Bicycle Mechanics - Got To See A Bottom Bracket Disassembled In Bike School Last Night

Doing this free, hour long, weekly, bike maintenance and repair class at an Olympia LBS, The Bike Stand.

http://www.alpinex.com/bike-stand/

Bill pulled a bottom bracket out of a Kona Dew sitting on the floor. Got to see it live, up close, and in-person. He made it look easy, and after several decades of wrenching that should not surprise me. At least now I have seen what I want to do in overhauling the bottom bracket of my '86 Schwinn World.

So I know I'll need a Crank Puller and a Lockring Spanner. Did not see him use a Pin Spanner, and I am not quite getting the use of a Pin Spanner. Does the Pin Spanner work in conjunction with the Lockring Spanner to exert more torque?

I am also learning that I am in deep, deep waters in this class. There are a couple of guys in class who are seasoned wrenchers, and at least one has already built a frame. Everyone is really nice and friendly, so mostly I'm worried about looking completely stupid with basic questions. Thus far, it does not appear to have deterred me from asking basic questions. I do find that sometimes if I just wait, listen, and hear more context from either Bill or the other guys in class, I will figure it out.

Because it's a rotating curriculum, in a few months when he does bottom brackets again, I will come back to hear it a second time.

So I know I'll need a Crank Puller and a Lockring Spanner. Did not see him use a Pin Spanner, and I am not quite getting the use of a Pin Spanner.

He wouldn't have needed a pin spanner on a current model Dew.

You might need one though, for a 1986 Schwinn.

Hard to explain without being able to just point and show you, but there is the big lockring which is easy enough to spot. That lockring wraps around a bearing cone that screws in separately. On some bikes, you will want a pin spanner on that.

You know what? I have a Schwinn right here, in my office, on the stand. I'll see whether I can grab a quick photo...

Didn't want to remove the crank arm just for the photo op, but below is an image showing more or less where you would use the pin-spanner.

Loosen the lockring. Then you can tighten or loosen the cone using the pin spanner in order to get the correct tension on the bearings. Then tighten the lockring.

In the case of the bike I'm working on, there apparently is some other tool that might be a better fit. On some bikes you can just use a standard wrench. Depends upon the specific configuration.

Hope this helps. Hope I've not overlooked some crucial detail.

254456

The only correction is that the pin spanner is used on the "cup" portion of the adjustable side of the bottom bracket. The cone is a part of the bottom bracket spindle.

To the OP:
Basically the pin spanner is used to hold the adjustable cup in position as you use the lockring spanner to tighten/loosen the lockring. Often you can get away with loosening the lockring without a pin spanner but the adjustable cup has a tendency to "walk" when you tighten the lockring which can negate any adjustment efforts made.

If you have a cup and cone style bottom bracket and plan to keep and do maintenance then grab a pin spanner as they are cheap and effective. The other readily available option that should work with whatever cranks you have (invariably they are square taper interface) is to eventually replace the bottom bracket with a cartridge type...but then you will need a different tool, so it may be best to evaluate what you have and what you might want and purchase tools accordingly.

-j

OK, I think I'm tracking now. This helps a lot.

I see that Park has two sizes of Pin Spanner: Red (2.3 mm) and Green (2.9 mm). Is it simply a matter of pulling the cranks to see what size Pin Spanner I need?

most BB cups use the red one .

OK, I think I'm tracking now. This helps a lot.

I see that Park has two sizes of Pin Spanner: Red (2.3 mm) and Green (2.9 mm). Is it simply a matter of pulling the cranks to see what size Pin Spanner I need?
The Red spanner is intended for the outer rings on Shimano self-extracting crank and a few other uses while the Green spanner is mainly for adjustable cups. However, the Red spanner does indeed work on adjustable cups even if the pins are a somewhat loose fit in the pin holes.

First you need to loosen the lockring to have any hope of the pin spanner moving the cup.

If youve already repacked hubs- Think of the cup like a cone in a hub and the locking as a locknut. The cup does all the adjusting and the locking simply "locks" it all in place by wedging itself against the BB shell of the frame, keeping everything from moving. With that in mind, the first thing you should do is loosen up the locking, then adjust the cup and only the cup, then lock it in place with the locking. Any contact with the locking brackets the cup adjustment- its the first and last thing you do for this job.

As is often the case just go to the Park tool site (Google Park Tool adjust bottom bracket to get there quickly) to understand the procedure. If the person demonstrating is not explain procedures better than that he's a poor instructor. I designed and taught a 60 hour mechanic's course and even in a professional course I did not assume a certain knowledge level. Rather you cover everything, so that you fill in the inevitable holes that everyone has when learning on the fly. He should have at least explained the following in a consumer course:


Diagnosis - when to determine if your bottom bracket may need overhaul or replacement.
Disassembly - The routine procedure, how to avoid problems, when to get expert help, covering both traditional and cartridge. Differing pitch and right/left threading issues.
Inspection - What signs of wear to look for, what parts to bring in to get a compatible replacement
Reassembly - Checking fixed cup tightness, how to easily put in grease and ball bearings and insert spindle/adj cup (traditional), importance of proper tightness/torque.
Adjustment (traditional) - How to use right crank arm as lever/pendulum to check adjustment, how to make an initial adjustment using lockring and pin tool or cone wrench, and then alter it slightly.


There are plenty of mechanics who can do a procedure but who do not know how to explain it fully to a person who has never done it. That's the fallacy in the saying "Those who can do, those who can't teach." The rest of the story is "Those who can do it can't always teach it."

As for being "stupid" that would be NOT asking questions when you have them, and believe me I can guarantee there are "seasoned wrenchers" in a class like that who are silently saying to themselves "Wow, was I stupid to do it wrong all those years." If you want to be smart and a real mechanic then learn to understand "why" as well as "how," such as with my lockring/adjustment explanation below - even if it's not explained that way to you.

p.s. The Park procedure will work OK; the marked masking tape is a bit much but go ahead if you want. However, when you initially tighten the adjustable cup you need to go beyond just touching the bearings to avoid extra tries to get it right. The reason is what the lockring does when you tighten it. It pushes against the bottom bracket shell and pulls the cup outward. therefore the initial adjustment should be slightly tighter than just touching. When you readjust all you have to do is hold the cup in place with the pin spanner, loosen the lockring and then move the cup a very small amount in the direction required.

When you adjust the BB make sure that there is a little preload that feels like drag on the bearings. Without this preload the cups and cones will wear prematurely.

That is correct, another error in the Park procedure that I meant to mention. Neither Park nor Sheldon (gasp!) is always accurate/complete.