Are you a fan of SRM or Ergomo simply because you could use it on your mountain bike? Finally Saris, who had one of the original power meters with the Power Tap, seem to be figuring out a way to have a mountain bike version of their famed hub.  What was the biggest hold up? Disc brakes.  The Power Tap measures watts via the hub, and using disc brakes screws with this measurement greatly.  I’ve talked to many Saris employees about this product, and I’m excited to see it is finally in prototype form.

Saris’ Powertap hub has developed into one of the gold standards of power measurement for cyclists with a well-documented level of accuracy and good track record for durability. The SL model shaved substantial weight from the original, and the most recent SL 2.4 added wireless transmission, but one model that has always been sorely lacking in the Powertap arsenal is a disc brake-compatible version for off-road use.

That slot will soon be filled by a new model spotted in prototype form during a recent trip to Fruita, CO. The pending MTB version is based on the existing Powertap SL 2.4, with fully wireless digital transmission and the same computer head that we’ve grown familiar with in recent years. The road model’s carbon-and-aluminum hub shell has been swapped for an all-aluminum one, though, and a proprietary stainless steel-and-aluminum disc brake rotor (developed by Powertap) fits around the hub’s bulbous power measuring hardware with an array of eight bolts.

Saris is still tight-lipped on a release date for the disc brake version but at least confirmed its existence. According to Saris’ David Cathcart, “As you know we’re constantly developing technology here at Saris Cycling Group and the disc brake Powertap is another example of that. Currently that project is in the testing phase. We don’t have a release date for it, however progress has been positive.”

Found at CyclingNews.com