Tuesday, February 4, 2014

Home-made Bicycle Work Stand

I'm my own bike mechanic.  Shocking.  Yes, and for years (decades?!) I've been mostly either just leaning the bike against something, or flipping it upside down on the handlebars and seat to work on it.  I've looked at the commercial clamps a few times, but they're just a little too much for me to justify.  I looked at DIY work stands on the web, and saw some ok ones, but mostly they looked kind of kludgy and like more hassle than they are worth.

Well, I bought a new bike last weekend to replace one that was stolen a few months ago.  First order of business is a set of fenders and a rack, but I also took a look at the work stand they were using in the store.  The mechanic was nice enough to let me take a photo of the clamp head, even.  It looked like such a simple, straightforward design...

Efficient Velo Tools bike workstand clamp

So my new bike sat in a corner in the basement all day on Sunday while I put this together.  It works great, and it only cost me about $10.  It's two pieces of oak scrap I had, about 7/8" thick, 1-3/4" x 12".  I clamped a ~1/2" scrap of cedar between them and used a 1-1/8" forstner bit in the drill press to bore a hole down the middle.  That made the two halves of the clamping saddle.  I glued some thin leather to the inside of the clamping part with silicone, to improve the grip and prevent marring on the bike.

A thin piece of cedar between the oak arms makes it easy to form a perfect pair of curved jaws with a Forstner bit
Then I screwed a block to the back of the clamp, to provide a fulcrum point, and tied a small piece of elastic bungee cord into a loop to hold the back together.  The clamping mechanism is just a 3/8" x 4-1/2" carriage bolt installed through the clamp halves 4-1/2" from the saddle end.  I reamed out the hole through one side by rocking the drill back and forth, to provide clearance for the bolt when the clamp halves pivot apart.  I used a 1/2" flat washer to spread the load at the head of the carriage bolt, and a 5/8" dia. spring in between the two clamp halves to move it open when I loosen the nut.  On the outside, I used a long 3/8" coupling nut to tighten the clamp, and got fancy with a turned handwheel made of poplar.  I cut a drilled hole into a hex shape in the handwheel hub with a chisel, and then epoxied it onto the coupling nut.  Having the long nut stick out of the handwheel is really handy, because you can pinch it and spin the assembly quickly into position when there's little force on the clamp, and then use the large diameter of the handwheel to torque it down.  Go easy, don't clamp any aluminum frame parts or anything carbon.  Aluminum seat tubes are cheap to replace, and pretty beefy anyway.
The seatpost is the safest place to clamp
To mount this clamp head, I drilled a couple of small holes and attached one arm to a 12" piece of 3/4" iron pipe with two 1/4" carriage bolts, lock washers, and nuts.  I made a couple of oak saddles for the pipe, by drilling a 1" hole in the middle of a small block of wood, and then cutting that in half.

The pipe is mounted into a 2x4, and fixed with a C-clamp for now.  I drilled a 1-1/8" hole near the top of the 2x4, and then cut a slit about 12" down the center of the board, splitting the hole in half.  The C-clamp at the top squeezes the two halves of the board together and tightens the pipe in the hole.  It's a solid connection, but it allows me to rotate the clamp head to any angle by loosening the clamp.  The 2x4 is also the weakest part of the whole assembly.  With a bike mounted in the clamp, the 2x4 will twist under pressure and allow the bike to wiggle - which is fine, for the most part.  If things are too solid, you could bend the bike, so I'd rather have the weakest section in the stand somewhere.  That said, I do want to improve the support post and clamp to make it easier to use.  Plus I need my C-clamp for other things.  Update:  I used a 3/8" x 5" carriage bolt, some washers, and another coupling nut through a 7/16" hole through the top of the 2x4 to replace the C-clamp.  It's basically the same mechanism that tightens the seatpost clamp.  It works great.  Much more powerful than the C-clamp, because of the finer pitch threads.
Pipe clamp is essentially the same as the seatpost clamp mechanism
In use, I clamp the 2x4 post into the big vise in my work bench, so I don't need a separate stand, but it would be pretty trivial to make one out of either steel pipe (especially if you don't care about the rotation clamp) or wood.  Now, time to install some crap on my bike.
Bike clamp in use