Is it better to have a slightly big or slightly small bike?

  • I'm planning to buy a Scott Speedster S30 (This is my first road bike) and I'm looking at the size chart. I'm around 177 cm tall, and this fits exactly in between the M and L section. Just wondering, in general, is it better to choose the bigger or smaller option?

    I have a Scott sporster at 180cm I'm on a L, I would go for a large if I was you.

    My first "real" bike was a hair too large, and I wish it had been smaller.

    try them both out, I err smaller

    Smaller, because you can increase the length of the stem to get the reach you need.

    I'd definitely recommend trying them out, but I think a slightly smaller would be wiser, a stool can be fitted larger but you can't just saw off a piece if it were bigger

  • If this is your first bike, go to your local bike store and have them fit you professionally. Then, ask if they have loaner bikes so that you can get a feel for the size of the bike before you invest. Some people prefer bikes on the smaller side and some prefer them a bit larger. You'll get a definite feel for this over time, but I wouldn't recommend learning this by purchasing an uncomfortable bike!

    I, for example, generally ride a 56cm road bike. However, I once rode a 56cm Surly Long Haul Trucker that felt too large. Some of that feeling was the components (stem length, in particular), and some of it was the frame geometry. Road bikes are built with a variety of geometries catered to every style of riding. Each bike is as different as each respective cyclist, but riding an uncomfortable bike will ruin riding for you. Your LBS will be able to help a great deal in picking a size and adjusting everything to fit you correctly.

    Lots of people ask for definite answers based on their exact leg/inseam/PBH/height-leg-ratio-distance-whatever...but most of it will come down to what fits comfortably.

    Experience also plays a big part, many novices are uncomfortable on a larger frame as they feel (are?) less in control, and unstable. Riding location does as well. If you are always riding flat ground, a larger frame might be preferred over if you have a lot of windy hilly riding to do. Also if you have come from MTB, you are probably used to a smaller frame than is ideal on a roadie, and may initially go for the smaller (possibly wrong) size. Trying (for a longer ride, not 2 minutes around the car park) is the best thing.

    @WTHarper, are you sure the feel of the long-haul trucker wasn't the rake of your fork? IIRC, the LHT fork is angled to smooth out small perturbations so that you can easily hold a curve, but they feel less responsive/twitchy when you do want to make small course corrections.

    @MikeSamuel it probably was that, combined with the longer wheelbase and 45mm tires that were on it. My go to bike has sport-tour geometry which is what I'm used to. The LHT felt big, slow, and graceless...but I've been told that it rides better with a load (which it didn't have).

    That being said, I do have much admiration for Surly.

    @WTHarper Agreed. As you lengthen the wheelbase your single will handle more like a tandem.

    @WTHarper, thanks for the link. If correct, "Chainstay length....too short, bike is too jumpy" might explain the difference between tandem handling and single handling, or maybe its just that every maneuver has to deal with the momentum of your stoker.

    fully agree. Sit on and ride 'em before you part with your cash and I reckon it'll be obvious which one to go for. If you do end up between sizes (I bought a Trek road bike and was slap bang between a 54 and a 56) then you can probably get away with either. (I bought the 54 on the lbs's advice but I have since bought another bike second-hand which was a 56, and this is fine too.)

  • Rivendell bikes argues that most road bikes sold are too small. They're probably in the minority opinion as far as bike shops go, but they have (collectively) a lot of experience in frame geometry and riding styles.

    Their argument is based on their belief that most shops assume that road riders should emulate racers -- experts who are willing to put up with a lot of discomfort to gain small efficiencies -- and that this alienates a lot of casual riders, commuters, and tourists who would be better served by a bike that fits comfortably.

    Most bikes are sold too small. We see it all the time: bars way below the saddle, the rider leaned over 35-degrees with arms straight out as his hands are on the brake hoods. If he took his hands off the bar he'd flop down and smack his nose on the stem. It's not comfortable or correct.

    When you come to us for a bike, we'll ask what size you ride now, and invariably put you on a bike that's two to five centimeters bigger. You'll still have crotch clearance, but your bar will be higher, you'll lean over less, and you'll be a lot more comfortable.

    and

    Sizing

    Most riders are most comfortable when the handlebar is a few centimeters higher than the saddle. Some like it four or five inches higher. Some like the look of the bar lower than the saddle, but few riders over 35 like a low bar once they've ridden a higher one.

