Thursday, December 24, 2015

Computing for the Gear Inches of MTB with two upgraded chain rings, 26 wheels; upgrade to 1 and 2 chainring and 42t addition

Wheels of Happiness

Rizal Philippines
December 24, 2015

                                       Converting to dual chain rings for MTB


1 2x9 transmission conversion

Workshop from bike radar - converting to single or double chain ring for 9 speed set up


One way of reducing weight of MTB is to go for 2 chain ring 26 and 36, remove the 18 or 17 cogs, for a 10 speed and add 42 t cogs (with the One upgrade that weighs only 55 grams).  This is possible if you have XT or XT R cogs.

        For an 11 speed set up with XTR, XT gear set.   with 26 er
                                                   26                         36

                10                                67.6                    93.6

                12                                56.3                    78

                14                                48.3                    66.8

                16                                42.2                    58.5

                18                                 37.5                   52    

                21                                 32.2                   44.5

                24                                 28.2                   39

                28                                 24.1                   33.4

                32                                 21.1                   29.

                36                                18.5                    26

                42                                16.09                  22.3


     However, I checked with Haooh in Taytay Rizal and told me  that 24 granny would be easier to acquire

Let us recompute for a 27.5 with a 10 speed  cogs.


As you can see, at 24 x 42, you can really a very low gearing at 15.71!!!    


                                                 24                       36    (for 27.5er)

             11                                59.99                  89.99

             13                                50.76                  76.15

             15                                 44                      66

           (17)                                38.82                 58.23 (this will have to be removed to accept the 42

             19                                 34.73                 52.10

             21                                 31.42                 47.14

            24                                  27.5                   41.25

            26                                 25.38                  38.07

           32                                  20.62                   30.93

           36                                  18.33                   27.5

           42                                  15.71                   23.57

At 36 you can just use one chain ring and not shift (may be this is their choice for single ring.  93 would be near 100 which is near the 50 x 12 gearing..   26 would be enough to cover most hills and ascents.  Now I understand the craze for single chain ring  the 36 choice, and the 42 cog.    Splendid

The upgrade will set you back:

One up 42          -     P2,300

New chain ring

           24     -            1,300

           36                  2,000

Total                        6,600

Image result for upgrade cogs to 42t



Adding One up 42t 



    Image result for upgrade cogs to 42t


Image result for upgrade cogs to 42t
                                          The One 42t upgrade

Image result for upgrade cogs to 42t


Image result for upgrade cogs to 42t
                                      Assembly and upgrade completed

Image result for upgrade cogs to 42t
                                     Upgrade installed at the MTB

Upgrade to single chain  ring 30 t.  

      According to an MTB rider I interviewed at Antipolo Church today, this is the best  uprade you can make.  It can easily lighten the MTB by as much as kg because you save on:  the bolts, two other chain rings, and the spider arms, the cable, the FD, the thumb shifter and the cables. And no problem with chain jumping missed shift of FD..  So mostly this is the set up for 29er.  Let us compute for the gear inches.

                      Chain wheel              30             Wheel size 29

Cogs

                             11                    79.09

                             13                    66.92

                             15                    58

                            ( 17 )                51,17

                             19                   45.78

                             21                   41.42

                             24                   36.25

                             28                   31.07

                             32                   29.00

                            36                   25.77

                            42                   22.09

The lowest here is only 22 vs the granny gear of 24 at double chain set up of  15.71.   For a 32 cogs set before, that is ultra low....

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