Road frame sizing?? Also what do these cost ish nowadays?

This is an awfully stupid question but here goes. I need some info on the best size road bike for me? I am 5'10" with a 31" inside leg (I think :? ). How do you go about sizing them up??

Any help would be much appreciated as I used to have a Specialized Allez (I suspect collective groans ) and I loved it but sold so I could go travelling. I want it back!

Any ideas' on cost to replace my old Allez?:

Commenting on frame sizes is a bit difficult for me as I live in the metric world but I'm sure someone will help you out.

As for a new bike, why not go for a GT Force or Rage or Strike or something?

From your measurements I'd suggest you start off looking at road bikes with top tubes measuring about 21 - 22inches. (Measure from centre of seat tube to centre of head tube.) Think carefully before going below say 20" or above 22" for this measurement.
Set the saddle height (measured from pedal axle when the crank is in line with the seat tube, to the top of the saddle to 33.75 inches (that's the Loughborough formula of 109% of your inside leg measurement. It's a good starting point.)
Set the saddle fore and aft so your knee cap is directly above the pedal axle when the crank is at the 3 o'clock position.

When you sit on a bike about this size holding the tops of the bars around the brake levers you'll probably find that the straight part of the bars appears to line up with the front axle. This will help set the the stem length and it's an old, but still reliable guide, I reckon.

Most books on road bike riding will give you more detailed set up guidance to take into account the sort of riding you want to do, whether you're a spinner or a pusher etc etc. But the above are reasonable estimates to start from.

Above is based on having been a qualified BCF/RTTC club coach in the 1980's, and 40+ years of riding. (Yes, possibly an out of date old fart!) No liability accepted now though - the qualification expired years ago and with it any insurance!

55cm looks like a sensible starting point, but generally these days with compact frames it's much more the reach which is the limiting factor.

The Allez is a nice bike and amazing bangs for the buck, even if the Dura-Ace snobs will look askance.

Thanks for the input chaps..... I really want to replace the old girl but I feel an obsession starting :?

I'm about the same height (177cm / 5'10) with a similar arm span. 55cm (measured center to top) would be perfect. I think top tube and stem length are more vital though. Long top tubes with short stems (-9cm) makes for steering as touchy as a feminists rump. Unless you have monkey-like long arms, I would draw the line at 56cm max for top tube length. The current trend is short top tubes with longer stems, however older steel frames tended to be the opposite.