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Singlespeed & Fixed Gear "I still feel that variable gears are only for people over forty-five. Isn't it better to triumph by the strength of your muscles than by the artifice of a derailer? We are getting soft...As for me, give me a fixed gear!"-- Henri Desgrange (31 January 1865 - 16 August 1940)

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Old 07-27-05, 07:45 PM   #1
phidauex
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Today I set out to replace the bottom bracket in my Maserati conversion with a square taper instead of cottered, so I could use the Sakae crankset I had found.

After making some measurements I had made the educated guess that I'd need a 107mm spindle, in a 70mm shell/Italian threaded bottom bracket. I ordered a Shimano UN-52 matching those specifications for 14.00$.

After it arrived today, I removed the cottered cranks, which is very easy, fortunately. (Actually, too easy, which is why I'm replacing them). The adjustable cup and spindle came out without trouble, but then I had to tackle the fixed cup.

Step one. Grab it with a lockring spanner. No dice, it can't get the right amount of purchase, and keep slipping off.

Step two. Grab it with a pipe wrench. No dice, it keeps stripping material off the cup, no matter how much 'dig' I get.

Step three. Verify that the threading IS Italian, and that it is right hand threaded. Yes, yes it is. Spray penentrating lubricant (PBlaster) liberally.

Step four. Put fixed cup in vice, and rotate frame above it to unscrew. Nope, it keeps slipping. Use a hammer to tighten the vice as hard as I can get it to go. Attempt to unscrew using entire frame as lever arm. End up shearing several of the teeth off the vice.

Step five. Apply heat from a MAPP torch. Light residual grease on fire.

Step six. Try the pipe wrench again. No dice.

Step seven. Try the vice again. No dice.

Step eight. Go to hardware store and buy 2" long 5/8" hex bolt, four lockwashers, a fender washer, and an appropriate nut, ala Sheldon Brown (http://www.sheldonbrown.com/tooltips/bbcups.html). Slip four lockwashers over bolt, and slide through bottom bracket shell, and through the cup. Put another washer over the bolt, and then the nut. Use a socket wrench on the inside, and a combination wrench on the other side to tighten the nut. I hold the combination wrench stable while tightening the socket wrench, with the hope that soon friction will take over, and allow me to unscrew the cup. No dice! Damn!

Step nine. Grab the 3' long cheater bar, and slip it over the socket wrench. Can't do it.

Step ten. Get out the seldom used air compressor, and the 250 ft/pound pneumatic impact wrench. The one I use for putting lug nuts on bus wheels. Attach the appropriate impact socket. Clamp the bike securely in a vice. Hold the combination wrench with one hand to help steady it, and then give the impact wrench a shot at its lowest torque setting. This tightens the nut down just a little further, but fails to release the cup. Jack up the torque setting. Nope, can't do it. Jack the torque setting up again. No, can't do it! Finally, at the highest possible torque setting and overpressured to 100psi, I just start wailing on it. I'm screaming as the impact wrench slams the bolt with all its might, for several seconds. I'm using the most destructively powerful tool I own, and damned if I'm going to let this fixed cup win!!! After nearly 20 seconds of impacting, I hear a loud squeal, and the fixed cup begins to move!!! It spins out quickly, and I shut down the impact wrench, marvelling at the sound of the now silent room.

I'm expecting the threads to be destroyed, but upon inspection, the threads are just fine! I run a quick rag over them to ensure their cleanliness, and proceed to install the new bottom bracket without incident.

But my troubles weren't over...

It turns out that 107mm wide spindles on 70mm wide bottom bracket shells is aggressively narrow. In fact, so narrow that my chainring hits the chainstay! Since my Sakae is a cheap no-spider variety, there is no way to move the chainring. In fact, to make matters worse, further measurements imply that 107mm is actually too narrow for my chainline! 111mm would have made more sense.

However, after what I've been through today, I was not about to end in defeat and order another bottom bracket. I grabbed my trusty ball peen hammer, and sat the frame down on my lap like an unruly child. After utilizing the hammer to carefully re-engineer the chainstay configuration (beat it into submission), I was finally able to clear the chainstay with my fabulous 52t chainring. Unfortunately, now the bottom of the crank was hitting the shell of the bottom bracket! A few quick wipes with a dremel shaved the top .5mm off the BB shell, and I was finally able to tighten the crank down without it dragging or hitting anything.

