Which cranks set is right for right 2x, 3x, compact, midcompact, what BB is compatible?

Wheels of Happiness

Rizal Philippines
March 4, 2018

It turns out  that for crankset alone, a lot has to be learned. There are various questions that raised:

1. What is meaning of compact, midcompact, and regular crank?

2. What is a triplet?

3. Which of number 1 fits me?

4. What about BB?

5. Can I use MTB cranks for RB or vice versa?

6. How about chaning the blades (the chains of the  chainsets)?

Crankset buying guide






Cheat Sheet for BCD (Bolt Circle Diameter) -Common Diameter of All Bolts in a Crank/chainset

Cheat Sheet For Finding Bolt Circle Diameter (BCD)

[table color=”grey” ]

# Bolts in Circle	Measurement Between Adjacent Holes		Bolt Circle Diameter ( BCD )
	Metric (Millimeter)	English (Inches)
4	45.3 mm	1.78 inch	64 mm
4	56.6 mm	2.23 inch	80 mm
4	73.5 mm	2.90 inch	104 mm
4	84.9 mm	3.34 inch	120 mm
5	43.5 mm	1.71 inch	74 mm
5	64.7 mm	2.55 inch	110 mm
5	76.4 mm	3.01 inch	130 mm
5	79.4 mm	3.12 inch	135 mm

[/table]

Look at the photos and compare to your crank or chainrings.  Find the number of bolts in the circle (Left Column) and the approximate measurement (metric or English) between adjacent holes.  Find those numbers in the table, then in the Right Column you’ll see the Bolt Circle Diameter (BCD).  Use this information to buy the correct chainrings for your bike.
__________

Again, Please NOTE:  This applies ONLY when the bolt holes are evenly spaced.  It will not apply, for example, to the newer 4-bolt road cranks from Shimano and Campy because the holes are not spaced evenly.

These newer cranks also have a bolt circle diameter, but you’ll need to measure directly across opposite holes to get it — not, as shown in the cheat sheet, center-to-center on adjacent holes.

Little education on Bottom Bracket tech when buying GS or Crankset - please check and verify before buying

Wheels of Happiness

Rizal Philippines
February 26, 2018

om brackets

                                     Cut  out view of BB 30 shell and crank

I got enamored with a GS and I was able to buy one cheap only to find out that its crankset is BB 30. BB 30 is short and adopted to mostly to Cannondale. It was invented by Cannondale. It consist of bearing only pressed fit into the bottom bracket shell vs a circlip engaged in the slot in the shell.  BB 30 cranks are fit only to BB 30 bikes! Its cranks are short....74 mm.. So with  BB386.  Some cranks are not interchangeable with one another. Some cranks are 30 mm in diameter, some are 24 and 22 mm (like the one I bought)  Things get more complicated if you go to MTB where BB shells can be or 86.5 or 91mm.   But Shimano cranks seem to be adopted to many shells.

Kaya pala walang bumili noong GS na iyon na BB30. Now its my problem if  the crank will fit my bike (hindi Cannondale)

BB 30, BB 386 BB 865 make for stronger crank  BB set up and is much lighter.  vs the traditional two piece BB or threaded BB shell (the thread makes the  BB shell heavier)  However, the  pressfit thing requires special tool for installation and removal... Only few bike shops and few mechanics know the PF.

Before jumping in to buy a crank set, ask questions and verify.  Like me I cant return the crankset.  I have to buy a new one (a 24 mm crank diameter) 104 mm long (the BB30 crank  spindle  is only 74 mm.. long (being BB30 crank)

A lot of mechanics and sellers are not very familiar yet with this. Those who are selling cranks cant answer too.

The buyers too must not sell their crank or GS if they will not fit the bike of the  buyer.

Salamat po

BB chart compatibility