Gripshift Cable Installation

I like grip shift. It's so simple. I mean seriously, the shifters have 3 parts. Changing a cable on them is a bit tricky sometimes, however. I think some people just replace the whole shifter instead of changing a cable. You don't need to do that, it's really not that difficult. First you separate the two halves:

If they don't come apart easily, twist to the first or last gear position and they should slide apart. Just don't lose that little metal spring. Now you can slide a new cable through. I've seen 2 different styles for the cable path:

The shifter on the right feeds the cable through the stationary piece, then around the inside of the twisting piece, then back through the bottom of the stationary piece.

The left side shifter has the cable hidden by a rubber cover on the twisting piece. These are the simplest and easiest types to work on, and I'll show you how to do these. Peel back the cover a little bit, then feed the cable straight through:

Now feed the cable through the stationary piece (I unscrewed the barrel adjuster to make this a little easier):

The last step is to slide the two halves back together:

Make sure the cable stays in its groove as you twist the two halves together, and check that it works properly. Seriously, these things are that simple. Cheers.

Cheap Derailleur Spring Tension Mod

In this older post, I showed you how to change the cage tension on Shimano derailleurs with aluminum knuckles. Those are easy. The ones with plastic knuckles are more difficult since there's no direct way to do this. This is still possible, however. Here I have an Acera derailleur that could use a little more tension:

On the side there is a small plastic cover that needs to come off. I like to drill 2 small holes one either side first:

Then I use 2 small screwdrivers on either side to pry it out (be careful, don't let the screwdrivers slip). This is a little easier if you have the derailleur locked in a vise, but anyway here is the result:

With that plastic cover out, you'll see a small metal retaining clip holding the knuckle together. Rotate the clip until the ends are facing you like this:

Now push the clip inwards with 2 small screwdrivers. When you push it far enough, the cage will simply pop out:

Now comes the fun part. You need to drill another hole for the end of the spring to fit into:

Centerpunch the location for the new spring position, then start drilling:

The drill bit size I used was a #52 (.063"). You can also use a slightly larger size, since the spring was a tight fit. It's important to keep the drill straight. I also used some oil on the drill bit to keep it cool. I didn't apply any extra pressure on the drill since the bit is so small and fragile, I just let the weight of the drill do all the work. Here's the final result:

Now clean away the metal shavings and grease the center post. Fit the spring into the new hole you just drilled:

Now slide the derailleur back together, making sure the other end of the spring is secure inside the hole on the other side. You have to twist the cage back a little until the tab is resting behind the stop on the knuckle, then push the assembly together. Finally, reinsert the E-clip:

The E-clip goes back in more easily than it comes out, just shove it back into its grove with a small screwdriver. The last step is to reinsert that plastic plug:

Now enjoy that extra chain tension.

Building a Bike

Sometimes a normal off the shelf bike won't do it for you. You can always build a bike exactly how you want from a bare frame. This is a good idea if you have access to lots of cheap parts, or have lots of spare parts that you want to use. If you want to buy everything brand new, however, then things will get pretty expensive pretty quickly. Anyway, if you're trying to cobble a bike together out of used parts or build your dream bike there are a few little details you need to know:

Frame size and type - Obviously you should get a frame that fits you perfectly. The type of frame will also make a big difference in how the bike rides. Road bike frames make fast, agile bikes. They also make terrible off road bikes because the bottom brackets are low to the ground, and you will strike your chainrings on every little tree branch in your way. Generally, build a frame that suits your intended purpose rather than trying to adapt everything.

Wheel size - You'll need wheels to match your frame, so pick a set that is at least close to the original size. 27" and 700c wheels are almost always interchangeable. If your frame was built for 700c wheels you might not be able to stuff a larger 27" set in the frame, but the opposite works since 700c is about 8mm smaller in diameter. You cannot, however, make a drastic change like putting mountain bike wheels on a road frame. Even if they physically fit the frame, you will never get the brakes to reach the rim.

