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27.5 x 3.8 VS 29 x 3.0 for dirt use

31K views 61 replies 30 participants last post by  sherwin24  
#1 · (Edited)
I have a 2017 Fatboy Expert Carbon which obviously has 26" wheels. When I bought it I only planned to use this bike in the snow so I swapped out the 26x4.0 Ground Control's for Bud/Lou 4.8's (which are awesome in the snow)

I am interested in a new wheelset for use during the winter when I am in AZ and UT on some primitive roads that are loose and sandy, and probably some 4wd roads here in CO during the summer.

Initially I planned to purchase a 29x3.0 setup but recently have been reading about 27.5 x 3.8's. From the overall diameter measurements I've been finding it appears that 29x3.0 and 27.5x3.8 should be similar diameter to my 26" Bud and Lou combo. Of course these measurements are from different sources so I'm not sure how accurate they are. Since the OE 4.0's are smaller in diameter than my current Bud/Lou's I can definitely go a little smaller than the Bud/Lou setup if needed.

Aside from sizing my real question is what makes the most sense for my described riding. It sounds like the 27.5x3.8's roll pretty fast on gravel and dirt although I'm not sure how they compare to 29+. Common sense tells me that 29+ will be faster with less flotation on the soft stuff. I would like to hear from people who have ridden both setups on dirt and get their opinions as to the best all around setup for me. Also I'm not doing any racing with this bike, this is all about fun.

I should add that I also have a Bluto with 120mm travel.
 
#2 ·
I am interested in a new wheelset for use during the winter when I am in AZ and UT on some primitive roads that are loose and sandy, and probably some 4wd roads here in CO during the summer.

Initially I planned to purchase a 29x3.0 setup but recently have been reading about 27.5 x 3.8's. From the overall diameter measurements I've been finding it appears that 29x3.0 and 27.5x3.8 should be similar diameter to my 26" Bud and Lou combo.
I am a HUGE 27.5x3.8/4 fan. I ride it year round, except for the 15~20 winter rides that necessitate studs.

post this same question in the plus bike forum, and they will say 29x3 0WNz aLL! :cool:

I would like to hear from people who have ridden both setups on dirt and get there opinions as to the best all around setup for me. Also I'm not doing any racing with this bike, this is all about fun.
i am all about fun, 100% of the time! :thumbsup: well, 99.837%. when i am on the toilet in the morning, i am all business... :skep:

in all seriousness, i had a stache 29x3 tired bike, and i did not get along with it. it did not match my style or the conditions/places i ride, so off she went.

Common sense tells me that 29+ will be faster with less flotation on the soft stuff.
:nono: tsk tsk my boy, this is the internet, common sense has no place here! :p
 
#6 ·
I am a HUGE 27.5x3.8/4 fan. I ride it year round, except for the 15~20 winter rides that necessitate studs.

post this same question in the plus bike forum, and they will say 29x3 0WNz aLL! :cool:

i am all about fun, 100% of the time! :thumbsup: well, 99.837%. when i am on the toilet in the morning, i am all business... :skep:

in all seriousness, i had a stache 29x3 tired bike, and i did not get along with it. it did not match my style or the conditions/places i ride, so off she went.

:nono: tsk tsk my boy, this is the internet, common sense has no place here! :p
What bike do you ride ?
 
#4 ·
I own and ride both. I didn't fall in love with B-fat. Speaking only for myself, they floated only marginally better than 29x3.0, they felt slow and heavy. All that said perhaps it was just the tire I chose, Minion FBF front and rear. This all in bikepacking usage. I know this thread is about B-fat vs 29x3 but for my own curiosity I weighed the rear wheel of both the B-fat and 26x4. B-fat build is Mulefut 50 rims, sapim race spokes, brass nips and the afore mentioned FBF. 26x4 was My Other Brother Darryl rim, sapim race spokes, alloy nips, Husker Du tire. No cassette or rotor on either and B-fat tubeless, 26x4 tubed. Both have Bitex fat 12x197 hubs. Already forgot the actual #'s but the B-fat was 5 oz. (142 grams) heavier.

