- This is the tech follow-up of the GMB video
where I actually tried a bigger wheel in my Scott Genius
where I ran a 29 up front and 27.5 plus in the rear.
If you've not seen that video already,
I would check that out before you watch this.
But also, I've done a video in the past
and we try and add 29s on both front and rear
and 27.5s so lots of different variations here.
Today, I'm talking about running the 29 up front, 27.5 rear
and I'm going to get in some of those stats about the bike.
(jazz electronic remix)
So the Scott Genius is designed to run either size wheel
and all we need to do is flip the chip between the two
to try and keep the angles about the same.
I'm lucky enough to have two pairs of wheels for this bike
and they're both identical, the DT Swiss with an M1825 rim.
Both of them are 30 mill wide so that shouldn't affect
the tire profile too much between the different sizes.
Of course, on the plus, I've actually got a 2.6 inch tire.
On the 29, it's just a 2.4.
So, it's narrower up front
and also not as deep as the rear tire.
It is really easy to swap the wheels
the one's that've got center lock rotor.
So all you need to is whip that off, change it over,
and then change its set.
I've got tires on so it's quite an easy thing to do.
Is it practical to do all the time?
I guess it is.
It's gonna be expensive if you want two pairs of wheels.
(jazz remix)
So the thing you do need to do on the Genius
when you're moving between wheel sizes
is actually flip that chip on that shock linkage.
Super easy to do.
All we do is undo the bolt and then turn 'em around
and put them back in.
And what it does is it keeps the geometry really similar
between the wheel sizes.
So it's 65 degree head angle on the 29 wheels
and it's 65.6 on 27.5.
So when I messed around and put a smaller wheel in the back,
it actually went down to a 64.2 head angle, so pretty slack.
That's getting towards downhill bike, that is.
And the BB went to 332 millimeters.
So for me, that is the biggest compromise
on that setting within the low.
It just felt like it was too low,
I'm gonna start clipping my pedals
on more technical terrain.
So I flipped it over and then I rode it
and it did feel much more balanced
so actually the head angle went back to a 64.8,
so almost 65.
The BB angle, BB height went up to 336.
So it actually only changed four millimeters
but that did make enough difference for me
to make the bike feel like that's how I'd want to ride it
if I was gonna do this setup.
(jazz remix)
So the first geometry values I gave you
are all from the Scott website so they're official numbers.
When it comes to messing around with the wheels,
I'm finding the other numbers.
I've actually used a tape measure
and I've borrowed Dot E's Wixey digital angle gauge.
I don't have one of these
because you need a nerd certificate to get one of these
and I'm afraid I don't have one.
So that does mean the numbers are a little bit approximate
but that is how it feels to me.
The bike does feel a little bit slacker, a little bit lower.
Also, the ride difference does feel...
Basically, you've got more volume in that rear tire
so that does make a difference as I talk about in the video.
It's those little bumps.
So when you're riding over little stones
and edges and things like that,
that bigger volume means it's a bit more compliant
so through my feet, I felt less bumps.
And then, it's the same thing really
with the bigger wheel on the front.
I've got thinner tires so less volume
but the bigger wheel has more rollover.
Like I talked about in the last tech video,
I got the two different tapes out,
show them rolling over that tool.
The bigger tape will actually roll over a little bit easier.
So, that does mean it makes it a little bit easier
on my wrists up front.
What I'm really doing is mixing up
the advantages and disadvantages of both wheels.
So, let's talk about advantages first.
Front wheel, greater rollover.
Real wheel, I've got more compliance
and I've got a bit more grip in certain situations
and it's a lighter wheel than the bigger tire.
Disadvantages, heavier wheel on the front.
And also, when we talk about the actual tread of that tire,
one thing I find on plus tires,
I talk about this quite a lot,
is in the wet, they can float a little bit.
They don't dig in quite as well as a thinner tire does
and on really hard-packed dirt,
you can find that you have to run quite high pressures
otherwise you'll be rolling that tire around quite a lot.
So all in all, is it a good idea to mix them up?
Um, for me, jury is still out.
Today the test was really wet.
While it was still quite grippy,
it was so wet, the mud was so thin.
But I think I need to try it out again
and actually, I think I need to put some times to it.
But on the trail, how much difference did I actually feel?
Surprisingly, not a huge amount, to be honest.
In the past for racing in (mumbles) on a bike like this,
I've actually run a heavier weight tire on the rear
or an insert like a Schwalbe ProCore,
because I find that I more often than not
get punctures on the rear
and also I give that rear wheel a lot of punishment
so I can ding the rim.
So it did feel a little bit like that.
I've got more air volume there
so it just feels like that rear wheel is more protected.
I'm not getting as much feedback through my feet.
It feels slightly heavier even though it's not.
That rear tire and rear wheel setup
is actually lighter than a 29er.
So, I don't know.
It's a hard one to tell, really.
I think I need to test it more, like I said,
but is it actually worth it?
I don't know.
Is it the future of mountain bikes?
Probably not.
The big problem here is the UCI.
So when it comes to racing bikes,
you've got to have the same size wheels front and rear.
Obviously, this isn't a downhill bike,
it doesn't count for that.
You're not gonna race cross-country on it.
And Duro isn't UCI regulated so we could see it,
I'm just not sure if the bike manufacturers
are gonna get on board with it.
So it's been nice to test this out.
Will I keep riding a mountain bike like this?
Probably not, to be honest.
I like this bike on 29 inch wheels,
so I'll be chucking that back on.
I also think it's a bit of a practicality issue
of having spares, so why are you gonna carry
two spare tires everywhere?
Tubes, not so much of an issue.
I'll let you into a little secret here.
26-inch tubes will fit anything.
They'll pump up and fill it so that's not a massive issue
but I think I'm just gonna go back to riding 29.
Leave us your questions, if you've got any down below.
I'm sure you've got some good ones
so what I'll do is I'll try and answer those
in the dirt shed next week.
Also, if you've not seen the original video
of me riding this bike like this, click up there flat one.
Give us a thumbs up if like it and star the video,
and like I say, keep leaving those comments.