Wcollins00

DrIsotope

Unless you have an exceptionally good aero position on your road bike, the tri bike will likely be 2-3mph faster over the same course for the same effort.

asgelle

Given my definition of huge, absolutely true.

asgelle

Given my definition of huge, definitely false.

Garfield Cat

Those who have purchased a tri bike in addition to their road bike: they will not give up their tri bike, once its purchased.

Its really about having two bikes. Maybe something about "faster" but mostly about having two bikes. Tri bikes are fun to ride and that's why two bikes. Don't get into the "what's faster" for a race.

Just more fun.

GlennR

Huge depends on how fast or slow you did the 70.3.

I bet some targeted training will yield a larger improvement.

jbell_64

It would also depend on the course. A flat, straight course will definitely favor the tri bike.

Homebrew01

Are you optimally set up on your road bike ? You may be able to make improvements on it.
It's not the bike's geometry that makes the difference, it's rider position mostly...Getting aero efficiently .

What's a 70.3 ?

HTupolev

Depends on the position you're achieving on the road bike.

Aerobars provide three main advantages:
1-They allow you to comfortably hold your arms narrow, which narrows your torso.
2-The make it effortless to keep your forearms level, making them more aero.
3-They allow your upper body to near-effortlessly carry a lot of weigh, allowing you to more easily maintain a posture where there's a lot of weight over the upper body.

Obviously a typical road posture is less aero than a Tri posture. It's usually more upright, the arms tend tend to be in a wider stance, and the forearms are typically not level and therefore creating more wind drag.
You can solve some of this by simply throwing aerobars on a road bike, without changing anything else. The aerobars create an extra hand position where the rider has a narrower stance with level forearms.

However, a road bike that happens to have aerobars tossed on is not the same fit as a Tri bike. On this "road bike with aerobars", the saddle is still a road saddle in a typical road position, which perches the butt well behind the bottom bracket. Usually the posture on the aerobars will be more upright than a true Tri posture.
If you try to lower the aerobars to create a true Tri posture, you may end up uncomfortable bending down to get so low; the angle between the legs and the torso gets really crunched, and it becomes harder to breathe and pedal.

The solution is to move the butt forward. Rather than creating a low aero posture by bending forward, you create a low aero posture by rotating your entire body forward around the bottom bracket. With a more forward saddle position, you can get very low on the aerobars while still being able to breathe and pedal. This forward position puts tons of weight over the upper body, but thankfully we've got the aerobars to deal with this!

BUT, we've got a few caveats.
First, creating a posture like this on your road bike obviously means that it's not set up in your normal road posture. So if you do non-aerobar group rides, your road bike will be fit very oddly for them unless you change it back.
Second, rotating your body forward around the bottom bracket rotates your pelvis forward around the bottom bracket. This means that you'll probably be resting on a fairly narrow region of "sit bone", and one which road saddles are usually marginal or terrible at supporting. Triathlon saddles are designed better for this.
Third, accomplishing a posture like this on a road bike can be difficult; you may need to do weird things with seatpost offset to move the saddle forward enough, the top tube and head tube aren't really optimized for Tri aerobar positioning so you might end up doing weird things with your stem, etc.
Tri bikes are simply much easier to create Tri fits on.

If you *do* manage to create a true Tri fit on your road bike, then a Tri bike won't provide a major advantage; it'll just be a much less kludgy solution.
(However, because Tri bikes don't abide by the UCI's fairing rules, a Tri bike will sometimes still be a smidge faster than a perfectly Tri-ified road bike.)

A 70.3 is a half Ironman. 70.3 miles is the total distance of the swim and bike and run combined.

A full Ironman can similarly be referred to as a 140.6.

DrIsotope

fietsbob

Treble the cost with a full disc rear wheel .. but, know , they will roll Loudly..

bruce19

Thank you. That was my question.

DrIsotope

The "70.3" refers to the total distance in miles (113.0 km) covered in the race, consisting of a 1.2-mile (1.9 km) swim, a 56-mile (90 km) bike ride, and a 13.1-mile (21.1 km) run.

Take out the swimming and running parts, and that sounds pretty good.

Wcollins00

veganbikes

It is a number between 70.2 and 70.4. It is probably also a radio station somewhere where you might consider turning it up and ripping off the knob. 70.3 Rock FM playing the loudest hits from Metaltallica and Limp Biscuits.
Pound Sign: RealAnswers!

One should always have more than one bike (especially if you race and don't take care of your bike often and well before a race) though those tri bikes are just not my thing. Then again running is the devil and swimming should be done with friends, pool noodles and maybe a nice cool beverage on a hot sunny day. Actually swimming I can dig but I was never great so I couldn't compete but if they did a triathlon minus one, you know maybe a dual-athalon with just the biking and swimming I could dig it.


Yes I know it would be a biathalon but I was channeling my inner Michael Scott.

musicmaster

The biggest thing was I was able to slowly dial in my fit for my tri bike without compromising my road bike rides that and I raced faster at lower wattage .

The Golden Boy 

Left of the dial.

Left of the dial.

texaspandj

Adding to the aero advantage of the "tri bike" aero bars, aero frame etc. The steeper angle (forward saddle position) allows you to mimic running (somewhat) and therefore allow a smoother transition to the run segment.

BirdsBikeBinocs

What is a Tri bike.?? You talking a 3 wheel recumbent.??

OldTryGuy

Gee-whizzz, alls I no is that this 63yo and then 64yo on my road bike passed bunches of much younger riders on their Tri Bikes during my 2013 and 2014 Ironman Florida 112 mile segments.

Sure must be nice riding one of those spiffy tri bikes though.

Steve B.

Just weighing in for my $.01.

If you are planning on doing more halfs or even a full Ironman, might be worth it to get a tri bike. Shorter distances or not the training required for the Ironman, maybe just throw an aero bar on the road bike for those moments when it's windy. I raced numerous shorter (Olympic and shorter) team tri's on a regular road bike with a Profile bar added on and was generally fine, but I wasn't running after. I also added a Profile forward seatpost that emulates the seat tube angle (generally around 78 deg.) of a real tri bike. That was OK, but generates it's own handling issues as your upper body weight is now way forward over the h-bar. A dedicated triathlon bike deals with this by changing the front center position of the body so handling is neutral.

As others have stated, the geometry of a tri bike does help the transition for the run. Another consideration is the type of course, I ride with 2 trigeeks and on some half and full Ironmans that are hilly, they use their road bikes.

texaspandj

Aero tubing on my bike is the only thing thst could possibly yield better results for me BUT, i aint gonna ride one of them. I feel i get a better all around position on my bike

Steve B.

Teamprovicycle

Fastest bike in a local time trial was a cervelo r4 or something with bolt on aero bars and hed wheels

Phil_gretz

...says the first person in recorded history to have that viewpoint. I suppose that root canals and having broken bones re-set are also a hoot...