Quill stem to A-head set adapter stuck

[Brucey]

I would repair that, and when I was done, the frame could be both lighter and stronger than it ever was before.

[Blackredgold1964]

Thx, intriguing and if you happen to have any links how to do that then please post here.
I'm offline though till middle of next week now.

[Brucey]

it is not difficult to do this repair. First cut out the centre section of the tube, leaving ~3.5" long 'stubs' of the original frame at each end. Clean the remaining parts of the top tube ('stubs').You will need two sizes of Al tube; one that is the same OD as the top tube (this is to become your new top tube) and another which fits inside that, to make two ~7" 'joiners' from. ~1/16" wall thickness will be pretty standard for both tubes. Probably the old top tube was only open going into the seat tube; Drill a ~10mm diameter hole at both ends of the top tube. SG the insides of the 'joiners' eg. using a powerfile so as to make the joiners so they are~0.5mm at the ends but still ~1.6mm wall thickness in the centre. Mitre one end of each joiner so that they fit nicely against the adjacent tubes. Wrap the mitred halves of each joiner with several layers of PTFE tape. Next, coat both the inside of the 'stubs' and the PTFE coated half of each 'joiner' in epoxy resin. Wrap both joiners in woven glass fibre/more epoxy resin until the OD of the joiners is a good fit inside the 'stubs'. Carefully insert the joiners into the stubs and leave them to cure. (If the fibreglass extends, without epoxy, beyond the mitres, this is unlikely to be a big problem, but you can trim it back if you like.)

Next, remove the joiners, removing every trace of PTFE tape in the process. Insert a 'prop' into the unmitred end of each joiner. The 'props' can be made from lengths of matchstick or w.h.y. and each 'prop' should be fitted with a tether and a shaped handle, so that each joiner can be pulled (using the handle and tether) in one direction, mitred end first..The shaped handle can be made from old spoke and can include several bends thus holding it central in the joiner. However, the handle needs to pass through 10mm hole, and be retrieved remotely, so it is probably best if the end of the handle includes a small loop.

Next, prepare the joiners for bonding, by roughening the outside (eg. via grit blasting) cleaning and degreasing prior to coating with a thin layer of epoxy resin. Also similarly coat the insides of the stubs, and (having suitably prepared it) the inside of the new top tube, for at least 7" at each end. Install the joiners, props and all, within the TT, so that the props are back-to-back inside.

Offer up the new TT; with it in position, use a wire hook tool through the 10mm holes to extract the handles, and pull the joiners ~85mm into position, being sure that the mitres are fitted correctly. It probably won't have escaped your notice that there is about twice as much epoxy resin as is really required, about half of which is outside of the joints. This surplus is mainly to be found in three locations; at each end, and in the middle. This is best dealt with whilst it is still fluid, which requires good access. To remove the props, use a wire 'pusher' through the 10mm holes, to push one end of each prop out of position. Having done this, it should be easy to remove the props and the tethers. The surplus epoxy resin at the ends can be removed via the 10mm holes. The surplus epoxy in the centre can be removed using a wire tool via the 10mm holes. If you coat the insides of the joiner with vaseline prior to bonding, it will act as a 'stopoff', preventing bonding. However, you are playing with fire here, since any vaseline that is dislodged by the handles/tethers can corrupt the epoxy within the stubs, so extreme caution is advised. It is probably better to use masking tape instead.

The net result is a frame that is stronger than before, and is somewhere between PG and DB in weight. The use of thinner walled Al tube allows even lighter weights to be attained. The Al to steel transition is best protected on the outside eg. using sticky tape. Internally the frame may appear to be impervious to corrosion, but it isn't. If any liquid water gets inside the frame, it may quickly degrade the bond strength

[Blackredgold1964]

Thank you brucey. I can’t say I understood the process very well and believe this is above my paygrade. One detail though, you mentioned the 10mm holes in the ‘stumps’. Would the existing holes for the cable routing do? Or would they even prevent the whole process as they’re somewhat in the way?

I’ll start dismantling my bike soon which allows me time to ponder all options. I wonder if welding would be easier? https://youtu.be/7ThWtZJkvHU?feature=shared

[rjb]

I see you managed to remove the stem adapter. Tell us more.

[Blackredgold1964]

Ah, of course, in all the excitement of bike tinkering on different bikes I forgot that original problem.

Twisting improved marginally and I kept spraying with release spray. I lost the wedge of the adapter into the depth of the steering tube. As I want to check if the wedge was 'wedged' or would move I turned the bike upside down and surprisingly the adapter fell / slid out. No idea how it happened so easily as the photo shows it had corroded. I've been very lucky here as previously the same problem happened and a bike shop had to laboriously remove it by sawing it to pieces

Then I kept spraying into the tube and the wedge loosened and I could extract that with the help of the long adapter bolt too.

