If you’ve ridden a fat bike or even a “plus size” bike, you already know what a huge improvement bigger tires can make. If you haven’t given fat or plus-size riding a try yet, here’s what you’re missing:
- Better handling through technical terrain.
- The ability to make your own trail.
- More fun.
Sure, there are tradeoffs (like increased rolling resistance), but after riding nearly a dozen fat and plus-size bikes I can tell you the tradeoffs are more than worth it. I badly want to make a full suspension fat bike my primary rig but alas, my “new bike budget” is limited at the moment. But it turns out there’s a solution: the 29er to 27.5+ conversion!
I’ve been riding my converted 27.5+ Santa Cruz Tallboy for several weeks now, and I love it. It’s a full suspension big tire bike that checks pretty much all the boxes for me, and I don’t foresee going back to regular 29er wheels anytime soon. Of course there are a lot of considerations before making this type of conversion, so I thought I’d answer some of the common questions here.
“Is there a way to make this work for MY 29er?”
Probably. I used the WTB Scraper rims to build up my 27.5+ wheels, and they’re a great choice because they’re much narrower than fat bike rims and even most standard plus-size rims. Clearance top-to-bottom is rarely an issue for 29er conversions since the outer diameter of a 27.5+ tire is roughly the same as or smaller than a standard 29er tire. Side-to-side clearance is the real limiting factor, though I can almost guarantee these 45mm rims will clear your frame and fork–but tires are another matter.
The mountain bike industry seems to have settled on 3 inches as “plus-size” when it comes to tires, and right now you can find 27.5+ tires between 2.8 and 3.25 inches wide. If you want to be safe, start with a 2.8-inch tire and if you have room left, go bigger. With my fork I could probably go with a 3.0 tire but in the rear 2.8 inches is about as tight as I’m willing to go.
“Will this affect my bike’s geometry?”
A little. With the Scraper rims and WTB Trailblazer 2.8 tires I found my bottom bracket was lowered about a quarter to half an inch. That doesn’t sound like a lot, but if you’ve been riding your 29er for a long time, you’ll notice. I find myself bashing pedals on rocks and roots more frequently, though nothing more than glancing nicks so far. The upshot is a lower center of gravity, which can actually improve cornering and overall bike handling.
“What do I need to buy to make this happen?”
The good news is you just need a 27.5+ tire and a wide-ish 27.5 rim. You can use standard hubs to build up the wheels, though you won’t be able to reuse your 29er spokes. I don’t know of any complete 27.5+ wheelsets that are meant for conversions on the market at the moment, but keep your eyes peeled. In the meantime, you’ll need to build up a set of custom wheels (your local shop should be able to help with this).
The great thing about this “conversion” is that you can easily switch back to your 29er wheels whenever you like. Slap on a set of 27.5+ wheels for bikepacking but keep your 29er hoops for racing.
Check out these in-depth reviews of the WTB Scraper rims and the Trailblazer 2.8 tires. I also reviewed a set of 27.5+ tires from VEE Tire Co., though sadly they didn’t fit my 29er frame.
“What kind of tubes can I use?”
Tubes designed specifically for 27.5+ tires are as rare as unicorn teeth at the moment, but not to worry! The Scraper rims are tubeless-ready and I haven’t had a single burp or flat during my tests. When I do get a flat, my plan is to use a 29er tube. Sure, it won’t be perfect, but should get me home. Some have also suggested looking for thicker DH-specific 27.5 tubes… but these can be heavy.
“How different is the ride quality with a 2.8-inch tire vs. a 2.35-inch 29er tire?”
For me, the ride quality is very different. I’d love to be able to go wider to get the same ride feel as say, a 4″ Salsa Bucksaw, but 2.8 inches still gives me improved technical handling and off-trail maneuverability and confidence.
“Does the 27.5+ wheel feel too small?”
I’m a tall guy (about 6′ 3″) and 29er wheels fit me like Michael Jackson’s glove. The 27.5+ wheels do feel a little slower, but overall the bike also feels more maneuverable–just as you would expect. I won’t be converting to 27.5 anytime soon, but 27.5+ is close enough to 29er for me.
“How much will this cost?”
At the moment, building up a set of 27.5+ wheels isn’t cheap. Plan to spend around $700 for a basic set, though that does include labor. You could get away cheaper if you do the labor yourself… or way higher if you choose blingy hubs and lightweight spokes.
Building up a set of 27.5+ wheels is a great way to turn your 29er into a dual-use rig ready to handle everything from XC racing to adventure riding to fast, technical descending. Have you converted your 29er to a 27.5+ rig? We’d love to see your photos!
Since adopting the Krampus early on, I can’t imagine riding on anything less than 3″ tires now. Yep, there are tradeoffs but what fun!
If anyone in rhe Denver area wants to try this out on their 29er let me know.
twowheelfunman, you got a set of wheels we can try out to see if they fit? I’m in Castle Rock. Have a Salsa El Mariachi with a 15mm TA Reba SL and can do either 142×12 or 135×9 in the rear.
I would love to do this to my Trek Superfly — 29in are just to much to handle on the train.
I converted my trek to 27.5 plus and it’s super fun than the 29er…i don’t have the trek super fly….i have the entry level trek marlin. but I can say superfly and marlin are almost the same.
ive got a Marlin (and a Superfly) im thinking of converting to 27.5+, whatd you end up using for tires, wheels, etc.?
I Jeff reallyrics great article! I was curious, I have a wfo and would love to try 27’s on it. I don’t have a spare lying around. Not interested in the thicker set and I was wondering if you or anyone know if more standard 27 would fit without adding to many spacers?
