This online resource library can answer most of the questions you might have. The library offers manuals, photos, videos and other useful information to help solve your issues and is organized by topic for quick referencing.
Simply select a category from the list on the lower right column. You can see the subcategories if you click on the arrows to the right of your category.
I'd like to add a suspension fork to my Bike Friday. Can I do it?
Most models require a different head tube angle to accept the extra stack height of the suspension cartridge. This is why the Pocket Gnu is different than the Pocket Llama and why the Air Llama is different than the Air Glide.
This rule is not true of the tandems, though, which will accept the suspension fork aftermarket without any trouble. You will also have little trouble with an older Air bike that has a removable front fork.
Everything else will require a new frame with a modified head tube angle. If you're in need, this may be a perfect time to consider our trade in program.