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How close in size (overall height) is a 27.5 plus tire, say a 2.8" on a 35mm rim, to a 29er: arguments sake lets say a 2.35" on a Stans Flow ex? I know there are many variables to consider, just looking for an approximation if they are close? Thanks!
 

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Discussion Starter · #3 ·
Too much variation in tires to say for sure, but the plus tire will be smaller by 5-15mm of radius most likely. That's a big range so you should measure what you have and what you want to use before swapping around.

-Walt
Hey Walt,

cool... I thought as much just thought I would ask around. Thanks!
 

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How close in size (overall height) is a 27.5 plus tire, say a 2.8" on a 35mm rim, to a 29er: arguments sake lets say a 2.35" on a Stans Flow ex? I know there are many variables to consider, just looking for an approximation if they are close? Thanks!
Yeah, I'm interested in the height difference too as too much BB drop would not work for me. I see WAlt said the radius would be anywhere from 5mm to 15mm smaller on the 27.5 plus but I read on another forum that it could be up to an inch difference between the 27.5+ and a 29. Anyone got pics and or measurements of a 2.35 tire on 29" flows or similar rims next to a 2.8" NN or similar tire on a asym 35 or similar rim?
 

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For what it's worth, I took a quick measurement of my 27.5+ vs 29er.

The pics shows the height difference between the...

Specialized Purgatory 27.5x3.0 on a Roval SL38 (38mm ID) = (28 3/4 inches tall)

Specialized Purgatory 29x2.3 on a Kappius KR-29-XCW (40mm ID) = (29 3/8 inches tall)

Here's the thread

John
 

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For what it's worth, I took a quick measurement of my 27.5+ vs 29er.

The pics shows the height difference between the...

Specialized Purgatory 27.5x3.0 on a Roval SL38 (38mm ID) = (28 3/4 inches tall)

Specialized Purgatory 29x2.3 on a Kappius KR-29-XCW (40mm ID) = (29 3/8 inches tall)

John
nice work.
 

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I was considering converting my TB to 27.5+ but the lower BB convinced me not to. Very rocky where I ride and I'm already getting pedal strikes. I did put Ibis 941 rims and 2.35 Ikons. Almost like riding a + bike. 15-17 psi gives great traction.


Sent from my iPhone using Tapatalk
 

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RAKC
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Some 29er tires vary a lot in diameter. My kendas 2.2 are a good bit taller than my bontrager xr2 2.2,2.35 or xr3 2.3.

I'm gathering that's why Walt gives a good size range of change. For me it's be closer to the 5mm drop (which I'm looking forward to) when I convert.

Also, a tire has a pretty fixed diameter. They'll stretch a little from new but rims don't have much effect in overall diameter of a tire.
Sent from my XT1565 using Tapatalk
 

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For what it's worth, I took a quick measurement of my 27.5+ vs 29er.

The pics shows the height difference between the...

Specialized Purgatory 27.5x3.0 on a Roval SL38 (38mm ID) = (28 3/4 inches tall)

Specialized Purgatory 29x2.3 on a Kappius KR-29-XCW (40mm ID) = (29 3/8 inches tall)

Here's the thread

John
If this is an extreme case then that's only a 5/16" drop in bottom bracket height. Personally I'll take the better traction over a taller bottom bracket for that little amount.
 

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If this is an extreme case then that's only a 5/16" drop in bottom bracket height. Personally I'll take the better traction over a taller bottom bracket for that little amount.
That is not an extreme case at all. He is using a 27.5x3.0 tire, which will be taller than a 2.8. That tire will not fit into most 29er frames, so most are forced to use a 2.8 tire for conversions. That's more like a best case.
 

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RAKC
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His math is extremely flawed though. 1/4+3/8 does not equal 5/16, it's 5/8 or approx 17mm. That's actually A LOT.

But those 29" tires are a bit on the tall side though. My bontragers aren't that tall so my loss will hopefully be less.

Sent from my XT1565 using Tapatalk
 
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His math is extremely flawed though. 1/4+3/8 does not equal 5/16, it's 5/8 or approx 17mm. That's actually A LOT.

But those 29" tires are a bit on the tall side though. My bontragers aren't that tall so my loss will hopefully be less.
5/8th it is and yes thats a heap off BB reduction.
 

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His math is extremely flawed though. 1/4+3/8 does not equal 5/16, it's 5/8 or approx 17mm. That's actually A LOT.

But those 29" tires are a bit on the tall side though. My bontragers aren't that tall so my loss will hopefully be less.

Sent from my XT1565 using Tapatalk
No his math is correct, yours is flawed. The diameter difference is 5/8", which makes the ride height difference half of that, 5/16", or about 8.0mm.

And 5/8" is 15.875mm, not 17mm.
 
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No his math is correct, yours is flawed. The diameter difference is 5/8", which makes the ride height difference half of that, 5/16", or about 8.0mm.
not really flawed in the context of the conversation as we are all on the same page just different parts of the page. In not seeing the total ramifications of ride height diff it's easy to miss.
 

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RAKC
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Oh yes your correct, I was thinking diameter and not filling in that he cut the result in half to equal bb drop, I very much stand corrected on that one. So both our numbers are right, I just forgot the other half of the equation (gotta stop trying to think when I first wake up lol)

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Ibis says the increased 'sag' in 27+ tires from the lower pressure means that they're even lower. Basically the same height as a regular 27.5.

Is that being taken into account here too?
 

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I was in my LBS to see the new Fuze compared to whatever Spec. HT 29er they had. The diff. in axle height is ~3/8" without sag or tire compression. 3/8 lower bottom bracket on a converted 29er would make me think about getting a B+ specific frame.

-F
 
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