I have a forum running phpbb 3 that is highly indexed on the search engines. If I install the simple SEO mod, will I lose my ranking if all my old thread links are suddenly broken?

Thanks!

No matter which url rewriting you'll be using in the end, when going from natural url to rewritten urls, you only need to install / activate the zero duplicate mod and make sure you do not implement the robots.txt before at least 2 month passed, starting from when you put the mod online.
This is explained in the install file (DIY part).

The zero duplicate will automatically perform the required HTTP 301 redirection for all your topics, forums and posts (you'll need to set post redirection to at least "guest" to do so).

This mean that you'll be redirecting pretty much all your urls, it usually occurs without any trouble, you should not loose anything SEOwise, same SERPs and same referrals, but PR will have to wait the next google dance to be updated on the new urls.

Such migration has already been made on pretty big forums, forums.phpbb-fr.com (excuse my French ) did this (from natural to url rewritten mixed mode) two month ago : http://forums.phpbb-fr.com/annonces-a-l ... 50243.html

All you need to make sure of for a successful migration, especially on big forums is to first cautiously set up your url settings, because you do not want to massively redirect to for example the simple SEO url before you, one moth after, discover that the mixed mode was indeed more suitable to your project. What you want is a sudden and final massive redirect, hesitation is the only source of trouble for doing this.

So I encourage you to perform some local testing with our SEO premod, you'll be able to easily try all the SEO mod released here and properly choose what you want to do.

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Great answer! I had this question as well! Nice to know that the re directs will keep the forum in tact and next Google update we'll be re cached and normally without issues!

I also have a forum running phpbb and would love to upgrade to this mod but I have many other mods and can't really do much right now but the new forum I'm starting is with your mod!

This is a great mod very well done and should maybe be considered something for a core change!