Stuck between two sizes - L and XL

larkim

If after having ridden both an L and XL in a given bike frame and you're uncertain which feels "better", and that tallies with the manufacturer's guides around height (5"08-6"00 L vs 6"00-6"04 XL for a rider who is 6"00 tall), which would you go for? Spend level is significant (£3k) and the rider is fit, confident and pretty handily skilled as a rider (i.e. it's not me!).

What might be pros and cons of riding a bike which does fit perfectly for either size but is either "bigger" or "smaller" than another bike?

Mad_Malx

Get the smaller. Easier to put a few cm on with stem length and seat setback.

whyamihere

That's good advice for a road bike, potentially less so for a mountain bike. What kind of riding do you do, and what bike is it? For more aggressive riding, you may prefer a bigger bike with a shorter stem, going too long on the stem will make it ride like crap. On the seatpost, you'll often want no setback at all so you can get forward on very steep climbs while keeping traction on the rear wheel.

larkim

Bike on the radar is a Nukeproof Mega 290 Pro, planned to be ridden hard and fast over just about anything. Test ride on both L and XL confirmed it hit the right notes (I'm posting 2nd hand here as the actual purchaser isn't someone who posts on here) and knowing how good he is I'm pretty confident he'll be well suited to the bike after having "made do" with a more trail / XC bike over the last few years (which did get ridden as quickly as he could in Morzine for example). He's got disposable cash of his own now so wants to spend wisely!

The L model is in stock in some places, XL he's not managed to track down since riding last summer at a demo day at Llandegla.

DeVlaeminck

Why get either - if I wasn't satisfied with the fit I'd get a different bike.

larkim

I think the point is he was more than satisfied with the fit of both sizes so looking for a reason to choose one over the other. He's in the overlap point where even Nukeproof would say both would fit. He tested out both sizes on the demo day, but didn't realise how much like hens teeth they would be to buy new.

steve_sordy

More than satisfied with either size?
If he is a weight weenie, then he will know that the XL will weigh more, but he is still uncertain?
Then he needs to get down to the geometry. Take a very close look at the geometry table for the bike and compare with a bike that he is absolutely certain he is a good fit for. Pay attention to stack and reach. Take into account his body shape, trunk length, wingspan and leg length.

I will give an example where studying the geometry can help. I have a normal leg length, but slightly shorter than you would expect for my height. Occasionally this causes a problem with the saddle height on bikes that come with a dropper post. When the dropper was fully inserted and the dropper fully extended, the saddle was 10mm too high for comfort. OK I hear you say, just use the dropper to lower the saddle. Exactly what I did, but the first time I used the dropper on a descent, I realised that I could not find that ideal height first or even the second time when restoring the saddle. Several see-saws later I finally got it - but it was distracting to say the least. What is so hard? Nothing if you are on a level and smooth surface but not otherwise.

That problem caught me out when I bought a YT Capra with a 150mm dropper. It was an internet purchase so no test ride. Fortunately the dropper failed after a few months and I was able to swap it for a 125mm travel dropper. . So maybe he should get a Large instead of an XL?

He can easily make small changes to get a better fit, but increasing stem lengths will reduce the steering response, better to reduce the stem length. So maybe he should get an XL and not an L?

Pushing the saddle back or all the way forward can have quite an impact on how balanced the bike is and can affect climbing, descending, lifting the front wheel etc. But as he is exactly in the middle of the overlap, I doubt that this will cause much of a problem.

Tricky, only he can decide.

larkim

Seems there's no default view! I'm not sure how you get to know whether you are a rider better suited to a precise stack / reach / ETT without spending a *lot* of time on bikes across a range of sizes on trails you know well enough to ride at your limit.

The difficult bit is how you get that experience. The right answer is probably not to over-think it and get the L bike that's in stock. He'll never know if the XL was "better" or "worse"!

I'd guess the world of road bikes, where handling characteristics are probably less intrinsically relevant compared to comfort, fit etc (which can be generated from a bike fit session), is probably an easier one to get an acceptable answer.

mully79

The XL will be more stable as its longer. Better for straight lining everything.

The L will be more fun and nimble. Better for turning, throwing whips and being cool.

Which is faster probably depends on the track.

joeyhalloran

I thought for mountain biking the current thinking was a longer top tube and shorter stem, so should the XL would lend itself to that?

steve_sordy

The whole range will be the same, longer top tube, shorter stem.
Potentially, the XL is already too long and may need things shortening to get a better fit. If the stem is already 30-35mm, then you don't have anywhere to go (or your choice of stem is severely limited). But if the L is potentially too short, then you can easily fit a longer stem.

DeVlaeminck

I still come back to the fit of a bike with a range 5'8"-6" can't be spot on if the next size up is 6'-6'4" is also spot on. They can't both fit perfectly.

steve_sordy

Well, I suppose if I was 6' tall and of the same perfect body proportions as used by the bike designer, then I might find either bike a good fit (I wouldn't go as far as to use the word "perfect"). But, like most of us I suspect, I'm not perfectly proportioned and one bike will feel better than the other. A test ride would decide, but who gets to do one of those these days?

In Nov'16, I found Canyon bikes too short in the Large, but the XL was too tall. At the same time, the Yeti I was looking at was too low in the Medium and too long in the Large. I ended up buying a Large Whyte T130. Now that WAS a perfect fit!

larkim

DeVlaeminck said:

I still come back to the fit of a bike with a range 5'8"-6" can't be spot on if the next size up is 6'-6'4" is also spot on. They can't both fit perfectly.

I do get that (and I'm only talking second hand here). But it's that usual dilemma - you pick a few bikes with a reputation for being what you might want, what you're prepared to pay, what spec they've got, what reviews they've got, what pedigree they've got etc. And boil it down to a smallish number, then test-ride. He's test ridden the other brands / bikes and for whatever reason the Mega 290 was the stand out for him.

Then tried two different sizes and both felt great.

No idea if either or neither or both are perfect, but both were great. But all based on the limitations of being ridden on a specific day on specific trails etc etc. The only way you get better info is to ride many multiples of bikes and sizes and days and conditions and tyre pressures and fork / shock settings and tyre choices and seat post height etc etc etc

And time nor availability of those things means it's simply not possible to get that perfect choice (for him anyway). Plus a rider buying a high end bike who is ambitious to want to ride better probably won't know on day 1 of a test what the bike will be like in their hands in 12 months time when their skills and precision have tuned in with the bike they are riding.

So that's why the question is being asked. I guess the question is more, if you were buying an enduro bike and hoped to progress your riding to extract the most of out if, would there be any advantage to a bike being "a bit big" or a "a bit small" in terms of how a rider will typically progress their skills.

If there's no consensus on what the right answer is, then no risk buying what's available (the L size), if the consensus was "buy big" then the XL would be the right option (and vice versa).

larkim

DeVlaeminck said:

I still come back to the fit of a bike with a range 5'8"-6" can't be spot on if the next size up is 6'-6'4" is also spot on. They can't both fit perfectly.

Unless there are different sizes for literally every height / arm length / torso length / leg length, almost by definition no bike fits perfectly anyway. It's whether you can tune it into a sweet spot surely?