Sunday, July 20, 2008

Shimano DX RD-M650 SGS overhaul




This derailleur came with Michelle, my 1991 Bridgestone MB-3. Apart from the replacement / upgrading of its jockey wheels to Control Tech sealed cartridge bearing pulleys, the unit has never been serviced.

A picture of the derailleur in its stock form here.





After an external scrub down.





Somehow, the B-tension screw bent over the years. I replaced it with a generic stainless steel 4 mm x 12 mm allen-head screw.





The steps for disassembling the derailleur are similar to those posted for the Shimano XTR RD-M950 GS overhaul. Exceptions are noted in this post.

The cage arm is secured by a single Philips head screw. Removing it allows the sub-assembly to slide out.





Contrary to the RD-M950, the longer prong of the RD-M650 cage arm spring fits into the cage arm. The factory position (tension setting) is the hole closest to the end of the arm.





The o-rings compressed over the last 17 years, allowing ingression of dirt and water.





Derailleur body.





Fully disassembled and cleaned.
41 parts.





All the o-rings were replaced.





For a little more reliability, I replaced the stock Philips head limit screws with stainless steel variants (4 mm x 16 mm set screw w/ 2 mm allen head). HBC's titanium versions will work too, but are overkill for this application.





Shimano RD-M650 rear derailleur overhauled, re-lubed, and reassembled. Don't forget that the B-tension, lower limit, and upper limit screws are now all out of adjustment.


Specifications
Total capacity:  38T
Minimum gear:  12T
Maximum gear:  32T (although I gotten away with 34T with some fiddling)
Weight:  320 grams


At some point in future, the derailleur cable clamp nut (which is beginning to corrode) might be replaced with a corrosion-resistant HBC titanium version.

Thursday, July 10, 2008

1991 Bridgestone MB-0 Zip






         Primus ab aequorea percussis cuspide saxis...





This page is missing from my catalog, so the late Sheldon Brown's archive will have to make do.










The year was 1991, her name is Joanne. For reasons I can't recall, I took delivery of a 46 cm (18.1") [center-to-center] frame instead of the 49 cm (19.3") as stated on the receipt. I guess Peter was concerned about preserving my virility (as if I'll ever be party to producing post-placental want machines  :-P  )


Travel: go for it, before you impregnate some haphazard-girl that'll only suck you dry and make you work for the rest of your life so she can shop at Wal-mart and drive a Soccer-mom-obile.
         (Kosher Princess)


Believe it or not, my other choice was a radio-controlled (RC) helicopter. I can't imagine how different life would be if I chose otherwise. With the MB-0, I was no longer held hostage to bus timetables or (past) midnight taxi surcharges — I went wherever my legs took me: I rode my first night ride, first round island, first off-road trail from Mandai Hill 265 to McRitchie Reservoir, first time down #@&%!!! Woodcutter's Trail; had my first endo, first time side-swiped by a taxi cab (before the PIE onramp outside Ngee Ann Polytechnic). But I soon exhausted all possibilities on the tiny isle.





On the summit of Bukit Ayer Lalang, Malaysia. The hill only exists in memories and old photographs now.










On the way to Desaru.





Then National Service came. After which I got bitten by the SCUBA diving bug and spent some time working as an assistant instructor and divemaster before leaving the country for many, many years. While I adjusted to a new life abroad — unused and unmaintained — the MB-0 quietly declined.

When I returned, she was a shadow of her former self.





         It broke my heart.






























         First bicycle disc brake in Singapore, 1992.





         The elastomers liquified over the years.








































Misadjusted settings, I can tune; broken parts, I can fix; dilapidated equipment, I can refurbish; relations (of any kind): once you are on my shit list, you stay there forever. So, it may not be the best idea in the world to ride with me once you pissed me off — it would be unfortunate if you mishear a yell of "Phear!" for "Clear!" and get yourself flattened by an approaching 12-ton truck. Then, all the king's horses and all the king's men...



         Anyway, a little TLC later:




MB-0 Zip frame weight:  1897 grams
Size:  46 cm  (18.1") center-to-center















Each country that manufactured a part on the MB-0 gets its flag on the frame.










The Specialized Direct Drive 1-inch threaded headset is still good. This version utilizes roller bearings for the lower race, as well as a floating race above the rollers (under the lower cup).















         BB shell:  unthreaded, 68 mm width.
         Faces chamfered 45 degrees using Mavic Tool 65234.





Mavic 610. ISO square taper.

