When former cross-country world champion Nino Schurter won the UCI World Cup opener in Pietermaritzburg on a 27.5er in March, it got more than just a few wheels turning.
What some consider the happy medium and others a meaningless compromise, proved itself on the testing Olympic course to put a new spin on the 26er versus 29er debate.
“In my opinion, it’s probably the best of both,” says Robbie Powell, product manager for Probike in Port Elizabeth, South Africa.
According to him, the 27.5er offers the agility and climbing ability of the 26er combined with the stability and power of the 29er on the flats. “It’s something that should have come a long time ago.”
Since its introduction in 2008, the 27.5 wheel (also known as the 650b) has kept a relatively low profile and is not yet widely available in SA.
Powell says it’s not a new concept and that the founding father of mountain biking, Tom Ritchey, first mooted the possibility when he built 10 prototype 29ers back in 1983.
“There was a debate about what would be best. The 650b option was also brought up but most of the guys settled on the 26-inch wheels for the cruiser bikes they used to ride; so things could have been very different.”
He says the 29er is now becoming the norm because “it really does ride better than a 26”, but the 27.5 provides a more comfortable option for shorter riders and better handling on the shorter cross-country courses.
“It’s really horses for courses. I personally think Nino would have done as well on a 26er as a 27.5er on that specific course because of the way he’s built.”
In terms of the local market, Powell believes the 27.5er will not challenge the 29er, as the larger size is ideally suited to the marathon racing that dominates the local off-road scene. “That’s why South Africa is the biggest consumer of 29-inch wheels in the world.”
He says what may happen over the next decade is that the 27.5er will replace the average, more affordable, 26ers that most fun riders are buying “just because of the convenience of it”.
From a technical perspective, says Powell, although Schurter rode a hardtail version, the new size is best suited to long-travel, full suspension bikes as it allows the frame builder to increase the leverage or suspension travel without affecting the length of the chainstay.
“With a 26er, you can build a suspension bike with eight inches of travel without having to lengthen the chainstay too much. Once you put a 29-inch wheel on, you’re going to either compromise on chainstay or travel length.”
He says a longer swing arm creates a range of issues. “It doesn’t climb very well, so you can’t use it for a cross-country bike.
“For a downhill bike, it doesn’t descend very well because in tight, technical stuff it becomes very unwieldy due to its long wheelbase.
“So along comes a 27.5er and you can use the same design as for the 29er and get an extra 50mm of travel out of it without affecting all those points.”
Powell says there is no truth to the rumour that you can simply put the new size wheel on a 26-inch frame.
“With full suspension, the rear wheel is designed to come as close to the frame as possible when it compresses without actually touching it to get as much travel and have as short a chainstay as possible for better climbing and handling.”
He says a larger wheel would undermine that design. “If it was a hardtail and the wheel fitted perfectly, then you’d still have to raise the bottom bracket above that crucial 30cm mark and the bike would be horrible to ride.”
Powell, who represented SA at eight downhill racing world championships, says the Olympic Games in August will be a telling sign of what direction the manufacturers are headed.
From a sales and marketing perspective, he says they may be loath to challenge the market share of their own 29ers, which have been doing so well up to this point.
“By 2013, all major players will have a 27.5er available. In what guise, I’m not sure, but I know what we’re doing and I think it’ll be a surprise.
“It will be interesting to see what interpretation the market has on the 650b.”
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