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How To Buy A Mountain Bike Size

Read on for some advice on what mountain bike frame size you should be considering, especially if you\u2019re in any doubt about it.\n\n A correctly sized bike will give you more control on descents. Andy Lloyd \/ Our MediaWe\u2019ll also help you understand the changes you can make to your bike\u2019s parts to help it perform better for your measurements, personal requirements and preferred discipline. For example, the best mountain bike suspension forks can be adjusted to suit you.\nBefore we get started, if drop handlebars are your thing, then head to our guide to road bike sizing.\n\u00a0\nWhat size mountain bike do I need?\nGetting the perfect mountain bike fit\nProblems caused by the wrong size mountain bike\nHow to get the perfect mountain bike fit\nComponents that affect comfort and control\nTyre and suspension setup and pressures\nWhat size mountain bike do I need?\n\n Named frame sizes require you to look at geometry charts to see the bike\u2019s dimensions. Our Media\nAsk an experienced rider about bike fit and they\u2019ll tell you that all bikes feel and ride differently, even if their numbers look almost the same on paper.\nManufacturers\u2019 listed mountain bike frame sizes can be confusing. How to measure a bike frame is not set in stone.\u00a0The traditional method is to list the seat tube length, but even that varies because some are measured to the top of the seat tube and some to the middle of where the top tube joins the seat tube.\nMany manufacturers simply list their bikes as S, M and L, perhaps with XS or XL at either end.\nAnd, more recently, bike manufacturers have begun listing their bikes\u2019 sizes based on reach figures rather than seat tube and top tube lengths.\n\n Getting a bike that\u2019s the perfect fit can seriously improve comfort, control and speed on the trail. Andy Lloyd \/ OurMedia\nThis means they\u2019ve been able to grow the bike\u2019s reach figure, wheelbase and top tube length while trying to keep seat tube lengths and stack heights shorter and lower.\nSmaller seat tube lengths mean shorter people can fit on bikes with a longer reach figure because they can adjust the seat height lower, opening up the potential to ride a larger bike.\nIt\u2019s still important to consider seat tube and top tube length when buying a bike. The seat tube length will dictate the lowest saddle height that can be set and the top tube length will roughly dictate how stretched out a rider will feel.\nSo, where do you find out what size frame you need? Like so many other things on a mountain bike, there is no one perfect solution because, within sensible limits, you can adjust your saddle, stem and handlebar to help make a slightly imperfect fit feel fine.\nWe\u2019d always recommend looking at manufacturers\u2019 own size charts, which will usually list a suggested height range for each bike frame size they produce, but here are some general guidelines:\n\n \ufeffBike sizeFrame sizeRider heightExtra-small13-14in152-162cm (5ft \u2013 5ft 4in) Small14-16in162-170cm (5ft 4in \u2013 5ft 7in) Medium16-18in170-178cm (5ft 7in \u2013 5ft 10in) Large18-20in178-185cm (5ft 10in \u2013 6ft 1in) Extra-large20-22in185cm plus (6ft 1in plus) \n\nImportant geometry terms and what they mean\nWe all come in different shapes and sizes, and so do most mountain bikes, so we recommend using the information below to help you understand what size mountain bike frame you should be riding.\nFirst, it\u2019s good to know the anatomy of a mountain bike, because we\u2019ll be referring to these terms.\n\n These key parts of a bike will define its geometry and how it fits. Matt Orton \/ Immediate Media\nA. Seatstay\nB. Chainstay\nC. Seat tube\nD. Top tube\nE. Down tube\nF. Stem\nG. Head tube\nWhen you\u2019re looking at buying your next bike, it\u2019s crucial to understand how the bike\u2019s geometry will affect how it rides and what each element of its geometry means. Understanding these terms will help you decide what size mountain bike you need.\nWhen you\u2019re looking at mountain bike frame size charts, these terms will also help you understand how each measurement affects the size of the bike.\n\n The image shows you all the key length measurements you need to know when considering a bike\u2019s size. Matt Orton \/ Immediate Media\nA. Effective top tube length is the length of a virtual horizontal line drawn between the top of the bike\u2019s head tube and the centre of the seatpost at the same height.\nB. Stack height is the distance between the centre of the bottom bracket and the centre of the top of the head tube. This measurement dictates the minimum height of the bars in relation to the bottom bracket and has a relationship with a bike\u2019s reach.