Running 27.5 wheels on a 29er frame?

tonyride

Don't piss off the red guy
Has anyone tried riding a 29er frame bike with 27.5 wheels? I'm specifically talking about a hardtail frame. If so then what do you think? I'm looking to build a hardtail with my 27.5 fork and I found a frame in my price range but it's designed for 29" wheels. I'm wondering how different (or bad) it will ride with 27.5 wheels? Any suggestions? Oh, the fame is designed for a 130mm fork and I'll be using a 150mm fork. Flame away.
 

JonF

Well-Known Member
There's probably a whole slew of issues that could present itself depending on the exact frame. But one definite one is a lower bottom bracket height and the increased risk of pedal strikes. It sit here typing this with a broken big toe specifically because of a nasty pedal strike as my foot whacked an exposed stump at the bottom of the pedal stroke with the frame bobbing up and down. Now adding some additional height with the fork may help, but not as much since its the front end and not the rear where the height boost is needed most.

Other factors may include the tire not fitting in the frame or needing to run a narrower tire because the tread is sitting back in the narrow section of the stays. Could be the difference needing to run a 2.2 instead of a 2.6.
 

Magic

Formerly 1sh0t1b33r
Team MTBNJ Halter's
Too many potential issues and may ride like shit. A 150mm 27.5 fork may be similar to a 130mm 29 fork axle to crown, so you may be back to the factory head angle, but your BB will likely be LOW. I would really recommend finding a 27.5 frame. They should be cheap because 27.5 non-plus is dead.
 
Has anyone tried riding a 29er frame bike with 27.5 wheels? I'm specifically talking about a hardtail frame. If so then what do you think? I'm looking to build a hardtail with my 27.5 fork and I found a frame in my price range but it's designed for 29" wheels. I'm wondering how different (or bad) it will ride with 27.5 wheels? Any suggestions? Oh, the fame is designed for a 130mm fork and I'll be using a 150mm fork. Flame away.
Being in your price range is to high on your requirement list.

What are you looking for and maybe we'll be able to find something that is a better fit of your requirements and even in budget.

My frame was 160...
 

tonyride

Don't piss off the red guy
All good points that I didn't think about. Maybe I should consider upping my price range.
 

serviceguy

Well-Known Member
I don’t think the issue is much about the wheel size as much as using a fork not designed for the frame. You should check the frame compatibility in terms of axle-to-crown distance in order not to mess up the geo. Then there are all the other issue that have already been brought up earlier (pedal stroke, tire clearance) assuming you want to switch to 27.5+ from 29. That said I did switch from 29 to 27.5+ on my full rigid using a 29” fork and had no issues, the bb dropped by “only” 7 mm.
 

tonyride

Don't piss off the red guy
Hmm... going to 27.5+ is an option because I know the 27.5 fork can clear a 2.8" tire.
 

tonyride

Don't piss off the red guy
The fork I want to use is a SR Suntour Aion 27.5 with 150mm travel that came from my wife's bike. I upgraded the fork on her bike and I was going to sell this fork but with so many extra parts I have laying around the garage I decided to build a complete bike around those parts. All I need is a frame. I also have a spare 200x57 shock but I think I'm just going to do a hardtail.
 
The fork I want to use is a SR Suntour Aion 27.5 with 150mm travel that came from my wife's bike. I upgraded the fork on her bike and I was going to sell this fork but with so many extra parts I have laying around the garage I decided to build a complete bike around those parts. All I need is a frame. I also have a spare 200x57 shock but I think I'm just going to do a hardtail.
What bike did she have?
 

Magic

Formerly 1sh0t1b33r
Team MTBNJ Halter's
A 27.5 fork is a 27.5 fork. A 27.5+ fork is a 29 fork. A 27.5 2.8 width tire doesn't mean it's a 27.5+ 2.8. It have a shorter profile and less volume.
 

jackx

Well-Known Member
Also, you may have to consider the impact of the offset of the fork e.g. 44mm vs. 51mm, as that impacts the trail. Although, maybe trail impacts head angle and steering speed more than height.
 

tonyride

Don't piss off the red guy
OK, I get where you're coming from with 27.5+ fork and profile compared to a 27.5 fork. I don't have to worry about the width because the fork is boost so 110mm is the same width wise, plus size or not. So the only concern I can see is the distance from the top of the tire tread to the bottom of the crown. I get that when you hit a bump the tire will widen up a bit but that's only at the part of the tire touching the ground. The top of the tire doesn't "deform" so clearance isn't going to change so that is not an issue as long as there's enough clearance to begin with. Here's a picture of a plus wheel with 2.8" tire in the fork to show the amount of clearance we're talking about.
IMG_20200728_165253724.jpg
 

tonyride

Don't piss off the red guy
I feel like you will be reaching one way or another you said you had all these parts, what parts do you actually have?
I have the fork, cranks, chain, rear derailleur, shifter, dropper, stem, bar, saddle, wheels and tires, grips, rotors, brakes, and pedals. Just need headset, BB, cassette, and the frame.
 
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