SunTour SMS Max
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Category:  Rear Derailleurs
Name:  SunTour SMS Max
Brand:  SunTour
Model:  MRC-50
Years:  1979 - ?
Country:  Japan
Weight:  451 grams (Actual)
Added By: Catnap on 07/24/13
Updated By: peterbman on 05/10/18
Additional Photos - click for full size
SunTour SMS MaxSunTour SMS MaxSunTour SMS MaxSunTour SMS MaxSunTour SMS MaxSunTour SMS Max
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Outer Plate MarkingsSMS MAXInner Plate Markings
MaterialAluminum Alloy; SteelDesign CategorySlant parallelogram
Attachment Bolt SizeClawCable Attachment Bolt Size8mm Wrench
Shifting SystemsCable AdjusterYes
Cage LengthShortMax Cog Size34
Max Chain Wrap  
General Information
From the Disraeli Gears website:

With the SMS Max SunTour (working with Bridgestone) decided to respond to the slightly dodgy engineering of Shimano’s Positron design with technical over-kill. 


The cable winds around the cylinder under the derailleur, and as it is pulled turns the cylinder turning a cam that drives a roller on an arm that manoeuvres the parallelogram into the correct position. As the roller ride over the ‘lumps’ on the cam there is even a tiny amount of over-shift before  the roller settles back into the ‘dip’ that corresponds to the gear. The SMS Max has a cam set up for five speeds.


The whole contraption is extremely solid and accurately made. However for a mass market product it is very complex, and therefore very expensive to manufacture and very, very heavy for the cyclist to drag up hills!


Other than the fantastic indexing mechanism, the design is a single sprung pivot slant parallelogram with adjustment screws on the back in the SunTour traditional style. 


Source: http://www.disraeligears.co.uk/Site/Bridgestone_SMS_Max_GT_derailleur.html
Quality:Rarity:
 
 
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Brand Information(click to expand)

SunTour (Maeda)

SunTour derailleurs have a two-letter date code. On rear derailleurs the code is stamped on the back side of the inner parallel arm. On front derailleurs it is stamped on the back side of the inner cage.

The first letter represents the year. Larry Osborn and I believe O (Oh) is 1972, V is 1979 and A is 1984. As with Shimano, the second letter is the month code, where A is January and L is December.

SunTour Year Code

N
O
P
Q
R
S
T
U
V
W
X
Y
Z
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
 
A
B
C
D
E
F
G
H
I
1984
1985
1986
1987
1988
1989
1990
1991
1992

SunTour Month Code

A
B
C
D
E
F
G
H
I
J
K
L
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

The earliest Suntour derailleur I have found with a code is marked OF. A rear derailleur marked OD (corresponding to April of 72) was reported by Leighton Walter. I have a bike that dates from between 1970 to 1972 that has the original SunTour derailleurs. These derailleurs do not have date codes on them, so I believe the coding started sometime between 1970 and April of 1972.

(source: vintage-trek.com)

 
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