Bob Jackson restoration

[Pat Dwyer]

Of course you're quite right. A case of temporary brain-fade on my part. From what I see of the American scene, most of their builders use vertical dropouts, no doubt as a safety feature. Track ends will permit of adjustment, but I don't know if it's possible to use a derailleur with them. I shouldn't imagine so. Does anyone know if you can get horizontal road dropouts (opening forwards) which don't have those screws? If you can't get cast or forged ones without the screws, I'd be sorely tempted to specify pressed steel ones, even for a frame of this class.

Know what was the most difficult job in stripping down the bike? Removing the old handlebar tape. It's like the sort of job you'd expect to do in prison on hard labour. I'm finally making inroads into the old adhesive with lighter fluid. The bars are beautiful Cinelli ones, although probably somewhat newer than the bike. Aesthetics are a funny thing where bikes are concerned. For me, the brake cables should describe gentle, graceful and equal curves above the front of the bike. This had the cables taped to the bars, which don't actually have those grooves for them. I'd only ever fit cloth bar tape. It's all I've ever used, but it's becoming hard to get hold of. I have a couple of rolls I got from SJS Cycles, whom I highly recommend. Their mail order service is excellent, and they have some real bargains.

[531colin]

two whole pages of ends/dropouts here.......http://www.framebuilding.com/

Good ol' Surly....track ends with a gear tab.....

[Pat Dwyer]

Thanks for that. A bewildering assortment of frame ends. I suppose the answer is to trust your builder or repairer to recommend components he knows to be reliable.

[Brucey]

as I hinted at earlier the idea that the holes in your dropouts made them weaker than pressed steel ones arises from a false syllogism. When a mech goes into the back wheel any dropout will have bend and many will break.

Good quality forged dropouts (with or without holes) are normally much stronger than pressed steel ones; pressed steel rear ones of the sort you want cannot be made in such a way as the material is not at some time or other stressed across the rolling direction, in which direction the material is considerably weaker.

You should also not compare cast dropouts with forged ones, not unless they are investment cast and heat treated correctly.

You can get rear facing dropouts with a gear hanger but it is a PITA to get the wheel in and out. If you use very thick pressed steel rear facing dropouts then they are arguably a little stronger than many others. But then they should be, you have just added 1/4lb to your frame, as if you had gone from an SL tubeset to a standard one...

If one of your local framebuilders is a metallurgist, he should be able to explain all this to you.

BTW if you are concerned about stuffing the rear mech into the wheel, try buying a mech that has a better shape near the top pulley, such that it won't so easily snag in the spokes. A fair number of otherwise good rear mechs are woefully poorly designed in this regard.

cheers

[Pat Dwyer]

In this case, the offending rear mech was a Campagnolo Gran Sport, which seems to have survived the incident quite well. I don't know if I mentioned it earlier, but I had a similar accident some years ago while riding a Sun Mist with pressed steel dropouts. The rear mech overshifted, and cut cleanly through several spokes. Thankfully, I wasn't far from home, as the wheel was considerably out of true. I had the wheel repaired, and fitted a small and discreet spoke protector made from aluminium. Sadly, these now seem to be made of plastic. In any event, there was no damage to the rear dropout, nor did it ever occur to me that there might have been. When I encountered the Bob Jackson, I was astonished to see what had happened. I suppose it's a good thing that the dropout fractured cleanly, possibly saving damage to the chainstay. I'm adamant in my belief that a dropout, regardless of material, must be weakened by drilling a hole right through the back of it - already surely the weakest part - and equally adamant that the new dropouts, whatever sort they are, won't be thus weakened, when I see no advantage to the adjustment screws. There seems to be quite a choice available, and I'm disappointed that Bob Jackson only seems to use two - the type I don't want and the type which doesn't provide chain adjustment when riding singlespeed or fixed - although I commend them for their prompt reply and advice regarding the age of the bike. I believe that framebuilders, like any tradesmen, although they may have strong preferences of their own, should be prepared to accommodate their customers' preferences, as long as it's understood that the customer takes responsibility. He, after all, is paying the bill. So, reviewing the previous post, is it correct that the best dropouts to have are forged ones?

[Brucey]

possibly the dropout that broke was a cast one, not a forged one? What make was it?

BTW if a Campag GS mech (one with an aluminium parallelogram) has survived an encounter with a rear wheel without being bent then it is a minor miracle. Perhaps the dropout you had was weak; I've seen lots of mangled GS mechs.

Note that it also makes a difference if you have a nutted exle rather than a QR one; perhaps this is part of the discrepancy in what you have seen?

BTW GS mechs are a case in point re hooking into the spokes too easily; when I can be bothered I remake the inner cage plate on mechs like that, so that there is a curved piece near the top pulley which won't snag the spokes in the same way.

cheers

[Pat Dwyer]

The wheels which came with the bike are very nice Mavic MA40 ones, and they are nutted rather than QR, which slightly surprised me. Don't know what make the dropout was, but contemporary catalogues from Bob Jackson seem to mention Campag dropouts on most of the models. I'm not especially concerned that I might ever overshift again. Once bitten, twice shy. When that happened, I didn't fully understand the function of the derailleur stop screws. Might even fit the dreaded spoke protector, if I can find one that doesn't resemble the Starship Enterprise, like I had on my old Dawes Galaxy. I just feel that the stronger the rear dropouts are, the better. Nor does the quest for ultimate lightness really concern me. The saddle fitted to the BJ was extremely light, but also extremely cheap, nasty and flashy, so I binned it. Just a plastic shell with some material trying to look like leather stretched over it. I'm going to be using my own saddle, a Wrights leather one of incalculable age, but in nice condition. This is not especially light, but it's my saddle.

