Forked Up

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Looks like a nice Reynolds 531 fork, doesn’t it?  Not!  While recently test riding one of my projects, I noted a lot of lateral flex in the front end of this 1976 Raleigh Gran Sport:

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I immediately thought that the giant bars, which are already flexible in and of themselves, were exerting forces over the front wheel, and combined with the long reach stem, gave the bike a very strange wobbly feel – somewhat akin to the handling characteristics of a mixte frame.  Certainly, this was not caused by the frame geometry itself, I was sure.

So, I installed some regular, narrower bars, but the same strange flex continued to occur.  Then, I rebuilt the headset, thinking that it was out of adjustment, and I adjusted the front hub again, even though it was also just fine.  Still, the flexible feeling continued.  Then, I disassembled the fork yet again (grrrr…) and examined it carefully.  Usually, you think of impact damage when looking at a fork.   But the blades and steerer tube were perfect.  There were no cracks or bends, and the paint and chrome showed no signs of any kind of damage.  I squeezed the fork legs together at the dropouts and found that they flexed quite a bit.  Fortunately, I had lots of other steel forks around to compare this fork to.  While all steel forks will flex when squeezed, this one REALLY flexed quite a bit more – several millimeters more by the naked eye.  I didn’t think the variation was caused by different tubing material, because I compared this fork to not only another Reynolds fork, but also to an ALAN fork, which is known to have a lot of flex.

I had previously checked the brazing at the fork crown, but now thought that I had better get my pick out and go over the brazing carefully.  Sure enough, on one fork leg, what I had thought was brazing, covered in a bit of road grime, turned out to be just…road grime.

fork braze

Brazing material is missing, tiny pinholes visible.

I prodded the area, got out my tiny flashlight and could see that this fork leg, while not on the verge of imminent failure, was not properly brazed into the fork crown.  It looks like the lug and/or fork leg were over-filed and too loose when inserted, and there was too large a gap to fill with brazing material.  Or, possibly the gap was too tight when brazed, and the leg loosened up over time, revealing the complete lack of any silver in the gap.  Below is a comparison of the two legs, the first one showing the normal looking braze.

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Brazing okay on this leg.

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Gaps in brazing on this leg.

I am thankful that I discovered this now, and thankful for my rigorous test riding standards.  And, fortunately, steel does a good job of warning the rider of a potential failure.  It’s another reminder of how important it is to not blow off any odd or unusual feel that your bike gives you.  Be careful out there!