\nC. Seat tube length is the distance from the middle of the bottom bracket to the top of the seat tube. This length determines how high or low the bike\u2019s saddle can be set, and therefore how long or short any given rider\u2019s legs can be.\nD. Down tube length is the distance between the centre of the bottom of the head tube and the centre of the bottom bracket. Down tube length figures aren\u2019t usually quoted on manufacturers\u2019 size charts, but it\u2019s an easy measurement for a consumer to do at home when comparing one bike to another.\nE. Bottom bracket drop denotes how far above or below the horizontal line connecting the centre of the axles the centre of the bottom bracket is.\nF. Bottom bracket height is the distance between the centre of the bottom bracket and the ground.\nG. Wheelbase is the horizontal measurement between the centre of the front and rear axle.\nH. Front centre is the horizontal length between the centre of the bottom bracket and the centre of the front axle.\nReach (not pictured)\u00a0is the length between the bottom bracket and the centre of the top of the head tube. Reach provides the best indication of how \u2018roomy\u2019 a bike will feel, especially when it\u2019s being ridden standing up. Click here to find out how reach and stack height affect each other.\nRear centre\/chainstay length (not pictured)\u00a0is the horizontal distance between the centre of the bottom bracket and the rear axle.\n\n Seat tube and head tube angles are important to understand and can affect the rest of the bike\u2019s geometry. Matt Orton \/ Immediate Media\nA. Effective seat angle is the angle of the line that connects the bottom bracket to the centre of the top of the seatpost when it\u2019s at pedalling height. Manufacturers often quote their effective seat tube angle, but the height at which it\u2019s measured isn\u2019t usually disclosed.\nB. Actual seat angle is the angle of the bike\u2019s seatpost measured from horizontal.\nC. Head angle is the angle of the fork\u2019s steerer tube measured from horizontal.\nGetting the perfect mountain bike fit\n\n With the right-size bike, you\u2019ll instantly have more control. Ian Linton \/ Our Media\nGetting a bike to \ufb01t you perfectly is something you need to work at. We know riders who\u2019ve ridden for years on what they thought was their perfect bike, with perfect reach, perfect saddle height, perfect handlebar shape, a perfectly set up fork and the best mountain bike tyres, perfectly inflated, until they discovered it wasn\u2019t.\nThey discover that a basic change, perhaps even a few basic changes, to that setup seems to make them ride better.\nIt\u2019ll often be something as simple as a different handlebar sweep, different tyre pressures or more or less suspension-fork sag. It\u2019s often minor details of bike setup that change the way you ride and feel about your bike.\nWhen we sit on a bike, we make contact in three places: our hands on the bars, our feet on the pedals and our backside on the saddle.\nIt\u2019s the relative position of these three areas that governs how the bike \ufb01ts and several variables in\ufb02uence their exact location: top tube length, seat angle, distance from bottom bracket to saddle, crank length, bar height and width, stem length and saddle angle all play a part.\n\n It can be a case of trial and error when finding your preferred bike setup. Andy Lloyd \/ Our Media\nTweak your ride setup from time to time, then give yourself a few rides to decide whether you like it or not. There are some things that feel wrong when you \ufb01rst change them, but right after a few rides.\nIn the following sections, we\u2019ll lay down the basic guidelines of bike \ufb01t, together with variations to consider and the reasoning behind them.\nDon\u2019t think of a bike \ufb01t and setup as something that\u2019s carved in stone, though. Use our guidelines as a starting point, then go out and experiment.\nSeat tube length and standover\n\n Minimal standover height can have painful consequences. Oliver Woodman\/Immediate Media\nWhen a bike is listed as \u2018X\u2019 inches, what does that mean?\nIn most cases, it\u2019s the distance from the bottom bracket axle to the top of the seat tube, but it can be to the middle of the top tube or to various other places \u2013 there isn\u2019t a universal standard.\nEven if there were, it would be no indicator that you could straddle the top tube and clear it because top tube shape and bottom bracket height vary substantially.\nThis all relates to \u2018standover height\u2019: an important aspect of any bike \ufb01t, since it governs the clearance of your crotch!\nThe seat tube should leave you with an acceptable standover gap \u2013 the distance between the top tube and your crotch \u2013 and usable standover clearance.\nTo get this, stand back as far as you can while over the bike and ensure there\u2019s a minimum of an inch of room from the top tube to your crotch area.