Advertisement
If you have a new account but are having problems posting or verifying your account, please email us on hello@boards.ie for help. Thanks :)
Hello all! Please ensure that you are posting a new thread or question in the appropriate forum. The Feedback forum is overwhelmed with questions that are having to be moved elsewhere. If you need help to verify your account contact hello@boards.ie

Bike Sizing

Options
  • 06-05-2020 1:25pm
    #1
    ckeng
    Registered Users Posts: 71 ✭✭


    Hello all,

    Quick question re: bike sizing/fitting. Would you be safe enough ordering a bike online using the manufacturer's sizing chart/app? I'd prefer to go bricks and mortar but I don't think my LBS is open in any capacity. Just reading Wailin's thread with interest which is in a similar vein - the two different Merida size charts give me some pause.


Comments

  • Options
    #2
    Tony04
    Registered Users Posts: 646 ✭✭✭Tony04


    ckeng wrote: »
    Hello all,

    Quick question re: bike sizing/fitting. Would you be safe enough ordering a bike online using the manufacturer's sizing chart/app? I'd prefer to go bricks and mortar but I don't think my LBS is open in any capacity. Just reading Wailin's thread with interest which is in a similar vein - the two different Merida size charts give me some pause.
    You can do just as good a job measuring yourself as any bike shop. And as long as you give the sizing some taught you should be fine. You can always use an old bike/friends bike to compare sizes/geometry.


  • Options
    #3
    magicbastarder
    Moderators, Category Moderators, Arts Moderators, Sports Moderators Posts: 49,580 CMod ✭✭✭✭magicbastarder


    it makes it sound more complicated, but in essence the bike geometry parameters you should be most interested in boil down to stack and reach. it's a distillation of how tall the bike is, and how long it is.


  • Options
    #4
    ckeng
    Registered Users Posts: 71 ✭✭ckeng


    Cheers lads, it seemed straightforward enough, but better to confirm before dropping any cash.

    On the gravel bikes, Trek has me at a 54 which matches up with my old Trek road bike. Cube puts me at 53 or 56, depending on which chart I use. Giant put me at the top end of small or the bottom end of medium and Merida have me in a small. So I guess they're reasonably consistent,no?

    Everything seems scarce enough, it should be a golden age of second hand bike sales in about 6 months


  • Options
    #5
    magicbastarder
    Moderators, Category Moderators, Arts Moderators, Sports Moderators Posts: 49,580 CMod ✭✭✭✭magicbastarder


    bike sizing used to be predictable when top tubes were horizontal. when they're sloping, there's many ways of skinning a cat, hence the benefit of stack and reach, which don't depend on how the tubes meet, they just take two main reference points and measure the distances between them horizontally and vertically.


  • Options
    #6
    ckeng
    Registered Users Posts: 71 ✭✭ckeng


    magicbastarder wrote: »
    bike sizing used to be predictable when top tubes were horizontal. when they're sloping, there's many ways of skinning a cat, hence the benefit of stack and reach, which don't depend on how the tubes meet, they just take two main reference points and measure the distances between them horizontally and vertically.

    Ah, got it now, your previous stack and reach comment went entirely over my head -my fault, I was skimming it while on a work call. You really couldn't have been any more clear.


  • Advertisement
  • Options
    #7
    dinneenp
    Registered Users Posts: 8,138 ✭✭✭dinneenp


    I'd advise phoning the company, giving them your height, inner leg etc. get their recommendations.
    Also ask them re the confusion over 2 Merida sizing charts


  • Options
    #8
    cletus
    Registered Users Posts: 7,997 ✭✭✭cletus


    magicbastarder wrote: »
    bike sizing used to be predictable when top tubes were horizontal. when they're sloping, there's many ways of skinning a cat, hence the benefit of stack and reach, which don't depend on how the tubes meet, they just take two main reference points and measure the distances between them horizontally and vertically.

    I'm going to jump in here, and ask some (possibly stupid) questions.

    How would I use stack and reach in determining the frame size of a new bike?

    Could I use stack and reach to establish that my current frame size is correct?


  • Options
    #9
    joey100
    Registered Users Posts: 3,425 ✭✭✭joey100


    https://geometrygeeks.bike/

    That's a great site for comparing bike sizing. Stack and Reach definitely the way to measure. But stack is usually measured on the frame so any headset caps and spacers have to be taken into account too when your measuring. Same as reach, need to take into account the reach of your current stem, and also the reach on your bars. Some bars will be 85mm and some 70mm, that's a fair difference. So even though the stack and reach may not be the exact same between different bikes you may be able to slightly adjust these to get them closer.


  • Options
    #10
    Taxuser1
    Registered Users Posts: 1,691 ✭✭✭Taxuser1


    As long as i'm cycling i still made a mistake - loving the look of the bike before checking for sizing. if you're not looking for the most aero position i think you can get away with making the calculation, as Kelly would say, and buy online. i bought locally and still made a mistake, went a slight fraction too high for the more aero position i wante (frame's on sale on adverts....)


  • Options
    #11
    ckeng
    Registered Users Posts: 71 ✭✭ckeng


    dinneenp wrote: »
    I'd advise phoning the company, giving them your height, inner leg etc. get their recommendations.
    Also ask them re the confusion over 2 Merida sizing charts

    Ah, they're a bit more than I want to spend anyway so I'm not getting hung up on them. Having said that, they do have an online calculator which gave me a sensible answer so I'd be inclined to ignore the charts and go with that.


  • Advertisement
  • Options
    #12
    ckeng
    Registered Users Posts: 71 ✭✭ckeng


    joey100 wrote: »
    https://geometrygeeks.bike/

    That's a great site for comparing bike sizing. Stack and Reach definitely the way to measure. But stack is usually measured on the frame so any headset caps and spacers have to be taken into account too when your measuring. Same as reach, need to take into account the reach of your current stem, and also the reach on your bars. Some bars will be 85mm and some 70mm, that's a fair difference. So even though the stack and reach may not be the exact same between different bikes you may be able to slightly adjust these to get them closer.

    That site cleared up so much confusion. I think by the time I'd done the rounds of the online shops and manufacturers websites I had recommendations of 53, 54, 56, S, S/M and M. Head to head they were all very close to my old road bike.


  • Options
    #13
    Tony04
    Registered Users Posts: 646 ✭✭✭Tony04


    cletus wrote: »
    I'm going to jump in here, and ask some (possibly stupid) questions.

    How would I use stack and reach in determining the frame size of a new bike?

    Could I use stack and reach to establish that my current frame size is correct?

    Firstly the best way to size a bike from a geometry chart is seat tube length but as nowadays most seat tube are not straight etc it's hard to visualise.

    Stack basically is centre of bb in straight line to center of stem so it measures how leaned over the bike you are. So if the stack is lower you are going to have to raise the seat tube more and you going be in a more bent over position, or on a mtb your weights going to be more forward.

    Virtual Top tube length measures centre of seat tube to the centre of headtube, so the length of the bike, stem length also needs to be considered. On all out race bike you would look at a relatively longer top tube to get into an aero position, on an all out fs mtb you would want a shorter top tobe to get your weight back for jumps/steep descents.

    To answer your questions idk exactly how you would calculate the perfect bike size relative to your proportions. You can tell by the feel and look of the bike if it's to big for you or not. If your buying a new bike use the size guide as this is what size bike the designer of it recommends for you. If there is confusion in the reccomended size use the geometry of a previous bike you have rode as a comparison.


Advertisement