27.5″ Vs 29″ Mountain Bike Wheels | The Wheel Size Debate Continues
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27.5″ Vs 29″ Mountain Bike Wheels | The Wheel Size Debate Continues

October 10, 2019


– The Scott Genius has
always been designed to be a very versatile bike. And this is the latest edition, it’s had a full frame re-design,
but one of the really cool features about this bike
is that you can swap out the two different wheel
sizes really easily. So in this video I’m going
to try the 27.5 wheels, swap them out for 29, and let you know how
it feels on the trail. How it actually changes the
ride characteristics of the bike How it stacks up against
the clock, and ultimately, try and decide which
ones I prefer the best, but also give you guys,
hopefully, a bit of an insight as to how it affects the
characteristics of this bike. But first, let’s get back to the workshop for the nitty gritty. – Right, let’s start off with some facts in the workshop about these wheels, The 27.5 wheel has a
two-point-six inch tyre, the 29er has a two-point-four. Let’s start with the weights,
so the 27.5 weighs in at 1.87kg and the 29er weighs in at 2.12, so a 25g difference. Don’t forget that’s just for one wheel so when we’ve got a pair of
29er wheels you’re actually going to be 50g heavier. Don’t forget, that’s
actually rotating mass so that does make more
of a difference than just static mass on a bike. So I’d expect I’m going to be
able to feel that on a trail, and I’d expect the 29er
to actually sort of plow through rough stuff
a little bit better and carry its speed a little bit better but be a bit harder and slower
to accelerate and decelerate. The two-point-six inch tyres
on the smaller wheels of course are wider than your
average mountain-bike tyre getting into those ‘plus’ sizes, but also they’re deeper and
that will make a big difference to how the bike feels. It’s about ten millimeters
deeper, so when we talk about the whole diameter of the wheel, it’s about a 20mm difference so it’s 20mm bigger on the 29er. That does mean that the angle of attack, when you’re rolling over
bumps, is going to be lowered on the bigger wheel so it
should roll over those bumps a little bit faster. Let’s talk about tyre pressure as well, on the plus-size tyres
you’d get away with running, I find, a couple of psi lower because of that extra volume of that tyre, you can get away with running
slightly higher pressures on the bigger wheel. So from those numbers,
I think on the trail I’d expect the 29er to feel
heavier, feel smoother, but harder to start and stop. The 27.5, I would expect a bit more grip because of that wide tyre, I’d expect the bike to feel
a little bit more lively and be able to change
direction a little bit easier and stop quicker. So how do the wheels actually affect the geometry of the bike? So let’s look at the head angle first, it’s slightly slacker on
the 29er, 65 dgerees vs 65.6 so not a huge amount. Bottom bracket is going to change slightly so it’s six millimeters higher on the 29er so it’s not going to corner quite so well, but you do have more clearance for peddling through the bumps. The big one here for me I think, is going to be the BB offset. So you’ve got a seven 7.5mm
more offset on the 29er so it feels like you’re
stood sort of more down and into the bike on the 29er. That definitely helps for
trying to get through the bumps, you’re going to drive that
bike a little bit better. Okay, enough of that chit
chat in the workshop. Let’s do the fun part. So, I’ve been riding this
bike with the 27.5 wheels for probably two or three months now. It feels great, it feels like you can get really rowdy on this bike,
really aggressive down the hills, it doesn’t feel like a true
sort of ‘plus’ bike to me so a ‘plus’ tyre could find
the biggest disadvantage really is in the mud, where they
float, they don’t really dig in. It doesn’t feel like that on this bike. The tyres are 2.6″ but the
treads are evenly spaced , they clear the mud, it
digs in, it feels like an aggressive little bike. So it’s time to try out the 29er wheels and I’ve not tried them in this bike yet, so I’m excited to stick
them on, see how it feels. I actually raced a lot
of Enduro on 29er wheels, so I think this bike,
could work really well 150mm travel, great for
British Enduros, not quite EWS you might want a little
bit more travel for that, but for my style of riding I think this could be a
rocket ship on 29er wheels but I’m looking forward
to trying them out. So I’ve got a set of 29er
wheels set up with tyres, both are tubeless by the way,
so it’s actually really simple to swap just the cassette and discs over. So realistically, you could
have two sets of wheels for the same bike and swap
them over as you please. Cassette is on, time for the rotors. One final thing to do
is just flip the chip. The chip has been
flipped, the wheels are on and don’t they look big. Actually I can see a lot of wheel sticking out in front of me,
the tyres are quite narrow, I’m back on 2.4’s now, so,
let’s go give them a ride. Right, I’ve put a time
in on the big wheels now and it felt good, it felt
like a really consistent run, felt like 29ers always have done for me when I’ve raced in Enduro. So on the stuff at the top where it’s quite a mellow gradient but it is a bit chattery with bumps, it felt like I was absolutely flying. It felt seconds faster
than the smaller wheels, but when it got a bit more technical, it feels like you have to be
a little bit more cautious. So, yes, they do Monster Truck over stuff, don’t drop into holes quite so much, but when I hit something big and I’m really trying to use
my body to soak something up I find that I stick my
bum into the back tyre and I did do it on that run. So, I’m 5’10”, pretty much average height which is a bit taller
than Martyn and Blake would have you believe, but
I do find that on 29″ wheels that sometimes I stick my
bum into that back tyre when I’m really trying to use
my legs to soak something up. I guess, if I just rode a
29er, I would get used to that but swapping between
them… it’s always been a tiny problem for me. So, I’d be interested to see the times, because that felt really fast actually. So that’s enough about the feel, let’s talk about results, and the time. Which one was the winner? So, it was the 29er, but
there was nothing in it. I did a 1:42 on the
29er, 1:43 on the 27.5, so there was only a second in it. But the interesting part for me comes when you look at the splits. The top section of that
track was fast, flowy, stuff where actually it
felt really fast on the 29er but I was three seconds slower up there, so not an inconsiderable amount, but it was four seconds faster
on that rough lower section. I think we can say that’s
down to that roll-over it’s where I’m hitting all those bumps and there were some big
breaker bumps on there. The 29er doesn’t dip in quite so much, so it’s less tiring to ride but also faster over those bumps. So actually for me, that’s
a really interesting test. And as a racer, I’m going to
go with the faster wheels. I’ve been riding that bike
an awful lot with the 27.5’s so I think it’s time to
leave the 29ers on there. Feels great fun to me, I
think the biggest disadvantage with the 29ers is stopping the bike. I’ve always felt that when
I’ve tried to race the bike and there wasn’t much of it on that test, so I could bear that in mind in future but for now, I’m sticking
the 29ers on there. It’s one of those great features I think of some of these modern bikes, that it’s really easy to swap out wheels. Realistically, you could
have two pairs of wheels for your bike at home, the
smaller and the bigger, and just swap them around
for different conditions, or you might find you
prefer one over the other and just sell the other wheels. So actually I think it makes
the bikes really versatile. If you have any questions
about this video, leave them down below because I’ll be doing a follow-up video
on the GMBN Tech Channel so I can get into the nerdy facts. If you want to see how a
tyre is made, click up there for a Continental factory tour and down there for the
Scott Genius First Ride. Give us a thumbs up if
you liked this video and don’t forget to subscribe
if you haven’t done already.

