Mountain Bikes by the Numbers: Which ones Matter?

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  • Mountain Bikes by the Numbers: Which ones Matter?
  • Premier Icon coolhandluke
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    Rorschach
    Member

    [video]http://www.youtube.com/watch?v=WrjwaqZfjIY[/video]

    kudos100
    Member

    does anybody think they could tell whether a bike was likely to suit them based just on travel, wheel size, head angle, BB height and chainstay length?

    Yes, it is how I choose my bikes.

    Rorschach
    Member

    If you added anti squat/pedal kickback and leverage graphs to your list numbers you’d still not know how it rode.

    slackalice
    Member

    Pantone 🙂

    Premier Icon jairaj
    Subscriber

    There are so many variables on a bike frame and its a constant balancing act. Change one thing on the bike and it will have an effect else where on the bike. hard to tell how it will feel just by looking at a few numbers.

    I go on what the bike is designed for and forget the numbers. I’ve ridden short travel bikes that descended better than a long travel bike and I’ve ridden slack head angled bikes that go up hill better than a steep head angled bike.

    You can’t test them all but you can do some research and narrow the choices down to a short list and try some of them out. If you try a handful of bikes and find one that really hits the spot, just go for it.

    There maybe a bike out there somewhere that might be a bit better but if you’re having fun on your current bike who cares? You’re not going to demo the other bike (otherwise you already would have) so you’re not going to know its better. As far as you’re concerned your bike is the best for your needs.

    Premier Icon roverpig
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    Interesting responses. Thanks.

    When it comes to road bikes I’m pretty confident that I can tell how a bike will ride without having to ride it. Or, at least, I can pick a bike based on the specs and know that it will suit me and that the differences between it and any other similar road bike are so small as not to matter to me. There is a standard design template and it’s pretty easy to tell what a few degrees here or there on the angles or a few centimetres here or there on the chainstays or head tube will do to he ride. But it seems much harder to do that with mountain bikes. There seems to be much less consensus amongst manufacturers as to the optimum set of numbers and less interest from buyers in the numbers.

    Funnily enough, is an awful lot of discussion about some aspects (wheel size and rear suspension design being obvious examples) but no interest in others. Instead we have this ever expanding list of confusing and overlapping categories of bike to choose from (XC, Trail, Enduro, All Mountain etc), which are probably just marketing short hand for a range of numbers.

    Premier Icon roverpig
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    I know some folk say that you should ignore the numbers and just ride a bike to see what it’s like. But there are a few problems with that approach. First, life is too short to test all possible bikes and second some of us just aren’t that good at telling how a bike will perform from a (short) test ride and often just end up testing the tyres and contact points rather than the bike.

    I reckon that, in theory at least, it should be possible to predict how a bike will perform from the numbers. Given that most bikes are pretty good these days then the numbers should tell you whether it is the right type of bike for your needs. But which are the numbers that matter most on a mountain bike? For example, does anybody think they could tell whether a bike was likely to suit them based just on travel, wheel size, head angle, BB height and chainstay length? I’m assuming that you can pick a size to fit and tweak things like bar, stem, saddle to suit.

    Euro
    Member

    Only number that counts is two.

    Only number that counts is 29

    Rorschach
    Member

    Either 42
    OR
    3 (cos it’s magic).

    Premier Icon jam bo
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    Only number that counts is 29

    I didn’t realise they were doing 13spd cassettes already.

    Euro
    Member

    I was trying to be deep and you baskets ruined it

    Premier Icon roverpig
    Subscriber

    Pondering my own question (bad form I know) about why it is that I can predict how a road bike will behave from the numbers, but find it harder on an MTB, I decided there were three factors at work.

    1. MTBs are a much more recent “invention” than road bikes, so there hasn’t been as much time for everyone to agree on the ideal compromise.

    2. The ruling bodies for the race scene are not as strict. Like it or not, manufacturers use the race scene to sell their bikes, so if you aren’t allowed to race on it then you don’t bother making it. If, for example, the bodies that govern the race scene had ruled that all entrants mush be on 26″ wheels we’d never have seen the emergence of the 29er.

