Saturday, March 21, 2009

Bike Projects, this and that.

A few projects I have worked on in the last couple months:
After quite a few other methods tried, by far the easiest and fastest way to take a old steerer tube out of a fork crown. Use bimetal hole saws.  Started with a 7/8 " ended with a 1".  Took only a few minutes. Now it is ready for a new steerer tube. 

There is a story of welders needed up high on a water tower.  The job was advertised as no certification required, and a long line of people formed to get the job.  However, it thinned considerably when it was learned you first had to weld the seat on which you would be sitting on, 50 ft or so in the air.   This is similar,  don't do it unless you fully trust your welds.   

I used an arc weld, 1/16 7014 rod.  Stick weld?  Yes.  It's what I am good at and its very fast as well.  And very reliable. (see )    The setup was perfect.  No gaps in between the tubes, and a slight chamfer.  I also did a test weld, and cut it apart, There was actually an inside bead as well as of course an outside bead.   I used a Lincoln invertec welder (which is also a tig welder).  Fairly new welder for me, and it is sweet.  It stick welds better than any welder I have used.  It also took some care to keep the the tubes concentric during the welding.  

Changed up my junker bike a little.  It is an old 27" (wheel) schwinn that i use 700c wheels on.  I made a new fork for it last year to accept big tires, like cross tires.  I wanted a little more clearance on the rear brake, so i cut the brake bridge and brazed it on a little higher.  Took maybe a half a day, a tad longer than i wanted, but it came out well.  The brass and flux that Henry James sells sure is great stuff.  Amazed again at how nice it flows. 

Last week I also built up a set of wheels.   Just a normal set 32 spoked.   When running with 32, 28 and even maybe a front 24 and a mid or deep v, you really don't need to do anything special to the rim to nipple interface.    The rear rim is an offset design, which, if I am going to do a 1 to 1 ratio of Drive Side to Non-Drive side spokes and and 8/9/10 speed cassette, is all I will use anymore.  It allows a little better tension ratio and thus a better wheel.  The front (not shown) was a 28 hole deep v design.  I paid maybe $25 a rim, $5-10 each for the shimano hubs, and maybe 10 cents a spoke.   So maybe $75 dollars and a half hour a wheel to build.  I suspect these will still be running fine 10 years from now, unless the sidewall wear from brakes.   In the background is a wood box with drawers I made to hold spokes.  I have quite a few spokes that i have purchased dirt cheap off ebay over the years.

 Here is a Rolf Rim modified from an 18 spoked rim to a 27 spoked wheel.  I used 221"two-to-one" spoking pattern.  I actually built it last year, but had to rebuild cause i screwed up the fit of the nondrive side flange unto the hub and start squeeking!  I was able to move it further outboard this time around, and now all 27 spokes have the same tension (a function of flange distance from wheel center) .  

The nipples are actually inverted and inside the rims.  I used some small washers as well (2.2 mm ID) in between the nipple and rim.  Not quite ideal, because the nipples had to be chamfered, rounded somewhat and the washers curved taco style.  So two lines of contact in between the nipple and washer. And it took some time. The rim will probably definitely not ever fail, given the washer spreading out the load.  The nipples, are quite a bit stronger as well, being up side down and being on top a washer that has a 2 mm hole (instead of typical 4 mm).   And finally, the rim should be more aerodynamic, with hidden nipples.  Truing and tightening was almost easy as with a normal spoke wrench using a square driver.   

2014 comments.  Whoa too much monkey business...  Now carbon forks for me :)  (Well as long as you can get the rake/trail correct).     That poor bike was stolen.  I think I still have that wheel though ?