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Want to know what SIZE bike to get? READ THIS.

supersonicsupersonic Posts: 82,708 Lives Here
edited September 2012 in MTB buying advice
A lot of people have been asking lately about what bike size they need for a given height. Unfortunately there is no set answer, just a rough correlation betweeen sizing and height. The reason is that the measurement the manufacturers give, ie 18inch, is just one out of many: the seat tube length from the bottom bracket axle. Arguably the top tube length is more important as that gives you the reach. Of course you need adequate standover clearance, and here we have another factor - your inside leg. Add to this that some manufacturers measure the seat tube in different ways, bottom bracket heights can vary by 3 or 4 inches, seat tubes may be extended, the top tubes bent for clearence, and of course some bikes are designed for different purposes! So a 17inch frame may be fine for a 5ft 6in person, AND his 6ft 2in brother given how they ride and their preferences.

So, what to do? Unless you know what youi want and what the numbers mean, TEST THEM. They vary from model to model, you will notice that a variety of bikes at different sizes will feel ok. Try not to get fixated on the number or size, go with instinct, advice from the shop and what feels best.
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  • nicklousenicklouse Posts: 50,675 Lives Here
    Frame size is more of a marketing tool and is only useful when comparing one brands frame to the next up or down in size.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
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  • scratscrat Posts: 25
    Yes you must go and test. Even if it means a 300 mile drive.

    What is the min standover clearance you should have for 'proper' mountain biking. I've heard many differant figures from 2 - 6".
  • supersonicsupersonic Posts: 82,708 Lives Here
    Again, what feels best for you and your riding! I would say a minimum of one or two inches - you may prefer more for extra manoevrabilty, and of course jumpers and DHers do. Roadies may just have an inch. Remember to pay attention to the reach, as smaller frame sizes usually have shorter top tubes (not all though).
  • silly lilysilly lily Posts: 505
    So, in summary, the original post says 'Go and test the bike'.... how does that justify the title of this topic??
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  • BlackSpurBlackSpur Posts: 4,228
    It stops people posting topics about what size bike to get - they will see this one and read it, getting the same info they would get if they posted their own topic without SS or someone else having to waste their time repeating the same story over and over.
    "Melancholy is incompatible with bicycling." ~James E. Starrs
  • supersonicsupersonic Posts: 82,708 Lives Here
    silly lily wrote:
    So, in summary, the original post says 'Go and test the bike'.... how does that justify the title of this topic??

    It tells them why they need to test it. And not go on someone saying, 'yeah, you are 5 foot 10, need an 18inch frame'.
  • silly lilysilly lily Posts: 505
    supersonic wrote:

    It tells them why they need to test it. And not go on someone saying, 'yeah, you are 5 foot 10, need an 18inch frame'.

    In that case, surely, why not title the post as such?? I.e Why you need to test a bike for size? Rather than get people under the impression that they'll actually get to read a size chart or whatever. Misleading.
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  • supersonicsupersonic Posts: 82,708 Lives Here
    Because it specifically relates to the number of questions that have been entitled "what size bike do I get?". I think it is more likely to be seen and read if done this way I feel.

    I don't mention anything about charts.
  • passoutpassout Posts: 4,425
    I'm disappointed, no body has told me what size bike to get!
    'Happiness serves hardly any other purpose than to make unhappiness possible' Marcel Proust.
  • supersonicsupersonic Posts: 82,708 Lives Here
  • passoutpassout Posts: 4,425
    Cheers - will do.
    'Happiness serves hardly any other purpose than to make unhappiness possible' Marcel Proust.
  • clarksonclarkson Posts: 1,641
    supersonic wrote:
    Medium ;-)

    lol, typical blokes response to anything!! :D:D
    I said hit the brakes not the tree!!

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  • supersonicsupersonic Posts: 82,708 Lives Here
    Lol, I usually add an inch or two when asked hehe
  • LordBanksLordBanks Posts: 358
    What about if you just want to buy a frame??