    To achieve that bar height, it helps to start with a bike that's the largest practical size you can ride. We suggest you get the size that allows you to put the handlebar at least 2cm higher than the saddle. That works great for most people. You can always lower the bar if you find it's too high, but it's rare when that happens.

    and especially relevant when dealing with sales-people:

    Sometimes a bike feels funny or uncomfortable, but the salesperson tells you that you're just not used to it, or you're using muscles you haven't used before, and it takes a few weeks to adapt.

    Don't believe it. There's always some getting used to it, but right off the bat, sitting on a new bike that fits you and is set up right so that it gives you a good position should feel about as natural as sitting in a chair. Your hands on the bars should feel like hands on a table in front of you. There is something to be said for breaking in your bottom or whatever, but it should feel at least reasonable right off the bat. You shouldn't have to adapt to or tolerate discomfort even a little, not even when the bike is new.

    I would agree that the typical bike on the showroom floor has the bars too low. I think this is because the low bar looks "meaner" on the showroom floor.

    @DanielRHicks, Grant Petersen is making a stronger claim: that bikes sold and fitted to customers tend to have frames that are too small and bars mounted too low.

    Yeah, I was just talking about what I see on the floor. With most bikes sold you would not be able to raise the bar up to reasonable height even if the bike fit, especially now that it requires a threadless extension.

    @DanielRHicks, Understood.

    But at the same time, this alienates people who have less money but rides a lot. I personally feel that most 'budget' road bikes are not aggressive enough, usually having more of an endurance geometry. Normally I fit on size 53-54, but since I don't have a lot of money, I'm forced to get endurance fit with size 50-52 to get the stack low enough. One size lower usually have big decrement on stack (1-2 cm) while having small decrement on reach (often less than 5 mm), so that with the same seat height and no spacers, and 1 cm longer stem, I can at least get long and low enough.

    I think this is very insightful writing, but on closer reading, I'd dispute a technical point here. Petersen thinks that many riders prefer bikes with negative handlebar drop - that is, the handlebar is actually higher than the saddle. That's not just a function of frame size, it's a function of the frame's overall design. He is talking about adding a lot of frame stack, which means how high the front end of the bike is vertically over the bottom bracket, and probably taking some reach out as well. It's not just a matter of sizing up, because you gain both stack *and reach* in doing so.

  • On a road bike its probably a toss up. Seats can be raised or lowered. Stems can be brought in or out. As long as the standover is comfortable, you should be fine on the large.

    but the standover cannot be adjusted, whereas the stems, seatpost, etc can -- therefore I say it's a bit better to have a slightly too small bike than one that is too large.

    thats why i said: "As long as the standover is comfortable"

    Most modern road bikes have sloping top tube though, so stand over height doesn't matter unless it's way way off.

  • I just returned a bike that was slightly too large. The issue with stand over height is a safety concern for your personal parts and to avoid injury (don't just 'stand over' it, lower yourself a bit, see how far you have before you might touch if you had to dismount quickly in that fashion), but the more relevant measurement for me ended up being the 'effective top tube' length (yes, exactly what it sounds like, the horizontal distance parallel to the ground ignoring the actual angle of the top tube). I was reaching too far forward for the handle bars and this was causing strain on my back and pressure on my wrists. I just bought at the top of my budget so I didn't have cash for a new stem, etc.

    Lowering the seat on the larger size helped but it was still too far to reach the bars. I stopped at the point where the pedaling would have become silly, so technically I could have lowered the seat more to have a shorter reach distance, but then the other issue appears. Indeed, I may end up getting a longer seat post, but that's not as important as avoiding back strain.

    I went to several LBSs in the area and all of them paired me with the larger size, partly b/c I was just at the edge of height range for the size down, so they didn't want me to get something too small. But bodies are particular and I would suggest a comparison ride of about 20-30 minutes on each size (that's what it took me in the end, and this was a big 'first' for me too, so I don't have my 'correct feel' honed yet) to figure out what really works. The 'parking lot' test definitely failed me this time around, and will likely continue to do so for future purchases. You need time to settle-in to feel what really works, especially if you're new to purchasing (actually sport activity experience aside).

    Yeah, the seat should be adjusted to get proper leg extension, not to compensate for top tube length. Stand-over height as a criterion only works to the extent that your legs and torso are "typical" in proportion.

    Yeah, I'm slightly far enough outside typical it's a problem with most everything concerning the word 'size' (lol).

