Guys, I've been riding a 170 mm Ultegra 6800 on my road bike for a couple of years now. And I ride a 165mm on my track bike. I don't have problems with both.

I love high cadence, can spin 100 average for hours, and reaching 145 in fast rides (Don't call them sprints, as I'm just not fast enough to be one ).

My in-seam is 29.5", so yes, I'm on the shorter side of things.

I love riding the local short hills, that have some 'walls' climbing at 12-15%. But they're short hills - so no long endless climbs that I would've loved. The longest continuous climb locally is about 1 km long stretch.


Now I just found a deal on a Dura Ace 9000 172.5 mm crankset.

The questions is, going from Ultegra to Dura Ace, how much gain there is?

And, going from 170mm to 172.5mm, for a short guy who likes high cadence, is it going to affect my performance/comfort levels?

Please let me know soon. I'm meeting this guy for his DA9000 FD + RD today anyways. And I already have the DA shifters. So, the DA crankset will complete the groupset, but I'm unsure of the 170 to 172.5 mm jump.

The only way that you're going to find out is to spend the money or borrow a bike with 172.5 cranks. The difference it only 5 mm ( 2.5 down + 2.5 up) which isn't much math-wise, but may make a difference to your pedaling and cadence. I'm of the "if it ain't broke, don't fix it" camp. I sounds to me like 170's work well for you.

My two bobs worth is that 165mm cranks are already the longest that I would recommend for you based on your inseam and that going longer is going to loose you more than you could possibly gain for a bit of bling.

Longer cranks will be harder to spin at high cadences and longer cranks will make getting into an aerodynamic tuck more difficult. If you are going to change anything I would be selling the 170mm cranks and finding another 165mm set.

Anthony

Thanks [MENTION=5993]jerry[/MENTION] and [MENTION=81545]Anthony[/MENTION], for great suggestions.
I didn't get the 172.5 mm (only picked up the DA FD +RD), as my legs are true and tried on the shorter cranks.
Much appreciated.