California homed WTB has released new and wider carbon Ci31 rims, which expands their carbon tubeless rim range following the launch of the Ci24 last year.
WTB Ci31 Carbon rims come in 27.5-inch and 29-inch options, weighing 455 grams and 490 grams respectively. They have a 39mm outer width combined with a 31mm full TCS profile inner width and have an overall depth of 31mm. Available only in 32-hole configurations to match the most common hub drilling configuration, the rims retail for $599.95 each and are currently in stock and shipping from the WTB warehouse in Novato, California.
Press Release:
WTB is proud to announce the release of their Ci31 Carbon rims, the newest and widest addition to their line of carbon rims with a 31mm internal rim width and further reinforced construction to overcome the increasingly aggressive terrain of trail and enduro riding. Debuted last year, the refined function and elegant appearance of WTB’s Ci24 Carbon rims was the result of more than two years of testing and development on the most unforgiving terrain Team WTB could find. While the 24mm inner rim width of the Ci24 has proven itself as a strong, dependable carbon rim for multiple usages ranging from cross-country racing to drop-bar exploration, the increased durability and wider profile of the WTB Ci31 Carbon rims now meet and exceed the demands of riders looking for reliable carbon rims to be used on the most ruthless terrain.
Fully TCS compatible, WTB Ci31 Carbon rims pair seamlessly with tubeless tires designed within ETRTO standards to ensure supple tubeless traction with true bead retention, while also allowing riders to mount their tubeless tires using nothing more than a floor pump. Established as a sweet spot for trail and enduro riding, the 31mm inner rim width provides additional sidewall stability through a wider base of contact between the tire bead and rim hook. The additional width of Ci31 Carbon rims also increases the footprint of a tire when compared to trail rims within the i21 to i25 range, yielding a tenacious amount of traction while minimizing rotational weight.
“When it came to developing the original Ci24 rims and then building upon them for our further fortified Ci31 rims, our testing method was simple.” stated Chris Feucht, head of WTB product development. “We designed them with features that we knew would provide optimal ride quality and structural integrity…then rode them with unforgivable manners until we broke them. Building upon each version, we added more layers of carbon where it was needed…until we couldn’t break them. “Quality Control” for the Ci31s consisted of strengthening high-stress regions of the rim, such as the area around the bead hook, until they were unfazed by bulldozers along the lines of Mark Weir and Ben Cruz.
WTB Ci31 rims feature 4D Drilling technology, where spoke holes are drilled at a precise departure angle from the rim to align the spoke heads and nipples with the angle at which the spokes exit the hub flange. Increasingly important on carbon rims, 4D Drilling eliminates both binding and excessive lateral forces on spokes and nipples, thereby increasing the overall strength and integrity of even the cleanest wheel build.
“Kona had a huge part in both the Ci24 and Ci31 coming to be,” stated Jason Moeschler, WTB’s OEM sales manager.
“When they came to us requesting carbon rims for their top-tier builds, i23 and i25 rims were the spec for a majority of their bikes. Taking that into account, we created the Ci24 rim to bridge the difference and cover a wide variety of usages.
“Fast forward a year and their team just won the BC Bike Race on our Ci24 rims, proving their strength and performance in a cross-country race setting that isn’t remotely easy on wheels! Kona also jumped into spec’ing wide alloy rims early on, with both our i29 ST and i35 Asym rims. This gave us a glimpse into where the sweet spot was being determined for aggressive trail and enduro riding.
“Knowing the Ci31 rims would be used on bikes in the 160mm range of travel meant we also knew they would receive a constant barrage beatings, so we built them to be strong like a bull and able to handle anything thrown their way.”
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490g for 29″ my middle of the road alloy one weight 470 & there are much lighter out there