I have a 80's vintage Raleigh. Reynolds 531c, built in England, standard (not Raleigh special) threading. Reddish orange paint with black rear triangle and black fork.
It has a sloping fork crown that inserts into the fork tubes (rather than integral lugs that are on the outside of the tubes). Very graceful fork arrangement.
However, today I noticed on one fork tube, the paint was cracked in a perfect line across the inside of the top of the tube (where it meets the crown). Normally one cannot tell where the tube ends and the crown begins. It is definitely not fatigue of the tube... too straight and too high.
Should I be concerned that the braze joint, or the crown itself, is failing?
today i noticed a crack in my fork, along the brazing line, of my integral sloping-crown fork.
I think this can happen even if the fork is fine. the fork will flex and the brazing may not have covered the joint evenly all the way to the surface in that area. In that case, both surfaces of metal could move in different directions during flexion and disturb the paint.
in addition, something as small as different coefficients of expansion, over a period of years, could also disturb the paint.
I have a 80's vintage Raleigh. Reynolds 531c, built in England, standard (not Raleigh special) threading. Reddish orange paint with black rear triangle and black fork.
It has a sloping fork crown that inserts into the fork tubes (rather than integral lugs that are on the outside of the tubes). Very graceful fork arrangement.
However, today I noticed on one fork tube, the paint was cracked in a perfect line across the inside of the top of the tube (where it meets the crown). Normally one cannot tell where the tube ends and the crown begins. It is definitely not fatigue of the tube... too straight and too high.
Should I be concerned that the braze joint, or the crown itself, is failing?
David
yes. take it to a frame repairer for a check-up, just to be sure.
in addition, something as small as different coefficients of expansion, over a period of years, could also disturb the paint.
if it were coated in some esoteric kind of glass, that may theoreticaly be possible, but a paint, even enamel, is /way/ more flexible than the truly miniscule difference in expansion coefficient of these materials.
in addition, something as small as different coefficients of expansion, over a period of years, could also disturb the paint.
if it were coated in some esoteric kind of glass, that may theoreticaly be possible, but a paint, even enamel, is /way/ more flexible than the truly miniscule difference in expansion coefficient of these materials.
Sorry, paint cracking is pretty common. But I'd scrape the paint away and see if the joint is cracked anyway. A fork failure is pretty painful. Phil Bbrown
today i noticed a crack in my fork, along the brazing line, of my integral sloping-crown fork.
I should have said that you should have a local frame builder check the fork for cracks (or mail it off, only costs $8 each way to ship it - far cheaper than a hospital visit.)
In the past 3 days I found that some cracks in a seatstay cap, that had decided to make a 90 degree turn and start traveling through a frame tube, on another bike of mine. Even if the framebuilder ok's it, you may want to check it periodically to make sure it isn't growing.
I know this fork and crown setup. Very graceful! I would be concerned about a braze joint failing. It could have been a cold joint, easy to do in a factory setting, hard for an inspector to spot. But paint cracks like that are usually bad news.
I would send the fork off to a really good framebuilder, someone like Richard Sachs who builds his own forks. If it were I, I would have the fork repaired. The fashioon today is flat crown, retro-lookling forks. I like those streamlined, full-sloping crown forks!
yes. take it to a frame repairer for a check-up, just to be sure.
by the sound of it, it's a failing braze joint.
Or a cracked fork blade, as there is a severe stress riser at this point. Jobst's views on internally lugged fork crowns are well known.
Wasn't the crack described by OP at the top of the fork blade, and isn't that stress riser at the end of the internal crown a little bit further down the blade?
yes. take it to a frame repairer for a check-up, just to be sure.
by the sound of it, it's a failing braze joint.
Or a cracked fork blade, as there is a severe stress riser at this point. Jobst's views on internally lugged fork crowns are well known.
Wasn't the crack described by OP at the top of the fork blade, and isn't that stress riser at the end of the internal crown a little bit further down the blade?
Jasper
I talked with a local frame builder. She is figuring the crown may be broken within the tube. She recommends a replacemnent fork, which is OK by me and that is what I am going to do.
in addition, something as small as different coefficients of expansion, over a period of years, could also disturb the paint.
if it were coated in some esoteric kind of glass, that may theoreticaly be possible, but a paint, even enamel, is /way/ more flexible than the truly miniscule difference in expansion coefficient of these materials.
Sorry, paint cracking is pretty common. But I'd scrape the paint away and see if the joint is cracked anyway. A fork failure is pretty painful. Phil Bbrown
it may be common to poorly prepped frames where detritis remains in the weld area, but it's not to a good frame that's been done right. the commonest cause is cracking. that's why it's vital to investigate asap.
yes. take it to a frame repairer for a check-up, just to be sure.
by the sound of it, it's a failing braze joint.
Or a cracked fork blade, as there is a severe stress riser at this point. Jobst's views on internally lugged fork crowns are well known.
blades don't just crack unless they're over-heated on brazing. internally lugged crowns are not fundamentally inferior to externals. it simply depends on design and ability of the fabricator to prep sufficiently well to ensure weld integrity. i agree that you can't "see" whether the weld is good, but reality is, you can't see inside the weld on external ones either. not unless you want to do the aerospace testing thing, and that's /way/ expensive. all you can see externally is the weld meniscus. beyond that, it's down to the welder's experience. technically, you're taking your chances on both.
