Homebrew01

Are Campy square taper Bottom Brackets and cranksets compatible over the years ? I want to put a new compact crankset on my daughter's bike and am fishing for an English bottom bracket .... As long as it spins smoothly, I'm not picky about year or model. How are those Token brand BBs I see on Ebay ?

PM me if you have a cheap one to sell.

cuda2k

How new is new? Campagnolo stopped using square taper in around 2006 or so. Also, what crankset? Record & Chorus took a different length BB than Centaur & Veloce. Lots of factors to consider in addition to taper when you're talking BB & Crank compatibility.

Ex Pres 

Pre 1994 Campy taper is somewhere about half way in-between the current ISO and JIS standards. Phil Wood actually recommends using JIS tapers for pre'94 Campy cranksets. In 1994 Campy adopted the ISO taper for its square taper cranksets produced until ~ '06.

What age and model crankset are you planning on using?
Edit: If I would read and comprehend I see you're talking about a compact, so you'll need a 102mm ISO if Record/Chorus, 111mm ISO if Centaur and below

Road Fan

I've seen Campy Record 102 mm BBs in English on Ebay, sometimes closing for $40, sold by people who upgraded to the two-piece design. New they are around $100. The Tokens are not bad, per some thread a while back. Centaur 111 mm are kind of hard to come by (I needed this for one of my bikes), but AC-H 111 is not uncommon.

What kind of compact have you bought? I got a Veloce last year, and it needed a 111, same as a Centaur. I used an AC-H, works great, and the chainline is correct. No problems! I'm not familiar with the Mirages.

Homebrew01

I'm looking at this Mirage Compact square taper BB.

https://cgi.ebay.com/CAMPAGNOLO-MIRAG...lenotsupported

pastorbobnlnh 

If you use the Mirage crankset, I'd recommend using the Veloce cartridge BB. I've used two, one on a Mirage crankset and the other on the new Comp Triple. They are well made, just a little heavier then the other Campy square taper BBs. Best of luck with your conversion!

https://www.universalcycles.com/shopp...6&category=607

cs1

Phil Wood is the only who says that. Campy USA said they're the same regardless of date.

Road Fan

Ok, this is the AC-S, which is the same as teh AC-H that I have used, except for a solid axle versus a hollow axle.

Get one of these!

Ex Pres 

Actually I tested this theory out with a single crankset on 3 spindles, measuring the tread/Q-factor with an ISO spindle, a pre'94 Campy spindle, and a JIS spindle. Pre'94 Campy ain't ISO as far as chainline is concerned. My q-factor using the old Campy came out exactly half-way between the ISO and JIS. (ISO crankset)

Charles Wahl

This is interesting. What spindles did you use? It seems to me that this experiment would only be valid, Q-factor-wise, if all three spindles had a configuration that put their right side ends in exactly the same spot when installed. If they had different "shell to end, right" measurements when installed (because different length, different offset, or different spacing of the bearing tracks), then differing Q-factors wouldn't mean that much. Were I to do it, I'd try to simply measure the "overhang" of the crank bolt washer seat beyond the spindle end. But maybe I've misunderstood. . .

My own attempts to measure the ends of various spindles have tended to corroborate your findings: that ISO indeed has the smallest end, Campy in the middle, and JIS largest -- but the differences seem to be extremely small! And when I put a crank on those spindles, it's really hard to tell how much pressure to use in order to make a fit comparison. It also seems to me that (uncontrolled) variations in the torque used to install the crank might be unavoidable.

Ex Pres 

CW, Qfactor is just the difference between the crank arms @ the pedal hole (outside). Symmetry has no bearing on the results. The spindles I used were not the same length, so I subtracted the qfactor from the spindle length to arrive at my results. If qfactor with an ISO spindle = x, qf Campy pre'94 = x+3mm, qf JIS = x+6mm.

Charles Wahl

OK, I get it; perfectly conclusive result.

Road Fan

This is just a slight derailment in topic, but I've found that chainline is important to having the shifting work at its best. Correct chainline in a taper BB depends on correct torque, so while we retro-grouches like our manual skills, I use a torque wrench. I've found that being in error on torque affects how far in the crank arms are pulled, which affects Q and chainline, hence comfort and shifting. Engineering-wise I think too loose can lead to distortion of the square hole, and too tight can lead to excessive stress in the aluminum casting. With this perspective I also only use a BB or spindle that is OEM-recommended for that crank and its application, because I value correct alignment and durability of my old parts.

Q factor BTW is the distance between the left and right pedal mounting planes, trying to level to common terminology.

It isn't guess-work or it need not be. For Campy GS (old), NR, and SR there is an applications chart on the Bicycle Classics website www.bicycleclassics.com. It's a bit of a challenge to follow, but the info is all there. It's a little in the vein of the Trek site, where a major best-effort has been made to collect all the historical application info into one place, without full benefit of good archival data, but it's the best I've seen. For later-era Campy, use the Campy website, to access pdfs of the original installation and application instructions.

The smaller ISO design has I think the same taper as the Campy, but if I recall the crank will sit closer to the bike centerline. This causes lower Q but incorrect chainline, and can lead to chainwheel/chainstay or crankarm/chainstay interference. I think the cranks may even bottom out on the flats. It's your own research project to determine how to make this work by going with a longer spindle, and even to see if its feasible.

jan nikolajsen 

Be aware that this BB, like almost all modern stuff, takes a component specific tool to install. The Park BBT-4 is one choice.

pastorbobnlnh 

When I bought the first BB I also bought the Park Wrench. I should have mentioned the need for this the first time. Thanks for pointing it out!