Only registered users can comment.

  1. It's a sales tactic…all my Bros who ride 27.5 cant keep up to me on my 26" wheels, light, strong and definitely not buying into this bike industry bullshit! I have over 10 -26" rigs , I've invested a lot of skrilla and I wont be upgrading anytime! Keep em, thanks for showing us that they are not worth it.

  2. im thinking of getting a new mountain bike and I've just turned 14 and im about 6,1 should i get 29 inch wheels or smaller??

  3. I have a bike on 27.5 wheels if you ride on asphalt be carefull when you turn because if you go fast like i do sometime the tire stretch and is almost expulsed from the wheel . Its a VERY scary feeling when it happen on the front wheel .be ready to have ALOT of rebound ,imo regular tire are by far better .

  4. No need for a war, just be creative:
    27.5 at front and 29 at the rear. Problems and discussion solved 🙂

    PS: i am owning a 27.5 bike and 26 bike. Tried a 29, but that felt horrible to me. i'm just 5 feet 9, so that's prolly the reason 😉

  5. I don’t think there’s much difference between the wheels but my girlfriend reckons inch and half bigger makes all the difference. I’ve never even seen her ride a bike so dunno how she formed that opinion.

  6. When you flipped the chip I would think it was in the low setting, so you are flipping it to the hi setting. Why would you want to do that with the B.B. already going up with the bigger wheels?

  7. I've got 26 in the front and 29 in the back.
    Awesome, it rides like a dragster.
    I've also attached a empty plastic bottle between the frame rubbing the back wheel for a really cool motorbike sound.

