SINZ 4 bolt chain rings are affordable, lightweight and machined for a perfect fit. Manufactured to fit the 4 bolt 104mm pattern found on many BMX and MTB cranks.  Laser etched logos and size markings make the SINZ chain rings stand out.  Fits 3/32 or 1/8" chains.  Available in 36T through 46T in black.

With the many gear sizes Crupi offers, we thought it would be good to offer you the most complete gear ratio charts available!

You can download and print any of these charts in a PDF format.

20 x 1-1/8 with 20 x 1" Tires              20 x 1.75 with 20 x 1.75 Tires

20 x 1-1/8 with 20 x 1-1/8" Tires             24 x 1-1/8 with 24 x 1-1/8" Tires

20 x 1-1/8 with 20 x 1-3/8" Tires            24 x 1.50 with 24 x 1.50 Tires       

20 x 1-3/8 with 20 x 1-3/8" Tires           24 x 1.50 with 24 x 1.75 Tires

20 x 1.50 with 20 x 1.50 Tires                  24 x 1.75 with 24 x 1.75 Tires