Sunday, March 4, 2018

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

Wheels of Happiness

Rizal Philippines
March 4, 2018


Road Cranksets buying guide

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


Cranksets 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)
445.3 mm1.78 inch64 mm
456.6 mm2.23 inch80 mm
473.5 mm2.90 inch104 mm
484.9 mm3.34 inch120 mm
543.5 mm1.71 inch74 mm
564.7 mm2.55 inch110 mm
576.4 mm3.01 inch130 mm
579.4 mm3.12 inch135 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.
Bolt Circle Diameter Measurement

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