What Year 531c frame?

[biggs682]

' Exage FH-HG50 ' Is as far as i am aware the shimano model name and number , so doubtfull to have date stamp on them .

 

[RecordAceFromNew]

I have pulled out the seat post and cleaned off the muck and the only number I can find reads 25.4, seems somewhat off your 27.2 or 27! Am I even looking at the right number?
With regards to the components I have had the bike and been riding it on and off for the last 15 years and have lost track of which components are original and which have been replaced. I think the hubs are original and the sticker reads "Exage FH-HG50" again, and apologies for the lack of knowledge, I presume this is not the date stamp and where would I find it on the hubs?

Thanks Rob

Hi Rob 25.4mm (exactly 1") seatposts were indeed common, but I am going to take a risk here and say that your frame might not be 531C as the transfer suggests. The reasons are as follows:

1) Practically all bikes of that era have seat tube outside diameter of 28.6mm (which is 1 1/8", a standard for practically all front mech clamps then - so any manufacturer deviating from that would be in some trouble matching components). Because 531C/ST have tube thickness of 0.6mm/0.7mm at the top respectively, and because of manufacturing tolerance, essentially all 531 seatposts have 27.2mm or 27.0mm diameter. This was explained by Leonard Zinn, and supported by Reynolds data such as e.g. this table.

2) Because the 28.6mm outside diameter is a 99.9% certainty, the only* "logical reason" one could end up with 25.4mm seatpost is if the frame material is not as strong as 531 thereby requiring thicker material, with of course negative consequence on frame weight. It is hard to imagine a 531 Competition steel frame, amongst the best and lightest of all time, has any of such characteristics. In contrast, many lower quality steel frames during that period did have 25.4mm seatposts.

3) This is just anecdotal evidence, but if you look at the tables in the Dawes catalogue I attached previously you will see that their 531C frames have 27.2mm seatposts. I am however sure I can find numerous catalogues from other manufacturers stating same.

4) I mentioned yesterday that I was surprised by the look of the fork crown. I said that because I have never seen such shape for a pair of 531 forks. That shape is however common for lower spec forks from that period. This however is of course only my impression of limited experience.

5) The Response in the Dawes catalogues I attached were not built from 531 tubings. Those Response have 27.0mm seatposts (because they have Reynolds 501, a heavier, lower quality tube than 531C). But of course manufacturers do change spec over different years. However there is also a chance that your frame might not even be a Response, or a Dawes. Many if not all better Dawes in that era had "Dawes" stamped on the slanted top of each seat stay - you can probably see that in the catalogues.

6) 531 transfers are cheap and easy to get. Dressing mutton for lamb has to be tempting for some.

I am sorry to be the one to have to bring you this.

* Unless your 25.4mm seatpost has been sitting in a 0.9mm thick shim in the seat tube. Hope so!

 

[HovR]

Hi Rob 25.4mm (exactly 1") seatposts were indeed common, but I am going to take a risk here and say that your frame might not be 531C as the transfer suggests. The reasons are as follows:

I was a bit suprised to see pressed dropouts on a 531c frame, where forged dropouts would normally be expected. This could (unfortunately) possibly explain it.

 

[Rob Brookes]

Well that is unexpected however it is still the bike my father purchased for me some 15 years ago and have ridden ever since and for that reason alone it could be made of concrete and I would still love it,

Thanks for all the info though still interesting to hear.

 

[RecordAceFromNew]

Well that is unexpected however it is still the bike my father purchased for me some 15 years ago and have ridden ever since and for that reason alone it could be made of concrete and I would still love it,

Indeed! It is in remarkably good, clean condition for its age. It might be a pound or two heavier than otherwise, but I wouldn't be surprised if it could last longer, and certainly long enough for you to pass on to your children.

 

[SS Retro]

I Bought a Dawes Linear new back in 1991 it had the same bottom bracket mounted cable guides and as with your frame no Dawes stamp on the seat stays it was also a 531c frame set as the previous years frame set for the same model was a 653 if I remember rightly. Don't know if this is of any help.