Wednesday, December 23, 2015

Versatility of MTB gear ratios (inches)

Wheels of Happiness

December 23, 2015


It will be Christmas in one days time.  Merry Christmas

I looked again at the gear ratios of the MTB vs the compact (50 x 34) chain sets and found the versatility of modern MTB cogs and chain sets.  As I mentioned earlier, for the 44 largest chain set x  11 to 32  cogs, the  biggest gear inches and the smallest would cover the gear inches for a 50 x 34 chain set

Roadie      50 x 34 chain set

                              50                       34

11                          112                     76

12                          103                      70

13                            96                      65

14                            90                      61

15                            84                      57

17                             79                    54

19                             71                    48

21                             64                    43

23                             58                    39

25                             54                    36.7





For an MTB with first two chain rings at  44 and 32 teeth

                                 44                    32

11                            109                   78.8

12                              99                    76

14                              79                    61

16                              74                    54

18                              66                    48

22                               54                   39

25                               47                   34

28                               42                   30

32                               37                   27

Note that the highest gear inches of 50   is  110 and lowest at 34 x 27  is 36.7 and the 44 chain set 11 to 32 cogs has 109 for 11, and  37 for 32 cog.  All you need is the 44 chain ring for all the gear ratio of double chain ring of 50 x 34 bike.

In order to save weight, and for dedicated use of MTB, there is a growing debate as to how many chain rings do you use, 3, 2 or 1.  For the 2, they will stick with 44 and 32;  for the single chain ring, they would elect o  use the 36 x  11 to 42.  The preferred supplier for this is SRAM.  for the 36 x 11 - 42 combi, the highest would be 88.4 and for the lowest (42) would be 23 ! (That is super low) and close to 22 x 25  gear inches of  21 (the third chain ring of a triplet)  No wonder many MTBs  are shifting to the single chain rings.

From Performance bike 3, 2 or 1 chain rings?






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