    And, of course, the rational solution on a non-custom bike -- to take the next smaller size, then raise the seat and bar -- is made less practical by the way bars are done: It's very hard (ie, requires work and maybe extra parts on the part of the LSB) to raise a bar up very high, due to the marketing-driven prejudice towards a "low and mean" look (for non-"comfort" bikes).

    Try a bike with a "ladies frame"

    Lowering the seat will also put you in a more forward position thus closer reach since the seat tube is sloping backward. And with raising the stem you will also get closer reach because the head tube also slopes backward, and should be better because it affect handling less than altering the stem length.

    I would just like to draw out that "I just bought at the top of my budget so I didn't have cash for a new stem" is a strong caveat on this answer. Certainly top tube length is an underrated measurement. However, swapping a shorter stem onto the larger frame might be the preferred fitting for a significant number of people.

  • Here is another take coming from a 67 year old. In my early twenties I picked up a used 55 top tube Peugeot, of course with down tube shifters. I am only 5'6", with short legs and long arms. I got used to the stretched out feeling, so have always preferred a big bike.
    The standover has never been an issue, because I never dismount a bike by going forward. I always lean the bike one side or the other and put down a leg. As I have aged and accrued various sports injuries, what has become important is to find a position that avoids aggravation. You need to know what parts of your body to favor. Remember that the shorter frame puts more pressure on the hands, elbows, mid back and neck. The longer frame puts pressure on the shoulder joint and lower back. Sitting up straight puts more pressure on the butt, less on the hands. You can develop chronic pain by not paying attention to what you are doing. Also remember that you will put pressure on your knees in different ways depending upon the relationship of where you sit and where the pedals move. I find standing and sitting forward puts pressure on the front ligaments and bones of the knee, also an effect caused by a shorter top tube. Remaining seated back on a saddle setback and long top tube causes me to use the muscles in back of the knee. Lifting the thigh from the hip joint during the stroke helps ease pressure on the knees. Be realistic in your biking aspirations. Go for comfort first. It will pay in the long run.

  • You can raise the saddle and handlebars on a medium to meet your needs, but lowering them on a large might be tricky, depending on the bike's design.

    Also, there's standover to consider. There should be at least an inch between the top of the frame and your "gentleman area" when you're standing forward of the saddle with the bike between your legs and your feet flat to the ground (not standing on tip toes). If you can manage that okay on the large bike then it should be okay for you. If not, go for the medium.

    Best bet is to actually try out the two different sizes for yourself if at all possible. Ideally you'd want to take them for a test drive, but failing that, at least do a standover test of both sizes in a bike shop.

  • As several have pointed out, it is best to get something that actually fits you but with that in mind, it is better to go a little smaller than a little larger of a frame. For example, look at George Hincapie. He is 191 CM or 6 foot 3 and rides a bike that is just a little bigger than my 56 CM and I am just 5' 10 or 155 CM. He rides a 57.5. Putting on a longer stem and setting the seat back as far as it can go and pulling out the seat tube is how he fits on a bike that is just a tad bigger than mine while having a lot longer legs and body than I do. If he got something more like a 61-63, his bike would be heavier and not as stiff.

    It also depends on a few other factors. The length of the top tube, riding preferences, riding style. Keep in mind that on a typical bike, if you got one that is smaller and just added a longer stem and pulled out the seat post as far as you could go, handling will also be a bit different because your center of gravity would be different than what it was built for. It wouldn't be as easy to go downhill, steering would be a bit more squirmy.

    All bikes are built different. I have been on 56 CM's that were too big and too small for me in the stock format and even though I have owned my own bike for years, I am always adjusting the fit according to where I am in the season or how I feel on the bike.

  • The most important thing is that you are comfortable riding it. In my experience a slightly smaller offers the benefit of more agility & lighter weight. However where you will be riding is a factor as well.

    As most of my riding is in city streets with traffic I find utility in a smaller fit for the above reasons, I tend to ride with my bars significantly below my seat height but not so far that I cannot grab the top of the handlebars & ride upright cruiser style. This gives me a reasonable balance between power transfer from the lower position to comfort when I have a load on my back in the upright position.

    However, riding like this out in the country can get old pretty quick. Mainly I think because in city riding there is a lot of stop/go & opportunities to adjust where as country riding tends to be more distance traveling.

    The bottom line however is still: If you cannot find a 'perfect' fit, which feels more comfortable to your style

  • It comes down to how much cash that you want to spend after buying a bike in order to set up "properly" ... As an alternate to having a custom built frame.

