mrblue

I have a Campagnolo Potenza groupset. The crankset is Power Torque with the self-extracting bolt, on the NDS crank arm. It's very much like Shimano and SRAM except for the DS bearing is installed on the spindle, not in the bearing cup.

Anyway, I noticed for 2018 Campagnolo redesigned the Potenza crankset to be Ultra Torque. This implies some advantages of Ultra Torque. What are those advantages? It seems to me a one piece spindle, like on Power Torque (and Shimano and SRAM) would be better than a two piece spindle bolted together in the middle. Then again, I am not an engineer.

Thanks.

dsbrantjr

The joint in the middle of an Ultra Torque crankset is a Hirth joint, which were first used to bolt aircraft engine crankshafts together so I imagine they can be made pretty strong. https://en.wikipedia.org/wiki/Hirth_joint

Ghrumpy

Yep. Used on roller-bearing crankshafts in aircraft and automobile engines. And, if I'm not mistaken, on S&S couplers on bike frames. Very good at transmitting torque.

I don't recall what reasons Campagnolo gives for the design. I can't imagine it's easier to manufacture. Clearly there is some advantage of moving the detachable interface away from the crankarms itself. Maybe it's something as simple as a patent issue.

alcjphil

One advantage of the UltraTorque design is that the cranks have a very low profile which helps with ankle clearance for people who pedal toes out.

kingston 

Some people don't like the power torque cranks because you need a special tool to remove the crank and another special tool to remove the bearing. Ultra torque doesn't require any special tools. I have never heard of power torque with a self extracting bolt.

alcjphil

I believe that the latest versions of PowerTorque cranks are self extracting, a huge improvement over the early versions. I prepare to be corrected if I am wrong

wschruba

Aye, Hirth joints are about as good as a separate-able power-transmission joint can be. Down side is they are $$$ to manufacture.

Advantage for a bicycle? Questionable...but the low profile crankarm end may matter to some people.

kingston 

While I'm a little skeptical since a quick google search didn't return any results, that does sound like a huge improvement. I had to spend over a hundred dollars on tools along with my athena crank.

alcjphil

I had a look myself and it doesn't appear that even new PowerTorque cranks are self extracting

Marcus_Ti

Reviews said Potenza was self-extracing back in 2016.

First Ride: Campagnolo Potenza group | VeloNews.com

Look for "Power Torque Plus".

mrblue

Potenza cranks, that are Power Torque, are, indeed, self extracting. It says so on the NDS crank arm and I've also removed them without any special tools.

Kontact 

The advantages should be size and weight. If the connection in the crankarm, there has to be room and mass for it, making it use up ankle clearance and (potentially) heavier. External bearing systems are already wide, so anything that keeps the width down is appreciated.

canamdad

I have both UT & PT cranksets on different bikes. UT is easier to pull out but need a bearing puller with thin feet if you want to replace bearings. I haven't needed to do that - mine are fine and going on 10 years now. PT (that is to say specifically a Veloce PT, there now seem to be some variations on the PT design) requires a puller to get the NDS crank arm off so another specific tool for that. Park makes a set that services both types of cranks. I don't see any reason in the near future to have the tools but if I have to service them at some point in time, I'll be faced either with tool investment or take them to a LBS.

ninja2

same case with me, but if you ever need to remove power crank, search automotive tools; i bought the puller for $28 some years back, for the alternator bearings removal. worked like a charm, i did it just to see if it was ok and it was perfect. probably will never use it, i don't even remember where i left it....
OTC (1022) Mechanical Grip-O-Matic Puller - 2 Ton, 2 Jaw (Reversible Jaws)


amazon has the above, mine is similar, stronger than park tool; if interested, i can check what i got , it must be somewhere in my storage. cheers