Winter has come and all 3 wheelsets now reside on my wall waiting for spring while I ride my Dillinger 5/Wrathchild studdded combo. I'll probably give the B-fat another try in spring.
 
#5 ·
I have both sizes and use both depending on where and what I'm riding( which is New England).
50mm carbon 27.5 rims with Hodags: gets used on my hard tail more because of the cush factor. Also used when it's wet or soft for traction and float.

38mm carbon 29 rims with Bontrager Chuapa XR2. Use these more on my F/S bike...and on the hardtail when it's smoother stuff. When it's dry...these things rule.

Tire choice and rim width make a huge difference.
 
#46 ·
29+ all day long.

B-Fat is a silly marketing gimmick IMHO, but in this specific case, why carry more weight for less roll over and overall diameter, when the conditions don't even require float?
For flow trails, you're probably right. But for northeast gnar & drops, B-Fat is the sweet spot.

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#12 ·
29+ is the obvious answer as numerous posters have attested to.

27.5x3.8 would be a complete waste of money. If you want a 4" tire, there are a gazillion 4" tires that fit on the wheels you already have. For summer use, the Jumbo Jim 26x4 tire is very popular.

I second the above poster who said that "B-fat" is complete marketing nonsense. If you want a fat bike, ride a fat bike. If you want something with a little more grip that rides like a more conventional mountain bike, then ride a plus bike. "B-fat" is neither.
 
#13 ·
As I stated above I do not want to change tubeless tires once or twice a month so a 2nd wheel is what I'm looking at. As a result I'm not considering 4.0 tires on my current 26" wheels.

I also had thoughts of possibly needing more float than 29+ so I thought, considering contact patch size, 27.5x3.8 might roll better and float about the same as a 26x4.0.

Most likely I'll end up on 29+ but worth getting some opinions since I'm starting from scratch for wheel choice.
 
#14 ·
A taller fat wheel and tire combo is just heavier. The knobs on fat bike tires are not as big as the knobs on regular mountain bike or plus tires, and so the available traction on loose surfaces isn't that different. I actually think my 27.5x2.8" plus tires have more grip when leaned than my 26x4.8" fat bike tires on gravely loose over hard (higher ground pressure, larger knobs). In sand, it's no contest; any fat bike tire is going to have much more flotation than a plus tire. On the flat and flowy, once the heavy wheelset is going, it doesn't make much difference. Speeding up and slowing down is where the fat bike tires me out. Making the rim and tire combo taller and heavier for the same width tire is just going to make that situation worse. That's why a 27.5 fat makes no sense. It doesn't do anything 26 fat wasn't already doing, it just requires you to speed up and slow down a greater mass.
 
#22 ·
I think Mike makes the most sense. For what it's worth, I have 26 & 27.5. I really like 27.5 and only put on the 26 to wear thru my tire stock and get a touch extra float in the soft stuff. 27.5 is faster and more nimble for me - but they are close enough that trying something totally difference (a la 29+) is a better spread. Can't help you on the 29+ specifically but the people I see rocking them seem to do pretty good blasting head on thru the chunk.
 
#17 ·
i own and ride both on a surly ICT. I find the 27.5x3.8 is great for flowing trails without a lot of rocks. When things get super rocky I like being able to fit my tire in tight spots without rubbing my sidewalls up, and I like a slightly higher bb, so I go with the 29+. Most of my riding is in relentlessly rocky areas so the 29+ stay on and the 27.5x3.8 set up sees very little use. I like to use the 27.5+ set up as a studded winter wheelset but I haven't found the money and there doesn't seem to be a good way to stud the hodags that I have.
 
#24 ·
I got one of the last steel Chumba Fat bikes and had it built up 27.5 X 3.8 with 80mm rims. Loads of fun, carves real nice and I'm no slower/faster because of the size.. I have had probably every size wheel over the years and as mikesee mentioned this is my only wheel set for this bike. Great guys at Chumba to deal with BTW.
 
