Can 29er MTB frame assembled with 27.5er wheels?

[Patrick C.]

SportingGoods, can you tell me how far from the axle the widest part of the Nobby Nic is?  I'm starting to order parts to build up the plus size wheels, and want to see if the NN might fit on the -057 frame.

Also, did you go with the XC or All Mountain Version of the rims?

[Carbon_Dude]

I'm also getting more interested in adding some 27.5+ wheels to my stable.  I'm just hesitant with clearance on either of my frames.

So far from SportingGoods he has posted the following info:

SportingGoods 29er to 27.5+ Conversion Summary
Frame = FR202
Fork = Rockshox Reba Solo Air
Carbon Wheels = 27.5" x 35mm (internal width), 40mm outer width (HR740C from Peter)
Tires =Schwalbe Nobby Nic 27.5" x 2.8" Front (70mm actual width),  WTB Trailblazer 27.5" x 2.8" Rear (65mm actual width),
Widest part of tires occurs 34.3 cm from the front axle on the Nobby Nic, 32.4cm on the rear axle for the WTB Trailblazer.
Clearance on the rear chain stays 4mm drive side /5mm non drive side
Rides great, faster setup, he prefers the 27.5+ over his 29er wheels.

Given the above information, we should be able to determine how much clearance any frame and fork would have with those tires and carbon wheels.

On my IP-057 frame:
I have a CS measurement of 71.5mm.  (71.5-65)/2 = 3.25mm clearance each side.  Seems like I better have a rear wheel that stays true, that is about as little clearance as I would ever like to see.

Rockshox Reba RLT Dual Air Fork, I have a measurement of 74.5mm.  (74.5-70)/2 -= 2.25mm clearance each side, even tighter than the rear if I use a Nobby Nic tire.

On my IP-036 frame:
I have a CS measurement of 76.5mm.  (76.5-65)/2 = 5.75mm clearance each side.  This bike might be able to take a wider tire in the back.  If I were to put a Nobby Nic on the rear, I might have only 2-3mm clearance on each side.

On my Fox Float 32 CTD Evolution Fork, I have a measurement of almost 90mm.  (90-70)/2 = 10mm clearance on each side.  I may easily fit a 3.0 tire up front on this bike.

If you run the same setup as SportingGoods, 27.5"x35mm IW Carbon rims, Nobby Nic up front, WTB TB out back, I should be able to use the new wheels with plus tires on either frame.

[bxcc]

I'm also getting more interested in adding some 27.5+ wheels to my stable.  I'm just hesitant with clearance on either of my frames.

Distance from axle to widest part of front and rear tires?  Need this measurement to check where on my frame/fork to measure the width.

My 062 has 75 to 76mm in of clearance and the Trailblazers worked fine. From my experience and from what I've read, 30 to 31cm's from the axle is where you will want to take your measurements. Another thing to remember is what you are looking to gain. More float for snow/mud/sand riding or more traction for trail riding? From what I can decipher on the interwebz is that trail riders tend to go narrower with rims and bikebackers and soft terrain riders like wider rims. I used 29mm internal and couldn't imagine going narrower. I find 29mm to be perfect with my 2.35 tires, so to me it just seems foolish to go up in tire width and not increasing rim width.

I'm still not sure how I feel about 27.5+ FS bikes. Seems like a lot of weight gain, especially in the tires, for more traction. Which for me, isn't my problem, lack of skill is. So far, I'm in the "plus is for rigid and HT's" camp. But to be honest, I've never ridden a FS plus bike. Riding style and location probably plays a pretty big role in the results too. I remember the first time I swapped wheel sets and lost over 600 grams of wheels between two rides. The difference was very noticeable and heavy wheels is something I know I do not like.

[Carbon_Dude]

My riding is mostly trail/XC, I'm already using 2.35" tires (actual measurements is about 56mm wide) and feel that even wider tires would work better in the mix of sand, hard pack clay, roots and rocks that we have in Georgia.  Traction is a nice thing to have more of on the trails around here.  More skill is also never a bad thing either.