Mavic's specially designed bottom bracket requires personal courage, real expertise, or professional installation, but will last you a life time. This bottom bracket is another variation of the floating style bottom bracket unit, this one is made to achieve very fine and minute adjustments. Installation requires that your bottom bracket shell is re-faced to make the shell faces perfectly parallel and chamfer the inner lip of the BB shell slightly.

The re-facing to make this BB fit will require the elimination of the outer few threads inside the BB shell. This is done to accept Mavic's special mounting rings that use a threaded compression fit. As the threaded aluminum lockrings are tightened, they compress 45 degree chamfered sides into the BB fixing the bottom bracket in place. The body of the unit is an aluminum tube into which sealed bearing cartridges are fit and then seated with an internal aluminum lockring (similar to their hub design).

The spindle is made of hollow machined steel and available in seven lengths. Also included are a pair of steel crank bolts and washers, (33 grams). With the spindle in place the entire unit is held by beefy aluminum locking compression rings at each end. You can adjust your chain line easily due to the bottom bracket's floating design. This BB has the bearings positioned at the extreme ends of the bottom bracket shell, which increases support, and lengthens the life of the bottom bracket.

Available in spindle lengths of 114 mm, 116 mm, 119 mm, 123 mm for Road bike use, and 124 mm, 128 mm, or 134 mm for mountain riders. The 114 mm Road model weighs 317 grams, including the 33 grams crank bolt/washers. In the 134 mm spindle length, it weighs 365 grams, (including the crank bolts and washers which weigh 33 grams), it isn't the lightest, but is one of the smoothest bottom brackets available.
         (BikePro)






Mavic bottom brackets require no threads in the shell to install, and are a viable alternative for repair of moderate-to-expensive bikes that have damaged bottom-bracket threads. The shell must be prepared for installation of the bottom bracket by facing it with the Mavic tool 65234. This tool faces the ends of the shell to be conical, to match the conical-faced bottom-bracket mounting rings. Face the shell until the face is chamfered to a depth of 2 ~ 2.5 mm (chamfering is to cut the inside edge of the bottom-bracket shell face at an angle).

To install a Mavic bottom bracket, grease the threads on the outside of the cartridge-shell unit. Put a lockring onto the end of the cartridge with the dust cap marked "Fixe." Slip a conical plastic fixing washer over the cartridge so that it is against the inside face of the lockring. Older versions of the bottom bracket will not necessarily have this ring. Slide the bottom bracket into the shell from the right side of the bike. If it will not slide in effortlessly, remove obstructions inside the bottom-bracket shell. Do not force!

Slip the other conical plastic fixing washer onto the left end of the bottom bracket (older bottom brackets may not have one). Attach the other lockring to the left end of the unit. Use one lockring spanner to hold one of the lockrings, and another to tighten the other lockring. Secure to 240 ~ 300 in-lbs (13 ~ 17 lbs @ 8").

Install the right crank arm and check the chainline. If it needs adjustment, remove the crank arm, break loose the left lockring, adjust the right lockring in or out to move the bottom bracket, and then re-secure the lockrings.

To remove the bottom bracket, remove either or both lockrings with a lockring spanner and slip the unit out of the shell.




Mavic 637 Crankset

The arms are forged of 2014 aluminum alloy, then numerically control machined, milling them to close and precise tolerances, and finally hand polished. The left arm after forging is machined to the approximate shape and then milled to create the flat surfaces, as well as the initial rounded contours on the arm. The arm is drilled, broached, and tapped for the pedal and crank bolt assembly. All of the front surfaces of the arm are then high polished to remove any trace of the previous milling work.

The final step is the etching of the "MAVIC" name on the front of the arm. The right arm is made similarly, forged of aluminum, machined into it's final shape, then high polished on the front and engraved with the "MAVIC" name. The arms are 32 mm wide at the pedal spindle, narrow slightly over the pedal, then gradually widens to 30 mm. The left arm at the BB spindle is 39.5 mm wide and cone shaped with a flat bottom. Both arms have a thickness of 11.9 mm at the pedal spindle that becomes 13 mm near the BB. The spider, (holding the chainrings to the crank arm) is a hefty piece of mill work that is deeply seated around the bottom bracket shell for a close fit to achieve a low "Q" factor. The spider encloses the BB shell to help prevent the chain from shifting off the inner chainring and jamming between the chainring and the BB spindle. In addition, the "Q" factor is reduced by having the arms built parallel to the line of travel on the bike. They do not splay out at any angle. They are straight.