  8. 1:07 the weight difference is 250 grams. Not 25 grams.

    Two wheel total is 500 grams, which is half a kilo, not 50 grams.

  9. I’m 11 and at 5.8 and a half, but still can’t ride with 27.5. I just find 29 inch wheels the best for how I ride.

  10. i am definately going to get myself a 27.5 as my nest bike, i just dont have the the money to swap out my old 26 so i guess i will have to stick with that one for a while.

    i personally have tried all 3 sizes, 26, 27.5 and 29. i don't like the 29, it just isn't playful enough for my taste and me being both short and really light does the extra rotating mass just make the bike stable and boring, it just goes straight forward but doesn't enjoy playing around.

    the 26 is what i have been riding all the time and due to budget do i still ride my bike from 2010, it is playful and light, i love how responsive it is and the feel of the trail is amazing, but it is a pain to pedal where there isn't as many fun parts.

    here is the 27.5 shining, it just keeps going unlike the 26, but it is not much less responsive than my 26, and in the case of a carbon bike with carbon rims, actually more responsive than my old alu bike.

  11. 15 years ago:
    26' is for kids, 28' are better!

    2019:
    27.5 is not "in" anymore, 29 is better!

    Marketing wins, people are buying new bikes to be "up to date".

  12. 26" is the best wheel size EVER! When I can afford a new bike, it'll probably be 27.5" is the best size EVER! Unless I buy a road bike then it'll probably be 700c is the… you get it…. Until then my '05 Specialized XC is the best bike EVER!!!!

  13. man my bike is only a hardtail type that is a 29er, i swear its goddamn good for trails but not on all use terrain cause i do highway cycling with it to with friends and its heavy af lmao, but i dont say its bad, its good but too much for a small guy like me lmao im only 15yearsold and im only 5"4

  14. I’m 5’6.5, 140 pounds and 15 years old. I’ve always ridden either 26 or 27.5 inch wheels but I’ve been interested in 29s lately

  15. Just bought 29ers for my Pivot Mach 429 trail which came as 27.5 plus and was not impressed by the bigger wheel . It felt faster but also did not feel in control I bounced around a lot and it did not absorb the rocks like my plus tires . Not try to discourage its just my personal preference. Whatever your comfortable with just ride on !

  16. [B]In the case of DH: [/B]

    The best option is for UCI is to collect statistics for the next 12 months and standardise the wheel size for Pro and Elite riders using the sample size as per average Athlete height and final speed+time… = Different wheel size = different categories and they should not mix up wheel sizes on the same category to be fair to everyone…

    [B]In the case of enduro:[/B]

    [B]If you compete[/B]e: The same as previous…

    [B]If you don't compete[/B]: 27.5 = more agile = more fun for every heights.

    [B]If you don't compete but care about speed and faster climb and fast flat-lines [/B]= 29" if you are taller than 6.1".

    I am 6.1" but I love agility and a 27.5 with a large or medium frame does my day with a huge smile…

  17. The wheels' difference is a shot of vodka lighter…lol… so you save weight if you don't drink that shot before riding lol

  18. I've seen bikes in the past where people run both a 29 and 27.5 wheel set up on the same bike. Have you tested this?

  19. I have 28" now and it's not ideal because when I want turn sharply, I am hiting my leg with wheel or mudguard. But it's not MTB, I hope MTBs have better geometry to prevent this. My father has old 26" MTB, I have modern 28" treking bike and honestly, I don't feel much difference, except 26" is better controlable. For example I have problem ride without hands on bars on my 28" bike, on that old 26" MTB it's not problem. But as I said, it's only trekking bike, not MBT so geometry is not ideal for such things. But someone said here wheel size should be coresponding with rider size, I have 165 cm So maybe 26" is really better for me.

  20. Man just freaking ride what you want to ride dude fuck people put too much time and energy into this shitl lol The times weren’t that much difference or is it a big freaking deal really if you got a stick up your ass so tight that a second or two matters that much and dude just chill you’re gonna die at a young age LOL

  21. Question: im 6.4 , 29 or 27.5 in xxl (Yt capra)? i have no where where to try them cause around is just citybikes shops, and before i had 29 (160/160) it felt good but it was in size xl and it felt slow in technical part of the track so im looking more in to 27.5 but im afraid it to feel small.. any exp with this here?
    Thank you.

  22. I ride a 29inch Gary fisher paragon and it may be old but I love it! Why do people care so much about weight I’ll never under stand it

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