    I would favor the smaller frame but likely replace the stem, seatpost and any other component necessary to place me in a position that I like. Stock:. Maybe the larger frame as it is more likely to fit off the shelf. However, smaller frames are more responsive than the equivalent larger frame, are stiffer, accelerate faster (IMHO) and are generally more fun. The exception might be for long distance touring which allow the rider to stretch out over distances and necessary for a balanced load when touring.

  • I believe that sizing down if you're in between sizes is the conventional wisdom. Some answers have alluded to this.

    You do need to be able to get the saddle up to your preferred height without exceeding the minimum adjustment limit of the seatpost. You also need to be able to get your handlebars to your preferred riding position, which will involve placing spacers under the stem; if you choose a frame that is too small, it is possible you will exceed the maximum number of spacers recommended. Chances are that neither of these will happen if you are in between two sizes, however. They should only happen if you are trying to ride a bike that is much too small.

    Frame size and handling

    The current set of answers don't appear to have discussed how the bike's handling will be affected by changing size. This answer focuses on the changes in bike handling. Overall, the change in handling should be small. Assuming you can achieve your desired handlebar and saddle position on both sizes, which direction to go may depend on your personal preferences.

    Longer stem = slower steering

    If you have two frames of different sizes that are otherwise identical, then you will have a longer stem on the smaller frame. The stem has a relatively small effect on the bike's handling relative to the other important parameters. However, all else equal, a longer stem will place more of the rider's weight over the front wheel. Moreover, on a longer stem, the handlebar has to be moved a greater distance to produce the same steering arc. Both of these will slow the front wheel's response to steering input. In contrast, for short stems, the first Cyclingtips article I cited says that

    A short stem, by contrast, will shift the weight of the rider back over the frame, unweighting the front wheel so that the steering will be a little lighter. As already mentioned, this won’t to do much to overhaul the steering if the bike has a slack head angle and/or lots of trail, but it can improve manoeuvrability, which explains (at least in part) the current fervour for short stems on MTB (where the amount of frame reach has been growing in recent years). It also explains how a short stem can render a bike near-uncontrollable if it already has quick steering.

    That said, considering the gaps between frame sizes, the different stem lengths you'd have to use should not create marked differences in handling.

    Smaller bikes may be more stable

    One other thing to consider is that not all else may be equal between bikes of different sizes. Trail is a key parameter in bike handling. Generally, bikes with more trail are more stable. They tend to bias themselves upright. It can take a bit more effort to lean them into a turn, but they are easier to ride in a straight line and won't get twitchy. It's been my observation that for most production bikes, the amount of trail tends to decrease with frame size. For example, the 49cm Specialized Venge has 63mm trail. The 52cm and 54cm Venge have 58mm. The 56cm and 58cm frames have 55mm of trail, and the 61cm frame has 52mm of trail. If you go down a bike size, you may go to a size with slightly different trail, and this will be more stable than the larger size.

    The conventional wisdom may be that smaller frames are more agile. I realize both the points I raised above contradict this. Professional bike riders are known to ride relatively small frames. I believe that they want to get their handlebars as low as possible. However, the second Cyclingtips article I linked above, which focuses on stem length, has this to say:

    “The longer the stem,” explains Tom Kellogg, “the more the rider’s weight pushing forward on the bars tends to keep the front wheel pointing forward.” As a consequence, the bike becomes more stable, especially at high speeds, which accounts to some extent why pro riders normally opt for a shorter frame and a longer stem. The extra stability also helps with the control of high profile race wheels in windy conditions.

    Again, the changes involved should be relatively minor. Also, humans can generally adapt to small changes in handling. Going from a 56cm to a 54cm bike is not going to change a performance road bike into something that handles like a touring bike, or even an endurance road bike.

    Standover height may be a relatively minor consideration also

    A last item to consider may be standover height: when you stand with your feet on the ground, how much space is there between your groin and the top tube? The larger frame will have less standover height. Georgena Terry, who has designed custom bikes for women for a long time, argues that standover height is quite important because you risk hitting your groin in a sudden stop. I am told that this is quite painful for women, and it will obviously be painful for men. This factor would also bias you towards taking the smaller frame.

    However, standover height may not be important for experienced road cyclists. I would definitely pay attention to it on mountain bikes. However, some posters on this Reddit thread, this BikeRadar forum thread, and this Bike Forums thread argue that it's not important, because you will never hit the top tube as you ride normally (at least on the road). I had a cyclocross bike with essentially no standover clearance at one point, and I never hit the top tube. However, it has been shown that men tend to underestimate risk compared to women, so you should assess this for yourself.

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