Crankset and Bottom Bracket - These parts go hand in hand with each other. If you're using old cranksets with square tapered bottom brackets, you need to know the bottom bracket shell width (check the frame first, it could be 68mm or 73), spindle length (determined by the crankset), and whether the shell is English, French, or Italian threaded. Modern high end frames use press fit bottom brackets, and many are a proprietary size so keep track of this.

Drive train - How many gears do you want? 1? 3? 27? Your back wheel will play a big part. If it is threaded for a freewheel, you can have up to 7 gears in the back. If you have the right cassette hub then you can have even more speeds. Old cassette hubs have shorter freehub bodies, so you might still be limited to 7 gears with those. If you want a fixed gear bike, then you need a rear wheel with a track hub. These have 2 sets of threading for a track cog and a reverse threaded lockring. I have also made fixed gear bikes with a normal freewheel hub by securing the track cog with a bottom bracket lockring and some threadlocker (same threading), but I would only do this if you have a brake. Otherwise if this arrangement loosens up you're screwed.

If you're using multiple gears, then you also need to choose your shifters and derailleurs. If you want indexed shifting, there are a few little details about which ones are compatible with what. Friction shifters are compatible with any derailleur and gear cluster, but indexed ones are picky. You need to match the number of sprockets in the back to the number of speeds in the shifter. You also need derailleurs that are compatible with the shifters.

Brakes - Generally you should use the type of brakes that the frame was built to use, but there are some exceptions. If you have cantilever studs then you can pick either V-brakes or cantilevers (just make sure you get the right brake levers to match). On mountain bikes with disc brakes you can sometimes change disc size with an adapter bracket. For road bikes you can choose between sidepull, centerpull, and dual pivot brakes (single pivot sidepulls are weaker than the other two types, but centerpulls need cable hanger brackets and dual pivots don't fit old frames without modification).

I guess the best thing I can tell you is to do your research. There aren't a whole lot of parts you need to buy to build up a bike frame from scratch, but there are a lot of little details that can set you back (like rear dropout spacing, cable routing, seatpost and handlebar stem sizes, etc.). Good luck, and most especially have fun!

Purple Trek 800 Tune Up

So I brought this bike home, and it could use bit of work:

It's a Trek Mountain Track 800 (looks like a Trek "80" with the U-lock holder installed). The tires and cables look good, and I dig the 90's purple color. It has a loose front wheel bearing though, so it's fixing time:

That escalated quickly. This bike has a cartridge bottom bracket, so no need to remove the cranks:

 
I took the bike apart to redo the rest of the bearings since 20 year old bike grease is going to be pretty dried up. The frame will also be easier to clean and polish out the scratches too.


When I took the front hub apart, one of the bearing cups was loose inside the hub shell. I guess the bike was always ridden with a loose front wheel. I cleaned out the shell and the cup as best as I could, then epoxied it back in place (edit: that repair is still holding up years later. It certainly beats relacing the wheel to a new hub).



When I did the rear hub bearings, I also took the cassette body off to put some oil in it. I thought this was kinda cool:

That long hollow bolt holds the cassette body in place on the smooth end, and threaded end screws into the opposite side of the hub.



When I reinstalled the brakes, the rear cable had a lot of friction in it. This is the first place I looked:

 

That housing piece is a bit too long, so I took the inner cable out again and shortened the housing to fit better:

That actually made a big difference. The rest of the bike went back together pretty easily. I did a more detailed writeup of a very similar bike here, in case you're actually looking for useful repair advice. This bike is kind of cool since it has a cassette hub (not bad for a base model), cartridge bottom bracket, and an E-type front derailleur. It also has a sticker on the frame that says "CroMoly" in big letters, and "Seat Tube" underneath in really small letters (why even bother, I mean how strong does a seat tube need to be anyway?). Oh well, it handles nice, and everything works so no complaints about this one.