Sunday, April 27, 2008

Mountain Bike to Road Bike Conversion

Since my '63 Huffy was stolen, I've been saving parts for a new bicycle. I wanted another road bike, but all I found was a used mountain bike. I hate mountain bikes! Still, it was in good shape, so I bought it. When a derelict road bike showed up at the dump, I combined them to make the bike I really wanted. The Frankenbike! Skinny wheels, drop handlebars, and a big ironic sticker on it that says "Mountain Bike".



It has a thick steel frame and extra low gears from the mountain bike. The cargo rack came from the junk bike; I need to paint it. Did I say I was making a road bike? Maybe I mean touring bike. This thing's a tank! But I like to ride slow and steady anyway.



My original intent was to just swap wheels, but the donor road bike was a real wreck - rusty frame, taco-ed wheels, and seized bearings had eaten the hubs. With the rims I wanted to use attached to bad hubs, and rims I didn't want attached to my good hubs, I hatched a plan I figured was either mad or brilliant. Knowing nothing about wheel lacing or truing, I decided I'd take all the spokes out of the wheels, and transplant the good mountain bike hubs into the road bike rims.



When I tried to lace the new hubs into the road rims, I found the road bike rims have a larger inside diameter. It wasn't much, but it was enough that the mountain bike spokes wouldn't reach. I needed to use at least some mountain bike spokes, because a few of the road bike spokes were broken. Usually when you lace wheels, you pick a lacing pattern and buy spokes the right length. I needed to find lacing patterns that used the random combination of lengths I already had!



I found a site which described the Crow's Foot pattern. This was perfect for what I needed, as I could use the shorter mountain bike spoke for the radial spokes, and the longer road bike spokes for the two crossing "toes". The pattern looks nice and it's very stiff. In this picture, you can see the distinctive 3-spoke crossings of the crow's foot.



That's a front fork but it's got a rear wheel hub stuck in it, sans gears. The mountain bike spokes were just too short, even for Crow's Foot. But a rear wheel hub has a larger diameter than a front wheel hub; it gets these shorter spokes closer to rim, just enough to make it work. Of course that caused problems all its own. A rear hub is wider than a front hub, which means the front fork isn't wide enough to go around the cone nuts. I didn't want to bend the forks out, so I had to bring the cone nuts in. Using the angle grinder and nerves of steel, I cut the cone nuts down to mere slivers, leaving only the sloped bearing race. I cut them so thin I could fit both them and the nuts that lock them within the forks. I also had to notch the axle bolt so it would slip into the smaller fork holes.



Despite the difficulties, using a rear hub for the front wheel is a great mod. Front wheel hubs are narrow and use smaller bearings on a smaller axle. Why? You'd think the front wheel is the one you'd least want to wobble, and it will take the brunt of any crash. Rear hubs, being wider, place the bearings further apart, so play in the bearings has less effect at the rim than with narrow hubs. It gives a steeper dish to the spokes, which also resists side to side forces better. And this hub has uncaged bearings, more of them, in a larger race. The difference is noticeable. There is zero wobble. None. It rides like it's on rails.



Funny story about the bearings. I tried the smaller axle from the old front hub to see if it would hold the large bearings in. It didn't, and the bearings went bouncing all over my shop. I recovered all but one of the bearings. When I finally found that last bearing, I noticed it had hole drilled through it. I'd never seen that before, and I couldn't figure out why someone would make a bearing with a hole in it! But it was clearly one of the right bearings - it was the same size as all the others, and the same shiny silver color. Maybe the hole was so it would retain grease? I shrugged and put it into the race with the others. Well the next day I found the missing bearing. I thought, if I'm holding the missing bearing in my hand, what the crap did I put into the bearing race yesterday? I removed the bearing with the hole in it and scratched it. Silver paint flaked off. What I had was one of those metalized plastic beads they use for craft necklaces! By chance it happened to be on the floor in the same place I dropped my bearings! I don't know what would have happened if I'd left it in, but the wheel turned fine with a plastic bearing.



