Having just finished our review on the RockShox Bluto suspension fork, Tim and I both agree that the fork is a good thing for fat bikes. Not so good though? The potential for issues when ridden below freezing. Officially, RockShox tells us that the fork will perform optimally from 0° C (32° F) to 38° C (100° F). Between 32° and 10° F, the fork’s performance will begin to degrade, and using the fork under 10° F is not recommended. Considering most of us tend to ride our fat bikes during the winter, this could be seen as a bit of an issue.

Coincidentally, just days after posting our review Turnagain Components has stepped up with an answer. After months of both lab and real world testing, Turnagain is revealing their new Extended Temperature Range (ETR) seal kit which seems to be the answer to our Bluto prayers. More than just a cold weather kit, the ETR seals are designed to work in a wider range of temperatures than the originals. That means even after the upgrade the fork should work just as well during the hottest summer months as the coldest in winter.

Available as standard equipment on their sister brand Borealis bikes, or as an aftermarket upgrade, Turnagain has Bluto’s back…

According to Adam Miller of Borealis Bikes and Turnagain Components, the Bluto fork uses the same seals found in many other forks like the Reba 29. These seals apparently have a wide enough tolerance that some forks will work fine below their recommended temperature ranges, yet others will fail when air escapes the positive chamber into the negative chamber causing the fork to suck down and collapse.

Because of this, the Turnagain ETR kit consists of 3 o-rings for the air chamber of the fork that are made of a different material which is not affected by changes in temperature. Along with tighter tolerances and Slickoleum grease, the seals have proven to be effective well below zero as well as during the Colorado summer.

Interestingly, Adam tells us that the installation of the kit does not include changing to a different weight oil. They found that opening the rebound 2 clicks was more effective than changing the oil. Not to mention that keeping the stock oil allows the fork to function just as well during the Summer. Turnagain is currently working on an install video which should be available in about a week.

Testing extensively with a group of 12 riders out of Goldstream Sports in Fairbanks, Alaska, the team used multiple forks, seals, and oils to carry out blind testing of the ETR kit. In all of their testing, not a single rider was able to get an ETR equipped fork to fail even at temperatures around -20°F. The real world testing was carried out in conjunction with laboratory testing to ensure that different oils, greases, and dirt wouldn’t cause the seals to fail. While many seem to be considering the Bluto as the fork for the Summer months, the ETR kit makes it a favorite for riders like Goldstream Sports Manager Tyson Flaharty, who said, “It’s amazing how much more control and speed I have on my fat bike when I am riding through tussoks and other frozen obstacles in the trail.”

When Adam mentioned the price of the aftermarket kit at $55, you could tell he wished it could be lower. In fact, he even went as far as saying, ” This isn’t a product we’re going to make money on. Due to the amount of testing it took to verify their function, it’s something we are going to sell because it will help expand the world of fat bikes.” Indeed, $55 may sound a bit steep, but until there is a cheaper option it seems like it will be worth every penny to anyone who wants to ride a Bluto year ’round.

Starting immediately, ETR seal kits are available as a dealer ordered upgrade for any Bluto equipped Borealis fat bike. Aftermarket kits will be available as soon as the packaging is finished, or by the end of the year at the latest.

turnagaincomponents.com