Breaking the 27.5-Myth [VIDEO]

PB Forum :: 27.5/650b
Breaking the 27.5-Myth [VIDEO]
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flag SlavIntruder
Posted: Feb 1, 2015 at 10:04 Quote
This video is supposed to by a scientific study:


"If you look at the descent, the 26'' was the quickest." (4:00)

Well, my next bike will be a 26'' again anyways... Big Grin
flag boxxerace
Posted: Mar 13, 2015 at 13:31 Quote
Definitely relative to the terrain. What I do know is that a larger wheel rolls over obstructions easier. Depending on the terrain, that might be faster, or the bigger wheel may be slower due to other phenomenon. (bb height, general goofiness, etc.)
flag NMK187
FL
Posted: Mar 16, 2015 at 7:47 Quote
I didn't believe the hype until I tried it... Feels faster, and Strava tells me I'm faster on 27.5 wheels. Climbing is easier too. Don't notice any negative effects cornering, but is a bit slower to accelerate.
flag tufty
Posted: Mar 16, 2015 at 14:21 Quote
Certainly the numbers are pretty damning but does it translate to real world riding?
It could well be that rather than getting the best of both worlds it gets the worst of them!
I think longevity needs to be taken into account as a 29er simply cannot make a hugely strong wheel.

When I first saw the video I was saddened because I just dropped 1.2k on a Whyte 901. However after a deep sigh I realised that it doesn't make any difference to me. I am not going to be racing anyone any time soon up or downhill.
For now I will sit back and eat up the offroad miles and forget the troubles of wheel sizes
flag Singletrackmac
Posted: Mar 19, 2015 at 22:03 Quote
Results make sense. 29er has the advantage in rolling faster for the flat, and the 26" has the advantage of better geo and maneuverability for the DH. 27.5" has much less rollover than the 29er and while it does have more rollover than a 26", it is only 1/2".

That small 1/2" increase comes at a big cost to maneuverability with needing to have a wheel that is 1" larger to gain the 1/2" of rollover. It's not just the moment of inertia from the bigger wheel that hinders it's maneuverability, but the negative effects on the geo to fit the 1" larger wheel as well with a higher stack, longer chain stay, longer wheel base and increased BB drop. This along with a heavier and larger wheel/tire negate whatever gain you get from the measly 1/2" increase in rollover.

The 29er also losses in maneuverability vs the 26" with it's larger wheels, but what it looses there, it gains with wheels that actually have a significant increase their ability to roll faster than the 26".
flag NMK187
FL
Posted: Mar 20, 2015 at 6:58 Quote
Singletrackmac wrote:
Results make sense. 29er has the advantage in rolling faster for the flat, and the 26" has the advantage of better geo and maneuverability for the DH. 27.5" has much less rollover than the 29er and while it does have more rollover than a 26", it is only 1/2".

That small 1/2" increase comes at a big cost to maneuverability with needing to have a wheel that is 1" larger to gain the 1/2" of rollover. It's not just the moment of inertia from the bigger wheel that hinders it's maneuverability, but the negative effects on the geo to fit the 1" larger wheel as well with a higher stack, longer chain stay, longer wheel base and increased BB drop. This along with a heavier and larger wheel/tire negate whatever gain you get from the measly 1/2" increase in rollover.

The 29er also losses in maneuverability vs the 26" with it's larger wheels, but what it looses there, it gains with wheels that actually have a significant increase their ability to roll faster than the 26".

You haven't ridden 27.5 much have you. I get it.It sucks that the 26 bike you have is "out of date". It's still a fine machine, and ride it until you feel like getting a new bike, but the advantages are real or the pros wouldn't choose to be riding and winning World Cup DH and EWS events on them. And have you heard of people who own them complain about them? I haven't.
I was steadfast against moving from 26-27.5, but a killer deal dropped into my lap, and I decided for resale value sake I would make the switch. I came from an SB66C so the advantages in ride quality that I'm experiencing are not due to a change to newer geometry. 27.5 climbs better in technical areas, is faster in rough stuff, and obviously rolls better. I have not noticed any draw back cornering. Though it does accelerate slightly slower. The advantages IMO far outweigh the disadvantages.
flag Singletrackmac
Posted: Mar 20, 2015 at 19:51 Quote
NMK187 wrote:
Singletrackmac wrote:
Results make sense. 29er has the advantage in rolling faster for the flat, and the 26" has the advantage of better geo and maneuverability for the DH. 27.5" has much less rollover than the 29er and while it does have more rollover than a 26", it is only 1/2".

That small 1/2" increase comes at a big cost to maneuverability with needing to have a wheel that is 1" larger to gain the 1/2" of rollover. It's not just the moment of inertia from the bigger wheel that hinders it's maneuverability, but the negative effects on the geo to fit the 1" larger wheel as well with a higher stack, longer chain stay, longer wheel base and increased BB drop. This along with a heavier and larger wheel/tire negate whatever gain you get from the measly 1/2" increase in rollover.

The 29er also losses in maneuverability vs the 26" with it's larger wheels, but what it looses there, it gains with wheels that actually have a significant increase their ability to roll faster than the 26".

You haven't ridden 27.5 much have you. I get it.It sucks that the 26 bike you have is "out of date". It's still a fine machine, and ride it until you feel like getting a new bike, but the advantages are real or the pros wouldn't choose to be riding and winning World Cup DH and EWS events on them. And have you heard of people who own them complain about them? I haven't.
I was steadfast against moving from 26-27.5, but a killer deal dropped into my lap, and I decided for resale value sake I would make the switch. I came from an SB66C so the advantages in ride quality that I'm experiencing are not due to a change to newer geometry. 27.5 climbs better in technical areas, is faster in rough stuff, and obviously rolls better. I have not noticed any draw back cornering. Though it does accelerate slightly slower. The advantages IMO far outweigh the disadvantages.

