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    CX frames comfortable or aggressive?

    I've been keeping an eye out for cyclocross bikes and frames, mostly to be used for commuting duties. They don't come up often and they aren't common in bike shops to take for test rides. And I would rather buy second hand for the price savings.

    Anyway, I was under the impression that cyclocross frames were a bit more relaxed compared to your typical road racing frame. This is good for both riding in traffic (more upright) and just general comfort.

    However I have recently been told by one bike shop that in fact they are quite aggressive and aren't really built with comfort in mind. And this was because CX races generally are only run for 1 hour or less, so comfort isn't a priority.

    So which is it?
    I want to live.

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    Senior Member thisisbenji's Avatar
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    I'm no expert and don't have a high end cx bike, but here's what I think. I ride my road bike with a 100mm stem, no spacers, angled down. I ride my cx bike with an 80mm stem, one spacer, and angle up. So between my two bikes the cx is hands down more comfortable. Also, I think that my cx frame actually is a little bit more relaxed. On a side note, if you google your question it says that they're more relaxed. You can also look at manufactures geometry specs.

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    Team Water Andy_K's Avatar
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    To some extent, it depends on the frame. Higher end CX frames tend to be more racing oriented and are therefore somewhat aggressive, though still less aggressive than a road racing frame. It's true that CX racing frames aren't built with comfort in mind, but the nature of what goes on in that hour tends to favor things like a shorter top tube, longer wheelbase and a longer head tube that naturally make a bike more comfortable.

    Entry-level CX frames tend to be geared toward general purpose riding, and are even more relaxed. There is some variability even within this group. For instance, the Surly Cross Check has a relatively short head tube and offers a relatively aggressive riding position, while the Specialized Tricross has a taller head tube, a longer wheelbase and more relaxed angles. That said, even the Cross Check is a pretty comfortable ride.

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    Have bike, will travel Barrettscv's Avatar
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    You have two different topics to consider.

    Your LBS might be discussing compliance, that is: the ability of the bike to flex and provide some shock absorption. Some Cyclocross bikes are very stiff for good power transfer, while others are more forgiving for ride comfort.

    The second issue is fit. Faster road racers like a more aerodynamic fit, with a large height difference between the saddle and the handlebars. Some Cyclocross competitors might want a large drop from the saddle to the handlebars, others may not, since speeds are often less while Cyclocross racing, compared to road racing.

    Most lower-cost Cyclocross bikes, especially those with eyelets for fenders and racks, are designed to be more comfortable than bikes designed for racing. In other words: Some Cyclocross bikes are stiff for power transfer and fitted with aerodynamics in mind, while others are designed for recreational use primarily.

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    Quote Originally Posted by Barrettscv View Post
    Your LBS might be discussing compliance, that is: the ability of the bike to flex and provide some shock absorption. Some Cyclocross bikes are very stiff for good power transfer, while others are more forgiving for ride comfort.
    This is an excellent point. We read a lot about bikes that are laterally stiff but vertically compliant, but in the real world a compromise tends to be made one way or the other. The aforementioned Surly Cross Check, for instance, I can testify, is quite compliant, as is common for steel bikes (this trait being one of the foremost reasons a designer would choose steel). I hear good things about the Soma Double Cross in this regard too. Of course, it is possible to build a compliant bike out of other materials such as aluminum or a stiff bike out of steel, but, as a general rule, if you want to build a compliant bike, steel is the easiest place to start, and if you want to build a stiff bike aluminum is the easiest place to start.

    Of course, even a fairly stiff CX bike isn't as stiff as most road racing bikes. My guess is that the LBS guy is talking out his rear, drawing on generalities that he knows to try to make himself sound authoritative about specifics that he doesn't know. I'd give him the benefit of the doubt and say that he's making a well-intentioned guess, but his guess is wrong.

    As an aside, bike manufacturers have noticed that a lot of cyclists are admitting that they are not racers, and so the "plush bike" trend has emerged with road bikes that are designed for comfort. (See, for example, the Specialized Roubaix.) I can't say how CX bikes compare to these, but the geometry looks similar to a relaxed CX bike.

