Dawes Galaxy top tube diameter

[wmydlarz]

Hello all

I have a Galaxy mid 90's ish with a dent in the top tube.

I'm planning on making a block to have a go at rolling the thing out, but can't quite work out the tube diameter used for the top tube to cut the block to.

With a caliper it measures 29.1 ish and the seat tube measures 28. 8 ish (both with paint) . I'd assume both tubes are 1 1/8" 28.6mm, but not sure if a 29 could have been used (if it exists).

Can anyone with frame building tube standard knowledge confirm what the diameter is most likely to be? I'd rather make one block right firtmst time rather than cut a few until I get it right.

Thanks in advance.
Cheers
Bill

[531colin]

Its inch and eighth.

[lighttourer]

Another way to do this, which worked well for me when taking a dent out of the top tube of my one of Roberts bikes, was to use a 28.6mm front mech clamp (the ones that you use with bolt-on front mechs, which sell for £10-15). The wider the band, the better. I found that by working it around the dent, gently tightening it each time, it did a really good job of taking out the dent (which was about 1/2 inch across)

Yes, in certain lights you can still notice some slight deformation in the tubing, but most of the time you wouldn't know it was ever dented. I put some thin paper (till receipts are good for this) between clamp and frame to protect the paintwork, which worked brilliantly.

Obviously, if you can easily machine it yourself from a block of aluminium, then that might be a better solution for you. But that wasn't an easy option for me, and I was rather proud with myself for having found a solution using a thing I already had. No more unsightly dent!

[rogerzilla]

Paint is rather thick on modern bikes, as it's usually lacquered powdercoat. That would account for your measured diameters.

[wmydlarz]

Thanks all for the responses.

Finally got round to giving this a go and it was a success.

I turned a 1 1/8 hole through a 2" bar of acetal, cut it in half, clamped it in the vice, rolled it around a bit and hey presto it's (as good as) gone! Surprised how well it worked.

The acetal being a nice bearing material hardly marked the paint too. Pretty chuffed with that. No more unsightly dent.

Cheers.

[Jdsk]

Thanks for adding the outcome. I might have a go at this.

Jonathan

[Brucey]

if you roll a piece of paper into a tube, it can be 'dented' and 'undented' much like a metal tube. There are various ways of dealing with a dented tube; one of the simplest is to gently squeeze it eg. using a vice. If a length of brake pipe is connected to the top tube (eg. via epoxy resin inside the seat lug) the top tube can be pressurised internally, pushing dents back out. Wooden plugs can prevent inadvertent deformation of the seat tube or the head tube. It is very much safer if the tube is pressurised using a liquid, not a gas, because there is likely to be much less stored energy.