Not a bike fitter, but my 2 cents. No difference between the distance between center of the bottom bracket and where I sit on the saddle. If I ran shorter cranks on on the tri bike then I would keep it the distance from the peddle at bottom of the stroke and saddle the same.

Same for me.

Assuming the same crankset length and saddle type the saddle height should be the same, at least as a starting point. Then there's complications.

Some saddles compress more than others and need a higher effective height.
Measurement of the saddle height along the seat tube doesn't accurately reflect where the rider sits (sitting on the nose of the saddle, like on a TT bike, effectively reduces saddle height)
Hip angle differences (more forward on a TT bike) can have not insignificant differences differences in hip joint elevation relative to BB.

All this to say I'd start off with the same height measured at the point where you sit, but keep a wrench handy and make small changes to see what feels best. FWIW my TT bike saddle is a couple mm higher than my road saddle, but it's a ISM split nose v fizik arione, so who knows the actual difference.

General question. Do world tour pros run different crank lengths? Hmm

I've been fitting athletes to bikes for 35 years. My opinion is they are the exactly the same, especially if you are doing a lot of miles on your road bike and then changing to your tri bike.

I'm sure there are other fitters who have different opinions but that's has served my customer's well.

Would this stay true if crank arm length is different between the 2 bikes?

---

Peak NA Cocktails for Recovery
WAE Clothing
Youtube

No.

My road bike is a few mm shorter. I tend to gravitate toward the middle of my saddle when riding easy, but for efforts when I’m going for speed, I’ll scoot back a bit to really flatten out.

I also scoot up quite a bit when going flat out, so I’m of the opinion that a few mm plus or minus just doesn’t matter very much for me. Has been like this for many years.

My Tri bike is one saddle position only, though, so it’s pretty locked in.

Some do. Yes

---

---

Heath Dotson
HD Coaching:Website |Twitter: 140 Characters or Less|Facebook:Follow us on Facebook

Saddle heights are similar between bikes. As someone else mentioned, it is also saddle dependent. I use a PRO Stealth saddle on the road and a Syncros Tri saddle on the TT bike. Within a few mm if you measure from the 80mm point on the saddle.

---

---

Heath Dotson
HD Coaching:Website |Twitter: 140 Characters or Less|Facebook:Follow us on Facebook

It comes across like you have an agenda with that question.

The answer is definitely "some do". The answer is also that multiple sites claim both Ganna and Bigham (both over 6 feet tall) ran 170mm cranks for the hour records. For an over 6' 4" person to run 170's, that would mean someone in the avg male 5' 9" range definitely would be on 165's or shorter.

It would be interesting to see how certain pros do crank lengths. I doubt Cavendish worries about switching lengths for TT's, just keep the same one and the same feel as road races. But interesting cases like Roglic/Vingegaard/GC guys could potentially find a small gain with different crank sizes. I suppose this question is more complicated because they're spending 95% of the race on a road bike, but the 5% spent on a TT bike is ~50% of the 'important miles' in the race.

As far as Bigham/Ganna running such short cranks, I wonder if this has anything to do with track v. road? A lot of track cyclists run shorter cranks than road, but I don't know how much of an advantage that would be in a track TT when the only material difference is G forces.

For an over 6' 4" person to run 170's, that would mean someone in the avg male 5' 9" range definitely would be on 165's or shorter. //

It would be more like 155's. And the more important measurement would be leg length, not overall height. But it is just much easier to observe peoples overall height, so it gets thrown around a lot as the metric. Most of your hip angle will have no bearing on how long you are from the belly button up...

Exactly the same as the difference in my leg length when I do the two sports.

On a serious note, a tri pad is typically thinner than a cycling pad; but that is offset for me by not using socks whilst racing. I'm one of those fairly particular folks where even a 2mm change in saddle height feels "off."

---

ECMGN Therapy Silicon Valley:
Depression, Neurocognitive problems, Dementias (Testing and Evaluation), Trauma and PTSD, Traumatic Brain Injury (TBI)