Sunday, December 5, 2010

Harvesting tubes

Oh what fun Mr. Copus is having! What joy he takes in the irony of chopping up a perfectly fine RB-1 frameset (in my size) for my daughter's bike.


It's a 1989 Bridgestone RB-1. With that weirdo Ishiwata EX tubing. In a nutshell, the butted profile is 10/7/8 for the top tube and the down tube.

Here's the money shot. That is Glen smiling btw. You've got to get to know him to recognize this look: it's glee.

The good news is that the steel is nice and clean. So by using this tubing, Maddie's frame will be reasonably light. By kid bike standards it will be feather-weight.

Imagine Glen's pure delight to find such a shoddily coped tube under this lug. You could drive a Mack truck through that gap.

Glen chopped out the seat lug cluster, the bottom bracket, and the headtube. We found little gems like this gap in each section. I'll save those details for a future post.

space

7 comments:

alex wetmore said...

Just as a FYI: A friend chopped up an MB-1 and the miters were even worse!

Alistair said...

Yep, my observations agree with Alex's. I've cut up a few factory made bikes with some pretty crude mitering. They had all held together up until that point though, amazingly, to me anyway.

Nate said...

At least Bridgestone was honest about its fabrication standards. If you knew the code:

RB=Rotten Brazing.
MB=Mitered Badly.
XO=Kiss Off.

In those days, a consumer could make an informed choice.

rory said...

random comment for the day:
I hope maddie's bike is the first kids bike to use braze-on centerpulls

John Speare said...

Rory: love the idea. But we don't have a set of brakes/braze-ons on hand. Glen has canti posts aplenty though.

Nate: you cracked the code!

Alistair/Alex: one of the tubes wasn't even touching the joining tube at all, it was just held in place by the lug. I never understood the idea of pinning, then lugging until I saw this poor miter and Glen explained the concept.
I understand why it was economically feasable to mass-produce zillions of lugged bikes for years. Lugs provide a pretty wide margin of error, mm'ery speaking.

rory said...

the difference from canti post and the manufacturer's centerpull post appears to be length of post, where the centerpull post are shorter then a canti's post. everything else looks to be the same. if it were mitered so the tabs pointed up for the spring(rather then to the side), i think you would be fine. I've been wanting to try this for a while, but don't have the frame sitting around for testing.

rory said...

and i have some centerpulls i'd donate for this experiment...