    How do you test ride one on those???

    hmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm??????????????/ :twisted:
  • supersonicsupersonic Posts: 82,708 Lives Here
    Usually people who are just buying frames are fairly experienced cyclists, and understand the geometry and their needs, and what to look for.
  • There was a fashion a while back for smaller frames for the XC racers - don't know whether it is still the case. My frame is probably too small for me (6'4") by conventional standards but a long stem (130mm with flat bars) and seatpost set high mean it is fine.

    Smaller frames seem to be that little bit stiffer and more manouverable, but that might just be me. Seems to be the case for road bikes too, they all ride compact frames but I guess it's just what is comfortable.
  • This should confuse you but demonstrate nicely the "whatever suits your body and style of riding" comment.

    http://www.on-one-shop.co.uk/?page_id=940

    I recon length of TT is more important than actual frame size.
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  • Some frames are sized SM/MED/LRG. What is this equivalent to in inches?

    cheers :D
  • Once upon a time i was told the best way to get a rough frame size is to do the following

    measure your inside leg

    then take away 10 inches (the average height for the bottom bracket

    the take away 3 inches (the clearence your looking fore been your love tackle and the crossbar)
  • supersonicsupersonic Posts: 82,708 Lives Here
    Which works for clearance (sometimes!). Average BB height is a bit more than that though, and varies with fork length and suspension travel. It doesn't give you any info about reach, nor does S/M/l (apart from you know one is bigger than the other!)
  • Stand astride the top tube with the front of the saddle touching you. If you can't fit your fist between your knackers and the bike, it's too big. If you can fit your fist between without touching anything, it's too small. If it just fits so it's touching both your knackers and the top tube snugly, it's just about right.

    Think Goldilocks and the three hairy mountain bikers...
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  • Hi I am looking to purchase a new bike (around £1500) I am 6"8 / 9 on a good day!

    I have been looking around and have been told that Kona and Specialized are the bikes to go for as they tend to come up the biggest.......is this true? I know you recommend testing a bike before you buy which I will but I need to know what ones I should be testing.

    Any help you can give would be much appreciated.
  • supersonicsupersonic Posts: 82,708 Lives Here
    I would say the biggest two of each range - probably the largest to start with.
  • saw this on US forom http://www.factionbikeco.com its a rigid fixie but you won't look overgrown on it when youre down wid ya homiez

    No price on the website - I'll post it up if the local shop moves their censored and gets a testbike in.[/url]
  • daftdaft Posts: 13
    I was told that for my height - 6' 1" - with inside leg around 33", that an 18" or 19" would be perfect for me for XC. Basically the smaller the better. Not sure how much to read into this but the guy is a very experienced MTB enthusiast, rides serious downhill & xc and has a range of bikes, so probably gonna take his word on it. But will test first as per this thread :)
  • supersonicsupersonic Posts: 82,708 Lives Here
    Well he is only half way there. There is no way he can know the geometry of all the bikes you are interested in, only his own. You could be between a 17 and 22!
  • rob08rob08 Posts: 10
    how do you test it is your are buying from the interent?
  • supersonicsupersonic Posts: 82,708 Lives Here
    You can't. Hence why I always recommend, if you are unsure, go to a shop. Internet retailers can guide you, but not quite the same. If you are up on all the geometry numbers, and know what you want, then will get a good idea of what you need. But still won't tell you how it rides.
  • projectsomeprojectsome Posts: 4,478
    LordBanks wrote:
    What about if you just want to buy a frame??

    How do you test ride one on those???

    hmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm??????????????/ :twisted:

    hold it between your legs like one of those wooden mop horses and gallop around the store.
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  • :? It can be difficult to get a proper feel from a bike at the LBS without riding the track...

    Can anyone give geometry advice based on pains in the back or loss of circulation in the feet?

    I understand the concept of finding a bike that fits based on the feel regardless of the label. Which is why I am considering going from L to XL or perhaps down to M. I get lower back pain on the longer rides and my feet go numb.

    Do I just need to open a can of harden up? Or will the correct geometry help with comfort? Does the numb feet mean anything to you guys?

    Cheers
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