    3. The terrain is much more varied so it isn’t clear that there is really any one set of “ideal” numbers. For example, we all want to be able to lift the front wheel at will, but we don’t want it popping up when it’s not wanted. So, we see a constant see-sawing of chainstay length and wheelbase.

    wordnumb
    Member

    Pantone

    Yes, but which shade of red goes fastest?

    soobalias
    Member

    davidtaylforth – Member
    Only number that counts is 2×9

    fo shizzle.

    Premier Icon unklehomered
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    For what? How fast it goes? You need three numbers – R B G 😉

    Premier Icon mikewsmith
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    No it can give you an idea. For a start half measure static and the other half sagged. Then some use a specific fork length which is different to others or suits the marketing bs they are appealing too.

    Take it as a indication but nothing more.

    Premier Icon stevied
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    I didn’t realise they were doing 13spd cassettes already.

    don’t think 29 is divisible by 13?? 😉

    I just chose a bike I liked the look/price of and went from there..

    robhughes
    Member

    Yes, but which shade of red goes fastest?

    Do be soft.We all know white bikes are quicker. 🙂

    Premier Icon stilltortoise
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    I know some folk say that you should ignore the numbers and just ride a bike to see what it’s like. But there are a few problems with that approach. First, life is too short to test all possible bikes

    I’ve been saying this until I’m blue in the face

    Premier Icon nickc
    Subscriber

    No it’s not, and to claim that you do it with road bikes is bollox as well.

    You can say how they “should” behave, but there just too many variables than just the numbers, material, how it’s put together, quality. Tube shape and size, pivot placement, bearing/pivot choice, and on and on….

    You could maybe use it to narrow down your search criteria ( 4 bar full sussers that would fit me) but to try to predict how it will ride is folly

    Premier Icon roverpig
    Subscriber

    You are right in theory but, at least for road bikes, none of that matters. I know exactly what numbers work for me on a road bike. I jolly well should do after 40 years. Obviously it is possible to make a crap bike with my preferred geometry, but as long as I buy from a reputable company that isn’t going to happen in practice. So, I can talk to a custom builder or buy from a catalogue and be pretty confident that the bike will suit my needs.

    Mind you, I’ve spent a lot of time reading stuff like this over the years:

    mike-burrows-bicycle-design

    Personally and I’m clearly in a small minority here, I’m sure that I can come up with a similar set of numbers that will work for me off-road as well. I’ve tested quite a few bikes and personally I think that most of the stuff people obsess about is frankly, to use your term, bollox. All modern full-suss trail bikes from half decent manufacturers with 26″ wheels, 120mm of travel and a 69 degree head angle (120/69), to pick a random example, will perform pretty much equivalently out on the trail. Yes, if you want to get really picky, you could detect differences between them, but these differences really don’t matter in practice (at least not to me). Switch to a 100/72 or a 140/67 bike, however, and you’ve got a whole different set of compromises to deal with.

    So, before you start worrying about suspension design, tube profiles etc, you need to decide on the basics first.

    Premier Icon stilltortoise
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    The terrain is much more varied so it isn’t clear that there is really any one set of “ideal” numbers

    This^

    A road bike is a relatively easy purchase because it’s more about fit than anything else. For many of us the deviation in riding style is relatively small in terms of ideal bike design. Other than the extremes – that most of us would buy a different bike for anyway – one bike can fulfil an awful lot of road biking requirements without being a big compromise on any one of them.

    Mountain biking is as much about skill than fitness when it comes to accepting compromise. The Santa Cruz boys or Chris Akrigg can ride the Holy Grail 140mm full susser at speeds and on terrain most of us would want a downhill bike or lightweight XC whippet for. For mere mortals who rely more on the bike than on skill, the compromises are easy to pick up on. This makes picking the right bike more nerve-wracking.

    Premier Icon nickc
    Subscriber

    Define basics? Saddle? Handlebars? Tube profile, weight?

