Campy Crankarm Question: Guru's Help!

[SoCal Al]

Before anyone asks I tried looking for this topic in previous threads but couldn't find it so if it's already been dealt with I'd be thankful if you would re-post the link.

So here's my question:

I have a 2014 Super Record Compact crank set with 175mm arms and my fitter is recommending 172.5mm arms. Since I don't want to buy a new 2014 crank set ($400+) and used 2014 SR 172.5mm Compact's are pretty rare but Standard's seem plentiful, can I take a 2014 SR Standard with 172.5mm arms and swap out the chain rings for the compact ones (i.e. go from 52/39 to 50/34)?

Thanks in advance!

[AngryScientist]

No, you can not.

standrd BCD (bolt circle diameter) is 135, and Compact is 110 (campy proprietary...) for the 5 arm cranks.

[SoCal Al]

Of course it is...

Thanks anyway!

[AngryScientist]

Originally Posted by SoCal Al

Of course it is...

Thanks anyway!

no problem.


as you discovered, that's why the standard sets are easier to find. these days, everyone wants LOW gearing, fat tires, disc brakes and fancy paint.

old school roadies are out of style.

[cmg]

Originally Posted by SoCal Al

Of course it is...

Thanks anyway!

Yep, bless campy for working a way to make it complicated and expensive. Use another brand for a compact.

[djdj]

Or get a Campag 4-arm crank, which handles compact and standard. Depending on the group level, or if you are willing to buy used, they are reasonably priced. Also, if you will consider used, check out the Paceline classifieds for the older style 110BCD; I've seen a few lately.

[Dave]

So you're saying that other brands always used the same bcd for compact and standard rings? I don't think so.

Campy now uses one bcd for all chainrings. SR is now 12 speed, so there's another problem.

If a person has been using 175mm for a long time they'll probably not even notice the change.

[Spaghetti Legs]

I have been idly looking for a decently priced 5 arm Campy 11 compact crank for about 2 years. I dream of the day I find an abandoned storage bin full of these and retire on the proceeds from their sale.

On a related note I am in the naysayer camp on whether 2.5 mm crank length makes a difference.

[Road Fan]

Originally Posted by Spaghetti Legs

I have been idly looking for a decently priced 5 arm Campy 11 compact crank for about 2 years. I dream of the day I find an abandoned storage bin full of these and retire on the proceeds from their sale.

On a related note I am in the naysayer camp on whether 2.5 mm crank length makes a difference.

After decades on 170s, I first tried 172.5s about 10 years ago. At first it seemed to get me more force, i.e less cadence for a given speed. Then my knees started to hurt abit so I retrained my feet to up the cadence, with some saddle tweaking. Now I own a mix of 170 and 172.5s, and I don't notice changing from one to another.

Does 2.5 mm matter? maybe when you begin the adaptation, but not after you have adapted.

[FlashUNC]

Originally Posted by cmg

Yep, bless campy for working a way to make it complicated and expensive. Use another brand for a compact.

All big three component makers' cranks were the exact same bucket of dual BCDs until a couple years ago, when Shimano and Campy finally went to a single BCD for their cranks. SRAM is still using two.

Just buy a current crank and put whatever size rings you want on there.

[oldpotatoe]

Originally Posted by cmg

Yep, bless campy for working a way to make it complicated and expensive. Use another brand for a compact.

Or get a 4 arm crank, first made almost 4 years ago.

[mcteague]

I have a difficult time believing 2.5mm will be noticed. Go to 3 fitters and end up with 3 different opinions.

Tim

[Lewis Moon]

Originally Posted by mcteague

I have a difficult time believing 2.5mm will be noticed. Go to 3 fitters and end up with 3 different opinions.

Tim

But...but...172.5 is MAGIC!!!!!

I have 3 sets of 175 compacts that I keep around in case the apocalypse occurs. Mad Lewis rolls crank not guzzline.

[m4rk540]

Buy a midcage Potenza rear derailleur and an 12-32 Centaur cassette. You'll have the gear range of a compact with 11-28 and better shifting.