Pro riders ride what their sponsors want to sell. Some can fight that for a while like Jared graves did last year riding his sb66c even after it was discontinued. He won the enduro World Series with it in a sea of larger wheel size bikes. But at some point you got to move onto the next design your sponsor wants to push.

I have demoed a few 27.5" bikes now. I can't tell any diff in rollover, but I just might not be as sensitive as others riders who can feel a 2% to 4% increase in rollover. A half inch is a pretty negligible difference. I could feel the almost 12% increase in moment of inertia from the 1" larger wheel though, especially when climbing, accelerating and in maneuverability. Also, my 26" FS frame can easily fit a 27.5" wheel with 2.5" tires so I wouldn't call it out of date due to the wheel size that is on it. The 1 1/8" straight steer is what makes that bike out of date. I also have an older rigid that can fit 27.5" as well, but that bike is from 1991, so it is way out of date, but still shreds.
flag SlavIntruder
Posted: Mar 21, 2015 at 12:33 Quote
Totally agree with singletrackmac.
And apart from all the pros, I will stick with 26'' simply because any bigger wheel size doesnt fit for people around 170cm height
flag Robino113
Posted: Mar 21, 2015 at 14:59 Quote
Hey guys. Just thought I'd comment on the whole 27.5" wheel size debate.
Yeah sure I can understand how some people can get annoyed with the bike industry always moving on and leaving things behind (like the 26" wheel size), I mean even I get annoyed when new standards are introduced all the time just to save weight or what not. I did however very recently purchase my first full suspension bike after many years of riding a hardtail. My new bike has 27.5" wheels, verses the 26" of my old bike. And from personal experience (not speaking from anyone else) I can understand the new wheel size. It rolls over terrain so much nicer than a 26", is more maneuverable in tight corners than a 29er, rolls quicker downhill then a 26" and theoretically has a greater acceleration than a 29er.

But I say all this and yet it doesn't really matter because other people will ride what they want to ride. People are always going to ride what they WANT to ride and choose a bike that matches their discipline.

So yes you can slag off the 27.5" wheel size as much as you want but for some it is the 'perfect' wheel size. For those wanting to have fun on the trails every weekend or go to the bike park with their mates for some R&R it has the best of a 29er and 26" wheel.

We don't all want scientific evidence that this thing does that job better than some other thing, we just want something that'll express our love for mountain biking and carve up the trails with a smile on our faces.
flag LeBrown333
Posted: Mar 21, 2015 at 15:07 Quote
I really like 26', I tried 27.5/650b and I also tried 29' and I really prefered 26'. 27.5 is not so bad, it's nice to ride but I prefer 26'. I really don't like 29'... i don't like the fealing and it's too big... That's my opinion but I think everyone have differents fealings about it and you have to try it to like it!

- And I hope you have a wonderful ride! Big Grin
flag gaz552
Posted: Apr 28, 2015 at 11:57 Quote
26" wheels with with a 2.8- 3.0" wide tire on a nice wide 30mm? Rim would probably make a lot of people happy. That is as long as the rolling resistance wasn't really awful.
flag slope
Posted: Aug 2, 2015 at 16:15 Quote
Back in 2001 I was running 3.0 tires on my BigHit, loved it!
What goes around comes around.
I still have 24" tires so I'm ready.
flag hig4s
Posted: Aug 21, 2015 at 8:20 Quote
One of the advantages of 29 over 26, (other than the being 10% taller for roll over,, 27.5 is 5% taller than 26, half way in between) is the difference in handling by being more in the bike than on it.

with most 26in mountain bikes, to get reasonable clearance the crank center is above the axles. With the weight of the rider being applied above the axles the bike is more tippy. 29s have the axle higher than the center of the peddle crank.

with most 27.5in bikes you get back half of the quick response from the smaller lighter wheels and tires, half the roll over advantage of the 29, and still have the center of the crank below the axles so retain most of the stability of the 29.
flag boxxerace
Posted: Aug 22, 2015 at 23:27 Quote
hig4s wrote:
One of the advantages of 29 over 26, (other than the being 10% taller for roll over,, 27.5 is 5% taller than 26, half way in between) is the difference in handling by being more in the bike than on it.

with most 26in mountain bikes, to get reasonable clearance the crank center is above the axles. With the weight of the rider being applied above the axles the bike is more tippy. 29s have the axle higher than the center of the peddle crank.

with most 27.5in bikes you get back half of the quick response from the smaller lighter wheels and tires, half the roll over advantage of the 29, and still have the center of the crank below the axles so retain most of the stability of the 29.

Interesting observation! Thanks for sharing.
flag a-d-e
O+
Posted: Aug 23, 2015 at 3:51 Quote
hig4s wrote:
One of the advantages of 29 over 26, (other than the being 10% taller for roll over,, 27.5 is 5% taller than 26, half way in between) is the difference in handling by being more in the bike than on it.

with most 26in mountain bikes, to get reasonable clearance the crank center is above the axles. With the weight of the rider being applied above the axles the bike is more tippy. 29s have the axle higher than the center of the peddle crank.

with most 27.5in bikes you get back half of the quick response from the smaller lighter wheels and tires, half the roll over advantage of the 29, and still have the center of the crank below the axles so retain most of the stability of the 29.
probably completely wasting my time but.... crank height is exactly the same on 26 27.5 29. just the wheels are different sizes & thus the differing radius would therefore put axles higher or lower relative the the bb.
lesson over.
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