Mavic believes that all crank arms should be straight so that if you are in a wreck, you can quickly sight down the end of the arm and notice immediately if it's bent. Crank arm problems, should they ever occur, are highly noticeable also because the arm is left un-painted. The Mavic 637 crankset comes with three hard anodized, round chainrings, using the standard 74 mm and 110 mm bolt pattern, that have been precision cut and then ground for a precise chain fit. The inner chainring has fifteen machined holes that give the chainring a slight ellipse. This "offset" element permits you to adjust the cranks to avoid rear wheel skid.

The 637 set also comes with a pair of crank arm dust caps machined from aluminum rod then Grey anodized. The cranks, chainrings and crank arm caps are made of aluminum. The fixing bolts, inner and outer are made of steel. The arms are a highly polished, un- anodized Silver color. These cranks will work with any 2 degree, tapered spindle, bottom bracket, (Mavic prefers theirs, which is a good choice if your BB shell has stripped threads). The cranks are made in 170 mm, 175mm, or 180mm lengths with the 26-36- 46 or 28-38-48 tooth chainrings. Mavic 637 cranks come as right arm, with spider, three chainrings, all the required fixing bolts, left arm and a set of machined aluminum crank arm caps. The 170 mm crankset, with all included parts, weighs 689 grams. These aren't made any longer and are no longer available.
         (BikePro)


The cranks require ISO standard square taper bottom bracket spindles, installation on J.I.S. standard units will ruin them.





In the fall of 1997, I disassembled the front wheel and brought the hub to be re-laced by Cupertino Bike Shop. Though it has easily clocked up 30,000 miles (48,000 km) by now (most of it on Ivy, my 1996 Specialized M2 FS Stumpjumper), the wheel has never needed truing and the hub remains as smooth today.





Reunited at last: Mavic Paris Gao Dakar Hubs. These babies are amazing. The rear hub hasn't turned in 12 (or is it 13?) years, and yet when I picked the wheel up and flicked it, it still spun smoother than any Shimano XT or XTR hub I've ever encountered.





Rear Mavic quick-release. The matching front unit was brought to California and was lost in my frequent moves around the state.










SunTour components are spec'd for this bike.





SunTour XC-Pro thumbshifters. Too bad they are not Shimano compatible. Though there's always the friction option  :-P





SunTour XC-Pro front derailleur. Despite the corroded finish on the cage, it still works.





SunTour XC-Pro rear derailleur. I am unsure if the cage assembly can be taken apart for maintenance. I managed to overhaul every part of the derailleur except that. Nevertheless, it's smooth as butter now.





SunTour XC-Pro 7-speed freewheel:  12, 14, 16, 18, 20, 23, 26T.





Oxidation only affected the surface of the cogs, the mechanism remains pristine.





SunTour XC-Pro track pedals with sealed cartridge bearings and Superb-Pro track cages. One bearing was gritty, so I decided to remove the whole lot (for possible replacement).


         Inboard bearing
         OD:  19 mm
         ID:  10 mm
         Width:  12 mm

         Outboard bearing
         OD:  19 mm
         ID:  8 mm
         Width:  6 mm





What is this?
(Clicking on the correct answer reveals a similar picture with more information. The wrong answer will leave you cold.)

a)  Something served at Chinese wedding dinners.
b)  Your ex-girl / boyfriend's nostril hair.
c)  A questionable accessory most likely designed by a surfer dude taking too many bong hits whilst watching Jaws re-runs on late night TV.





Dia-Compe Advantage 5-SL (super light) brake levers, specially drilled, clear-anodized and hand-polished for Bridgestone. I didn't like them. They hurt my fingers.





What I found in my old parts bin:  Dia-Compe #986 Cantilever brakes, specially clear-anodized and hand-polished for Bridgestone. The rear pair is missing.

Exploded diagram.
Set up instructions.
Info from BikePro.

Oh yes, I hated these brakes.

Dia Compe 986 brakes. I've seen more than one experienced mechanic brought to tears by those brakes. I used to have them on my old Dean and, between the flexy ti stays and the even flexier brake arms, they rarely worked. They also have a goofy system of spring adjustment that requires a cone wrench and a 5mm allen wrench. Once the brakes get old, it's nearly impossible to keep the pads in one place when you try to tighten the allen bolt that (supposedly) holds them in place.

