Whether it's a modern high-tech bicycle like Chris Boardman's which sold for £25,000 sterling (€38,000) at auction last year, an early 1817 Driasienne machine or maybe that old bike gathering dust in your garage, collectors are willing to pay handsomely for cycles.

Mr Nicholas Oddy, a consultant on cycles and cycling memorabilia at Phillips Auctioneers which has a cycles and cycling memorabilia auction on August 21st, says "there's money to be had" even in modern bicycles if they are in some way exceptional.

"The Lotus sports machine which we sold last year - which was ridden by Chris Boardman - was a very high-tech machine, it had a very noted history, and because of that it merited the £25,000 that somebody paid for it. But normally from the more recent period you really are not talking huge sums of money."

A Strida foldable bicycle, the "funny triangulated thing from the 1980s" with a rubber belt rather than a chain is selling "for a bit more than £200". Says Mr Oddy: "They would have been a good investment if you'd bought them at the lower end of the bargain discount stage."

But the most collectable machines are from the later part of the 19th century, the classic or high-wheeled period of 1870 to 1885 or 1890, "where the collectors who pay the biggest money are to be found", according to Mr Oddy.

The penny-farthing bicycle - "people like to call them high wheelers" - tend to sell for between £1,000 and £3,000 sterling.

Tricycles were produced with high wheels because gearing hadn't been thoroughly worked out so they increased the size of the wheels to make them go faster.

A tricycle of that period (for adults) can fetch "right up to £20,000" or more. An 1882 Rudge Rotary tricycle in the auction "is likely to go for about £8,000 or £10,000", he says.

An Otto dicycle in the auction, a two-track bicycle where you sit between the wheels and balance forward and backward (creating a very different kind of cycling experience is expected to fetch about £30,000. (A similar machine last year fetched £36,000.)

The pneumatic period effectively begins from 1890, although most bicycles that are seen date from about the 1930s. "They're not particularly desirable unless they're really in pristine condition. You can still get a really good quality roadster in really nice condition for £100 or less, which might be 60 or 70 years old."

Designed for comfort rather than speed, roadsters were heavily constructed to withstand normal rough road surfaces.

"Huge numbers of very good quality British-built machines were exported to Ireland and many makers actually had what they called an Irish model in their catalogues," he says. The Irish model of a standard bike was often better built, more heavily constructed or had extra tubing to withstand rough, potholed roads.

Cycles with solid rubber tyres are seen as having a certain cachet. An 1880s solid tyre bike sells for about £1,000 to £2,000, although Mr Oddy believes cycles with pneumatic tyres from, say, the 1890s are underrated, quite rare and were initially expensive to buy reflecting "the quality of build".

Signs of early manufacture and enhanced value include primitive chain-type drives with an inch instead of half-inch pitch, primitive braking such as a plunger brake on the front tyre rather than a rim brake and no free-wheeling facility. Good original paintwork is highly valued.

Other valuable bicycles include 1950s lightweights by Hetchins or Thanet. Very high quality machines, they originally retailed at £20 to £30 at a time when a cheap bicycle was only £3 or £4.

A mint 1920 Raleigh roadster should fetch £200 "but a mint Sunbeam from the same period would be £400 or £500".