London Fixed-gear and Single-speed SJS Cycles

INTRO:

This is a quick guide to using an angle grinder to remove braze ons and unwanted bits off bike frames and forks. This can include cable guides, light mounts, dérailleur hangers, pump clips, or just about anything. You can also use it to slim down the size of your drop outs or even cut them off totally if you know someone who can add tack ends to your frame...

OK, I find it easiest to take some old bicycle frame or forks to try it on before you commit to your favorite bike. Find an old Universal MTB frame thats been dumped somewhere for a test run. This way there will be no tears at bed time. If you have done this sort of thing before then you may not need to worry...


KIT REQUIRED:

1. Angle grinder with thin metal cutting disk and thick grinding disk
2. A medium course metal file
3. 120 grade wet and dry sandpaper (emery cloth is really good too)
4. A vice (I don't use one, but it is highly recommended if you like having fingers)

also, these are not essential, but i would recommend:

4. Safety kit i.e. a boiler suit, gloves, goggles etc.
5. A power drill with a stone grind head and a sandpaper flap wheel
6. Some old spray paint to check your work
7. Some body filler (you shouldn't need this, but hey accidents happen. Also bear in mind that this will pop out if you have the said item powder coated.)


SAFETY FIRST:

Most importantly always remember your safety and the safety of those around you. Safety equipment is always a must, especially goggles and gloves when grinding. I have spent 6 hours in A&E waiting to have metal shards drawn out of my eye due to simple, and avoidable mistakes. Make sure that you are in an area away from flammables, and i only mentioned a boiler suit because I could imagine someone going and doing it in a windbreaker style jacket. Plastic melts and catches fire easily. I only mentioned a boiler suit as an example. An old pair of jeans and a hoody will be quite substantial enough. A nylon tracksuit will not!


STEP 1:

Remove all components from frame and forks. Separate everything. I am going to demonstrate by removing the light mount from a set of rigid Claude Butler tourer bike forks. Set up your area and clamp your item up in a vice. I do not have a vice and do it by holding the forks. This is really stupid and risky. Get you angle grinder with a thin profiled metal cutting disk. Use it to cut the bulk off the are leaving a couple of millimeters sticking out.


STEP 2:

Then remove your cutting disk from the grinder and replace it with a grinding wheel. Get up close and gently nibble away at the left over bits. Remember to take your time as you may end up with some deep cuts and will have to fill the area to create a clean finish (this is fully avoidable).


STEP 3:

File the area down. This will leave a rough finish. You can then use a mixture of flap wheels on drills, and sand paper for tubing for clean the area up on tubing, leaving a smooth finish. Or if you are removing say a dérailleur hanger then a drill and grind wheel set up will be fine to round the area off.


STEP 4:

Clean up your work then maybe spray some paint ove the bare area. Allow to dry for an hour and go back and have a look. This will indicate if you are going to need to do any more work, or if you have gone a bit over kill and have to do some bodywork repairs with filler.


OK, so that is all cleaned up and ready to go. Next step painting, or better yet powder coating.

that's a good guide, and I'm not knocking it, but for general 501/531/4130 a propane torch could also be used for melting the filler out

If you don't have this equipment it is possible to remove cable guides using a drill (with a fat bit to drill through and break the bond / reduce bonded area) a chisel (to use as a wedge and whack off the guides once main bond has been broken) and a file (to smooth over after). Did mine OK but would use a blowtorch next time I think.

I think propane would not be hot enough. Frame brazing is done with oxy-acetylene which gets much hotter than propane.

You can get blow-lamp canister things with acetylene in them though, you can just about get them to melt thin metal & brazing rods but it takes a while.

Angle grinder is the way to go. Propane will not get the area hot enough to melt out the filler. In addition, you'd be pouring heat into a structure that has been carefully triangulated and in many cases, stress-relieved. Without some pretty elaborate jigging, it's all to easy to warp a frame well out of true. And you'd have a hell of a time using one to remove a derailleur hanger boss, as they're usually cast integral to the dropout, or welded on (not brazed or soldered).

I tought myself this little trick by removing AD-990 brake bosses off my bmx frames over the years. I have got it down to a fine art now. Glad you all liked the thread. First time I saw this method was watching my mate pat do it. He is a welder, makes his own bmx frames and has Mig and Tig welders in his garage and always swore by an angle grinder.