Classic steel road bikes still ride beautifully, and they cost less than new. Here's which ones to buy and what to check first.

Start with fit, then condition, then tubing. A boom-era ten-speed that fits and has a straight, clean frame beats a famous race bike in the wrong size. Entry models like the Peugeot UO-8 used plain steel and sold in huge numbers, so they're easy to find. A step up, bikes like the Raleigh Super Course had Reynolds 531 main tubes and feel livelier. Race frames in fully butted 531 or Columbus SL are lighter again and usually came with better parts. Whatever you buy, plan on new tires, brake pads and cables before the first long ride.

Zoom in and read every word. Reynolds decals say how much of the frame is Reynolds. Before 1981 the three common ones were butted main tubes, all tubes 531, and "531 main tubes", which meant plain-gauge main tubes only. From 1981 they name the set, like 531 Competition or 753R. Reynolds also made decals for 501 chrome-moly and SMS hi-ten, which look similar at a glance. Columbus decals show a dove, and from the mid-1980s they often name the set, like SL or SLX. No decal at all means you're trusting the seller and the catalog.

The bottom bracket shell is threaded to one of a few standards, and the cups have to match. English (BSA) is 1.37 in by 24 tpi with a left-hand fixed cup, and it's the easiest to buy parts for. French is 35 mm by 1 mm and Italian is 36 mm by 24 tpi, and both use a right-hand fixed cup that can work loose. Older Nottingham Raleighs used Raleigh's own 26 tpi thread. French bikes also had 22.0 mm stems that are slightly thinner than standard. Cartridge bottom brackets exist in French and Italian sizes, so a French bike is still easy to keep running.

Ask how the seller measured. The old way is center to top, from the middle of the bottom bracket to the top of the seat tube. Many makers measured center to center instead, to where the top tube's centerline meets the seat tube, which reads smaller on the same frame. Then ask for the top tube length, center to center, because it decides your reach more than the seat tube does. On a level top tube, you want an inch or two of clearance when you stand over it. Before the early 1980s sizes usually went in two-inch steps.

Many bikes sold in the US before the mid-1980s used 27 in wheels with a 630 mm rim. 700c is 622 mm, so a 700c rim sits 4 mm closer to the hub and the brakes need that much more reach. Tubular rims are already 700c size. Rear spacing is the gap between the rear dropouts. Five-speed bikes are usually 120 mm, six- and seven-speed road bikes 126 mm, and modern road hubs 130 mm. A steel frame can be cold set wider by someone who knows how, and the alignment checked after. Aluminium and carbon frames shouldn't be.

Original paint tells you more about the frame, and collectors pay for it. A repaint can be a fine buy, but it hides rust and cracks and erases the factory decals that confirm the model and tubing. Ask who painted it and for photos from before. Reynolds still sells replacement decals and needs the make, model and serial number first. Its pre-1989 designs come through H. Lloyd Cycles, and some replacements read "Renovated" to mark a repaint. A newer-style decal on an older frame usually means a repaint too. For a bike you'll ride, a good repaint on a sound frame is often the better deal.