Trek Introduces Smart Wheel Size - Different Wheels for Different Frame Sizes

Since the introduction of the 29 and 27.5″ wheels, wheel size debates have become as common place as debating your favorite post ride beverage. Many argue that wheel size is correlated to rider size – if you’re a bigger rider with a larger frame, the wagon wheels are naturally a better fit. Smaller riders similarly benefit from the smaller 27.5″ wheels which are lighter (apples to apples) and allow lower bar positions.

Not all that long ago, a few companies started offering the same bike in both 27.5″ and 29″ wheels but in different sizes. Smaller frame sizes got the small wheels and the larger sizes obviously got the 29″ hoops. Now, Trek has joined in on the trend with their new Smart Wheel Size geometry.  By offering 13 and 15.5″ frame sizes with 27.5″ wheels and 17″ and up frames with 29″ wheels, Trek hopes to take some of the confusion out of the bike selection process. The move will also undoubtedly help dealers keep the number of bikes for inventory down since they won’t have to stock essentially two lines of the same bike, just with different wheel sizes.

Trek Introduces Smart Wheel Size - Different Wheels for Different Frame Sizes

Sold in 7 different sizes, only the 13.5 and 15.5″ Marlin frames will use 27.5″ wheels. Meanwhile the 17.5, 18.5, 19.5, 21.5, and 23″ frames will run the larger wheels – which should offer frame sizes to fit most riders. The new Marlin will be available in three models – the 5, 6, and 7.

The Smart Wheel Size system will also be integrated into the new Skye WSD as well. The Skye looks like it gains some significant improvement on the frame including partial internal cable routing and a much more slender appearance.

The takeaway? Both bikes will offer modern wheel sizes that are the best fit for each frame size at impressive prices.


  1. 27.5″ is all marketing driven by bike brands. Nobody wants them in our shop, with exception of a few short women and the occasional 160mm trail bike.

  2. @Ryan – I’ve experience the exact opposite. Nearly every high end mountain bike we sell is a 650b, and customers ask about them constantly. Personally, I enjoy my 29er despite my short stature, but I actually don’t care what people like or ride.

  3. Ryan, if your shop isn’t selling 27.5″ bikes then they probably aren’t such much of anything else either.

    customer demand for 27.5″ came before the marketing push. I wish people would get off this already

  4. I run 26″ wheels on my DJ and DH bikes, 29″ on my SS and cross country bikes and 27.5″ on my Enduro bike. I guess if I could only have one bike I would be grumpy too.

  5. @al, amen brother!

    Yeah if you actually ride bikes religiously and have the knowledge and experience to be able to tell the difference in wheel sizes then each size is great for various types of riding. I’ve found if you want one bike to do everything on then 27.5 is the way to go. The 26″ market is definitely shifting to the kids bike sector, with the exception of hyper specific disciplines. Trek is smart to do this, though I do hate trek’s mindset and them as a company overall, so I hope it fails.

  6. @Padrote

    Well said..The internet forums weren’t secretly infiltrated by big bike company employees with a hidden agenda…

    Mtn bikers as a whole tend to think out of the box, so it’s no surprise back 650b clawed it’s way back.

    I actually discussed this same concept with a co-worker not too long ago..I think you can certainly optimize a small or extra small size frame’s geometry with a 650b more than with 29″, and get some of the (slightly) larger wheel advantage.

  7. It’s just a preference and just because you don’t like something that doesn’t make it suck. I loathe Kanye West but he has more people that like his music than don’t.

  8. The 26″ wheel size was decided on because the taxes on importing sporting goods was higher than on importing toys (which 26″ wheeled bikes were considered). Ritchey was putting the 650 size on mountain bikes a long time ago.

  9. Trek’s about 2 years late on this. Yeti has been doing it since 2012 with the debut of the ARC-Carbon (27.5 & 29er) and SB-75/95. Big business trying to take credit for the little (better) guys’ ideas.

