How best to approach archiving badly optimised content

[freezedriedmedia]

I signed up SEO Moz about a month ago as i'm currently rebuilding my site from scratch and wanted to learn from current mistakes.

At present I use the forum software Invision Power Board to manage my site and one thing i've learnt is that it is terrible for SEO, there are so many thousands of errors listed by the crawler that it's not even worth trying to fix it.

However because it has 5 or 6 years worth of content alot of which is on Google I don't want to totally remove it, rather I would prefer to archive it of with a big banner at the top letting anybody that visits it know that it's no longer in use and pointing them to the frontpage.

I should note that it is in a subfolder already so the location of any of the links won't be changed.

So the few questions I have are:

1. The forum index has alot of link juice and I would like to redirect that to the new forum index, however for archive purposes the old index still needs to be accessible.
2. Some topics are very popular and appear high in Google and have alot of backlinks. The important information in these forum topics will be available elsewhere on the new rebuilt site. Again I would like to redirect both link juice and users to the new page, however being a forum topic there are tens or hundreds of pages of old comments that need to still be accessible for reference.
3. There are bound to be duplicate meta title and description issues with new similarly named categories appearing both on the new site and the old forum, is this going to be that much of a problem?

So really what i'm asking is, how should I go about archiving this of without destroying content and rankings, but still making sure that the new stuff is getting the right exposure both to users and search engines alike?

[freezedriedmedia]

hmm that's very interesting, i've had another look at the stats to give more insight.

150,000 visitors hit the forums from search engines every month, of these only 10 landing pages get over 1000 visitors and 168 get over 100. This amounts to 76,000 visits or roughly half.

The other half comes from visits to a whopping 16,222 different landing pages.

So whilst manually redirecting those 168 may be a manageable task it would mean the loss of half of the visitors the forums pull in.

It also doesn't deal with the problem with letting users still browse the old content whilst transferring the link juice to newer areas, since Search Engines would not take kindly to being treated differently to an actual user.

[EGOL]

We have a blog that gets about 2000 to 3000 short posts per year.  Most of those posts have a temporary value and have very little archive value.

The posts are filed in folders by year such as /blog/2010/ .

Once a year we run analytics to identify old posts that pull in significant traffic or old posts that have valuable links.  Where possible we create a new page of evergreen content on the same subject and 301 redirect those posts.

All posts that receive very little traffic are considered to be "dead weight" on our site.  We delete those posts and redirect the entire folder to the homepage of the blog with an .htaccess file at /blog/2010/.htaccess.  This also reduces the size of our database.

With a forum, you might be able to delete some of the worthless material and feature some of the archival gold.

[freezedriedmedia]

Thanks for the response you're right it is not a simple problem, but i'm hoping people on this forum may be able to provide some very useful tips or advice from past experience, i'm sure many will have had to tackle this sort of dilemma before.

Just looked at some stats which demonstrate it's importance, 51.76% of visits come from Google and land on the forum currently.

Given that stat it may seem ludicrous to want to change the site so drastically but as you can imagine having everything managed on a forum can become very messy compared to a custom coded site where every page and content type is tailored to its specific needs and of course keeping the urls is not going to be an option when it's all tied into "topic ids".

[EGOL]

I don't think that this is a simple problem.

A good diagnosis should be considering historic traffic information, past and potential linkage structure, keywords, external links, premium content vs worthless content, usability and more.

If this forum is low value it maybe be best just redirecting everything.

However, if there is a lot of value there I would want to put some careful consideration and planning into the solution.  Certainly more than the five-minute-look that most visitors to a Q&A forum are able to provide.