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    Bianchi Goddess Bianchigirll's Avatar
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    for a commuter, unless you really want drop bars, I would suggest a upperend Hybrid with soem MTB bars ends or 'trekking' bars.

    one thing I don't see mentioned skimming the above replies is, the BB of a CX bike is higher than that of a road bike. so if you ride a 56cm road bike a 54 CX bike may fit better

    how much are you looking to spend? and what size? http://austin.craigslist.org/bik/
    Bianchis '87 Sport SX, '90 Proto (2), '91 Boarala 'cross, '93 Project 3, '88 Trofeo, '86 Volpe, '89 Axis, '79 Mixte SOLD, '99 Mega Pro XL Ti, '97 Ti Megatube, , '90 something Vento 603,

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    There is no general rule. The comfortable fit of the bike depends how you set it up... one of the first responses in this post said his road bike has a long low stem and his CX bike has a shorter higher stem and the CX bike is more comfortable... well that says to me that the road bike setup is less than optimal. If a particular bike is uncomfortable because the bars are too low, raise the bars. It's not brain science.

    As for the 'compliance,' there is no properly constructed frame in the world that can absorb shock anywhere near as well as a 35mm wide tire inflated to 75 psi. And since most road bikes do not have room for 35mm wide tires, CX bikes have an instant advantage in absorbing shock. But put a 23mm wide tire inflated to 125psi on your CX bike and that advantage is suddenly much much smaller.

    In short, the advantage of a CX bike is not that it is or is not more or less comfortable, but that it is easier to set up with the comfort you want and still able to come close to the performance of a road bike.

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    coprolite fietsbob's Avatar
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    Bigger section tire is a big difference , a touring bike frame will be made to carry weight ,
    so thicker wall tube is specified.

    Racing Cross is not about comfort.. but the bikes sell well for commuters,
    because , I suspect, they accept tire widths more than 23mm, and look racy.

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    i find that many XC bikes have shorter head tubes than their road bike counterparts... that seems to make necessary for adding spacers etc to prevent huge saddle/bar drop.

    I do find that STEERING is more geared for 'comfort' typically slower steering

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    Quote Originally Posted by adam_mac84 View Post
    i find that many XC bikes have shorter head tubes than their road bike counterparts... that seems to make necessary for adding spacers etc to prevent huge saddle/bar drop.
    Some of the difference is that CX forks are about 20 mm longer, but some CX bikes do have short head tubes. I wouldn't have thought that the net difference is shorter compared to a road racing bike.

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    Quote Originally Posted by Bianchigirll View Post
    one thing I don't see mentioned skimming the above replies is, the BB of a CX bike is higher than that of a road bike. so if you ride a 56cm road bike a 54 CX bike may fit better http://austin.craigslist.org/bik/
    This is not really true. Compare the BB drop of a Van Dessel (7cm) with a Ridley (6.1cm). There is a lot of variation in cx BB drop.

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    Senior Member grolby's Avatar
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    Quote Originally Posted by Andy_K View Post
    This is an excellent point. We read a lot about bikes that are laterally stiff but vertically compliant, but in the real world a compromise tends to be made one way or the other. The aforementioned Surly Cross Check, for instance, I can testify, is quite compliant, as is common for steel bikes (this trait being one of the foremost reasons a designer would choose steel). I hear good things about the Soma Double Cross in this regard too. Of course, it is possible to build a compliant bike out of other materials such as aluminum or a stiff bike out of steel, but, as a general rule, if you want to build a compliant bike, steel is the easiest place to start, and if you want to build a stiff bike aluminum is the easiest place to start.
    No. It's "easier" (meaning, more in line with the intrinsic properties of the materials) to make a stiff bike out of steel, and a floppy one out of aluminum.

