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27.5+ Front Wheel and Standard 29 Rear

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garrybunk

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Discussion starter · #1 ·
I was considering converting my 29er into a 27.5+ bike, however the rear of the frame will not accommodate a 27.5+ tire. It's my understanding that a 27.5+ wheel is very close to the diameter of a standard 29 wheel, so would it be kosher to mix & match the two? My 29 currently on the rear is about as big of a tire as I can go now.

I know some of our local club members have put 29+ tires on the front with standard 29's on the rear. My fork won't fit a 29+ and I would think that combo would have more affect on changing geometry than my planned 27.5+/29 combo.

Thoughts?
-Garry
 
#4 ·
It all depends on what 29, 27.5+ and 29+ tire you are talking about. If you are running a 29x2.0 or 2.1 in the back, a good sized 27.5x3.0 or 3.25 will not change your geometry much. On the other hand, if you are running a 29x2.4 in the back and can only fit a 27.5x2.8 in the front, yeah, your front end will drop at least a half inch, if not more; And yes, you will notice. With a 29+ front, again it depends what tires you are talking about. 2.6, 2.8, 3.0, 3.25? All will raise the front a bit, but the change will be less than putting a small 27.5+ tire. Also, raising the front a bit is usually better than dropping it...
 
Discussion starter · #5 ·
I'm running a Panaracer Rampage 29x2.35 on the rear (WTB 19mm internal width rims). I measured the tire (mounted) with digital calipers at 2.23" at the widest point and a height of 1.96" (measured from the top edge of the rim, not down inside the rim). On the front I am currently running a Continental Trail King 29x2.4 which measures 2.25" wide x 2.30" high. So perhaps my rear tire is already on the small side as far as height goes.

-Garry
 
Discussion starter · #7 ·
Thustlewhumber said:
Try 2.8's, like the Rocket Rons. I'm sure they will fit just fine.
Click to expand...
You mean on the rear? What kind of dimensions do they run? And are you referring to a 27.5 x 2.8 or 29 x 2.8?

-Garry
 
#8 ·
OK straight up, you're asking people to give blind advice basically, you need to provide more inf about what bike you have and the actual setup.

My blind advice not knowing what bike or setup you have is, as others have said, B+ is not the same height as a decent 29x2.3", you will loose anywhere from 1/2-3/4" depending on what B+ tyre you try.

If your bike is rigid, then I can give some experience on that, ran my KM with a 29x2.4" rear/29x30" front because I couldn't fit a bigger 29er tyre. Since then I have figured out that a 650B x 2.8" like the Nobby Nic will fit in the rear and so now run B+/29+ and love it.

On my Paradox running an F34 fork, I cannot fit anything like a true 3.0" tyre, I run B+ rear/29x2.4" front and it works well, would not go the reverse unless I had a really slack HTA to play with.

Best bit of advice is to get an actual caliper and measure just how wide your stays are and then compare that to stated measured widths of B+ tyres to see if one would fit - to measure you'll need to measure about 3/4" behind your where your 29er tyre sits in the stays.
 
Discussion starter · #9 ·
Sorry about being vague. My bike is a budget setup (and I'm trying to stay budget with wheel & tire upgrades too), a 2014 Gravity 29Point1 from BikesDirect. I've been upgrading components along the way over the past 2 to 3 years, most of which do not pertain to this issue. One that does is the fork I just installed - a RockShox Reba SL.

I've not taken a measurement on the rear for clearance on a 27.5" tire, mainly because I wasn't sure how far back to take that measurement from the 29" tire (I'll try 3/4inch back from the top of tread on the 29" tire as soon as I get a chance).

According to my notes I measured rear chainstays width at 2.60" (based on 29" tire position) and 375mm from center of axle (I think that 375mm is to the point where the chainstays really pinch down narrow - about the top of tread of the 29" tire). On the front (Reba) I measured 3.06" at the narrowest point and 380mm from center of axle to bottom of fork arch.

Perhaps I should try to go with two 29 x 2.6 front and leave my rear as-is. I think 29 x 2.6 options are limited and pricey though.

Here are a few pics that may help (calipers measuring my Panaracer Rampage dimensions):











-Garry
 
#10 ·
Yup, I think that would probably be the best solution, but honestly, you have a sus fork, so not sure why the want/need of a PLUS tyre upfront. A good 29x2.3-2.4" with some good edge knobs should more than provide the lever of grip you need, where you need cush is outback, so I'd spend my time trying to figure out if that's possible.

On a side note, that's not a frame I would have spent money upgrading parts on, heck that Reba you just put on would have cost about what the entire bike cost you new, you would have been better off looking at a new PLUS HT, with "modern" geometry, in the $800-1000 range.

Perhaps I should try to go with two 29 x 2.6 front and leave my rear as-is. I think 29 x 2.6 options are limited and pricey though.
Click to expand...
 
Discussion starter · #11 ·
LyNx said:
On a side note, that's not a frame I would have spent money upgrading parts on, heck that Reba you just put on would have cost about what the entire bike cost you new, you would have been better off looking at a new PLUS HT, with "modern" geometry, in the $800-1000 range.
Click to expand...
Oh I got a heck of a deal on the Reba used (freshly rebuilt) from a local club member. Believe me, I was hesitant to consider putting much more money into this bike. The need to replace the fork was the main reason I quit considering pricey upgrades in the first place, but now that the fork is taken care of I am revisiting this "27+ conversion" idea.

LyNx said:
. . . but honestly, you have a sus fork, so not sure why the want/need of a PLUS tyre upfront. A good 29x2.3-2.4" with some good edge knobs should more than provide the lever of grip you need, where you need cush is outback, so I'd spend my time trying to figure out if that's possible.
Click to expand...
Well it started because of local club riders switching to 29 x 3.0 on the front (with susp.) and raving about it. Also consider that I had been riding on a pogo stick fork for 2 to 3 years! I've not been out on the bike since installing the Reba, so you're right, I might find that there's so much improvement that I don't need to go bigger on the front tire.

I have been eyeing up 27plus hardtails in the $1,200 range for my next bike, but budget isn't allowing this anytime soon. I ended up with this bike as one that I could get started with on a tight budget and honestly I've not been disappointed considering the price.

-Garry
 
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