29 wheels on a 27.5+ frame

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This topic has 10 replies, 6 voices, and was last updated 4 years ago by toomuchtime.

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29 wheels on a 27.5+ frame
toomuchtime
Free Member

Good morning one and all

Due to being bored I’ve been messing around with stuff and I was wondering if my 27.5+ frame which runs a sweep non boost 140mm fork can run 29″ wheels if so do I need to get 120/130mm 29 fork ?
Advice always warmly welcome

Posted 4 years ago

chakaping
Full Member

What’s the BB drop on the frame? Check that annd see how it compares to 29er frames.

And check that there’s room for a 29er wheel & tyre in the rear of course. You’ll probably have a friend with a suitable wheel.

Posted 4 years ago

toomuchtime
Free Member

The 29″ rear wheel has a shed load of room when put on the frame

Posted 4 years ago

akira
Full Member

I’ve done it the other way, 27.5+ish on a 29er frame and a 29/27.5+ fork. Seemed to work okay, couldn’t fit a huge tyre on the rear due to clearance but had big tyre on the front, seemed to work and ride okay.

Posted 4 years ago

alanf
Free Member

I run both on my Genius.
2.8 rekons on the 27.5 wheels and 2.35 NN/RR combo on the 29er wheels.
With the tyres on the wheels there is not that much difference in the diameter of the 2 wheelsets, I would say less than 30mm so if you have more than 15mm clearance on your fork I would say you’re good to go. If the frame is 27.5+ then it should be built for it.

Posted 4 years ago

chakaping
Full Member

Again, what’s the BB drop on your bike? Should be on the geometry chart.

Posted 4 years ago

toomuchtime
Free Member

I have no geometry charts it was a bit of a prototype so I have no figures at all sorry

Posted 4 years ago

chakaping
Full Member

Did the BB feel high or low particularly?

Did you clip your pedals much compared to other bikes?

Posted 4 years ago

welshfarmer
Full Member

Same as alanf here, but on a Scott Spark 710 plus. I either un it withe the 27.5/2.8 tyres it came with, or swap them out for 29/2.35 tyres for more cross-country duties. Geo stays the same and a few mm more under the BB is a good thing as in plus mode it is damn low. Plenty of frame and fork clearance too.

Posted 4 years ago

wzzzz
Free Member

https://www.bikecalc.com/wheel_size_math

2.9 X 2.4 = 743.92mm dia
27.5 X 3.0 = 736.40mm dia

Your BB will be (743.92-736.4)/2 = 3.76mm higher than before. Bet you won’t notice that.

29×2.25 is about the same dia as 27.5×3.0

Posted 4 years ago

toomuchtime
Free Member

Thanks Wzzz that’s all I needed to know many thanks all

Posted 4 years ago