To rectify the chainline problem (my chainline is now about 38mm) on the hub side, I had to flip my Soma cog over on the nashbar hub. Don't worry, there is still a satisfactory 'flat spot' for the lockring to engage. After securing the cog, I delicately made sure that the chain wouldn't hit the spokes (ha, it doesn't!), and reassembled the bicycle. A final chainline measurement indicates that chainline is within .5mm! Hows THAT for a beater?

To celebrate my success, I taped the flipped and chopped bars with double-discount clearance rack too-ugly-to-sell camo bartape. Oh yeah. Next steps will be a paint job once I decide on a color, and to shave off all the cable stops. Oh, and a longer seat post.

Photo legend: A photo of the reengineered chainstay. I'll sand it smooth when I paint it, and no one will ever know. The clearance there is less than .5 mm at its smallest point. Amazingly tiny. There is also a photo of the shell clearance, also about .5mm. If you look close, you can even see a line cut into the chainring from when I first installed it and made a few test revolutions as I noticed that it was dragging against the shell. Then the whole bike, so you can marvel at its stereo-typical beater/conversion goodness.

I post this in hopes that someone with similar problems will be able to use my experiences to decide what NOT to do to their poor bike.

peace,
sam

P.S. with the straight chainline and the 'real' cranks, the bike rides like never before. Its a dream come true!
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Old 07-27-05, 07:50 PM   #2
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goddamn. you showed that thing who's boss.

also, there is nothing ugly about that bartape.
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Old 07-27-05, 07:55 PM   #3
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goddamn. you showed that thing who's boss.
Hell-ya! You hear that, bottom bracket? I'M BOSS! NOT YOU!! ME!! YOU AREN'T MY REAL MOMMY!!!

*still high from the bashed-knuckle endorphins, and the adrenaline of victory*
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Old 07-27-05, 07:57 PM   #4
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Good work, now ride I say ride!!!!
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Old 07-27-05, 09:19 PM   #5
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Great story!

It's not that I'm so smart, it's just that I stay with problems longer.
~Albert Einstein

When you come to the end of your rope, tie a knot and hang on.
~Franklin D. Roosevelt

With ordinary talent and extraordinary perseverance, all things are attainable.
~Thomas Foxwell Buxton

He conquers who endures.
~Persius

When the world says, "Give up,"
Hope whispers, "Try it one more time."

~Unknown
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Old 07-27-05, 10:26 PM   #6
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<Step ten. Get out the seldom used air compressor, and the 250 ft/pound pneumatic impact wrench. The one I use for putting lug nuts on bus wheels. Attach the appropriate impact socket. Clamp the bike securely in a vice. Hold the combination wrench with one hand to help steady it, and then give the impact wrench a shot at its lowest torque setting. This tightens the nut down just a little further, but fails to release the cup. Jack up the torque setting. Nope, can't do it. Jack the torque setting up again. No, can't do it! Finally, at the highest possible torque setting and overpressured to 100psi, I just start wailing on it. I'm screaming as the impact wrench slams the bolt with all its might, for several seconds. I'm using the most destructively powerful tool I own, and damned if I'm going to let this fixed cup win!!! After nearly 20 seconds of impacting, I hear a loud squeal, and the fixed cup begins to move!!! It spins out quickly, and I shut down the impact wrench, marvelling at the sound of the now silent room.>

Wow.
Next step, check frame alignment.
No just kidding. That is no more torque than a 500 pound person pounding up a hill.
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Old 07-27-05, 11:20 PM   #7
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Lol, next time you see a 500 pound person pounding up a hill, let me know, I've got some more bikes for them to disassemble. In the end, I think it wasn't so much the overall torque of the wrench, but the peak torque achieved by its 'hammering' action. Peak torque is probably incredibly high, and the extreme vibration has a real way with breaking loose tough fasteners. I love my impact wrench...

The frame is actually still surprisingly straight, though I did need to tweak one of the dropouts a bit afterward.

I went on a nice little ride afterward, and then came back and cinched down the crank bolts a bit as everything wiggled into place. Now there is no creaking at all, and the chain tension is even across the whole rotation, which was a real problem before. Now I can trackstand better, skid better (though still not very well), and backpedal without having this intense fear that the cotter will come shooting out of the crank like a bullet, impaling a bystander, as the crank slips loose and I fling my nutsack into the stem like a beanbag, crushing it into jelly.

