Originally Posted by smunderdog
Since I'm relatively new (both here and to the tandem world), what is the difference between a regular and tandem fork?
About $100 - $150... Seriously though, sometimes there's not much difference if a cross fork or Clydesdale model was overbuilt to begin with and has a relative longish axle to crown length of ~395mm to allow for larger diameter tires.
However, when compared to conventional 700c road bike forks, tandem models usually have the aforementioned longer axle to crown length, usually use a larger diameter fork mold along with additional material, and usually use an alloy steerer or at least an alloy insert in carbon steerers. I say "usually" on all of these accounts because you will find exceptions, e.g., True Temper's Alpha Q X2 tandem fork has 374mm fork legs which is well short of standard tandem length and just a few mm longer than single bike length... which also limits your front tire size to 25mm.
The other thing to be attentive to is the fork rake and steerer tube size. For example, Santana uses 55mm of rake and a 1.25" head tube. The only fork that meets this exact specification is a carbon fork co-developed by Santana and Reynolds for Santana's tandems, the Ouzo Pro Tandem. Reynolds just recently started to offer that fork in a 1.125" steerer tube model. However, if you have a Co-Motion, a 55mm fork is going to alter your steering and handling just as a 45mm fork would alter a Santana's steering and handling.
Bottom Line: You need to understand the specifications for a fork on a given tandem before entering the market for a carbon replacement model. You may or may not a fork model that fits those same specifications and once you start to diverge from the OEM fork spec you need to understand what the trade-offs will be in terms of handling and clearances.