We noticed at last week’s Specialized Stumpjumper launch that with the exception of the 6Fattie (27+) Stumpjumper, no other bikes came equipped with the new open ‘standard’* for Boost148 rear hubs. Since Trek first launched the Boost148 system a year ago it has been put forward as a better way to build stiffer 29r wheels. It’s subsequently been used by a collection of manufacturers on 27.5 wheels but the original concept was always designed to solve the issue of larger wheels losing stiffness as the distance from hub to rim increased. We thought it a bit off-trend for Specialized to shun something that would seemingly make their new Stumpy’s stiffer. Do Trek and Specialized, two of the biggest global players in the MTB development market disagree on the benefits?
So we asked them why only the 27+ 6Fattie had a Boost148 rear and not the 29r Stumpjumpers. And this is what top Specialized bike designer Brandon Sloan told us.
So we primary[sic] went with a 148 spacing (and the wider chainline that comes with it) for chain clearance with the bigger 3.0 tires on the 6fatties. The extra stiffness is an extra benefit.
We don’t use 148 on the std Stumpys for a couple of reasons. One, 148 is not that established just yet so there are not many aftermarket wheels actually available for riders to build up framesets or swap wheels… Once 148 becomes more of a “standard”* it will make sense to move more bikes to it. It is not going to be fun for riders, dealers or manufacturers to juggle the different standards. The second reason is that our 142Plus** setup (that we have run for years on many bikes) has a drive side spoke flange than is in 1mm of 148….so much of the stiffness increase is already on the bike and the bike is compatible with a more common 142 wheel instead of only 148 setups.
So 6Fattie has to run 148 for chain clearance (if you are going to run a real 3.0 tires and our short stays) and std Stumpys will be reevaluated when/if 148 becomes the standard.
Specialized sell all their Stumpjumpers as frame only options and to us it makes a lot of sense to ensure that your potential customers of framesets have the ability to swap their existing wheels over to the new frame. Unless you already have a Boost148 bike and don’t like it, if your new frameset comes with 148 rear that’s going to force you to buy a new rear wheel too, which sort of defeats the objective of buying a frameset for most people. So that all makes sense to us. Also the fact that Specialized’s use of 142+ rear hubs that increase the spoke pitch in the a semi-boosted way enough that they add some of the stiffness of Boost148 hubs makes sense too. But we can’t help but feel there’s a little reticence on the part of Specialized to jump on board the Boost148 wagon that is being pushed hard by other manufacturers. Is Boost148 looking like being one standard too far? Tell us what you think.
*you will notice that pretty much everyone now wraps this word in inverted commas in a kind of ‘Standard? Another one? It’s got nothing to do with us!’ kind of way. It’s like the whole bike industry is trying to distance themselves from the embarrassment that the mere mention of the word now invokes.
** 142+ moves the cassette 2mm further out from the centre of the hub, allowing the flange to flange distance to increase by 2mm. This increases the pitch of the spokes on the drive side, which stiffens the wheel and reduces the amount of dish in the rear wheel.
