TandemGeek

It depends...

1. What brand/model/year tandem are you considering it for?
2. What are you trying to accomplish: a direct replacement, or a change in handling?
3. Are you willing to do some trade-offs if the ENVE isn't a "direct replacement fork"?

Unless you're a bit of a geek, your best bet is to consult the company that designed your tandem to get their recommendation based on where your head is on the answers to Questions #2 & #3.

Here's the deal, ENVE's forks use an axle-to-crown dimension of 367mm compared to most stock tandem forks @ 395mm to 400mm. Therefore, unless a tandem was designed around an ENVE (or a True Temper Alpha Q X2 for that matter, as they use a 374mm axle-to-crown dimension), you're going to alter the geometry of your tandem's head & seat tubes as well as lowering the front bottom bracket height.

Many of us have gone ahead and made the trade-off in geometry/cornering clearance against the lighter weight and vibration dampening characteristics of a composite fork and adjusted just fine to the change. Some of the first Alpha Q's made by AME used 48mm of rake and the early Wound-Up tandem forks used 47mm. 45mm eventually became the default. However, if your tandem was designed around a 73° head tube angle, lowering the front end of the tandem by 2.1mm for an Alpha Q would increase / steepen that head tube angle to something closer to 73.5° or 74° depending on the length of the tandem's wheelbase. So, you didn't get a linear change in steering trail when you went from say a 50mm steel Co-Motion fork to a 45mm Alpha Q given the associated change in head tube angle that came with the shorter fork. The ENVE fork just exacerbates that condition since it's another 7mm shorter than even the Alpha Q. Now days, you have folks like Co-Motion and Calfee designing their tandems around these single-bike-based fork designs to fine tune the handling so that there aren't any trade-offs and any good custom builder who has spec'd a composite fork for a customer's tandem has likely done the same when setting the head tube angle and adjusting front bottom bracket placement for toe-overlap considerations.

Again, many tandem owners have switched to composite forks on tandems that weren't designed around them without ever considering the geometry changes and quickly adapted to the net result and continue to enjoy the way their tandems handle. Many of these changes in geometry are only an issue for teams where the captain is very sensitive to bike handling nuances and/or has a stoker that is either large or prone to moving around a lot... and for those teams adding steering trail is not always the right answer. It's also worth noting that the net change in handling will be greater on tandems produced by Cannondale who spec's a 53mm rake fork as well as Trek, Santana and a few others who spec'd a 55mm rake fork and KHS, Bilenkly/Sterling and others who used varying head tube angles and fork rakes that were even greater than 55mm.

Just some food for thought.