Mountain Bike Reviews Forum banner
1 - 17 of 17 Posts

Registered
Joined
65 Posts
Discussion Starter · #1 ·
What were to happen if 27.5 inch wheels were put on a bike that originally came with 29 inch wheels without changing the front suspension and what wheel the suspension was meant to accept?
 

Registered
Joined
26 Posts
Your bb would be much lower unless you can roughly match the diameter with 27.5+, assuming it鈥檒l fit in your stays.
I put 27.5 on a pony rustler, which comes as a 29 (horse thief) or 27.5+ (pony rustler)鈥ame frame. What I can tell you is that the bottom bracket was way too low and made pedal andBB strikes unbearable. Decided it did not work and went back to larger diameter.
 

Registered
Joined
161 Posts
This is a pretty common thing to do, and in-fact a lot of bikes with 27.5" wheels were just that. Overall the Bottom Bracket would go down slightly and thats about it (other than your standard 27.5 vs 29" wheel things). You could also mullet that baby and just go 27.5 in the back. This would slightly reduce the bb height but also slacken the headtube angle for more fun.
 

Out spokin'
In cog? Neato!
Joined
17,980 Posts
I鈥檓 trying my GG Smash that way right now.

Typically I run 29x2.6鈥 tires on i30 rims but for the off season I鈥檓 going to give 27.5x2.8鈥 tires on i45 rims a try. Already had the wheels so what the heck.

Only done two rides so far but both went well. Luckily my old school aluminum frame Smash has a high BB to begin with, so despite putting smaller wheels on it, pedal strikes haven鈥檛 been a thing.

Handling seems great 鈥 not much different than with the bigger wheels, really. That surprised me. Suspension feels different, tho. Despite running lower tire pressures in wider/smaller tires & wheels, the suspension feels harsher with them. Must be the difference between Maxxis Forecasters and Schwalbe Magic Marys. Ya think?
=sParty
 

Premium Member
Joined
8,702 Posts
This is a pretty common thing to do, and in-fact a lot of bikes with 27.5" wheels were just that. Overall the Bottom Bracket would go down slightly and thats about it (other than your standard 27.5 vs 29" wheel things). You could also mullet that baby and just go 27.5 in the back. This would slightly reduce the bb height but also slacken the headtube angle for more fun.
A 27.5 rim is 584 mm in diameter, a 29" 622 mm, so 38mm. 1/2 of that (19mm) is how far the bottom bracket drops when switching from 29 to 27.5 with the same tire size (i.e. 2.5). Running a plus tire on a 27.5 rim helps lessen this difference.
 

MTBR Member since 2001...
Joined
330 Posts
Coming from a 26" I knew 27.5 was the way to go, but I will own a 29'er at some point too.

Some bikes do it well, others like the Pony Rustler suffer strikes galore. I've seen several posts from people who talk about the rude awakening of riding at speed than bam. Cool if you own a bike that swaps or mullets without too much BB height difference.
 

Out spokin'
In cog? Neato!
Joined
17,980 Posts
Did it to my wife's e-MTB hardtail and it works fine and no pedal strikes. Probably depends on individual frame, but shorter 170 mm cranks didn't hurt.
Yup -- good call.

My GF's size XS Levo SL came with 29" wheels and a miserable 100mm dropper. We fitted the longest dropper that would fit (OneUp 150mm) and swapped the 29" wheels for 27.5"ers -- now she can stand flatfooted while the saddle is all the way down. Before, the bike was simply too big for her. Meanwhile she like the revised handling just fine and her miniscule 5'2" height means she's fine with shorter cranks (think the bike came w/165mm cranks.)
=sParty
 

Registered
Joined
433 Posts
As much as I would love to try pure 27.5鈥檚 versus my current 27.5+ I cringe at the idea of giving up any clearance I鈥檝e gained from shorter cranks and bumping up my fork travel. I鈥檓 leaning towards trying 29er instead because I鈥檓 curious to see how it is. My hope is that a narrower width tire will make climbs easier.


Sent from my iPhone using Tapatalk
 
1 - 17 of 17 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top