I know there is a small weight penalty, about 400 grams.  Which would then make my hardtail weigh in at around 20.5 lbs, or my FS bike weigh in at around 25 lbs.  Not bad in my opinion.  There is a slight drop in bottom bracket height of 0.25"-0.40", not huge but I wonder if it's a little more when riding given the flex of the tire.

I've been looking at the Trek Stache as well as the Chinese Carbon 27.5+/29+ frame that Peter has available.  However, I'm not really wanting to build another bike, but swapping wheels onto an existing bike might be fun.  I may even prefer the 27.5+ tire over my 29er tires.

[SportingGoods]

Oops, I see some questions for me here! I was out in the last 10 days (spent a week in USA   and then Easter break).
I'll make some measurements for both WTB TB and NN, both in 2.8, and get back to you.

I have clearly moved away from a pure weight weeny and I keep my Reverb dropper post as well as my 27.5+ wheels. Despite the weight addition, these 2 make me way faster (and we talk about XC Marathon here, where weight does matter).

[bxcc]

My riding is mostly trail/XC, I'm already using 2.35" tires.  However, I'm not really wanting to build another bike, but swapping wheels onto an existing bike might be fun.  I may even prefer the 27.5+ tire over my 29er tires.

This is pretty much where I was at. Luckily I already had the 27.5 wheels with 29mm internal rims so all I had to get was the tires. The WTB Trailblazers were 66 to 67mm wide at the widest point on my wheels.

[bxcc]

Also, measure 32 cm from the axle and if you 75mm or more you should be good for the 2.8's on 30mm-ish rims.

[Patrick C.]

No worries, SportingGoods.  Hope you enjoyed your trip to the US.  Were you able to ride anywhere?

I got impatient and ordered all the bits to build up the wheelset and the Nobby Nic 2.8 tires.  I found a few measurements on MTBR.com that gave me a little more confidence that it would fit.  It's tough to get a good measurement, but it looks like I should be OK.  I will definitely have less tolerance for dishing that with a normal tire, though.  If it doesn't fit, I guess I have to buy a new frame to go with the wheels.

[Carbon_Dude]

Patrick, I'll let you go first, let me know how much clearance you end up with on your -057 and how much your bottom bracket height changes.

[SportingGoods]

OK, I pulled out the measuring tape and found:
- WTB TB 2.8: 32.4 mm from axle, for the widest point of the tire. This is the side of the tire. 65mm wide.
- Nobby Nic 2.8: 34.3 mm from axle. The reason of the difference is that it is not the side of the tire that is the widest point but the tread. The widest point of the side of the tire is approx the same as WTB (which is about 1 mm thinner then the tread). 70 mm wide.

PS: I did not manage to ride any bike in US but made some plans for my return trip in July! I'll need to pack my shoes, pedals, helmet and kit!!

[Carbon_Dude]

Thank you for posting those measurements SportingGoods.  I will check both my Chiners when I get back from riding this evening and report back if I think your setup will fit on either my -057, -036 or both.

[Patrick C.]

The -057 frame is going to be very tight  

I may have to switch to a WTB in the rear, which is disappointing since my 29er 2.4 Continentals are 59 mm wide.  I guess an extra 3 mm all around is a lot more volume, but it doesn't sound like it.

[Carbon_Dude]

Currently my Suguaro tires are 57mm wide so for me it would be a 10mm increase in the rear.  On my -057 frame, I am measuring 74mm at 13.5" from the axle.  So that would give me 3-4mm per side of clearance.  That's a bit tight but at least a WTB TB would fit.

[SportingGoods]

I just want to highlight that you need minimal clearance with WTB as the wide point is the side of the tire. It won't catch mud and get wider. On the other hand, the NN's wide point will get even wider with mud as it is on the tread. You need a lot of clearance for the NN.

[Carbon_Dude]

Looking at the WTB Trailblazer tire, the tread isn't exactly my choice for grip, the pattern appears like it would roll fast but I can see the grip would not be as good as a Nobby Nic or the WTB Trail Boss 3.0.

Would be nice if there was a 67mm wide choice that had the tread blocks spaced a little further apart.