Unconventional Coaster Brake

I decided to take the coaster brake apart on an old Austrian made Free Spirit. This hub is a bit different from other coaster hubs I've seen, and quite honestly I still don't know exactly how it works (this one is labeled "Styria" on the reaction arm). Anyway, here are the pictures that I took. First I unbolted the reaction arm:

After removing the wheel from the bike, I had to remove the gear from the hub. It's held in place by a snap ring, twist it off with a screwdriver:

Keep track of which order the pieces come apart. With the cog removed I unscrewed the bearing cone by hand, and removed these pieces:

This hub had 5 roller bearings arranged inside a large retaining piece. After unscrewing the lockring that holds the reaction arm to the other side of the hub, I was able to extract these remaining pieces:

The braking mechanism resides inside this splined barrel, which is connected to the reaction arm:

Here is the nearly empty hub shell:

And here is how the inside pieces fit together:

I'm still not sure how everything works, since this isn't like a traditional screw type coaster brake. Regardless, I cleaned the parts up and started reassembling them with lots of grease. First I installed the pieces from the reaction arm side:

Next I replaced the roller bearings:

Then the ball bearings and the axle:

Now I slid the drive mechanism back into place:

And secured it with the bearing cone:

Now the cog can be reinstalled. I lined up the spacers in the order which they came off, then slid the cog into its 3 grooves and locked it in place with the snap ring:

Finally I reinstalled the reaction arm:

Done.

Suicide Brake Levers

Those extension levers that you see on almost every old 10 speed road bike seem to have a bad reputation. I always thought it was because they don't provide as much braking force as the lower brake levers, or maybe it's just because other people think they look stupid. I didn't realize that they might actually be dangerous until I saw this:

That red piece is broken off halfway where the mounting bolt attaches the brake lever to the handlebar. It appears that using the extension piece puts a bending stress on the red cylinder since it attaches to only one side of it. The lower brake lever instead attaches to either end of the cylinder, and in theory it shouldn't put any stress at all on the vulnerable middle part with the hole going though it. Here's the lever put together showing the missing pieces for the extension lever:

In other words, don't rely on the extension pieces in an emergency stop, you're much better off using the lower parts of these brake levers.

Cassette Disassembly

Cassette cogs can be replaced individually if they wear out. Most cassettes are held together with three rivet pins, however. These need to be removed in order to free up the individual cogs. Here's how I do it:

After removing the cassette from the rear wheel, I centerpunch the rivet heads (so that the drill doesn't wander around). Next I drill each rivet until most of the rivet head has been removed. Next I take my drift punch and hammer the rivets out part way:

You can use something like a long nail if you don't have a punch. Anyway, once these pins are broken loose you can pull them out from the back side with pliers:

All done:

Don't lose the cogs or spacers if you plan to reuse them. The pins are not essential and shouldn't be reinstalled (the cassette lockring will hold everything in place). Also if you're replacing individual cogs, try to get replacements from the same cassette group (Shimano cassettes have their group designation stamped on each cog, like ac, e, w, etc.). If you use mismatched hyperglide cogs, the shifting might be noticeably worse on those cogs. This method doesn't apply to high end cassettes like Ultegra or Dura-Ace though, since the cogs are mounted to aluminum carriers and aren't individually replaceable.

Freehub Body Removal

Cassette hubs usually have a removable freehub body. There are a few instances when you might need to remove or replace one, so I'll show you how. First remove the axle and ball bearings (described here). Next you'll need either a long arm allen key or a hex socket bit (10mm for Shimano hubs):

Stick the tool into the freehub and unscrew it counterclockwise. These can be on there pretty tight, so don't be surprised. Once it's broken loose, remove the hollow bolt and the freehub body together:

Here is the bare hub shell, showing the splines that transfer your pedaling force to the wheel:

And here are all the pieces that you removed from the wheel:

The hub goes back together the same way you took it apart. This is a good time to clean the bearings and reassemble them with fresh grease. You might want to replace your freehub body if you try to pedal forward and your pedals just spin without turning the wheel. You would also want to replace it if you upgrade an old 7 speed bike to 8, 9, or 10 speed, since newer cassettes don't entirely fit on shorter 7 speed freehub bodies.

Polishing Metal Parts

Bare aluminum brakes, seatposts, handlebars, stems, cranks, etc. tend to look a but dull over the years. You can make them look close to new again with some polish. Here's an old aluminum brake that I took apart a long time ago:

It looks a bit dull so I thought I'd use it to show how I polish metal parts. First I rub a thin layer of polishing cream onto the surface:

Then I use a small towel to rub the polish into the surface. I stop when I see a black film appear:

 

The last step is to buff the part with a clean, soft towel:

All done:

The difference is more noticeable in real life, but you get the idea.