[Brucey]

... the 10mm holes in the ‘stumps’. Would the existing holes for the cable routing do? Or would they even prevent the whole process .....

The cable routing through the top tube is very probably responsible for it rotting out. In my scheme, what are presently the cable entry and exit points would be part of the 'stumps', but any associated protrusions inside the tube would be ground off and the cable run made external.

This would be a fairly easy repair via welding; a new steel tube could be let in to replace most of the top tube eg. using the 'burst' strategy.

Although I am a fan of welding, I think that the bonded solution.will be easier, faster, cheaper, and better. It also has the attraction of not requiring the frame to be refinished; the paint can stay on the 'stumps' and the Al can simply be polished.

[Blackredgold1964]

a new steel tube could be let in to replace most of the top tube eg. using the 'burst' strategy.

sorry, this is all new to me. Is 'burst' the same as 'explosion', as described here, https://www.twi-global.com/technical-kn ... ss%20steel. ?

And would replacing the tube be better than just welding the crack as in the video that I posted above?

[Brucey]

.....And would replacing the tube be better than just welding the crack as in the video that I posted above?

yes, because the crack is almost certainly just the tip of a very nasty iceberg. I very strongly suspect that your top tube is rather badly corroded inside. I have seen a break like yours before, just at the start of the thin-walled part of a DB tube. It may seem a bit brutal to cut the tube out like that, but this replaces all of the tube that is probably corroded, and places the repair welds in the thickest part of a DB tube, which is both easiest to weld and least stressed. If you search my posts for 'burst strategy' you should find a good write-up.

ps. if you inspect the inside of the tube using an endoscope or small camera, you can check for any corrosion before you do anything. You can drill a larger hole between the seat tube and the top tube, for better access, if required.

[cycle tramp]

a new steel tube could be let in to replace most of the top tube eg. using the 'burst' strategy.

sorry, this is all new to me. Is 'burst' the same as 'explosion', as described here, https://www.twi-global.com/technical-kn ... ss%20steel. ?

And would replacing the tube be better than just welding the crack as in the video that I posted above?

We are probably look at a situation where the crack is a symptom of a larger issue... I suspect was has happened is that rain has got into the top tube through the internal cable holes, and there is a line of rust at the bottom of the tube, throughout its entire length... where the tube has cracked was at the point where the tube was most rusted/thinner. Without poking the lower part of the top tube with a screwdriver (wear strong gloves if you're going to do this) you can't really be sure if there's gonna be enough metal either side of the crack for a strong weld - you might just start blowing holes through either side of the crack

(Sorry post crossed with Brucey's)

[cycle tramp]

I'm not really sure who though it was a good idea to run internal cabling with the holes upwards in a steel frame, in Britain.... but I hope he didn't get paid very much

[Brucey]

it is almost good enough to used as part of a working definition of 'optimist' as one who believes it is going to stay dry in there.

[Blackredgold1964]

Brucey, read the 'burst strategy' in 'a tad out of true?', so I got a vague idea of the technique now. And like you and cycle tramp fear, the tube might be too weak overall for a repair just in one spot.

[Blackredgold1964]

I'm not really sure who though it was a good idea to run internal cabling with the holes upwards in a steel frame, in Britain.... but I hope he didn't get paid very much

I guess it was a fashion then, in 1991, in Germany where I bought it.
The frame is Koga Miyata, Dutch/Japanese, I guess countries where it also rains quite a bit.
that's the bike before a respray around 10 years ago.

[cycle tramp]

I'm not really sure who though it was a good idea to run internal cabling with the holes upwards in a steel frame, in Britain.... but I hope he didn't get paid very much

I guess it was a fashion then, in 1991, in Germany where I bought it.
The frame is Koga Miyata, Dutch/Japanese, I guess countries where it also rains quite a bit.
that's the bike before a respray around 10 years ago.

Good Lord..... 1991, that's...um... 33 years ago! If its any consolation, that's not a bad life span for a frame with holes in its top tube (or perhaps any frame). I'm guessing, the original manufacturer had only envisaged a life expectancy of some 10 or 15 years for the whole bike...

..I've got the exact same problem with my new alloy stem - its 45 degrees and the face plate has been designed in such a way that there are gaps between the handlebars and the stem... if it rains hard, water gets into these gaps, is funnelled down the stem and then held against the steel steering tube.. a less than ideal situation.. last time I found quarter of an egg cup of water there..
.which means I've got to come up with some sort of bung to stop it happening again...