Bike shop or engineers?

allen-uk

New Member
Location
London.
I've got a frame which for reasons of butchery needs a new seat-post tube (the top of the existing one is missing, or largely missing).

What needs doing (I think) is a steel tube needs interference-fitting down the existing tube, leaving about 3/4" exposed, which would then need a couple of slots cutting into it, and that would be the NEW seat-post tube, obviously with an undersized clamp.

Questions:

Does this sound like a sensible way of restoring the frame to good use?

Is it a job for a good local bike shop, or do I need an engineering works?

If the engineering works, then the biggest problem in NW London is that there aren't any, any more. Used to be several, but over the years they've gone the way of all. Anyone know of any such places in this area?


Thanks.


Allen.
 

HJ

Cycling in Scotland
Location
Auld Reekie
Read 15 Ways To Unstick a Seatpost by Sheldon Brown... ;)
 

Clive Atton

Über Member
Is it only the piece of the seat tube that is above the junction with the seat stays/cross bar that is knackered?, if so I would go to your local dump and find a bike with the correct diameter seat tube, ask if you can hacksaw off the bit you need or failing that sell you the bike for a fiver. Look up welding services in yellow pages and give them the bike and replacement tube. The more preparation you can do the better as that is what takes the time and obviously adds to the cost, so if you can saw the old damaged part of the seat tube off and prep the new piece so it is just a matter of welding it on that will save you money. Once welded often there may be some penetration of weld into the inside of the tube, a tool like a Dremel (or equivalent - about 30 quid from Toolstation) is the easiest to use to clean it up but a decent half-round file will do the job.

Yep it takes a bit of time but this should reclaim your frame perfectly well.
 
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allen-uk

New Member
Location
London.
Thanks Clive, but I think the previous answer might have misled you.


Just to clarify: it is my seat post TUBE (i.e. the bit of FRAME into which the seat post goes), that is damaged. The seat post itself is fine, pristine, untouched.

Someone unwisely took a hacksaw to the frame in order to lower the seatpost 3/4", so it is the FRAME that has been butchered, not the seat post.

So, the question stands: is the idea sound, and then is it bike shop or engineering works, plus ideas for the latter in NW London.


Ta.

Allen.
 

Clive Atton

Über Member
Hi Allen, it was the seat post tube I was talking about (it's so much less confusing having a conversation rather than typing posts!). Providing you can saw off the damaged seat post tube just above the seat-stays and the top tube (or cross bar as it was called when I were a lad!) junction, the welding on of a new piece of seat tube post, complete with seat post clamp etc would be a doddle for any competent welder.
 

Hilldodger

Über Member
Location
sunny Leicester
Mmm..........to be honest, unless it's a very rare/valuable frame it just isn't worth the trouble. We've done this kind of repair before here at Cyclemagic but to get a decent finish takes a LOT of work. And you might do even more damage to the bike by heating the lugs up enough to baize the new piece in.
 
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allen-uk

New Member
Location
London.
Thanks again Clive, Hilldodger.

Yes it IS an expensive frame, so a hundred or more quid would be in order. I have got a very old-fashioned bike shop locally, so I will go and kick it around with him.


Allen.
 
I know Mercian in Derby can replace a seat tube, they quote prices for doing this - I can't remember what the price is though, might be worth looking on their website.
 

Grasen

New Member
Location
CF24
why waist time doing what you suggest.

if the frame ( a picture would be nice) is ok at the junction of the top tube, seat tube and seat stays then file it nice and flat and give it a touch of paint.

then use it like the old french or italian bikes do.

the french ( for ex LOOK or PEUGEOT ) just inserted a skrew in from behind to fasten the post

the italians (for ex MOSER ) used a quill type post to fasten it in the frame.
just make sure that it sticks 8 - 10 cm down the seat tube
 
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