Shimano is the major company making Brake / Shift levers for mountain use. Please read these reviews in the order presented, so we can avoid explaining the same principles with each of the three items. We chose top write about the XTR first because it is the longest in production of the 3 and wanted to discuss how the Rapid Fire shifter has changed in the current Optical Gear Display version. Incidentally this the last year the M900 will be made. For 1995 Shimano will introduce an OGD version of the XTR brake/shifter.
We want to remind you that all indexing systems for shifting reside only in the shifter. Any rear derailleur can be used with any indexed shifter, there are some very fine adjustments that are invisibly built into "systems" but the indexing will function with any index shifter. Some makers of bike parts have chains and rear gears that might add speed to achieving the shift. These Shimano shift systems are designed to use the industry standard of 4.8mm spacing on-center between rear sprockets. They will work with any rear changer, chain, or cassette...no matter who made it.
There are very few differences between the M737 and M564 levers. There are different marks on the lower side of the clamp section to indicate that it is an "M564" rather than "M737". The plastic pieces are glossy Black instead of Grey. The painted surface of the aluminum parts are glossy Black rather than Grey. The actual handle of each lever is left in a Silver anodized finish, not painted like the M737, and has Shimano in raised lettering on the inner back side. The M737 has no raised lettering. The Carbonworks XTR, XT, LX lever can again be used to replace this aluminum version. The right lever of the LX M564 will only shift through 7 gears rather than the 8 gears of the XT which we can explain with the shift winder detail photos.
We took the right shift lever sets of the M737 and the M564 apart to see the exact difference. Each of these images is of the exposed right shift lever. The one on the left is the 7 speed model, the one on the right is the 8 speed. They are identical except the 8 speed lever has one added groove which makes the "8th detent" when shifting. It's hard to see, so we have a reference line at the sides of the shifter in the proper area to look at. Notice the clear square area on the left, it lacks the detent making it the 7 speed LX model. The XT one on the right has the extra groove making it an 8 speed shifter. (How much do you think it costs to put the piece in making it an 8 speed? How much do you think it costs to run two assembly lines making two near identical sets instead of one? $30 a unit?) Those are the differences. The left lever is so identical that it weighs 198 grams just like the XT M737 left lever. The right lever of each set also weighs exactly the same. The Optical Indicator has no weight bearing on this small lever change, and has a very minor adjustment made in the interior printing so the LX will show 7 rather than 8 speeds in the window. The right shifter like the M737, will shift through 4 gears with a single push.
The M564 set comes with a well constructed, heavy duty brake cable set with Black housing weighing 166 grams. Shimano also includes a shift cable set and matching Black housing weighing 89.5 grams. It is the same cable set used in the M737 XT lever set. The left lever, complete, with brake and shift functions weighs 198 grams. The right lever complete, with brake and shift functions weighs 188 grams. The total set weight is 641.5 grams.
Next - SHIMANO DEORE LX 8 SPEED