Sprint Course bike choice

Yeah, you said you're able to stay in your aero bars for the majority of the ride - that'll make it worth it to bring the TT bike.

The only real reason you'd  have to swap to the road bike would be if you were getting out of your aero bars on every one of those corners and bleeding off speed... doesn't sound like that's the case.

I'm in the road bike group. 23 turns through a 4.5 mile loop is a lot of up and down time. Add in the fact that there will be other racers out there and I would want the handling that comes with the roadie.

Is it possible to go out and ride the course on your road bike before race day?

If you are ever in question, ride your tri bike. Even if you are sitting up a good portion of it, you are still going to be faster than you are on your road bike.

Change the gearing if you need to, not the bike.

Road bike all the way...

Road bikes are better for technical courses.

Good luck! Sounds like a fun race!

I'd love to see some examples of why this is true.

Thanks for all the good input so far.

I'm planning on heading back this week with both bikes to check the time difference. So that's one part of it.

The other part is that on race day, they'll be 100-200 other people out on the course. So if this was a time trial where riders are evenly spaced by start times, and maybe you pass one person the whole time (or none at all), I'd go with the tri/TT bike. But I'm guessing on laps 2 and 3, I'll have to pass multiple times. It's likely I won't be able to take every corner as fast as I'd like or take the line I'd like. I'm guessing the route will be pretty clogged.

I'm leaning towards the tri bike. I'll let you know how the time trial test goes later this week.

Not to be a (mod edit) starter, but I would like to see some examples of why this is true.

Isn't the advantage of a tri bike that you are in a more aerodynamic position? If you sit up on a tri bike and a road bike why would you still be faster on a tri bike? If your most efficient position on a tri setup is in aero wouldn't you be in an inefficient position is you are sitting up. On the opposite side, wouldn't the roadie position be more optimal sitting up than the tri?

The advantage of a tri bike is indeed in it's positioning. Would you plan to ride 100% of the ride on the bullhorns of the tri bike? In that case, indeed you may be faster on the road bike. However, even on VERY technical courses, we know this just isn't true... you are going to ride at least some portion of it in aero. (the two very unlikely times I could see this is if it were very technical...unlike most "technical" sprint triathlons... and raining/snowing/etc. Also, if fear was an issue and you were simply afraid to get down in the aerobars... which is a valid reason to ride the road bike.) It's just as unlikely to say that you would ride 100% of the time in the drops of your drop bars. Some portion of the time you'll be on the hoods, which is generally an inferior aero position.

The time you are in aero however, you just have such an advantage (considering your position is at least passable) over being in the drops that it WILL make you faster. Aerodynamics are always at work... it's BS when you read "if you aren't in aero 99% of the ride you are slower than on your road bike."  - No. You aren't. Unless you are Greg LeMond'ish in your road bike positioning or sit up extremely tall in the front of your tri bike. There is a reason pro's and tour de france riders ride a tt bike in almost every tt (i think there was one exception when they were climbing the alps) since 89'. It's faster.

Again, there are good reasons to ride a road bike over a tri bike. Generally speaking, speed is not one of them.

TT bike...no question.

IMO, the course doesn't sound that technical.  If you're talking about the entire race meaning bombing down 5% grades at 40+ mph...then we can talk about sacrificing speed for safety.

Ok...lets do some math.  Assuming 23 turns, over 13.5 miles, that's 1 turn every 0.59 miles.  At 20 mph, that assumes one turn every 106 seconds.  Even a poor handler of the bike should only need to get out of aero for 6 seconds on a turn...if at all.  So...even if you use a TT bike, and get out of aero for every single turn...the ratio of aero to non aero would be 100 seconds aero and 6 seconds non aero.  That's over 94% of the time.

Just to clarify - it's 23 turns per lap or 69 turns over the 13.5 mile course. That's closer to one turn every 0.2 miles.

If there are quite a bit of turns (not bends) on the course, you're probably going to be getting out of the aerobars, for cornering and braking...

The OP did post there were quite a bit of turns on the course...

Ok...so triple the time you're out of aero.  So you're still aero 82% of the time, and out of aero 18% of the time.  Again...this assumes you need to get out of aero on every single turn...and for 6 seconds...which is generous at best given it's a race...not a training ride.

ETA:  I am hesitant to believe that this course is actually that technical.  Can anyone actually show me a map of what a 4.5 mile loop with twenty-two 90 degree turns and one 150 degree turn looks like?  It must be like a maze or something...in which case the entire course has to be closed off to traffic, which means you can hold much more speed and take a more aggressive line during the race than during a training ride of the same route when cars are present.

tri808 - are you suggesting I can't count? Just kidding. Your math was actually very helpful in putting things in perspective. And perhaps I did count one bend as a corner...and according to mapmyrun, each loop is actually 5.05 miles, so maybe you're right - 22 turns in 5.05 miles isn't that technical...

This is many more turns than I typically make in a 40k time trial. In 9 fewer miles.

The RD has said the course will likely not be closed to traffic.

I'm very comfortable on my tri bike and having lived and ridden in NYC for a decade, I'm pretty comfortable riding in all sorts of traffic.

I appreciate all the input and while I'm definitely leaning towards the tri bike, I'll be heading back later this week to time both bikes.

You'll have to post up the difference in times between the two bikes.

Also, that course looks ridiculous. Looks like it'd be a BLAST, if it's completely closed to traffic and you know the corners though... but then, I thoroughly enjoy flying through corners at high speeds.

That is a funky looking course.  But yeah.  It's technical in the sense that experience will help you anticipate the upcoming turns, what line you should take, and how much speed you may need to reduce or shift up/down in advance.  But it's doesn't seem technical in the sense that you would be better off on a road bike. 

There appears to be a few stretches where you will likely be on the horns for a good potion of the time weaving left and right...but there also appears like there's some sections where there are nearly 1 mile straightaways where you can take advantage of the aero position.

I can't imagine the course not being closed to traffic though.  I would be p*ssed if I was in a car and got caught in the middle of that loop waiting for an opening to get out.  If it's 3 loops, there's bound to be bikes all over the course.