\nIf you adhere to this advice then your frame should provide you with a large range of adjustment at the seatpost, which is important for finding your optimum mountain bike seat height.\nWhile this holds true for beginner and cross-country bikes, depending on the shape of the frame the rules change slightly, for example if it has a low-slung top tube or if you\u2019re looking to buy a downhill or enduro bike \u2013 which have different geometry entirely.\nIt\u2019s therefore important to not use seat tube length and standover height as the only measure of a bike\u2019s fit. It also highlights how crucial sitting on different sizes of your prospective purchase is.\nSaddle height and crank length\n\n Crank length can make a difference to how your bike fits, especially if you\u2019ve got long or short legs. Andy Lloyd \/ OurMedia\nThe majority of mountain bikes have 170mm or 175mm cranks, which do the job perfectly well for most riders. But if you have short legs, you may \ufb01nd the cranks are too long to turn without your knee bending excessively at the top of the stroke, resulting in the wrong muscles being used.\nSimilarly, if you\u2019re long-legged you may bene\ufb01t from a longer crank so you can make the most of your lofty dimensions.\nFor general trail riding, aim to set saddle height on your bike for maximum power and ef\ufb01ciency. Too high and your hips will rock from side to side, wasting energy; too low and your muscles won\u2019t deliver power effectively.\n\n Make sure your saddle is set at the correct height. Finlay Anderson \/ Our Media\nAdjust the saddle height so when your heels are on the pedals at the bottom of the pedal stroke, your leg is fully extended \u2013 this means when you move your feet to the right position, your knee won\u2019t lock out.\nIf you need more clearance, drop your saddle an inch or two.\nTop tube length and reach\n\n The top tube length is responsible for more than just your comfort. Scott\nAnother important consideration is the top tube length. Together with seat height, stem length and handlebar position, top tube length dictates the comfort and efficiency of your body on the bike.\nTo confuse matters further, the aspect of top tube length that matters is not the top tube itself, which often slopes, but the reach number.\nAlthough top tube length will give a good indication of how a bike will feel when you\u2019re seated, the reach figure is most relevant for when you\u2019re standing up and is particularly pertinent to descending, but also helps contribute to the feel of a bike\u2019s size.\nA cross-country rider may prefer a long, stretched-out position, but a beginner who has never taken a bike off-road may want to be more upright for extra comfort, with less weight on their hands and wrists.\nYour reach is often a compromise between comfort, control and pedalling ef\ufb01ciency.\nFind what works best for you, but avoid being too hunched or too stretched out, since this can cause discomfort and back problems.\nSeat angle and effective top tube length\n\n A steeper seat tube angle will position you further behind the bottom bracket, putting your weight towards the rear of the bike. Privateer Bikes\nThe cranks (or bottom bracket) are never situated directly below the saddle, and for good reason. If they were, you\u2019d be placing excessive weight on your arms to support your upper body when you lean forward.\nThus the seat tube lies at an angle, which determines how far behind the bottom bracket the saddle will be and how you\u2019re balanced when seated.\nToo much can be counterproductive, but luckily the range of angles is usually quite narrow, so this measurement isn\u2019t normally that important.\nIf we take two bikes with the same ETT length but different seat tube angles, the slacker-angled machine will have a bottom bracket that\u2019s further forward in relation to your saddle and vice versa.\nThe upshot of this is you can have two bikes with the same reach that handle differently, due to how they distribute your weight.\n\n Saddle rails allow you to extend reach, though having it too far back can make the front end of the bike lift on climbs. Oscar Huckle \/ Our Media \nOne of the biggest mistakes made by beginners is to slide the saddle too far back. While it may be psychologically reassuring to sit well back from the \u2018attacking terrain\u2019 position, too little weight on the front of the bike can make the steering feel vague and stop your suspension fork from compressing ef\ufb01ciently.\nSit further forward and you\u2019ll get maximum use of the fork, full use of the front tyre tread and the bike will handle better.\nThis is all assuming that the reach is correct for you. As a general rule of thumb, if you drop a plumb line from the centre of the saddle it should cross the chainstays almost exactly halfway between the bottom bracket axle and the rear wheel axle.