[boblo]

I'd talk to Jackson's again if that's who you want to use and tell them what sort of dropouts you want. If they won't budge, go elsewhere.

[Pat Dwyer]

Maybe I will. However, such is their reputation, and so great would seem to be the demand for their work, possibly a small job such as mine might not be high on their list of priorities. Geography is rather against them as well. Although my experience of Skelmersdale suggests that I'll probably get lost looking for Steve Goff's premises, and spend what remains of my life driving hopelessly round link roads and roundabouts like a latter-day fliegende Holländer, the risk might be worth it.

Although, as I stated above, I'm not overly concerned about ultimate lightness, I acknowledge that weight, or lack thereof, is very much an indicator of the quality of a bicycle. To assess how good this machine is, and how much it's worth my spending on it, any clues to its quality will be valuable. It's certainly very light compared to anything I've handled before. I just weighed myself with and without the frameset and subtracted one figure from the other, on a good set of electronic scales. The frame, forks, headset, bottom bracket and single Campag friction downtube lever would seem to weigh exactly 7 pounds. How light is that compared to other steel bicycles? Looking at Bob Jackson catalogues from the period when this was made, I notice that all his machines were double-butted 531 throughout, but some are described as extra light 531. I didn't know that there were different weights of 531. It's hard to say exactly which model this might be, given the fact that it's had a respray and new components, but it would be nice to think it might have been one of the better ones.

[mig]

steve goff can be no harder to find than he was years ago. in '97 he was in a farmhouse/barn affair literally down a track between fields of crops. the place was marked by an old bicycle wheel propped against the gatepost. great place though!

[Brucey]

in round numbers the BB, headset and shift lever will weigh around 1lb, so your frame and fork weigh ~6lbs, perhaps a touch over. This is par for the course for a 531DB frame around this time. If the fork is around 1.5lbs this is 'normal' too. This kind of frame was popular amongst clubmen for many years; light enough to race on but sturdy enough to tour on too, provided the total load carried wasn't excessive.

Some frames would be fitted with slightly thicker seat stays if the frame was more touring-oriented, and some builders would routinely select different tube gauges for different riders/sizes without making a big fuss about it.

IME 'standard' 531DB tube gauges work very well in frames from around 21.5" to 23" , for riders of normal weight. Heavier riders and/or larger frames mean that things get somewhat flexy and smaller frames / lighter riders end up a bit stiff.

Since the fork may be of different provenance, it is worth inspecting it. The style of the fork blades and the rake give a clue to the tubes used but the clincher is the steerer. If a 531DB fork then the steerer will be cold drawn (no seam internally) internally butted in a specific fashion, and will be marked (stamped with shallow stamping in a small font, circumferentially) 'REYNOLDS BUTTED TUBE', typically 1-3" above the fork crown.

The fork blades will also be stamped similarly near the top of each blade; however in this case the stamping is even more shallow (presumably in view of the thinner tube at this point) and is very difficult to see. In either case it is preferable to remove the paint in order to be able to see it and in the case of the fork blades it is pretty well essential; I think I have only once been able to see these marks through some (very thin) paint on the fork blades. Refinishing and/or shot blasting can be plenty enough to near-erase these marks, so if you don't see them it doesn't prove it isn't 531 but if you do see them it of course does prove it is.

cheers

[Pat Dwyer]

Thanks for that very informative post. It will be a great help in unravelling the bike's provenance.
Today, I removed the forks. I had one large spanner which was just a bit too big for the Campag headset. Here's a tip. I don't know if it's bad practice, but it worked for me. I found the combination of feeler gauge blades which just made up the difference when I inserted them between the spanner and the headset nut. The forks, when I originally removed the front wheel, went around in a series of click stops. The headset was very dirty, but I cleaned it up and greased it, and it seems fine. However, I'm not a great fan of clipped ball bearings, so I may replace them with loose ones. When I had the forks out, I noticed something stamped on the steerer tube, so I'll have another look when I take it apart again. I'll probably strip the paint off the forks to see if there's anything stamped there. However, as it's had a respray already, the shotblasting process may have removed any marks. There was a number stamped on the steerer tube. I was hoping it would be the same as the serial number under the bottom bracket, but it wasn't. It was a 3-digit number, 231, I think. So I don't know for certain if the forks are the originals, but they look just like the ones fitted to Bob Jacksons in the 1970 and 1972 catalogues (mine was built in 1971, but there's no catalogue for that year on threespeedhub.com). I do think the fork ends look a bit basic. The catalogues mention Campagnolo fork ends, but I'm not sure what they look like. I'd expect them to have machined faces, though. Next step is to acquire a BB tool, and it's off to Skelmersdale.

[tooley92]

I wouldn't worry about the spanner, Steve will remove the headset & bottom bracket for you ( doubt he will even charge you) tell him that Mark from Brighouse sent you

[julianm]

Here`s a bit of a tip for you - Steve Goff`s unit is next to Chris Hayter Transport
- http://www.chrishayter.co.uk/depots/wigan-logistics
gives a handy map. I got there from York & actually got home again! I did stop in Chorley just to get some Chorley cakes though ...

[tooley92]

That's a good point Julian, it's one of those places that if you don't know where it is you will never find it! First time I went I had to call Steve to talk me in!