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| Category: | Bottom Brackets |
| Name: | SunTour Micro Drive |
| Brand: | SunTour |
| Primary Group: | SL |
| Model: | SL10-E XC Pro MD |
| Years: | 1992 - 1995 |
| Country: | Japan |
| Weight: | 291 grams (Spec) |
| Added By: | onespeedbiker on 05/25/13 |
| Updated By: | peterbman on 03/11/14 |
Additional Photos - click for full size |
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| Bearing Size/Count per side | 5/32"/ 12x12 | Spindle Markings | ML-SL68 |
| Fixed Cup Markings | Microlite, WTB Suntour Grease Guard, Japan 1.37 x 24T HF | Adjustable Cup Markings | Suntour, Japan, 1.37 x 24T,HF,ML |
| Spindle Style | Square Taper (JIS) | Axle Material | Steel |
| Available Threadings | English/ISO: 1.370 x 24;
Italian: 36mm x 24 | Length(s) | 115mm - Engish |
| Tools Needed | Spanner, Locknut Wrench and Fixed Cup Wrench | | |
From BikePro.com: The Suntour Micro Drive
groups require a shorter length bottom bracket spindle to pull the
cranks in toward the frame appreciably, to try to reduce the Q-factor.
The standard XC Pro spindle is 125.5mm long, but to make the 115mm
length they required immediately for the MD group, Suntour chose to use a
modified Road Racing bottom bracket. They settled on the SL series
bottom brackets, which do come with a 115mm long spindle. For the XC Pro
version the SL Microlite model is used, a standard type, fixed cup
bottom bracket with aluminum alloy cups. The cups and spindle are
modified to accept Suntour's implementation of the WTB Grease Guard
principle. The cups are machined from aluminum rod with the inside bored
for an opened sealed bearing cartridge to be pressed in. The opened
cartridge is seated against the back of the inner face. A thick rubber
gasket surrounds the spindle leaving open a tiny hole in the spindle to
fill just the bearing cavity with grease. A small recess cut inside the
hole where the spindle exits the cup allows a rubber gasket to snap in.
The gasket permits grease to leave the bearing, but does not allow
outside contaminants to enter. The bearing uses 12 steel ball bearings.
The spindle is machined from steel rod. Because the original SL
Microlite B/B had a sealed bearing cartridge, the spindle has no bearing
races ground into it's surface. Suntour instead manufactures a separate
steel race that presses onto the spindle where the cartridge bearing
would rest. This race is machined, with a smoothly ground surface where
the ball bearings revolve on it. The adjusting cup has six equally
spaced holes for pin spanner final adjustments. The lockring for the
adjusting cup is made of steel and chrome plated. This B/B comes with
chrome plated steel crank bolts that are drilled through with a tiny
hole for the injected grease to pass into the spindle and thereby the
bearings. Also included are chrome plated crank arm caps that have a 5mm
hex head for removal and a tight fitting round rubber gasket pressed
into the inside. The gasket has a small hole in it so grease injection
to the bearings can be performed with no part removal. In case of
interior frame condensation, Suntour provides a tight fitting, plastic
sleeve that fits internally between the two bearing cups. The weight of
the SL10-E XC Pro MD B/B, including caps, bolts, sleeve is 291 grams.
Silver, English thread only for 68mm (with 115mm spindle), or 73mm (with
119mm spindle) wide B/B shells.
What I find so remarkable about this bottom bracket is how Suntour, instead of re-engineering a new Grease Guard Bottom Bracket, took their existing SL-10 sealed cartridge bottom bracket, pressed a steel (open cartridge bearing) race into the aluminum cups and manufactured some steel races the slipped onto the spindles so it would work with caged bearings. Amazing
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| Quality: | | Rarity: | |
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| Component Variations | View Detailed List Manage Variations |
| Variations of Component exist (Component is 1 of 2) | Brand | Group |
| SunTour BB-SL00-I, SL | SunTour | SL |
| Component Groups |
| Primary Group Name | Brand | Quick Info | Browse Group Components |
| SL | SunTour | 1991 - 1994, Road Race | View 15 Components |
| Details: Early 90's group (found in 92 catalog) |
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
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N |
O |
P |
Q |
R |
S |
T |
U |
V |
W |
X |
Y |
Z |
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1971 |
1972 |
1973 |
1974 |
1975 |
1976 |
1977 |
1978 |
1979 |
1980 |
1981 |
1982 |
1983 |
| |
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A |
B |
C |
D |
E |
F |
G |
H |
I |
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1984 |
1985 |
1986 |
1987 |
1988 |
1989 |
1990 |
1991 |
1992 |
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SunTour Month Code
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A |
B |
C |
D |
E |
F |
G |
H |
I |
J |
K |
L |
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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)