For the rear wheel, I used Crow's Foot on one side, and made up my own pattern for the other. I came up with a daring plan to use an unbalanced lacing pattern. There are two forward-pulling spokes for every one backward-pulling spoke. The idea is that when you're pedalling, there are two spokes transmitting your torque to the ground for every one that's not. Does it lead to the wheel twisting under load? It's hard to be sure because the rim was already bent when I got it. But I've been riding it like this and haven't had a problem. I call it the "Dreamcatcher" lacing pattern; the spokes weave many times.



I didn't want to restring the shifter cables, so I kept the original shifters. Unfortunately they were designed for a straight bar. On the drop bars always the shift lever was blocked, or the cable interfered with the brakes or my hands. Putting them on the outside was the least bothersome place. I'm saving the two levers on the stem for clutch levers to engage the motors if I make the bike electric.



The handlebars had awful rubber grips that kept slipping off. I got rid of them and wrapped the handlebars with some good Cinelli cork tape. Not bad for my first try.



Well, that's my bicycle. There's nothing like riding a bike knowing every piece that makes up the whole is there because you chose it, not the factory.

Thursday, April 24, 2008

Ferron's Guaranteed No Mess No Mixups Method for Swapping Rims without Relacing

I'm restoring my fiancée's bicycle. The hub and spokes are ok, but the bottom of the rims once sat in a puddle until they rusted out. Luckily I had a spare pair of rims left over from my last bicycle project.



It's fairly easy to de-lace a wheel. But getting the lacing right when you put the new rims on looks really hard! All those criss-crossings and spokes going alternating ways... Who can keep track of it? And if you miss a spoke, you'll throw off the whole process. I found websites which provide wheel lacing patterns, but I've got a much easier way than lacing from scratch.



The basic idea is that you only transfer one lace at a time. You copy the pattern from the old wheel step by step, and you'll never miss a spoke.


Start by holding the two wheels side-by-side between your knees. Make sure the right side spoke holes in one wheel are next to the right side holes in the other, and the left are by the left. As seen in this picture, the valve holes might not line up although the left-right spoke holes do.



With a flat head bit, completely unscrew a left side nipple.



Move the spoke over to the other rim and screw it in loosely.



Spokes which cross underneath are blocked by the ones on top. Always transfer the spoke that crosses on top first, then transfer the one that crossed under it.



As you go around transfering each left side spoke, loosen but do not remove each right side nipple.



Save any extra nipples you can get off other wheels, because you will most likely round off a few nipples during the transfer, and you'll need to replace them.



When you've transferred all the left side spokes, you will end up with this. If you welded these rims together, you could make a monster "dualie" mountain bike!



Now work around the wheel and transfer the remaining right side spokes one by one. Except this time, transfer the one that crosses under first, so it will reach, then do the one that crossed over.



Ta-da! Now the old rim is free, and the spokes are all in the new rim. Yet you never undid more than one spoke at a time. Magic!



Don't try to ride it yet! You still need to true the wheel. I'll explain in another post the technique I came up with to true my wheels without special equipment.

cheaphack.net

Just wanted to extend a little link-love out to Nick Johnson's cheaphack.net. When I first started reading his blog, I expected it to really take off, so I've been surprised by how few comments I've seen around there. If you enjoy reading about electronics projects, building things on the cheap, and the occasional post about bicycles, then you'll really enjoy cheaphack.net. Check it out, and leave a message if you like it! That's how we know whether or not anyone reads the stuff we write.

Bicycle Shop

In March I finally cleaned out my basement so I'd have a place where I can work on my bicycles. I have an alcove that's just right for parking one or two bikes by the door so I can easily wheel them outside.



I even have a cool sign!
(Disclaimer: I do not run a real bicycle shop!)



Since clearing this shop space I've already completed 1 1/2 bicycle projects! I'll post about them soon.

Let's Do The Time Warp Again

This morning it was 7 o'clock three times in a row! Wow!



Clearly I must be caught in a Time Loop! So I did what any sensible person should do when they're caught in a time loop; I went back to sleep!



Later I discovered this switch on the top of my clock. It was on "alarm set".



D'Oh!