Plus, the straight chainline is a dream. Its so quiet! I snuck up on a couple making out in the park, I snuck up on some people walking down the street, and just slunk around in the dead of the night like some sort of troublemaker. Plus the camo bartape just made me friggen invisible. I feel faster and more confident on the bike now, too. Someone mentioned here once that the crankset makes or breaks the bike for them, and now I agree, I'm going to put good cranksets on all my bikes now (and start looking for a better crankset for this one, the Sakae was almost free, but its a spiderless variety, so no changability for me. Oh well, I'm happy with 52/19 (72") for now.

peace,
sam
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Old 07-27-05, 11:41 PM   #8
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Originally Posted by phidauex
and I fling my nutsack into the stem like a beanbag, crushing it into jelly.
LOL What a poetic turn of phrase. That actually made me laugh, despite how excruciatingly painful it would be.
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Old 07-28-05, 06:18 AM   #9
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holy q-factor, batman! 107mm spindle in a 70mm shell? or rather, a 69.5mm shell...

i just perfected the chainline on my commuter mess (a french frame) by putting in a 107mm spindle, and while it mated well with the existing tange cups there is very little clearance between the sugino glp arms and the cups themselves. still, the whisper-quiet drive train is worth the fight, don't you think?

tip: take that thing apart and reassemble it every couple of months, just to know that you still can.
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Old 07-28-05, 07:57 AM   #10
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After reading step ten, I think I need a cigarette.
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Old 07-28-05, 09:17 AM   #11
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Originally Posted by cicadashell
holy q-factor, batman! 107mm spindle in a 70mm shell? or rather, a 69.5mm shell...

i just perfected the chainline on my commuter mess (a french frame) by putting in a 107mm spindle, and while it mated well with the existing tange cups there is very little clearance between the sugino glp arms and the cups themselves. still, the whisper-quiet drive train is worth the fight, don't you think?

tip: take that thing apart and reassemble it every couple of months, just to know that you still can.
Yeah, the narrow Q is great. I'm a short person with narrow hips, so the narrow Q seems to help my spin. At least thats what my ride last night seemed to indicate.

And yes, all said and done, it was definately worth it.

I'll be disassembling and reassembling soon, since I'm going to be painting the frame once I decide on a color, and it will give me a good chance to convince myself that I really am the bike's master. I anti-seize compounded the heck out of those threads on the shimano BB, so I'm not expecting it to give me any trouble. And besides, the UN52 was sitting right there on the bench watching me hammer away at that cottered BB, so it KNOWS what its gonna get if it gives me trouble. Grrr!

peace,
sam
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Old 07-28-05, 09:33 AM   #12
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Originally Posted by WaitUpForMe
Great story!

It's not that I'm so smart, it's just that I stay with problems longer.
~Albert Einstein

When you come to the end of your rope, tie a knot and hang on.
~Franklin D. Roosevelt

With ordinary talent and extraordinary perseverance, all things are attainable.
~Thomas Foxwell Buxton

He conquers who endures.
~Persius

When the world says, "Give up,"
Hope whispers, "Try it one more time."

~Unknown

Don't forget: When You Earnestly Believe You Can Compensate For A Lack Of Skill By Doubling Your Efforts, There's No End To What You Can't Do.
~http://www.thinkgeek.com/cubegoodies...air/3673/zoom/

Just kidding, you are a real champ. But do you think the reengineering of the chain stay may have compromised the inetrigty of the frame?
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Old 07-28-05, 09:53 AM   #13
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Don't forget: When You Earnestly Believe You Can Compensate For A Lack Of Skill By Doubling Your Efforts, There's No End To What You Can't Do.
~http://www.thinkgeek.com/cubegoodies...air/3673/zoom/

Just kidding, you are a real champ. But do you think the reengineering of the chain stay may have compromised the inetrigty of the frame?
Doh... Now I feel thoroughly demotivated. J/k, I actually have that exact poster in my cube at work.

I think the 'reengineering' probably has not had a significant affect on this frame's integrity. The chainstays on this bike already had a sort of crimping on them, and I just extended an existing crimped region a bit. Plus, this tubing is very thick heavy stuff. I would not have attempted an adjustment like this on more fragile Columbus SLX tubing, for instance, but this gas pipe stuff is so thick that I don't think I made a big impact.

And finally, the excuse I use whenever I attempt bike activities or repairs that defy conventional wisdom: "I only weigh 120 pounds, and I'm very weak."

peace,
sam
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Old 07-28-05, 05:34 PM   #14
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but I think I have ended up
where I intended to be."

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Old 07-28-05, 05:41 PM   #15
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"I may not have gone
where I intended to go,
but I think I have ended up
where I intended to be."

-- Douglas Adams
How zen.
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