After Market Cranks and Bottom Brackets!

[bike_it]

During my build up of the Parlee Z1 I discovered and interesting and challenging fit scenario. The build on my Z1 included a compact crank taken off my Colnago Master X Light. The bottom bracket was Record, but I changed to a lighter and smoother Phil Wood square taper 102mm spindle (same as Campy Record length).

When I installed the BB on the Parlee Z1 along with the crankset (carbonlord) the clearances between the chainstay and the inner chainring was at best 2mm, and on the no drive side maybe 3+mm - NOT MUCH! So I thought because of the chainstay tube sizes it must be the problem. I went thru the calculations and determined the chainline was right on 43.5mm. Based on that I then calculated the added distance I wanted for clearance on each side and determined I needed a longer spindle. So I purchased a 110.5mm Phil Wood to replace the 102mm spindle width, which is the Campy Std.

After installing the BB and crank I now created a different chainline that left me with more noise as the chain left the rings. There was no way I could adjust this out. It shifted fine however.

The remedy: I purchased a Record 10 Spd Compact and replaced the after market compact, went back to the 102mm Phil Wood and the noise is gone, shifts quietly, smoothly and there is plenty of chainstay clearance. It was not a Parlee design issue at all, but the crank I originally used.

The moral of the story: Even thougth the quality of the aftermarket compact is very good, and they claim compatibility, which is true in some cases, the bottom line there are reasons that Campy and Shimano works, fits and shifts smoothly as a integrated system. So I have a few components to sell!

Perhaps others may already know of this, but the hard way is always the expensive way. Really not sure how one would ever figure this out based upon statements of "Compatibility"? Thanks for reading.

[Serotta PETE]

sounds like something I would have done.......PETE

[Michael Maddox]

I've seen this on old builds, too. I fitted a Mavic 631 crankset to my Vitus using a Shimano Sante BB (108mm). With the flexibility of the frame, the rings could easily touch the chainstays under torque (I could make it happen with my hands), so I dropped it and moved to a wider spindle from a Suntour group I had.

My newest crank is a Truvativ Rouleur Carbon that I've put on my 85 Serotta Nova Special (can't say thanks enough, Sam!). Integrated Giga X Pipe BB (external bearings) and a perfect fit. Funny how this stuff works. I'm hunting for a classic Mavic BB, now...if I can find the one that doesn't require chamfering the BB shell.

[Dave]

I'd say your problem was one of inaccurate measuring. The chainring spacing between any crank on the market today does not vary more more than .6mm. The c-c spacing should be very close to 7.5mm. If you had an appropriate spindle length on the Carbon Lord crank, you would have the same clearance with the chainstay (assuming both rings have the same tooth count).

The easy way to check chainline is using a scale off the side of the seat tube. Measure to the tip of a tooth on the big ring (center of the ring). It should be in the 47-48mm range, minus half the seat tube diameter, to verify a 43.5mm chainline. Why manufacturers use the 43.5mm dimension to a point out in space, where it can't be measured, baffles me. Triple cranks are all dimensioned sensibly, usually at 46mm to the center of the middle ring, which is easily measured.

With the longer spindle, the cranks should have been 8.5mm further apart. With a Phil BB, that has an adjustable chainline (no fixed cup on the right side), there is no reason that the proper chain line could not be attained. If the chainring only had 2mm of clearance before, it could have been adjusted to 4mm or whatever you have with the campy crank, with no problem.

Even if you had a chainline that was as much as 4mm further to the left with the longer spindle, it would not create a noise problem, except when the chainline is at it's most extreme, the big ring and next to largest cog.

Triple users have to deal with this "problem" all the time. The middle ring is within 1mm of the big ring position on a double crank and the big ring is about 6mm further to the right than it is on a double. To avoid a chainline that is more extreme than occurs on a double, the middle ring and largest cog should be avoided and the big ring should not be used with the two largest cogs. None of the other combinations will cause a problem.

[bike_it]

Dave, thanks for your detailed explanation. For the life of me I cannot figure out the problem other than there are differences in crank design. When using the aftermarket crank along with the adjustable Phil Wood 102 mm BB the clearance between the inner chainring and the chainstay was less than a dimes width at best (1.5mm), on the non drive side it was maybe a quarters width (2.0mm). This little clearance is of concern in the event the inner chainring was to rub on the carbon chain stay.

With that said the Phil Wood BB are adjustable 5mm in either direction as the cups are not fixed to the BB. But with this little clearence where do I go?

When I used the same 102mm BB with the Campy Record Compact I had ample clearance on both sides with the BB centerd compared to the same set up with the aftermarket crank. I could even adjust one way or the other if needed and still provide clearance of min. of 5mm. Go figure?

At any rate the Record Compact is quiet, it works in almost all the gears without cross chaining and has proper clearance for my comfort. The overall pedal distance is less point to point, or right to left which helps me.

Your point is well taken howver re: Chainline. As I supsect this was a pilot error in adjustment with the larger spindle width (110.5mm) used. Thanks!!!

[Too Tall]

What Dave said...I mean the guy knows what up or what right?
Without seeing the setup I think the chainstays are quite "fat" and the answer would have been to order a Phil 102 with 2mm non driveside offset.

Playing games with BBs I know of what you speak. Setting up high perf. tandems gets to be fun city at times.

[Dave]

The longer spindle seems appropriate, if there was little clearance on either side. My point was the the chainline should be pretty accurate with the same chainstay clearance as your campy crank, since chainring spacing is pretty much the same.

The other questin that comes to mind is if you're sure the Carbond lard was intended to work with a 102mm spindle and a Campy taper and not a 103mm shimano? Campy's ISO taper is smaller (but the same angle) so a shimano JIS taper crank would go too far onto the spindle (about 3-4mm per side).

The longer spindle will increase the Q-factor or tread width. Just for kicks, you could mount the carbon lord crank on the 110.5mm BB and align both arms in the same direction, then measure Q. Somewhere in the 140's is common. A triple will have about a 160mm Q. MTB triples are wider still, at about168mm.

[bike_it]

Hey Dave, thanks again for your take on this situation. I just assumed the crank I requested was indeed intended for the Campy taper. The cranks are advertised to be compatible using the 102mm Campy Record tapar BB. I believe though that their Shimano Compact is only made for the Octalink spindle.

Since my Z1 is now set up with the Record Compact and now using the Phil Wood Campy 102mm BB with comfortable clearances on both sides I will either put it back on my Colnago Master X, or sell it along with the Phil Wood 110.5mm Campy BB. Thanks again for your comments and ideas it is greatly appreciated!