Originally Posted by RK1963
My "501" sticker has "Reynolds 531" written on the bottom. Could that mean that the balance of the bike (other than the main tubes) is 531? Also, "simplex" is written on the derailler hanger.
There were two common Reynolds 501 frame decals (and their French equivalents)
1. "Guaranteed built with Reynolds 501 Chromalloy M fork blades, stays and butted frame tubes". This means all the tubing in the bicycle is Reynolds 501, though only the top. down and seat tubes (and steering column) are butted. The remaining tubes are plain or taper gauge. Lugs, dropouts and fittings would be from various suppliers.
2. "Guaranteed built with Reynolds 501 Chromalloy M butted frame tubes." This means the top, down and seat tubes are Reynolds 501 butted tubing and the head tube is Reynolds 501 plain gauge. The stays and forks may not be Reynolds. Lugs, dropouts and fittings would be from various suppliers.
Normally Reynolds sold the tubing in sets. The framebuilder could buy a complete set or a main triangle set and reynolds supplied the appropriate decal. If a manufacturer bought the complete set, then from a marketing point of view, it would make sense to apply decal #1. Applying decal #2 might discourage a knowledgeable customer, who is looking for a full Reynolds frame.
Main triangle sets allowed the framebuilder to provide a slightly cheaper and more competitive product by using alternate materials for the stays and/or forks. The frame is still attractive to the novice buyer who recognizes Reynolds as a good tubeset, but does not appreciate the fine print, nor understand that the bicycle may be only partially Reynolds. This was a very common practice.
Usually, when building frames with mixed tubesets, framebuilders would utilize the better tubing in the main triangle and use lesser grades for the stays and/or forks. In the late 1980s, 501 was Reynolds base tubest. There was no lower grade. So by applying decal #2, it implies non-Reynolds stays and forks. However, the forks can be covered indendently, by using a separate Reynolds 501 foerk decal, which implies that only the stays are hi-tensie steel.
Now, Peugeot was a very big and long time customer of Reynolds, so there is the possibility that they could order custom sets, and that Reynolds would produce a special decal, just for them. However, higher grade stays mated to a lesser grade main triangle would have been non-conventional. Normally it wass the other way around. To get a better idea, you will have to provide the exact wording from the decal.
Please note that modern trends are somewhat different than in the past. It is quite common to use different stay and fork material than the main frame. However, this trend usually involves mating of entirely different materials, with metal main triangle usually being mated to carbon fibre forks and stays. The purpose of the carbon fibre is provide a more comfortable ride by damping out vibration, which is a serious problem with the modern, super stiff, oversize, main triangles.
Pending further information, I would say that the main triangle iof your Peugeot is Reynolds 501 and that the stays are hi-tensile. The fork may be Reynolds 501, but there should be decal, if it is.
Simplex manufactured your dropout. It was typical for most manufacturers to purchase the dropout from the derailleur manufacturer, to ensure optimum compatibility and performance.