What I think you’re asking is if you can run regular 27.5″ wheels on a 29er and if so, the answer is no. 27.5+ wheels with tires end up about the same outer diameter as a set of standard 29er wheels but slightly smaller. A standard set of 27.5″ wheels has a significantly smaller outer diameter (closer to 26 than 29) so a conversion won’t work.
Jeff- how much does you 27.5 tallboy we igh now?
Most recent weigh-in clocked right around 28 lbs.
@jeff Barber….with your setup, how wide is the rear wheel at it’s widest? I have a 2010 Raleigh 29er SS that I would like to change to this setup. I rode a 29+ SS the other night and just loved it, so this will breath new life into my SS. Knowing the width, will help me determine if this will work.
Good question! I just measured and it turns out the Trailblazers mounted to Scraper rims come pretty close to their stated width (2.8″). I measured just under 2.75″ But with a little weight on the bike and depending on air pressure, that value will certainly increase to 2.8″ and maybe a little beyond.
Jeff, thanks for the super-fast reply! I’m thinking this will work.
I just picked up a 2012 Santa Cruz Tallboy C – which appears to be identical to what is pictured in this post. Can this frame support 2.8 out back? I have a Reba 2015 up front, not sure if a 2.8 would fit here either. Any advice is welcome!
Yes, it should fit, though clearance is tight. You’ll really just notice it in muddy conditions and you might get a little chain rub when you’re in your biggest cog.
I have a 2014 Scott Genius 910. Aluminum rear triangle. Has anyone had success in converting with this bike? Im interested in doing this but dont want to drop close to a G to find out it wont work. You mentioned tire diameters are about the same so would I take a measurement at narrowest point of chain stay where my 29″ tire currently sits? Thanks for the help
Right, measure at the narrowest point in the seat stay AND chain stay, and use the smaller number.
Your best bet will be finding someone with a set of 27.5+ wheels already built up and trying to fit them on your bike to be absolutely certain. Your LBS might also be able to help out with this if they have a plus bike hanging around.
For anyone with a 29r wishing to try 27.5+, it works for my Yeti SB95. In fact it is the best upgrade I have ever made! I put Maxxis Ikon 2.8’s front and back. I have tested it on everything from aggressive XC, ridiculous sharp rock on fast terrain, 5′ drops to flat & 6-8 foot gaps. It is faster and more sure footed by a large margin. I do however change pressure based on the terrain. Anywhere from 15 front, 18 rear to 18 front, 22 rear
Hi Mark Knowles: Curious if your SB95 has the alloy rear triangle or carbon? I’ve heard the alloy is more narrow…
I know this post is a bit old already, but i have a quick question. Im planning to convert my Tallboy LTc to 27.5+, can i use RS Pike (2016) 160mm Travel with WTB Asym i-35 TCS Rim (35mm) rims and WTB i Ranger 2.8 tires?
thanks.
Probably. The only part that might give you an issue is the 35mm rims. These will make the Ranger 2.8 tires taller than if you used, say the 45mm Scraper rims I used for my conversion. As long as you have the heigh clearance, you should be good on width with these rims.
Thanks for the quick reply. I am building the bike as i got the frame only.. btw the pike is for 27.5 only. Should i be concern for the clearance or should i get the fox 36 29 fork?
A 29er frame should have a 29er fork. Using a 27.5 fork will screw up your geometry, not to mention the 27.5+ tire will likely not fit.
Really glad I stumbled upon this! I may end up doing this to my pre-plus trek stache! I have been pondering a new bike, but this may be a great alternative. I just really hope everything fits before ponying up a handful of cash.
I’ve just done a conversion on my 2013 29er Trance. Oozy spank 395+ (35mm), 3.0″ WTB Bridgers front and back with 150mm PIKE shock. 118 Kg fully laden, 18/18 psi first outing: terrible reverb on the rear and hence problematic braking on steep terrain and pogo stick landing on jumps. Great grip in berms once you get used to the fact that noisey tyres does not mean they letting go in loose terrain.
Any advice on suspension tuning for a 29/27.5+ conversion?
Has anyone tried doing this the other way around? I have a genius plus and would like the option to run 29ers for longer flatter days riding but don’t know if axles etc are different widths? Can anyone help?
Axle widths are the same for 27.5+ and 29er, though obviously not from bike to bike. So if your bike is Boost, just make sure you pick up a set of 29er Boost wheels.
How much vertical clearance do you have on your fork and rear triangle? That’s really the limiting factor as 29er wheels are slightly taller than 27.5+.
Nice conversion, I’ve being considering the change to 27.5, the only point is the BB distance, switching from a 29er to 27.5 the BB will drop down about 3/4 Inch. This may be an inconvenient. But I’m still considering as an option.
Sweet conversion! This would be really cool to do on my 29er… but I’m not sure if it would work/fit in the rear chainstays. Is there anyway to do some measurements to figure out whether or not it will work before actually buying the gear to attempt the conversion?
Mtbr.com has several threads on their 27+/29+ forum, and it gives measurements with different rims and tires, where all you need is a simple set of calipers measured at I think 330mm from rear axle and it will let you measure. I did this on my Specialized Camber with 2.8 TB and absolutely love it.
Hi Seth.
I have a Camber as well. A 2014 Camber Comp. Did you build your own wheels or find anything assembled that worked?
I have a stumpjumper fsr 2014, you think I can fit a 3.0 on the front? To go 3.0 and a 2.8?
Hmmm… Wonder if I could pull this off with my El Mariachi.