    Quote Originally Posted by Andy_K View Post
    Of course, even a fairly stiff CX bike isn't as stiff as most road racing bikes. My guess is that the LBS guy is talking out his rear, drawing on generalities that he knows to try to make himself sound authoritative about specifics that he doesn't know. I'd give him the benefit of the doubt and say that he's making a well-intentioned guess, but his guess is wrong.
    No offense, but the preceding doesn't give me much reason to believe that you know any more than this LBS guy. In fact, that guy has a point: cyclocross is a racing discipline, and traditional 'cross bikes are racing machines, built for speed. Of course, they're "uncomfortable" in the same sense that a road racing bike is; they shouldn't be, if fitted for the riders' proportions and relative fitness. But no matter; "cyclocross bike" is a fairly generic term that encompasses both straight-up race bikes and more commuter/consumer-oriented bikes that aren't built purely for racing. The Cross-Check, and, to a lesser extent, the Soma Double Cross, fall into the latter category. They have things like bottle cage mounts and fender eyelets, but they also have geometry that is perfectly suitable for racing.

    As for "aggressive," it's a misleading word when applied to geometry. It doesn't really mean anything. True CX racing geometry is indeed "aggressive," (or, rather, intended for hard-core, even - you might say - aggressive racing), but with the greater emphasis on slow speed stability rather than high-speed agility, compared to a road racing bike, they tend to have shallower head tube angles than a road bike. But it wouldn't be "aggressive" to build a CX frame with road geometry, it would be silly.

    Quote Originally Posted by Andy_K View Post
    As an aside, bike manufacturers have noticed that a lot of cyclists are admitting that they are not racers, and so the "plush bike" trend has emerged with road bikes that are designed for comfort. (See, for example, the Specialized Roubaix.) I can't say how CX bikes compare to these, but the geometry looks similar to a relaxed CX bike.
    A quick look at the Roubaix geometry chart, for example, shows that the geometry is broadly similar to classic "sport touring" geometry, which have somewhat steeper head angles, on average, than a cyclocross bike. I wouldn't pick a Roubaix, but I do think that a lot of really good sport-touring type bikes like the Surly Pacer or Salsa Casserole are sadly overlooked in favor of 'cross bikes because 'cross bikes are talked up so much. Not that I have anything against using 'cross bikes as commuters, but there are more options out there.

  13. #13
    Team Water Andy_K's Avatar
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    Quote Originally Posted by grolby View Post
    No. It's "easier" (meaning, more in line with the intrinsic properties of the materials) to make a stiff bike out of steel, and a floppy one out of aluminum.
    Could you say more about this? I'm not doubting you but would like to better understand what you're saying, as it doesn't fit with my understanding of things (which I admit is limited when it comes to materials). My claim was largely based on the fact that cheap steel bikes tend to be flexy and cheap aluminum bikes tend to have a harsh ride, while high-end bikes of either material can be made with whichever quality is desired. Perhaps this has more to do with the characteristics of the commodity-level tubing available in either material?


    Quote Originally Posted by grolby View Post
    No offense, but the preceding doesn't give me much reason to believe that you know any more than this LBS guy.
    In some regards, that's definitely so. The main qualification I'm claiming over him is having ridden many miles on several diffferent CX bikes.


    Quote Originally Posted by grolby View Post
    In fact, that guy has a point: cyclocross is a racing discipline, and traditional 'cross bikes are racing machines, built for speed. Of course, they're "uncomfortable" in the same sense that a road racing bike is; they shouldn't be, if fitted for the riders' proportions and relative fitness. But no matter; "cyclocross bike" is a fairly generic term that encompasses both straight-up race bikes and more commuter/consumer-oriented bikes that aren't built purely for racing. The Cross-Check, and, to a lesser extent, the Soma Double Cross, fall into the latter category. They have things like bottle cage mounts and fender eyelets, but they also have geometry that is perfectly suitable for racing.
    I completely agree with what you've said here. There may be a level of miscommunication in either the OP's representation of the LBS guys remarks or my interpretation thereof. I understood the OP to be comparing CX bikes specifically to road racing bikes (which in itself encompasses more bikes than it ought to), and my remarks were generally oriented to that perspective.