Rear Derailleur Spring Tension

I've encountered a few used derailleurs that don't seem to put enough tension on the chain. When this happens, the chain can flop around and fall off the gears more easily. This can even cause "chain suck", which is when the chain doesn't release from the bottom of the front chainrings when you shift the front derailleur. My best guess is that the spring inside the pulley knuckle looses a bit of its "springiness" over the years. There's a relatively quick way to fix this, however. If you see two small holes next to the guide pulley, then you can move the spring over to the next hole to increase the spring tension. This is very easy on derailleurs with aluminum knuckles. First unscrew the small bolt that holds the cage together with a 2mm Allen wrench, shown here:

Next remove the bolt and the cage can be pulled from the knuckle. Then the spring can be gently unwound:

Notice the two holes on the bottom of the derailleur? Move the end of the spring into the adjacent hole to add more tension to the chain:

With the spring in its new position, wind the cage back until the tab on the knuckle is behind the stop on the pulley cage:

Now push the cage back into the knuckle:

And reinstall the set screw:

That's it. On higher quality derailleurs this is a very simple procedure. For cheaper ones with plastic knuckles, you will have to pry out a metal clip and drill another small hole to get the same result. I might show that procedure in a later post. Finally, if your derailleur is especially worn and dirty, you might want to check out this post about doing a full overhaul on it.

Wheel Building

In an older post I wrote about how I typically build wheels. I thought it was a bit hard to follow, so I'm going to include some pictures this time. First make sure your rim is straight, and that you have the correct length spokes (I like to use a spreadsheet called spocalc to find which length I need). Now you can start lacing the spokes to the rim:

The picture shows the first group of spokes laced to the rim. Basically you just thread a spoke through a hole in the hub flange, and then secure it to the rim with a spoke nipple. You want to skip every other hole on the hub, and skip every 3 holes on the rim (not counting the valve hole for the inner tube). Also make sure the spokes are exiting the hub on the same side, and that you lace them to the holes on the rim that are closer to the side you're working on. Once you have the first group of spokes finished you can start with the second:

The spokes from the second group be laced in the opposite direction from the spokes in the first group. Just how many spokes they cross will determine the crossing number (this wheel is a 4 cross pattern). The crossing number is actually determined by the length of your spokes, so longer spokes will have higher crossing numbers (generally a 32 spoke wheel should be 3 cross, and a 36 spoke wheel can be 3 or 4 cross, so measure your spokes with this in mind).

The spokes in the second group should also twist over the last crossing spoke from the first group as shown above. Now you can lace the remaining spokes in the second group, leaving every other hole empty at the rim:

 

Then you can start the third group. I like to start with the spoke nearest the valve hole to make sure that it's positioned correctly between 2 parallel spokes:

The rest of the third group is laced like the first group, and you should now leave every third hole empty at the rim in addition to leaving every other hole open at the hub flange:

The last group of spokes is laced like the second group. Just remember to twist around the last crossing spoke from the third group. Here is the wheel after lacing all the spokes:

Now is a good time to screw the spoke nipples the same amount on each spoke. I turn them until the threads on the spoke are just barely hidden. This allows me to tension the spokes more evenly later on. I start tensioning each spoke by one full turn each with a spoke wrench:

 

After every round of tensioning I check to see if the rim still spins true (or mostly true, since I'll fine tune it later). I can check this by putting the wheel on a bike frame and watching it wobble between the brake pads. I also have an old fork that I like to stick in a vice for doing front wheels.

To true a wobbly wheel, you need to loosen the spokes on one side of the wheel while tightening spokes on the other side:

This should bring the rim back to center. Don't get carried away, half turn increments are plenty.

Once the wheel is mostly true and the spokes have good tension, you need to stress relieve the spokes. Basically just grab pairs of spokes in your hands and squeeze as hard as you can:

If you're using new spokes, they will probably lose some tension so you'll have to tighten them up again. Basically you need to keep tightening and truing the wheel in small increments until the spokes are nice and tight, and the wheel spins true. This takes some practice (and patience), so don't be surprised if your first few wheels come out wobbly. To verify if your spokes are tight enough, you can pluck the spokes from a good wheel and compare how they sound to the ones on your wheel. Their pitch should be similar (spokes emit a higher pitch as they get tighter).

Quick Release Skewer Disassembled

So I have an old broken quick release skewer lying around and I always wanted to know how these things worked.

This one is held together with a nut so it can be taken apart:

Here are the internal parts. There's an off-center cylinder attached to the handle which turns inside that big hole in the skewer. This moves the skewer back and forth as you flip the lever. Here's a better look at the cam mechanism:

Cool.