5-Arm Campy chainring question

[Nick12]

Hi all

Just trying to find some info on the pre-2015 5-arm Campy cranks and chainrings.

I read somewhere that the 50/34 chainrings cannot fit on the ‘standard’ cranks, which I’ve taken to mean that if I have 53/39 on my cranks, I can’t install 50/34. Is this correct?

Taking it one step further, if I bought a crankset with 50/34, can I also install the 53/39?

These are the crankset I’m referring to (which I hope I’ve correctly described as pre-2015).

Thanks!

Nick


Sent from my iPhone using Tapatalk

[rain dogs]

Correct. Standard cranksets have a 130mm/135mm BCD. Compact is 110mm. A 39T chainring has too large a circumference to fit in a 110mm bolt circle diameter (34T).

If you have a 110bcd crankset like that pictured you may be able to find aftermarket chainrings in 110mm that are as large as 53teeth. I believe Stronglight makes them. But many brands do not. BUT, you cannot use the 53/39 chainrings from your standard set (135mm) on the compact crank arms (110mm) because the holes are further apart.

Put the two crank designs side by side in a picture and see how far the chainring bolts are from the center of the axle and you'll see it.

[AngryScientist]

Originally Posted by rain dogs

correct. Standard cranksets have a 130mm/135mm BCD. Compact is 110mm. A 39T chainring has too large a circumference to fit in a 110bolt circle diameter (34T).

If you have a 110bcd crankset like that pictured you may be able to find aftermarket chainrings in 110mm that are as large as 53teeth. I believe Stronglight makes them. But many brands do not.

this is partially correct. campy 5-arm compact BCD is not exactly 110, it's more like 110 with a 112 thrown in there. all that is to say that shimano/sram compact chainrings will not fit campy compact cranks.

it's a real PITA.

The new 4-arm cranks have a single BCD that will fit standard or compact rings.

[rain dogs]

Originally Posted by AngryScientist

this is partially correct. campy 5-arm compact BCD is not exactly 110, it's more like 110 with a 112 thrown in there. all that is to say that shimano/sram compact chainrings will not fit campy compact cranks.

it's a real PITA.

The new 4-arm cranks have a single BCD that will fit standard or compact rings.

Yeah, I know, but I didn't wanna write an essay to explain the basics!

I don't have time for that, I'm to busy raging against 3kg groupsets one door over!

[Rusty Luggs]

Originally Posted by AngryScientist

The new 4-arm cranks have a single BCD that will fit standard or compact rings.

Chorus 12 BCD not the same as Record BCD.........

[AngryScientist]

Originally Posted by Rusty Luggs

Chorus 12 BCD not the same as Record BCD.........

haha, well now that's true, and adds to the complication. The chorus 12 adds an even smaller bcd to allow for the subcompact rings, and they are unique. i suspect this will carry over to the other groups since it was so popular, but who knows, my campy crystal ball is always foggy.

[Nick12]

Thanks everyone!

[SDJ]

Nice crankset!

Miche, TA Specialites and Stronglight have campa compatible 110 compact chain rings which I have had good experiences with.

I am currently testing an old set of standard 110 compact chainrings as easier to find and cheaper - it works (after some filing of the hidden bolt hole) but the fit isn't 100% so am monitoring it to see how it holds up.

[Mark McM]

Originally Posted by Rusty Luggs

Chorus 12 BCD not the same as Record BCD.........

When it comes to chainring BCDs, Campagnolo doesn't know the meaning of the word "standard". Ever since they abandoned the 144mm BCD for road cranks 40 years, every new BCD they used has been unique to Campagnolo. Every. Single. One. Other companies have used proprietary BCDs here and there, but not the extent that Campagnolo has.

Actually, that's not true. Their very first compact double crank used the industry standard 110mm BCD. But they quickly fired the guy that did that and converted all their compact cranks to a proprietary neither-here-nor-there 110mm/112mm BCD.

[8aaron8]

Originally Posted by Mark McM

When it comes to chainring BCDs, Campagnolo doesn't know the meaning of the word "standard". Ever since they abandoned the 144mm BCD for road cranks 40 years, every new BCD they used has been unique to Campagnolo. Every. Single. One. Other companies have used proprietary BCDs here and there, but not the extent that Campagnolo has.

Actually, that's not true. Their very first compact double crank used the industry standard 110mm BCD. But they quickly fired the guy that did that and converted all their compact cranks to a proprietary neither-here-nor-there 110mm/112mm BCD.

Haha, this is the best! It's too bad those 5-arm ones look so good.

[gbcoupe]

Originally Posted by SDJ

Nice crankset!

Miche, TA Specialites and Stronglight have campa compatible 110 compact chain rings which I have had good experiences with.

I am currently testing an old set of standard 110 compact chainrings as easier to find and cheaper - it works (after some filing of the hidden bolt hole) but the fit isn't 100% so am monitoring it to see how it holds up.

+1 on the other brands mentioned here. Also filing the oddball arm hole works well. I had no issues with 2 sets I modified.

[tanghy]

You can run 52/36 with the compact cranks but u might need new crank bolts

[SDJ]

Originally Posted by tanghy

...but u might need new crank bolts

oh yes - forgot about this - depending on your chainset model there might be some proprietary campa bolts which do not work with chainrings from other brands.

The bolt holes in the arms might also be to small/narrow for standard bolts so recently I had to buy some special bolts mentioning just this exact issue. Was an American brand in fact - will have to look it up

Just buy some fitting back up bolts just in case when you get the chainrings

[oldpotatoe]

Originally Posted by Mark McM

When it comes to chainring BCDs, Campagnolo doesn't know the meaning of the word "standard". Ever since they abandoned the 144mm BCD for road cranks 40 years, every new BCD they used has been unique to Campagnolo. Every. Single. One. Other companies have used proprietary BCDs here and there, but not the extent that Campagnolo has.

Actually, that's not true. Their very first compact double crank used the industry standard 110mm BCD. But they quickly fired the guy that did that and converted all their compact cranks to a proprietary neither-here-nor-there 110mm/112mm BCD.

Glad you only mentioned road stuff(actually 135mm BCD happened 37 years ago-1984) because many companies-yikes, even the big boy shimano, who has made more cranksets in a day than Campagnolo does in months..varied BCD, well, quite a lot. Particularly in the 4 arm shimano MTB type.

https://www.sheldonbrown.com/cribsheet-bcd.html