    Quote Originally Posted by grolby View Post
    A quick look at the Roubaix geometry chart, for example, shows that the geometry is broadly similar to classic "sport touring" geometry, which have somewhat steeper head angles, on average, than a cyclocross bike. I wouldn't pick a Roubaix, but I do think that a lot of really good sport-touring type bikes like the Surly Pacer or Salsa Casserole are sadly overlooked in favor of 'cross bikes because 'cross bikes are talked up so much. Not that I have anything against using 'cross bikes as commuters, but there are more options out there.
    Again, I agree, but let me follow up on this line of exploration. The Roubaix is the epitome of high-end plush bikes, I think. Now, looking at it's geometry, its head tube and seat tube angles (for a 54cm model) are 72 and 73.5 degress respectively. The Specialized Crux, in the same size, has angles of 71.5 and 73.5. The Roubaix has a 165mm head tube, while the Crux has a 140, but if you factor in a typical 20mm difference in fork length between road bikes and CX bikes, these have a fairly similar axle to handlebar offset. The Roubaix has a 1000mm wheelbase, compared to 1028 for the Crux, due to the Crux's much longer chain stays. The Crux also has 65mm of trail, compared to 59 on the Roubaix.

    So, it seems to me that the geometry of the racing-oriented Crux compares favorably by "relaxed" geometry standards to the Roubaix. The more consumer/commuter oriented TriCross adds a taller head tube to the Crux geometry, but is otherwise about the same.

    That said, I'll definitely grant that a bike like the Casseroll has more relaxed geometry than either the Crux or the Casseroll. I'll also admit that I'm largely speaking based on numbers, having never ridden either one. Certainly, the Roubaix has other features, such as its Zertz inserts, that are at least intended to lend it more comfort, and I would expect that it's a better bike for charity rides than the Crux.

    In any event, none of this changes the fact that I agree with you about the suitability of the Pacer and Casseroll for much of what CX bikes are hyped for beyond the sand and mud.

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    Senior Member grolby's Avatar
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    Quote Originally Posted by Andy_K View Post
    Could you say more about this? I'm not doubting you but would like to better understand what you're saying, as it doesn't fit with my understanding of things (which I admit is limited when it comes to materials). My claim was largely based on the fact that cheap steel bikes tend to be flexy and cheap aluminum bikes tend to have a harsh ride, while high-end bikes of either material can be made with whichever quality is desired. Perhaps this has more to do with the characteristics of the commodity-level tubing available in either material?
    Sure. IANAMS (I Am Not A Materials Scientist), but: steel is, intrinsically, a much stiffer material than aluminum. In fact, IIRC, aluminum has about 1/3 the stiffness of steel (but that might be density, so don't quote me on that. In any event, it's a lot less stiff). The real-world consequence of this difference is that an aluminum tube built to the same dimensions of a steel tube will be much floppier, and this is exactly what was done in the early days of aluminum bike building. Vitus made famously floppy aluminum bikes, and its reputation as noodly became pretty well established by the early 80's.

    This is the point where Cannondale stepped in and really broke the aluminum bike world wide open as they showed that, by using (at the time, comically) large tube diameters, you could build a bike that fully took advantage of aluminum's much lower density, yet was stiffer than any steel bike out there. Cannondale also really cleverly took advantage of the reputation that aluminum had for softness to claim, in their marketing materials, that their bikes were not only stiffer than steel bikes, but rode better. I doubt they were able to get away with that claim for long, because the new generation of super-stiff aluminum frames completely altered the perception of aluminum as a frame material. And even though the concept of large-diameter, thin-walled tubes was also eventually applied to steel bikes, there are limits on how far you can take it. It would actually be trivially easy to make a steel bike that was much stiffer than even the stiffest aluminum frame out there, but because of the much higher density of steel you would have a tank. The lightest metal frames are really riding the edge of what you can get out of manipulating the size of the tubes, and you can just take aluminum further in terms of stiffness while still making an acceptably lightweight bike. Aluminum isn't any stiffer than steel; you can just make really big tubes without making them ridiculously heavy.


    Quote Originally Posted by Andy_K View Post
    In some regards, that's definitely so. The main qualification I'm claiming over him is having ridden many miles on several diffferent CX bikes.
    Well, fair enough and we'll leave it at that.




