I came across this link while looking up the differences of 27.5 vs 29 wheels.
I'm wondering why 27.5 has all but died for new, modern geometry bikes (long, low, slack). Physics don't change, and the facts mentioned in the linked page seem to be pointing at 27.5 being a "better" wheel size, especially with weight (lighter by ~1kg) and acceleration.
I mostly ride cross country, and I'm curious if a 27.5 cross country bike with modern geometry could potentially be faster these days. Modern XCC/XCO courses have more surges of acceleration while climbing, and the descents could definitely be taken care of with a 27.5×2.4 tire.
by g3rardvcruz
3 Comments
I think it just comes down to what people are buying. I bought a new Spindrift this year. Only after I decided on Ohlins did I realize that the RXF38 only came in 29″. I emailed Ohlins USA to ask about it, like maybe there was something coming out soon. They replied and said they weren’t working on a 27.5 size since there was just no demand for it. Most bikes are just 29 these days.
I see people asking about 27.5 every so often. As a smaller rider, 29 just feels like a boat to me. For racing, I think the 29 makes sense, the greatest obstacles are literally the obstacles. You’ll always get better rollover on a 29, even if there is a smidge less acceleration to be had.
To add to what the other commenter has said, it seems like a lot of bikes are running a mullet setup with a 27.5 in the rear right now. I think it’s primarily to make the bike a bit more agile in the rear, but it could also affect acceleration I’m guessing.
Giant went all in on 27.5 wheels and tried to convince everyone they were the goldilocks size. It was not a success and they now have switched to mostly 29in models.
Brands figured out the geo challenges with 29ers, partially with mullets for smaller sizes. The weight penalty is real, but Giant is citing the top end of the difference. I have both a 27.5 and 29in bike. I personally prefer the 29in bike for where I ride, but the 27.5 is also super fun.