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Why do people get bikes too big?

  • 11-01-2022 8:51am
    #1
    Registered Users Posts: 836 ✭✭✭ byrnem31


    Ok, so regardless of covid and people buying any bike they can and ending up with an incorrect size; why do bike staff recommend crazy sizes to customers.

    I would have been fine on a medium defy, yet i was told to get m/l. Then i was told a large tcr was the size i should be looking at if getting one. Yet if a m/l or m defy fits me, (im in between sizes) surely a medium tcr would be perfect as they have a longer reach, more aggressive etc.

    The same goes for a cube. 56 ive been told by a shop but cube recommend a 53. Im 177cm height with 76 cm inside leg.

    And this is not a case of trying to sell me stock thats lying there. Its me ordering it in and waiting a few months for the bike.

    I thought a snug fit on a bike was best.



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Comments

  • Registered Users Posts: 8,014 ✭✭✭ 07Lapierre


    Go to a bike fitter and get a bikefit done? Tell him/her what Brand of bike you intend buying and he/she will determine what size frame is best for you.



  • Registered Users Posts: 3,841 ✭✭✭ MojoMaker


    Cube do size small alright - a 56 in their range is more like a 54 when you look at the geometry charts. Having had a loan of a Propel a few years ago I would say M/L is too big for someone at 177cms. Unless you like a comically short seat post that will annoy you every time you look at the bike, and given the horizontal top tube on a Propel that's a reality.

    M in Giant road bikes all the way up to 180cms. 'Stretch' the bike by adjusting the finishing kit by all means, but never ride a bike too big for you - it's instantly visible on the road and you'll never be truly comfy.



  • Registered Users Posts: 6,807 ✭✭✭ CantGetNoSleep


    Some brands size differently, and some people size differently. I'm about your height or 1cm taller. I've a medium TCR which is perfect (L would be way too big), a 56 Cube which is perfect (and I'm pretty sure Cube would recommend a 56 for 177cm), and needed a smaller stem on a 54 Cannondale CAAD.

    As suggested above a bike fit is a good idea and there are sites where you can compare geometry of different models which are particularly useful in the event that you have a bike which you know is a good fit. A decent bike shop should also be able to help you with sizes though.



  • Registered Users Posts: 1,959 ✭✭✭ VonLuck


    I'm currently trying to figure out the best bike size for me and feel like I'm in between medium/large and large. Out of curiosity I googled bike fitting and see that it can cost about €220! Seems like crazy money to me. Is that right? Maybe it's only intended for professional cyclists...



  • Registered Users Posts: 3,841 ✭✭✭ MojoMaker


    There are quite a few cowboys out there milking the disposable income of middle-aged males on a rush.

    However, the best bike fit I ever had was in the (now-defunct) Bike Hub in Howth - €60 and a brilliant hour well spent fettling and tweaking.



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  • Registered Users Posts: 836 ✭✭✭ byrnem31




  • Registered Users Posts: 836 ✭✭✭ byrnem31



    I also think certain bike makes will fit a person better. I think cube road bikes fit me way better than a giant road bike even if they are both the correct size for me. But that could be just in my head.



  • Registered Users Posts: 3,841 ✭✭✭ MojoMaker


    The same size could have different geometry so that would normally be the case. Also, different brands measure 'size' in different ways - very annoying.



  • Registered Users Posts: 1,959 ✭✭✭ VonLuck


    I'm not very knowledgeable in the area so I'm not confident I'm even sizing myself correctly. I would go to a bike shop directly and get sized, but the cynic in me thinks they'll push me towards the bike size they have in stock, regardless of whether it's the right fit or not.



  • Registered Users Posts: 64 ✭✭ YakerK


    Can't speak for the Giant - but I'm exactly the same height and inside leg as you. I have a 56cm Cube Attain. No way is a 53m big enough, assuming the Atain fits the same way as whatever Cube you are looking at the 53cm would be too small, so reckon the bike shop is right in this case.



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  • Registered Users Posts: 8,014 ✭✭✭ 07Lapierre


    They usually do a "Bike Sizing only" fit which is cheaper.



  • Registered Users Posts: 8,482 ✭✭✭ Macy0161


    Well I'm an M/L (and have been fitted) on Giant Defy Disc. My TCR Advanced is also M/L, but LBS fitted a shorter stem to match the fitting sheet from the Defy. fwiw, my Topstone is a medium.

    All brands and then models are different, but when looking at bikes I tend to start with the stack and reach figures I got from my bike fit (open to be corrected whether that is the correct approach though).



  • Moderators, Sports Moderators Posts: 43,409 Mod ✭✭✭✭ magicbastarder


    you're better off comparing stack and reach figures rather than whatever the company uses (tea leaf reading, maybe) to settle on to declare it's a 54 or 56or whatever.



  • Registered Users Posts: 6,807 ✭✭✭ CantGetNoSleep


    At different points I've owned a Cube Attain, Nuroad and Peleton and all had a very comfortable geometry



  • Registered Users Posts: 371 ✭✭ Mr. Cats


    I’m one of the middle aged milk herd that had a bike fit at one stage when I was thinking of buying a TCR. I’m 182cm & fitter recommended a M/L. I’ve a Cube Attain and it’s a 58 and fits perfectly. I’m a 56 in almost all other makes.