  10. I distinctly remember a video on dexter (trek’s b2b for any who don’t know) about how they could fit anyone on any size wheel, and it wasn’t a size preference so much as a riding style preference. I love seeing the big T backtrack. That said, this idea is better, so the end result is good. Trying to fit a 5’2″ woman on their 29ers, no matter how shredly she is, is a bit problematic. Obviously it can be done (see Emily Batty), but giving more options for actual need rather than marketing purpose is good.

  11. I don’t know what the fuss is about here. Orbea had already done this in 2013 with their BWC (Big Wheels Concept). Matching the smallest frames up with a 27.5 and the largest with a 29er only. The Med and Large could be optioned with either wheel size. It wasn’t done to pander to anyone, simply to improve the handling on smaller bikes and larger bikes. Far cleverer than just picking one size and saying, ok, you can’t have this in 27.5 or 29. Still, imitation is the sincerest form of flattery.

  12. A well respected bike manufacture who builds bikes all the way from kiddies balance bikes to adult bikes states that you should use “the biggest wheel possible for every frame size”. Regardless. Using this philosophy the 27.5 should only be used when the geometry would have to be adjusted the fit the wheels in. I know a lot of short women who absolutely love there 29er. If you ain’t racing why does the bar height matter ?

  13. I’m under 5’2″. Niner’s XS Jet 9 is the best fitting Mtb I’ve ever ridden. Someday maybe I’ll venture into 650b world. I’ll be curious to see the specs on Treks 650b. As of summer 2013, no one made a 650b frame with a short enough stand over height for me. The XS Niner rocks and I have stand over clearance. All I can say is if the bike fits and you love it, who cares about all this hype?

  14. My wife loves her 29er Superfly (15.5) and is only 5’1″. Like others said, where and how you ride and your preference…

    The semi-interesting thing in the article is the Marlin line of bikes. Does this just replace the low end x-caliber models? The Marlin and Wahoo had been replaced by x-caliber name with the 4, 5, 6, 7, 8… models. Note it only talks about two lines of bikes doing this with the wheel sizes, the Marlin and Skye.

  15. What I find really funny about this “new” marketing idea is that Trek has always said that wheel size has nothing to do with rider height. Ever since they started making smaller size 29ers they have been adamant that anyone can ride a 29er, and that wheel size difference was purely for performance.

    Way to stick to your guns, Trek…

  16. The problem with this is not all small riders want to ride smaller wheels. 26″ and 650b/27.5 don’t roll over stuff as well as a 29″ bike.

    Wheel size choices are a good thing, and calling out wheel size as appropriate to rider height is a bad move, IMHO.

  17. I don’t understand why people are mocking rider-height-specific wheel sizes.
    We have 12″, 16″, 20″, 24″ wheels for varying sizes of kids. The wheel sizes exist so that massive compromises to frame geometry are not required to get around toe overlap, bar height, chainstay length, and top tube length issues for various rider heights. There’s no reason for this logic to be dispensed with when it comes to adults.
    I’ve been doing bike fitting in retail for 13 years and 29″ wheels on 13″ frames is more often than not a problem for the rider. Providing a frame and wheel size that is appropriate to rider size makes all the sense in the world. Bigger wheels do not always make a bike more efficient. If the rider can’t manoeuver the bike easily and with control, they will not be efficient and big wheels will slow them down. Bike efficiency is a combination of wheel size, suspension, weight, stiffness, and handling. If handling and weight are compromised to allow for 29″ wheels, then the rider be less efficient and the added roll-over ability of 29″ wheels will be thrown away. Even novice riders can tell the difference between awkward and comfortable.

    I thank Trek for offering wheel size variance in a couple of their bike lines. If it proves popular, the trend will likely expand to more of their models in the future.

    No where does this article, or Trek, claim that Trek is pioneering this idea or taking credit for a smaller brand’s idea and stepping on the little guy. It simply says that Trek is joining this trend because they think it’s a good idea and it makes sense. END OF ARTICLE! There’s no big drama or debate here!

What do you think?