Updated 1.18.2023

BASICS

1.) Original condition, in general, is very important in both components and finish including decals. Restoring, in other words “repainting”, can greatly diminish value, especially if braze-ons are added. This is especially true for bicycles which are common enough that original examples are available. Extremely rare bicycles with well executed and painstakingly accurate restorations may be an exception; although even then an original with an appealing but worn finish will be more highly prized by collectors. In general, choose to repaint a bicycle for your own satisfaction and not for any enhancement of it’s future selling price.

2.) Being a very well known bicycle frame maker greatly enhances it's appeal. Nostalgia drives most buyers. Sadly, even high quality workmanship means very little if it is an obscure make. Not fair, but true.

3.) Older is almost always better, but see #1

4.) "Fancier" models trump lower-in-the-range models. The higher the model is within that maker's line, the more appeal the bike will have.

5.) Genuine historical provenance can significantly increase monetary value -  BUT it must be proven, the seller must have valid, original, confirmable documents that support the claim.  Without that, it is just hearsay and adds no value. In fact, unconfirmed hearsay can make potential buyers suspicious.

6.) Predict what the selling price might be is extremely difficult for any bike. On occasion, a particular bike might sell for a very high $ amount, but we cannot assume all similar models will match that high price.  In various venues, we see very high prices placed on For Sale bikes, but too often we find that was not the actual selling price. To find out what a similar item has actually sold for (not just what was initially asked) we can check "sold items" in eBay Advanced Search.
    Also there is a section in BikeForums.net called "What's it worth; Appraisals & Inquiries". The opinions as expressed by its members vary significantly based upon their locale and their experience. Be cautious in accepting the comments there.

7.) Owners often exaggerate their bike values (it must be an ego thing?) In the end, your bike is only worth what a specific person is willing to pay, right now, today. Anything other than that is just wishful thinking. Be realistic!

8.) If nicely asked and supplied with very good pictures (see #2 below), most vintage lightweight bicycle enthusiasts will give you an opinion/an educated guess of what your bike might sell for. It takes a little research to find those people. Unfortunately, as per the rules, the Classic Rendezvous Google forum members are not allowed to be asked "value".  But the individual members may be asked privately.

GETTING READY TO SELL:

1.)  Clean the bike -Carefully, gently but scrupulously; use a tooth brush, car cleaning products like Armorall or equivalent (no build-up in crevices...) Just as in selling a home or an automobile, a dirtyy item will not appeal to most buyers. (There are some who prefer to leave the patina 100% untouched. Certainly if this a historical bike, something like Gino Bartali's actual bike, that makes sense.) But, as with a nice object of any kind, clean & well adjusted trumps rough.

2.) Many high quality digital pictures are needed, of whole the bike plus many details of frame, decals, and components. Find a very plain background and shoot on a slightly overcast day. (Avoid "scenic" backgrounds; grass, trees, seascapes, etc. and do not shoot outside on bright sunny days) Use natural light and no flash.  It's best to upload these pictures to a photo-hosting web site like Flickr, Google photos, Smugmug, etc. and then offer link to potential buyers. They can also be linked in some online selling sites. A secondary benefit is that good pictures can start discussions in online forums,  then stimulating interest in new potential buyers. Onlookers can learn & discuss your item, this then helping your selling effort.

3.) List and describe in detail the make, model and dimensions of every component part.

4.) List the physical bike frame dimensions. At minimum, include the seat tube length ,center-to-center and center-to-top, the top tube c-to-c, the bottom bracket height, the chain stay length and the fork rake or offset. See this diagram. Ask a cycling enthusiast to help if you do not understand this stuff.

WHERE TO SELL

1.) Person-to-Person
   - Through a local bike shop. This process will likely be a large commission because your used bike will take the space and staff time of one of their own new bikes.
   - Local/regional Swap Meet or Flea market.  Usually with mostly unsophisticated buyers and very often a low selling prices.
   - Purported local online services like NextDoor, Craig's List and Facebook.  Be cautious because people outside the immediate area often use these as well. Be cautious of overly generous offers, odd means of payment, lonely places to meet buyers. Perhaps meet to do the transaction at your local, already-friends-with bike shop?

2.)  Online
     (Remember, these will include  packing and cost & risk of shipping.)
   - BikeForums's Classics and Vintage SALE section:  Requires an upgraded ($) membership.
   - eBay:  Yes, it costs about 15% or so off-the-top, but you get world wide exposure and millions of potential buyers - this simply cannot be matched by any other means. Start high and let the market tell you if that is not going to work. It costs a pittance to place an item up for auction; they get their $ when it sells.
   - Facebook: Has quite a few pages where vintage bikes may be offered for sale, like Steel Is Real, Vintage bicycles UK, and others. 
   - The Classic and Antique Bicycle Exchange: covers a wide range of types and age bikes.
   - Our Classic Rendezvous Google group:  requires joining (free) to access the 4000 + members. The For Sale announcements can be posted only one time, must have pictures accompanying the offer and must include an 'up front' set price. Therefore, as with any serious attempt to sell something, quite a bit of preparation is necessary before posting.
 

                                           Best of luck!

Thanks to the Classic Rendezvous Google group members who assisted in compiling this information.