasting over a minute in T1, messin' around with my bike computer ... and got passed by a lot of people in the T-Zone ... as for the bike, just rode it as a hard tempo, one minute up to 38kph and next minute going at 21kph .... and, as for the final 5K, second run, just fell into my usual happy steady tempo (err, marathon goal pace) effort ... I will have another 1 or 2 more sprint duathlons in August to tweek things out, however ...