#26 · (Edited)
Missing from this conversation is the rims that go with your tires.

If you have 27.5 x 3.8 with 80mm rims, you still have a fat bike. A bike which can handle sand or snow.

For dirt, I run 27.5 x 3.8 with 50mm rims. The weight difference is tiny compared to 29+ and I would love to see some real data showing they roll slower than 29+. Tire choice is always a bigger factor than width anyway. In fact I might be willing to place a bet my 27.5 hodags are faster than 29+ with minions on gravel/hardpack. I do know that every time I've gone out with guys on standard bikes (27.5 or 29) I roll faster than they do when coasting on gravel or hardpack. They might have the weight advantage, but the roll over of the big diameter rubber is a real thing.

In any case, I ride where most buddies are on full suspension, so I liked the idea of the extra volume and lower pressures front and back to soften the ride.

So back to your original post, I'd say you can't go wrong with either choice, especially if you use light and narrower rims with the 27.5 option.
 
#30 ·
Missing from this conversation is the rims that go with your tires.

If you have 27.5 x 3.8 with 80mm rims, you still have a fat bike. A bike which can handle sand or snow.

For dirt, I run 27.5 x 3.8 with 50mm rims. The weight difference is tiny compared to 29+ and I would love to see some real data showing they roll slower than 29+. Tire choice is always a bigger factor than width anyway. In fact I might be willing to place a bet my 27.5 hodags are faster than 29+ with minions on gravel/hardpack. I do know that every time I've gone out with guys on standard bikes (27.5 or 29) I roll faster than they do when coasting on gravel or hardpack. They might have the weight advantage, but the roll over of the big diameter rubber is a real thing.

In any case, I ride where most buddies are on full suspension, so I liked the idea of the extra volume and lower pressures front and back to soften the ride.

So back to your original post, I'd say you can't go wrong with either choice, especially if you use light and narrower rims with the 27.5 option.
Nope, weight is more important. Rolling resistance is highly dependent on the knob arrangement, but a 3.8 tire will be considerably heavier than a similarly knobbed 3.0 tire. And it will roll the same or slower.

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#34 ·
Interesting thread. Having just put 400 miles on my new build Fatboy C with 26 4.8 JJ I started considering another wheelset for the summer time. What rim width would be recommended for a 29x3.0 tire?
 
#39 ·
I kind of have the same idea / question as OP. I have 26"x4.8" and was wondering if 29+ would be good for the 3 seasons.

OP has a suspension fork and I assume you answers took that into account. I don't and don't plan to. Would for a rigid fork a 29+ still be better in summer? My fear is it would give me less dampening over roots etc. (a wheelset will cost me close to $500, so hard to just try out :).
 
#40 ·
I kind of have the same idea / question as OP. I have 26"x4.8" and was wondering if 29+ would be good for the 3 seasons.

OP has a suspension fork and I assume you answers took that into account. I don't and don't plan to. Would for a rigid fork a 29+ still be better in summer? My fear is it would give me less dampening over roots etc. (a wheelset will cost me close to $500, so hard to just try out :).
A Krampus is $1500 and opens up options. You're going to spend $750 on wheels and tires, plus a brake rotor and a cassette. You're halfway to having a second bike!
 
#47 ·
I own a Rocky Suzi-Q with the stock 27.5X3.8 setup as well as a 50mm 29er setup and have run Minion 3.0 as well as the Chupa/XR2 so can comment based on vast experience.

Snow/Soft - No question the b/3.8 offers more float and is far better as a soft conditions setup. Aslo, they roll far faster than 26X4.0 with a similar footprint. The format is far more than just marketing hype. I would say roughly 25-40% more

Speed/hardpack - 29X3.0. Not even close
 
#48 ·
If I had to keep only one for the riding I do - 27.5x3.8 on 50mm rims is my pick. Overall, for me it’s more capable and more fun to ride. Absolutely not a waste of money and not a marketing hoax. Gnarwhal front, hodag rear is absolutely marvelous for all sort of trail riding in all kind of conditions. 29x3.0 is more efficient in terms of speed, I like it too. But my heart is with 27.5x3.8. I wish there would a bigger list of FS bikes that can takes such tires...
 
