Stack and Reach: Why It's Your Best Friends

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  • TL:DR - bike size said top tube is short, turn out you sit too far forward, by the time you move your saddle back enough to be comfortable, the reach felt too long now.

    Sounds about right. The first bikes I bought were way too long for me, even though the shops reckoned they were the right size. Have to give thanks for LFGSS pointing me towards the Bike Whisperer.

  • This is also true for large frames, they slacken the seat tube making the TT longer but not affecting the reach. One reason they do it is so that they can use common downtube sizes over a few frame sizes, very annoying! As someone who is very tall and doesn't have much setback on my saddle this really limits me on frames that fit well

  • Indeed, not only that but a long steerer can make the frame unstable to ride, Lennard Zinn is the best when it come to making huge bike felt as good as a regular sized one.

  • morgan hasnt posted has he?

    get fucked pint-size

  • Any other calculators out there for stack and reach measurement of current bike?

    Disclaimer: I still dont own a massive spirit level

  • Spirit levels are a useful tools in the house, your house must be crooked.

  • Cervelo demonstrated how the geometry of many manufacturers frames move the headtube relative to the BB in a completely inconsistent way as frame sizes change.

    Bloody hell - this diagram just gave me a headache :/

  • Excellent tx Ed :)

    Shortarse here needs a setback for her 49x51 Ciocc...too much weight on my hands atm. No toe overlap though with 700C on such a tiny frame.

    But the way to get there was to move the front wheel forward and seat tube more "vertical" which means more set back is needed. However vintage seatposts/saddles don't offer this, so a cheap modern one is needed.

  • Would any women of circa 5'6 care to share their stack and reach requirements? I'm trying to get a rough estimate for my wife, so she knows what size frame to look for broadly.

  • Trying out some bicycles in a shop would be better, 54/56cm (medium/large) would be a start.

  • Would any women of circa 5'6 care to share their stack and reach requirements? I'm trying to get a rough estimate for my wife, so she knows what size frame to look for broadly.

    Or get a measuring tape out and actually measure her, plug the values into this calculator, and get some frame size options back:­catalog/fitCalculatorBike.jsp

    I'm 5'4", one of my bikes is "medium", one is "small", one is "extra small", etc. I don't think I own any that are the same size as each other (though they all fit (mostly))

  • Best way to calculate stack and reach if a regular geo chart is published?

  • The graph a few posts up has a formula for estimating reach when not specified as a starting point...

  • Thank you!

    Geo chart 1:­yg/­g
    In size 54 I am getting stack and reach 534mm and 382mm

    Geo chart 2:­u=lf%2B4znVnFEYUw3Xf%2FT4rmMUsBkchq%2BuO­E1isoRDjy3P5nGTiOkQdGOCgv0APMFvSxdu7Bz9Q­bzNvv4%2Bsu%2BYvN0gqw%2B9a3maH1brTUX37A%­2BQgEgzF75oMuU7a%2BAE%3D&b=1
    In size 54 I am getting stack and reach 532mm and 387mm

    Although in the second chart they have published the stack and reach and the diff is substantial to what the spreadsheet is saying ..

  • Will putting measurements in BikeCAD and reverse engineer stack and reach be more accurate than that spreadsheet?

  • Comparing my old track frame which is a 60 (traditional geo) to a modern cx bike which is 58; the stack of both frames are very close (7mm longer on the cx bike) but the reach is different (30mm shorter on the cx bike). Would the 58 cx bike be the right size or do I need longer reach?

  • What stem do you have on your track?

    If it's quite short, 8 cm or so you may get away with the longer stem on the cx, but it's it 10 or longer you may end up with a 13 cm stem, which is a tad long perhaps.

    Bear in mind on CX you probably sit more upright, but it's something to consider. I cycle a tourer with a 6 cm stem and it's OK as the geo is MTB like, but I believe (help, Ed?) most frames suit between 8-10 cm stems.


    For what it's worth I'm 5"5' and I cycle pretty short top tube bikes...51 seems OK. Reach is the big one for me usually. But my bikes are all pre-fancy-geo, bar the Ciocc the seat angles are quite standard and a standard setback saddle does the job.

    @edscoble I can go measure stack and reach on them if you want? For funz as they're old frames anymore.

  • How much range can you allow either way of your ideal stack and reach? And do geo charts allow for the stack of the headset and spacers?

  • They tend not to, there's an online calculation tool that allow you to see how much shorter the reach is when adding spacers.

  • 120 with risers & 110 with drops.

  • Is that the one you linked earlier in the thread?

    It might also be useful to be able to work out your ideal measurements for different styles of bike; cx, mtb, race etc

  • Have a word with Islabikes Ed:
    "I am afraid we cannot supply stack and reach measurements. From experience we have found that they are not helpful when trying to ensure a fit and cannot be relied on when comparing bicycles. Our sizing is very difficult to compare with other manufactures. Our designs are based around large wheels and with thousands of measurements of real children we have designed our bike geometry to best fit the dimensions of growing children."

  • Let me quote one thing from the articles.

    growing children.

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Stack and Reach: Why It's Your Best Friends

Posted by Avatar for edscoble @edscoble