\nFoot position and cleats\n\n A top tip is to mark your preferred cleat position when you\u2019ve found it; this makes it easier to set them up again when you replace them. Stan Portus \/ Our Media\nThe best mountain bike pedals can be flat or clipless. With \ufb02at or platform pedals, the ball of the foot usually drops into a comfortable position above the pedal axle.\nHowever, clipless pedals can be more problematic to get right, so it\u2019s essential to know how to set up clipless pedal cleats. A good place to start is to \ufb01nd the ball of your foot and place the cleat directly underneath.\nOnce you\u2019ve found this spot, adjust back and forth \u2013 minor changes can affect which muscles are utilised and how effectively you pedal.\nSee what works best for you. Lateral positioning is a personal preference: a narrower stance can improve ef\ufb01ciency, but be careful that your shoes don\u2019t hit the cranks during the pedal revolution.\n\n It is best to try different cleat positions before you commit to one. Mick Kirkman \/ Immediate Media\nThe angle of the cleats should match the natural angle of your feet, which you can see easily if you use \ufb02at pedals.\nMany of the latest clipless pedals have built-in \ufb02oat, which helps your foot achieve a natural angle and is a good option if you\u2019re unsure what\u2019s right for you.\nExperiment with the \ufb01nal setup; once you have this sorted, the pedal stroke will feel \ufb02uid with no twisting of the ankles, knees or hips.\nThis can take a few rides, but is worth persevering with \u2013 when you hit that sweet spot, draw a line around the cleats for reference when they need replacing.\nProblems caused by the wrong size mountain bike\n\n Knee, hip and back pain can ruin rides. Mick Kirkman \/ Our Media\nIf you do end up on the wrong-sized mountain bike, whether that\u2019s too small or too large, you could end up not enjoying yourself as much or, as a worst-case scenario, getting injured.\nAches and pains can be caused by aspects of bike setup, but also by other things, so don\u2019t take this list as gospel; it\u2019s a rough guide.\nSee your doctor if something is really hurting, especially if it continues to be painful after riding and it\u2019s not solved by the adjustments mentioned here.\nBe aware that a lot of your aches and pains on a bike are simply caused by insuf\ufb01cient muscle support. In other words, you may just need to ride more and do some core muscle training to work things out.\nHere are some common ailments and their causes:\nKnees: Knee pain when riding can be caused by your saddle being too high or too low, or your shoe cleats being poorly adjusted. Some riders \ufb01nd that a pedal\/cleat system with more free \ufb02oat gets rid of knee pain.\nBack: Back pain during\/after riding will often be related to poor core muscle support, so there may not be a quick and easy setup \ufb01x. But try changing the position of your handlebars and\/or your reach from the saddle to the bars. We know a lot of riders who\u2019ve solved lower-back pain simply by putting the stem up or down by half an inch, or getting a handlebar with more backsweep. Back pain can be indicative that your bike\u2019s frame is the wrong size.\nShoulders\/arms\/neck: We\u2019re putting these three together because it\u2019s often similar aspects of setup that cause aches and pains in these areas, namely too much stress being placed on these bits of your body. This may be caused by being sat too far forward on the bike, but it can also be down to sitting too far back, making you curl your shoulders and preventing you holding the bar properly. Experiment with stem height and saddle-to-bar reach. Try different bar shapes: a lot of riders \ufb01nd that more backsweep or upsweep on a bar will make them feel far more comfortable. Also try anatomically shaped grips, which support your hands better. If your shoulders, arms or neck are hurting, they could be telling you that your bike is either too big or too small.\nHips: A lot of hip problems among cyclists are caused by the saddle being either too high, too low, tipped too far back or forward, or not offering the right sort of padded support.\nWhen your bike is the correct size:\nArms: Good bike position results in relaxed shoulders and slightly bent elbows.\nSaddle: Correct saddle position is essential for balance, control and pedalling ef\ufb01ciency.\nKnees: Having very slightly bent knees at the bottom of each pedal stroke is perfect.\nFrame: Getting the correct frame size is essential, but it\u2019s only a starting point for perfect bike setup.\nShifters and brake levers: Don\u2019t just leave them in one position. Experiment with setting them further in on the bars or tilting them.\nAlthough everyone is different \u2013 some folks may have longer legs and a shorter torso, while others may h


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