    As someone mentioned above, look at the reach and stack. If you use https://geometrygeeks.bike/ you can compare a bike you know fits with the various sizes in the model you’re looking for. If between sizes, go for lower stack and reach as you can stretch and raise bars with stem and spacers.



  • Registered Users Posts: 3,356 ✭✭✭ joey100


    Pre-bike fitting can be expensive but not as expensive as the bike you are buying. It's nearly a one off purchase too (based on flixibility), once you do it once you get your stack and reach numbers, can then compare to what ever bike you are looking at buying. Means you buy a bike that will fit and probably be more comfortable and perform better than one that looks cool but doesn't really fit. I used to always be on small frames, done a pre bike fit and now on a M TCR, have bought few bikes since based on the numbers provided and they all fit really well. Much better than the small bikes before. The numbers you get at the pre bike fit also means you can set up the new bike to them, so it's really a pre bike fit and a bike fit.

    Stack and reach are the best measurements to use really. Consistent across all bikes, not individual to manufacturer. Take into account stem length, spacer height, bar reach and drop and you should be able to get pretty close to your ideal fit.

    Pre bike fit would be one of the things I'd recommend the most.



  • Registered Users Posts: 1,959 ✭✭✭ VonLuck


    Is it best to go to an independent fitter that don't have any skin in the game, or do bike suppliers like Giant do a decent reliable service?



  • Registered Users Posts: 3,356 ✭✭✭ joey100


    Personally I went with bikefit studio in North county Dublin. He has a jig bike so the changes can be made very quickly. I found the whole process very good. He doesn't sell any bikes so will just give you info on what bike will fit best based on your numbers. When I went I had an idea of the bike and size I was looking at it so he set it up similar to that and we went through it.

    If your a CI member I think there's a voucher in the membership pack for him too. I've never done one with anyone else so can't really compare him to others.



  • Registered Users Posts: 3,281 ✭✭✭ jamesd


    Im 177cm and ride a 53cm cube, had a 56cm and it was too big even with a short stem.



  • Registered Users Posts: 427 ✭✭ ARX


    Don't forget seat tube angle. At my height (184 cm) a 1 degree difference in seat tube angle makes a 14 mm difference in the position of the saddle, all other things being equal.



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  • Registered Users Posts: 8,482 ✭✭✭ Macy0161


    I went to Aidan Hammond, but I already had a bike and it was a good few years ago. No idea does he have a jig (but I'd kinda be surprised if he didn't).



  • Registered Users Posts: 306 ✭✭ MangleBadger


    I have a 56cm Attain and have had 2 bike fits, one with Aidan Hammond and one with BikeFit studio. I'm 178cm and they had no issue with my frame size. Lately I have noticed that I am a bit more comfortable with my hands further back on the bars so thinking I could probably use a shorter stem, or that a smaller frame would have suited me, I think I'm right on the cube cutover.

    I'm currently looking around at what bikes are out there and trying to figure out what size I should get. I've flipped my stem and there are no spacers left under it so I can't go any lower but if I was to move to a bike with a less endurance based geometry how am I to know if I can fit a lower stack etc?



  • Registered Users Posts: 427 ✭✭ ARX




  • Registered Users Posts: 13,472 ✭✭✭✭ loyatemu


    thanks for the info, I'm 173 and Cube's website says I should go with 53 but the shop are saying 56 (current bike is an M but quite different geometry and I've always felt a bit stretched out on it).



  • Registered Users Posts: 3,841 ✭✭✭ MojoMaker


    Shop is way off (IMO).

    Post edited by MojoMaker on


  • Registered Users Posts: 6,437 ✭✭✭ G1032


    Very good question OP. I don't know why manufacturers recommend such big frames. I just don't get it. I have 2 road bikes. First I bought a few years ago and was totally clueless. 58cm Sensa. I'm 182cm tall. Inside leg is 88cm.

    So, ultimately the bike fits. But it's huge. So when I was buying a CAAD12 in 2019 I asked a bike fitter (he fitted me on the Sensa after I bought it) what size to go for. He recommended a 54cm CAAD12. Best recommendation ever. It's perfect. I've a 120mm stem on and it fits perfectly.

    Smaller frame is lighter, stiffer, looks better, nice seat post extension. I just don't understand this push for a big frame.

    I think Cannondale size big. So I reckon a 54cm Cannondale is equivalent to a 56 Sensa (just a hunch - haven't compared geometry). I should really have been sold a 56cm Sensa,but it doesn't seem to be the done thing



  • Registered Users Posts: 2,185 ✭✭✭ SuperBowserWorld




  • Moderators, Sports Moderators Posts: 43,409 Mod ✭✭✭✭ magicbastarder


    that's nuts, i'm probably within a cm of you and no way i'd have considered a 56.

    edit; just to compare - on my 52m equilibrium, stack and reach is 55.8cm and 38cm. 53cm cube agree is 54.4cm and 38.3cm; 56cm is 57.2cm and 39.1cm.

    so reach is the same pretty much between the 52cm genesis and 53cm cube. stack is higher than the cube, but closer to the smaller cube.



  • Registered Users Posts: 13,472 ✭✭✭✭ loyatemu


    it seems to be the perception that Cube frames are "small". Also they're referencing the reach in their sizes and other manufacturers reference the seat tube so difficult to compare.



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  • Registered Users Posts: 3,281 ✭✭✭ jamesd




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