#50 ·
I didn't see any numbers here for actual overall diameter of tires. The OD of a 29x3 is quite a bit taller than a 26x4.

Can someone give me an actual OD of 27.5x3.8 Maxxis Minion, at say 12psi?

If I built some up I'd probably go with a 50mm rim, but from my measurements over the years rim width doesn't affect OD by much at all. Maybe if comparing a sub 30mm to a plus 100mm you'd get more, but anywhere in the same ballpark is going to be about the same OD.
 
#51 ·
I didn't see any numbers here for actual overall diameter of tires. The OD of a 29x3 is quite a bit taller than a 26x4.

Can someone give me an actual OD of 27.5x3.8 Maxxis Minion, at say 12psi?

If I built some up I'd probably go with a 50mm rim, but from my measurements over the years rim width doesn't affect OD by much at all. Maybe if comparing a sub 30mm to a plus 100mm you'd get more, but anywhere in the same ballpark is going to be about the same OD.
745-750mm (29.3-29.5") on 50mm rim.
 
#52 ·
Owning and riding both diameter 3.8 Hodags on a pair of Farleys, I can't say it's marketing hype. Especially for non-winter riding. The 27.5 x 3.8 Hodags over the 26r have a more trim profile and don't leave me feeling too bouncy.

Also owning modern era wide 29r rims (29 mm inner) with modern big but not plus tires currently on a modestly priced Honzo I can't imagine wanting the others for general trail riding.

It all works. I've also used and rented plus size and bigger fatties. Thing is, the big 29r wheels have some got your back and confidence but leave you with a bike that feels far more fun, speedy, more responsive to pump, and just overall feeling great.

It will all work. We've got a pair of parents and pair of twins same height sharing same fleet of bikes. They'll all work if you want a trail ride but those wide (not plus) 29r wheels are versatility and fun at same time. They do duty as a gravel bike, short distance commuter, they send it on a jump line, and work for an hours or many miles ride.

If anything's left me thinking hype or hit the peak it would be 27.5 Plus against 29rs.
 
#59 ·
The 27.5 x 3.8 Hodags over the 26r have a more trim profile and don't leave me feeling too bouncy.

Also owning modern era wide 29r rims (29 mm inner) with modern big but not plus tires currently on a modestly priced Honzo I can't imagine wanting the others for general trail riding.
I'm guessing that isn't with a rigid fork? Would your preference tilt in favor of a 3.8 if it was?
 
#61 ·
Have a similar setup as you. Winter 26' 80mm rims 4.6 studded Wrathies. Summer has been 27.5 65mm wheels with an assortment of tires. My fatty is rigid so been trying to balance some cush with the attributes of rollover. I love the Hodag for singletrack, all of which is not smooth, rocks, roots, but I also don't use it for gnarly stuff. For gravel I prefer using 4.5 Barbies and really like them, but what a handful on tight twisty stuff. Changing tubeless isn't fun, so I end up leaving one set on for stuff and accepting it's downfalls, then changing and doing the same.

So this summer finally committing to 29+ and that will be for gravel, bikepacking, smoother stuff. 27.5 will just get the Hodags for trails and barbies will be in reserve for the occasional exploring unknown destinations.
 
#62 ·
Should add, was given a set of 27.5x3.0 Teravail Coronado light and supple mmmm that I never really gave a chance because my rims are 65mm. Finally threw them on last fall just to say I tried them. I was surprised at the round profile and the sidewalls that felt like a lambskin condom were well beyond the rims, probably 1/4-3/8" beyond. They rolled very well on gravel, soaked up things nicely. Then I tried them on singletrack and didn't care for them, but they aren't really meant for that from what I can tell. Bit of a one trick pony, however, if 27.5++ is your thing, and smooth or gravel is in the cards, they would be an option that is overlooked I think. They seem to be between bfat and 27+.