M8 is 5’6 or so and currently rides a medium spesh, & has been offered a newer model large spesh. He’s got it on loan for a short while, so we went out last night for a short run (he doesn’t normal night ride). I’m 6′ odd and it fitted me very happily, he has bugger all standover, but was happy with it after a test ride. Admittedly he did feel it was slower in the twisty bits, but it wasn’t the simple yay or nay outcome we both expected. He’s probably gunna buy it now & decide which to keep after a few more runs (decent price & nice level of kit, if very used).
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I’m not asking for advise on whether you think it’s right for him, more interest if anyone else has gone against the percieved sizing advice, that you should get the smallest frame that fits, rather than a larger one..

I had Inbred’s in 18 and 20 and always felt happier on the bigger one. I was right in the middle of the sizing mind you

the 1980s called – they want their sizing guide back …. at 5ft 6 there is no way he should be on a large – is his seat strapped to the top tube and his stem sitting directly ontop of his steerer !

he is the same size as my missus who could never ride my large framed bikes propperly ! (she has mediums)

I’m a shortarse

he has bugger all standover

This would scare me, even on an xc race bike, it’s nice to be able to get a foot down on uneven ground!

😀 admittedly I’m guessing at his height, looking down on @ wee ppl makes it difficult to guess-timate 😉
His seat wasn’t on the TT, and I was the first to say it’s too big, you won’t be right. I’ve only ever tried smaller frames, and simply know when it too small, never been in this position ( though I’ve alway fancied trying a 20″ inbred over my 18)

I’d seriously advise against your mate taking that bike. I find a Spesh large size bike is quite nice for me and I’m 6ft3in (right on the cross between L and XL). Slightly OT, but I’ve just swapped my old Heckler for a Prophet for the longer top tube, but they both the same size frame though (19″ seattube/L). I don’t know what the bike/frame your talking about, but maybe quite different geo between the newer and old bike?

Im 175cm (just over 5′ 9″) and ride a large Santa Cruz Chameleon (600mm top tube) with a 90mm stem. I much prefer it to my medium cannondale I had previously that had a 580mm top tube which is more conventional for medium sizing.

My road bike too is a size larger, 56cm Cervelo with a 565mm top tube and 110mm stem. 54cm road frames are just too short, my old Giant had a 545mm top tube and even with a 120mm stem was causing lower back problems from being hunched up.

Zippy I think you’ve got a good point with the question you pose.

There has been a real fashion in the past to buy not just the smallest bike that fits, but often the smallest bike you can get away with. It sometimes seemed like people would be buying 16″ frames with 22″ top tubes regardless of their own dimensions just because that’s what the Pro’s rode.

Personally I think that a lot of people end up on bikes that are too small for them and they then end up struggling to get their weight balance right or find themselves cramped on the climbs.

Having said all that, the whole sizing thing for mountain bikes is ridiculous anyway. The terms small, medium and large might as well be substituted with red, green and blue.

What size would sir like?

Oh I’ll have a blue one thanks.

The reach and stack measurments have gone some way to make size measurements more meaningful but it’s going to take time before we all understand what it really means.

Seat tube of 17″ on a medium? Yep, so what? When did the ST measurment ever make the slightest difference to how a bike handles or feels in terms of size?

Horizontal Top Tube measurement of 23″? OK we’re getting closer to something meaningful, but raise your saddle or drop your saddle and what happens to the horizontal TT measurement? Yes, that’s right, it changes!

Wheelbase on a medium vs. wheelbase on a large, oh hang on, another change! So a medium will ride differently to a large then. The bike will have a different balance point, different weight distribution, will corner differnetly and so and so on…….

Bike sizing is a mess. It’s all fecked up. Why don’t chainstays change with bike size for example? That way we’d have bikes that had constant wheelbases and constant balance points between sizes. Who needs an 18″ seat tube either? I’m 6ft tall and my ST measures 15″ for crap’s sake with a 23.5″ horizontal TT and 45.5″ WB, but that’s because I was able to specify how long I wanted.

OK rant over……

raise your saddle or drop your saddle and what happens to the horizontal TT measurement? Yes, that’s right, it changes!

does it? how so.

With the saddle higher your weight is further back, effectively increasing the TT measurement. True it doesn’t change if you simply draw a line from the top of the headtube to it’s intersection with the top of the seat tube, but that’s not what the rider ‘feels’.

It’s why the ‘reach’ measurement is more meaningful as it reflects how ‘long’ the cockpit feels regardless of where the rider is on the bike, i.e. are they sat down seat up or crouching with the saddle down.