Thursday, April 2, 2009

What sound does a Moose make?

Thursday was Bullmoose bar day.

Kevin's rainbow Ibis mountain bike has been sporting a mix of original parts and modern updates, most notably the Mary bar mounted on the front. Kevin wanted to go with a more period looking piece for his modern hand position, so we decided to work up a modern Bullmoose bar for his steed. Unlike the original bars of old, this bar would have some diverse design elements to over come. With the Mary bar, Kevin had to use a 150mm stem to get the 40 degree grips into a comfortable position. To create a single bar to duplicate this spec, it is going to take a significant extension and long backswept grips, a visual that is quite different from the original bars that were popular in the early 80's.

Kevin had hoped for a sweeping bar with smooth curves. I pulled out every trick in my book to try to create these radical bends with the thin wall tube; full dies and mandrel, cerro-bend, sand, even ice...no dice. The wall would either crimp or split open every time I tried to achieve the 40 degree angle. After destroying a pile of tubing trying to stretch the material into the correct bend angle, we had to switch to the backup plan; mitered grips.

Here's the original set up we are striving to duplicate;
I am building the bar to use an aluminum stub expander in the steerer tube for his threaded headset. The steerer piece will have pinch bolts to fit an 1.125 steerer should Kevin ever decide to use it on a modern threadless set up.
So let's get going...cutting in the center section miters...
With the pattern drawn out on the table, mocking up the fit to insure accuracy...

All the pieces together for a pre-fab party...

The main bar section welded up...

Laying it over the original Mary bar to insure the angles are exact to the original...

I normally like to build everything in a fixture, but as this is a special one-off project, I'm trading off the time and expense of making a fixture for the time of double checking square and levelness during the process. Here we are with a steerer tube that has been squared to the alignment table and fixed in the vice. As I tack the main pieces together, I'm using the level to insure all is straight and happy...

The main bar welded up and ready for pinch bolts and a special cable hanger...an Ibis handjob from an old keychain, pretty trick!
Once completed, the bar will get a blue/purple pearl paint job, should look pretty funky.
I had hoped to get out of the shop early to sneak in a ride at Mohican Forest, but alas, this bar kicked my butt and took more time than I had hoped it would, so the ride at Moho was sacrificed. 70 degrees today, supposed to be 20 and snow Sunday and Monday... yuck!
Tomorrow I'll finish stripping the last of the 10 frames, blast them all, and paint up the Bullmoose bar and Jeff's Ti bar.
See y'all later,
rody

2 comments:

martn said...

wow, that's a nice bullmoose. and i don't think it would look better with bent tubes, the mittered grips are perfect!

Anonymous said...

Would it have been much easier if he had started with an "off the self" Luv bar?
I know it would not have been just the right sweep, but pretty close....