Reynolds Tubing reamed out

[Tanktopman]

Hi Folks,

Have been rolling on a vintage Dawes Galaxy (exact year unknown but probably 1970s). The original seat post is very short and measures 25.3 on a vornier. Am told this size is no longer made and have two options; use 25.2 and make a shim or have the tubing reamed out to 25.4.

Anyone have experience of this ? Don't want to ruin the frame.

 

[snomaes]

Hi Folks,

Have been rolling on a vintage Dawes Galaxy (exact year unknown but probably 1970s). The original seat post is very short and measures 25.3 on a vornier. Am told this size is no longer made and have two options; use 25.2 and make a shim or have the tubing reamed out to 25.4.

Anyone have experience of this ? Don't want to ruin the frame.

Hi,

Have you physically tried a 25.2 into the 25.3 tube? A 0.10 mm clearance is negligible and should clamp without resorting to a 0.05 shim (when wrapped around the tube, this will give 0.10mm).

If you have acees to a 1" (25.4mm) reamer, it would be simple to open up to the correct size and should not thin the tube to a dangerous condition, although it's difficult to tell without seeing the frame.

Another alternative is to check out Ebay, as there are often listings for old non-standard parts.

 

[Tanktopman]

Thanks - shall try 25.2 today.

 

[Tanktopman]

OK - 25.2 is too loose so next question, how do I make/buy a 0.1mm shim that will do the job ?

 

[TheDoctor]

Personally, I'd make a shim from thin aluminium. A cut-up drink can should do perfectly.

 

[Globalti]

Yep... aluminium is soft and sticky and a drinks can is easily cut to shape. It also comes ready curled and I may be wrong but I think the wall thickness is about 0.1mm.

If you have ever read Zen and The Art of Motorcycle Maintenance you will know that using a drinks can for a shim is described in the book as the romantic approach to engineering, which is likely to horrify a classical engineer.

 

[gwhite]

Yep... aluminium is soft and sticky and a drinks can is easily cut to shape. It also comes ready curled and I may be wrong but I think the wall thickness is about 0.1mm.

If you have ever read Zen and The Art of Motorcycle Maintenance you will know that using a drinks can for a shim is described in the book as the romantic approach to engineering, which is likely to horrify a classical engineer.

As I remember it, the writer advocated the above as being the ideal material for shimming and the person that was horrified was the owner of the BMW motorbike who knew absolutely nothing about engineering. Great material for a shim though.

 

[biggs682]

good old fashioned but safe bodge cut section coke tin and wrap around stem or even part round stem and hey presto

 

[henshaw11]

Have you measured the ID of the seat tube itself ? - there may even be enough tolerance to get a 25.4 in there anyway.
I've used a coke can shim on a unicycle in the past, worked fine once it was in but was a bit fiddly to get the lot assembled together.

 

[bobg]

I've skimmed a bit off oversize seatposts in a lathe, seems to work fine. at least I've not been impaled ( yet)