    As a for instance my Principia RS6 has the most evil looking triangular alloy seatstays, it looks like it should be a stiff old ride….but it’s not…and the numbers won’t ever tell you that…*

    * mostly as rear comfort is all about the top tube…. But the numbers still won’t tell you that.

    You can use numbers to eliminate the outliers, but the closer in you get, the less information they actually give you

    IA
    Member

    For me, being of a lanky persuasion, the ETT number matters the most.

    It’s a good initial filter for “is it long enough to pedal comfortably”.

    I look at the largest size, see if it’s about long enough, and this is enough to discount most bikes.

    Effective Top tube is a very handy guide, but you have to bear in mind the seat tube angle~ frames with slacker seat angles may have a seemingly long ETT, but the BB position means the reach may be far shorter than expected, leading to toe rub.

    Going back to the OP, when choosing a frame, I generally have a comprehensive look at the geometry chart, though as already mentioned, there is no standardized system of how figures are measured.

    It gives you a good idea of how the bike will ride, but ultimately the numbers only tell half the story; being as there are so many interacting parts in the dynamic structure of a frame, a bike with all the right numbers may fail to make the grade due to factors such as lateral flex in the back end, an overly harsh ride, or a ropey suspension curve, that you couldn’t diagnose from pure objective figures.

    Premier Icon roverpig
    Subscriber

    As a for instance my Principia RS6 has the most evil looking triangular alloy seatstays, it looks like it should be a stiff old ride….but it’s not…and the numbers won’t ever tell you that…*

    I think you are confusing two things here. I’m saying that I could tell how the RS6 rides based on the numbers, not how it looks. By the way, I used to ride an RS6 and now ride a Rex and an RSL-AS, all of which behaved exactly as I’d expect them to. But then I never expected the stiffness of the frame to have much effect on the stiffness of the ride. I like Principia frames because they are very stiff, light and the geometry suits me. Then I fit the wheels, bars, saddle etc that I want to get the ride I like.

    Premier Icon roverpig
    Subscriber

    a bike with all the right numbers may fail to make the grade due to factors such as lateral flex in the back end, an overly harsh ride, or a ropey suspension curve, that you couldn’t diagnose from pure objective figures.

    Why not? Surely they are all things that are measurable. Isn’t it just a case that you are not being provided with the numbers that really matter (and are being bombarded with a mass of numbers that don’t)?

    Premier Icon stilltortoise
    Subscriber

    Surely they are all things that are measurable

    I can see where you’re coming from with this, but will it make bike buying too technical and complicated for the largest part of the market?

    Take suspension. Fox, Rockshox etc could quote spring rates and the frame manufacturers could quantify that in terms of leverage ratios and damping, but most punters need that demystifying to mean something practical. Is it therefore worth it for the bike companies to go to that trouble for the small part of the market who can usefully interpret it?

    Why not? Surely they are all things that are measurable. Isn’t it just a case that you are not being provided with the numbers that really matter (and are being bombarded with a mass of numbers that don’t)?

    I honestly don’t think you could ever give a complete breakdown of a bikes ride qualities simply through numbers~ for example, even if you did give figures for lateral stiffness, it wouldn’t give the full picture… you could have 10 bikes with the same figure on paper, but all with flex originating from a different point.

    Even if you were presented with a full animated simulation of various bikes characteristics, though you could perhaps predict some of the nuances of their ride characteristics, with so much varied terrain and conditions, you still don’t really know how they ride because you are not engaging the relevant stimulus (senses far beyond the 5 we were taught in school) to feel the reality (and FUN!!) of it.

    Premier Icon jamj1974
    Subscriber

    11. How much fun am I getting on a scale of 1-10
    11. How much I am enjoying the company I’m with on a scale of 1-10
    Infinity. How many miles there should be left when the above two scores are 11.
    0. The amount of miles left to ride when I realise I am totally knackered.
    10. The age I feel when I am having a great time on the bike!
    0. The amount of miles left when I am too physically unfit to ride in my old age.

    These are the only numbers that matter to me…

Viewing 33 posts - 1 through 33 (of 33 total)

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