Bad memories.
         (white lobster)




Somewhere down the road, I apparently replaced the rear brakes with a pair of 1991 Shimano Deore DX BR-M650 Super Low Profile Cantilevers.





Dia-Compe straddle cable hangers.





Ritchey Logic front brake cable hanger. I am not a huge fan of this design. The hanger takes the place of a spacer under the locknut of the 1" threaded headset. Operation of the brake gradually causes the locknut — and thus, headset — to come loose. I think I found a band-type (also Ritchey) at Peter's. 'Will post a picture if it fits.





Mountain Cycle Suspenders System II inverted suspension fork.

It utilizes a Pro Stop cable-actuated, hydraulic, single-piston disc brake, with a floating 230 mm rotor. Paired with the unit is a custom 12 mm through-axle Bullseye hub (regular 100 mm spacing).

The original urethane elastomers turned to Gummy Bears (and then later, glop) over the years. Scrubbing them out with an old toothbrush was about as much fun as learning Chinese 10 years of coerced rote learning Mandarin / Chinese. Also in the picture are replacement elastomers, spare elastomer guides, spare brake pads, the old rotor (which is 55 grams heavier and non-directional), as well as 2 bleed kits.

More on Mountain Cycle here.

Both fork and hub have been overhauled and mothballed.





The original front fork is missing too. The fork from Michelle, my 1991 Bridgestone MB-3 — aside from the paint job — is an identical unit.


         Specifications
         Ritchey Logic triple-tapered butted.
         Forged end / dropouts.
         1.6 lbs (700 grams)





Ritchey Force handlebar:  butted, 560 mm, 6 degree bend.
Manufactured by the Japanese company, Nitto.





I don't know what to do with the Ritchey Force Comp stem. I could have it sandblasted, but the satin silver finish is gone. I guess I could paste a NDP 2008 sticker on it and hand it to the PAP balls-carriers to polish...





That, and the stem is most likely too short and low for me now.


Specifications
Tange / Ritchey Logic Prestige tubing — custom butted, shaped, and heat-treated Chrome-Molybdenum steel.
Tungsten Inert Gas welded.
Manufactured by Nitto.
1-inch quill.

More info from BikePro.





Also contract manufactured by Nitto, this is lost as well. Once I grew past 6 feet (1.82 m), the Ritchey Force seatpost's 300 mm length became too short for me. So, out it went. Then, one night, the Underpants Gnomes came and took it away...





An American Classic 353 mm Mountain Seatpost took its place. A possible upgrade is a 380 mm Lay back or Cinch Moots seatpost.





This Selle Italia Turbo saddle was upholstered in white suede, specially for the MB-0. It used to be white  :-P

I plan to replace it with an old school Selle Italia Flite Ti saddle, in black, brown, or tan.





What is this?
(Clicking on the correct answer yields more information. The wrong answer exposes your über-grueling secret training regime to the world.)

a)  The carnage that results when BBWs take a turn at pole dancing.
b)  A secret weapon developed by a Chicago company, and utilized by the son of a US diplomat, to climb faster than anybody else.
c)  The underwire in Dolly Parton's bra.




Zefal HPX 2 frame fit pump.

The Zefal HPX pump (pictured left) is perhaps the finest frame fitting pump ever made. If there was a bench mark portable pump this is it. It's changed very little in 15 years and many are still working (mine included) after over a decade of punctures - they are a very hard act to follow.
         (Guy Andrews)


Like he said, this is one remarkable pump. (Paul Smith thinks so too.) The threaded cap (where the tire valve goes into), body, handle, and lever, are all made of aluminum. The shaft is made of steel. Only the mounting peg on the left, and the pressure selector on the right, are made from plastic. BikePro has more. And they are still available!





A little deft sanding and primer would take care of the scrapes and nicks accumulated over the years. "Tusk" would be a tough color to track down though. Maybe I will get lucky by mixing different vials of automotive touch-up paint.

I am contemplating the possibility of rebuilding Joanne into a road-only singlespeed. Perhaps with a gearing of 44 x 14 and Continental 26" x 1" Grand Prix slicks. That would mandate the re-dishing of the rear Mavic Paris Gao Dakar wheel. The installation of Paul Component's Melvin or other variants of chain tensioners may also be required.





Or, I might just get lucky with a half-link  :-P


Other considerations

Spokes:  Sapim CX-Ray (rear wheel) — if it is getting re-dished.
Handlebar:  dropbars or straight bar with short bar ends?
Pedals:  Crank Brothers Eggbeater SL





Hmm...