Help with mountain bike sizing...

Hi,

I'm a long time road cyclist looking to buy my first mountain bike. I'm stuck on sizing and looking for a bit of advice. I'm 6'3" or 191cm with a 35" inseam and ride a size L Cannondale (58cm top tube) which is suited to people 180-193cm . I'm looking at the Vitus Mithique 29 VRX and I'm right on the edge of an L (180-190cm) and an (XL 190 - 201cm).

I know with a road bike it'd be quite easy to say get an L and buy a longer stem if needed but I'm not sure what the deal is with mtb's so any advice is appreciated!

Cheers

Get an XL.

Mtb sizing is all over the shop but it will piss you off no end if it’s too short and too low.

Recently discussed in the mtb thread

Ah cheers, will check the thread out now.

That's it in a nutshell.

@alxwtn Just had a look at the geometry, of that and my bike. The Vitus isn't as long and the seat tube is a bit steeper, if you've got a long trunk you might find the XL a little small.

My trunk is about 64cm/25inches...not sure if that is long or not tbh. What sort of reach should I be looking for in a mtb?
The XL Virus has a reach of 484, MBR.co.uk size guide recommends if you're 6′ 2″ to 6′ 6″ then you should aim for a reach of 470mm to 510mm. Does that seem about right?

With each successive iteration of a model the geometry seems to get longer - and the head angle slacker, BB lower and seat tube steeper.

I'm 187cm, ride a 56cm road bike and for my return to MTB'ing I bought a Large - on reflection I should have got an XL, but I've very much enjoyed my bike nonetheless.

My new MTB has a reach of 503mm for reference (it's an XL).

So the XL vitus does look like it could be a little small if anything... would a longer stem work as a solution or would getting one long enough change the handling too much? Looks like a good beginner bike for the price so it'd be a shame if it wasn't suitable as I don't want to spend more.

The trend is for shorter and shorter stems, also - the goal being (I believe, but mind you I'm relatively new to modern MTB) is to get you behind the bars, centred on the bike.

Pace say that the XL I'm waiting for is for riders 6'-6'4", and I'm roughly in the middle of that band.

How long has the specific model of Vitus that you are looking at been available?

Norco have released the Optic recently, it's a trail bike that got a lot of great reviews, here's the rider size chart:

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And here's the geo of an XL:

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Here's a review of the Vitus, the 5'11' tester is on an L to get the reach that he wants, but has issues with saddle height: https://www.mbr.co.uk/reviews/full-suspension-bikes/vitus-mythique

Mountain bike sizing is all over the shop.

My bike has a 476mm reach (but the seat tube is fairly slack by modern standards) and I'm 6'2", and is the right size for me, but I generally prefer a smaller bike. I've got a trunk of about 74cm for reference. If I were you I'd get the xl, but make sure you can fit that dropper in.

The reviewers issue with the saddle height - my 150mm dropper fits exactly in my frame, and cannot go any lower because of the pivot.

Stem length-the way of thinking now is that where your hands are on the bars should intersect the steerer tube axis, 45mm wouldn't be long enough for me as I like the bars rolled back.

If you're unsure don't drop all that cash and just just wait until you find something you're happy with .

Also should add that in not what I'd consider broad, and ride 800mm bars. And for comparison with @Dammit I also a 56cm road bike.

Another data point, my current bike (L Cannondale Scalpel SE) has a reach of 442mm, I've got a 60mm stem with the bars rolled forward to give me more length, but combined with the relatively slack seat tube angle even with the seat all the way forward on the rails you have to (literally) lie over the bars to keep the front wheel down on steep climbs. Guess why I think I should have picked the XL, although tbf it's only got 8mm more reach.

My new bike is 60mm longer on the top tube, but the stem is 32mm.

On my 56cm road bikes I'll run a 120 or 130mm stem.

Cheers guys, really appreciate all the info. I'm gonna have to do some maths because one minute I think the XL will be fine and the other I'm not so sure...

The mbr review is an interesting one. Seems to be mixed overall. I appreciate the negative points but presumably, at this price range there are always going to be a few issues here and there. The general consensus of other reviews I've read or watched on youtube seem to be pretty promising overall.

Ideally, I'd go and try a few out because I have zero experience with mtb's but unfortunately my gf's dad is in the high-risk category so were trying to avoid any unnecessary trips out to shops at the moment.

I don't know where you are but some bike hire places (situated at trail centres) are open again, I noticed that Quench is hiring bikes at Bedgebury for e.g.

You could take a look at what's near you, see what stock they have and what size it is and potentially hire one or two bikes (maybe back-to-back) of different sizes/geometries.

That way you could ride them in a way that no shop would allow for a test ride (unless they have a demo fleet, which tends to be the high value stuff).

Swinley is back open, not sure the bike hire is, but they have a Marin there.

Is there any reason why you're going with Vitus? Other than the value for money?

Value for money mostly plus I like the colour scheme more than other bikes in the range.
Initially I was going to go for a better spec hardtail but I already have a gravel bike so want to have something the other end of the scale to play with. Also, kids are on the horizon in the next year or so and I figure now is my chance to try a full suspension bike before I'm skint for a while....or the rest of my life.

Think about where you want to ride this - if you size it up so you’re stretched out like on a road bike, it might end up uncomfortable on rough stuff where a shorter frame will be better. You don’t want loads of drop to the handlebars if you’re planning to ride it down steep hills or over moguls etc especially if you’re likely to be riding out the saddle a lot.

As others have said, merterber sizing is all over the place and you either need to take a tape measure to a frame or really be able to eyeball the geometry to decide what you’re going to get.

To be honest it'd mainly be around Richmond park, Surrey hills and the odd trip to Swinley Forest...went for a walk there for the first time at the weekend and now I'm even more desperate for a mtb!

Looking at the geometry of the vitus again, it seems the 27 version has a longer reach (492 v 484) than the 29 version and a lower BB drop (18.78cm v 28.74cm) so maybe the geometry of that would be better and slightly less flexible as mentioned in the MBR review...I'd just planned to go for the 29 as from what I've read those wheels would be more suitable but now I'm having second thoughts.

Well, I went ahead and got the XL Mythique VRX and it arrived on Monday.
The size feels fine but holy crap does riding a fs mtb feel weird after 10 years on a road bike! I'm going to give the 800mm bars a chance but I think I'd like to cut a few cm off eventually. I need to figure out my position a bit too, for some reason I keep ending up with my foot too far up the pedal when climbing. Also, the dropper fits right down into the frame on the XL but it isn't high enough when fully extended, I can pull some of the seatpost out but then when it's dropped it isn't as low as it could be. I'm wondering if one with more drop might be useful in the future...

That aside, it's great fun! I almost feel like I'm learning to ride all over again.

So I've been riding this over the last few months and although it's more comfortable than before it still doesn't feel quite right.

The main issue seems to be that the saddle is set as far back as possible but my knee is still a bit too far forward when the crank is at 3 o'clock and I don't feel like I'm pedalling very efficiently. To have my saddle as high as I'd like it, and for me to stretch my leg properly when pedalling, it has to be so high that I can barely touch the ground when stopped and have to hop off. I've made sure the shock pressure is correct but I just feel I'm losing a lot of power. Is that just how as fs mtb should be? Am I just trying to get my bike to fit like a road bike?

It's still fun, but there is part of me wanting to try a hardtail to see if that's more what I'm after.