Strategies for dealing with a Raleigh fork

[rogerzilla]

The Bob Griffin turns out to have a sodding Raleigh threaded fork (26TPI - I have counted).  Options seem to be:

1. Get a 26TPI Raleigh headset and use the top half of it, with something better sealed on the bottom*
2. Force a 24TPI alloy headset on.
3. Get a new fork (but this one is sprayed to match the frame!)
4. Get a new steerer (more expensive than a new fork)

2 is cheapest as I already have a Tange Falcon.  1 will cost about £20 for a NOS headset.  3 is difficult as the fork has very long blades (made for 27" wheels) and a relatively long steerer at 178mm.  4  is prohibitively expensive and it's only a a hi-ten fork.

What does the panel recommend?

*I may have shot myself in the foot here by having the crown race seat turned down to ISO...Sheldon says 26.4 is right but it seems, from a bit of research, that Raleighs actually had 27.0 crown races, so a full Raleigh headset won't fit anyway.

[hubner]

If the forks is not original and it's hi-ten, I would say don't use it.

If the rest of the bike is worth it, you could get a new custom built forks, sprayed to match the rest of the frame or have it chromed.

Cost would be high compared with the other choices!

[rogerzilla]

It is original; Bob didn't make his own forks.  Just didn't expect him to have fitted a Raleigh fork in the early 80s; he must have got a job lot of them cheap.

A new fork would be £250 from Argos, and therefore not worth it.

[Chris N]

http://www.columbustubi.com/eng/4_2_7.htm

[Wobbly John]

If it was me, I'd join a new top section of steerer in - cut low down and internally sleeved (the steerer sounds long enough to do it without interferring with the stem) before gas welding...

...but then I've got access to a workshop where I can do that.

I had to do it with some carbon suspension forks I bought for the MTB and the steerer was a couple of cm too short.

[LittleWheelsandBig]

WJ's option is a standard solution for my framebuilder friend but it works with either welding or brazing.

[Brucey]

if you run a 24tpi die down the steerer you will end up with a patch of bad thread every 1/2" or so. It'll got from top to bottom, good-bad-good-bad. The height of the first bad bit will vary a little with how long the die is that you are using and how well it fits, but it is usually about 1/4" down from the top.

  Because the height of the threaded portion of the adjusting race varies from one headset to another (by about 1/4" or so) you can, if you have a selection of headsets, choose a headset that uses good bits of thread only and avoids the bad bits. 

If you have access to first-class welding (eg TIG as done by an expert welder), you can butt-join a 24tpi threaded section to the steerer. Once the welds are dressed the result can be sound. You can install the stem so that it reaches well below the weld, thus if there is the slightest worry about weld failure, it won't result in a nasty accident.

 In point of fact the weld would have to be absolute rubbish to weaken the steerer any more than threading it does; the remaining wall thickness in a 1/16" wall steerer, once a 24tpi thread is cut on it, is only about 0.8mm from the thread root to the ID, and the thread root form makes a nice notch....

cheers

[rogerzilla]

I'm going to do the mix and match headset solution, which is the soundest engineering option short of a new fork.  The top half of a Raleigh headset never wears out anyway.  If stack height is an issue - and I have 40mm to play with, so fairly generous - I'll have to get an uphanger or stem hanger for the centre-pull brake.

[Brucey]

if you try and fit an uphanger with a CP brake, you may find that the mounting bolt is nowhere near long enough, and in addition many uphangers are not tall enough.

I'd expect you to be able to fit a standard hanger, 40mm is plenty of stack height, isn't it?

cheers

[rogerzilla]

It should be: only needle bearing or cartridge headsets usually exceed 38mm.  I need about 3mm for the hanger.

[mzjo]

If you want I still have the fork of my defunct Carlton complete with Raleigh headset  yours for free. I will check the lengths. You will have to find a way of picking it up from Kidlington at the end of the month, it can go with the girls

[rogerzilla]

Thanks - I think I've got this sorted but won't know for sure until NOS pristine Raleigh headset arrives fron the USA (!).  However, if your headset is rust free (most eBay ones look ratty by now) and I can get it quicker, it will mean I can turn this pile of parts into the fashionista singlespeed it should be.

[rogerzilla]

Is there any reason NOT to use a cartridge bottom end with the Raleigh top end?  I know cartridges are usually fitted in an opposing arrangement, with the smaller diameter 45 degree tapered surfaces on the crown race and adjustable race, to give self-aligning qualities*.  I suppose the worst that can happen is that it doesn't last long.  A cartridge bottom end is much better sealed than a normal ball race.

Frame and fork have both been faced by Argos so should be spot on.

*for crappy facing or steerer flex when riding

[Brucey]

if the preload requirements are very different between the top race and the bottom race, you might run into trouble.

IIRC the Raleigh headsets used a deep groove design with a nominally zero degree contact angle.  It has been my impression that, when subjected to lateral loading, such headsets may generate a very large axial reaction loads, that the other race might not like.

cheers