    Quote Originally Posted by Andy_K View Post
    I completely agree with what you've said here. There may be a level of miscommunication in either the OP's representation of the LBS guys remarks or my interpretation thereof. I understood the OP to be comparing CX bikes specifically to road racing bikes (which in itself encompasses more bikes than it ought to), and my remarks were generally oriented to that perspective.
    I see what you mean, I guess I was agreeing furiously.





    Quote Originally Posted by Andy_K View Post
    Again, I agree, but let me follow up on this line of exploration. The Roubaix is the epitome of high-end plush bikes, I think. Now, looking at it's geometry, its head tube and seat tube angles (for a 54cm model) are 72 and 73.5 degress respectively. The Specialized Crux, in the same size, has angles of 71.5 and 73.5. The Roubaix has a 165mm head tube, while the Crux has a 140, but if you factor in a typical 20mm difference in fork length between road bikes and CX bikes, these have a fairly similar axle to handlebar offset. The Roubaix has a 1000mm wheelbase, compared to 1028 for the Crux, due to the Crux's much longer chain stays. The Crux also has 65mm of trail, compared to 59 on the Roubaix.

    So, it seems to me that the geometry of the racing-oriented Crux compares favorably by "relaxed" geometry standards to the Roubaix. The more consumer/commuter oriented TriCross adds a taller head tube to the Crux geometry, but is otherwise about the same.

    That said, I'll definitely grant that a bike like the Casseroll has more relaxed geometry than either the Crux or the Casseroll. I'll also admit that I'm largely speaking based on numbers, having never ridden either one. Certainly, the Roubaix has other features, such as its Zertz inserts, that are at least intended to lend it more comfort, and I would expect that it's a better bike for charity rides than the Crux.

    In any event, none of this changes the fact that I agree with you about the suitability of the Pacer and Casseroll for much of what CX bikes are hyped for beyond the sand and mud.
    Bringing up trail is a good point, and more informative than just the head angles; however, 6 mm of trail does make for a bike that is edging into a different category of handling, rather than being essentially the same geometry. That's a noticeable difference in trail. Though there is definitely going to be overlap between that categories.

    Overall, I would say that we agree, though I would add one more point, which is that I don't think that minor differences in trail or head angle are going to make a difference in riding comfort. With the addition of differing stem lengths as a confounding factor, I doubt you would find any consistent difference there. When it comes to elements affecting ride comfort that are intrinsic to the frame, I think seat angle and chainstay length are far more important, and a racing-oriented CX bike is still going to have very short chainstays. Any reasonably objective difference in ride comfort between a road racing bike a CX bike will probably, in my opinion, be attributable almost entirely to the bigger tires on a 'cross bike. One more argument to get a comfy road bike rather than a 'cross bike, if that's what you're after!

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    Senior Member meanwhile's Avatar
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    Quote Originally Posted by Andy_K View Post
    This is an excellent point. We read a lot about bikes that are laterally stiff but vertically compliant, but in the real world a compromise tends to be made one way or the other. The aforementioned Surly Cross Check, for instance, I can testify, is quite compliant, as is common for steel bikes (this trait being one of the foremost reasons a designer would choose steel).
    As discussed many times before, this is garbage. The amount of cushioning that come from a frame is minute compared to the effects of tyres, and powertap experiments show that all frames transmit virtually all the power put into a bike. Ditto the idea that steel is the preferred choice for "soft" frames. The Crosscheck rides the way it does because of its geometry - even a slight increase in chainstay length will make a big difference to how a bike rides.

    As for cross bikes - the handling characteristics vary enormously with model in my limited experience.

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    Senior Member meanwhile's Avatar
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    Quote Originally Posted by grolby View Post
    Sure. IANAMS (I Am Not A Materials Scientist), but: steel is, intrinsically, a much stiffer material than aluminum.
    It shows. Sorry, but the above is nonsense. Do you mean stiffer for the same weight? Or the same volume of material? If you specify equal weight, then will the alu tube have the same wall thickness or the same tube radius??? All these things change the relative stiffness of the two materials.

    In practice, given the world constraints on bike construction (the most important of which is the tendency of large thin walled tubes to dent, alu is the stiffer - in the sense that is the material that can be used to make a stiffer frame that is still practical.

    If you want to understand cycling metallurgy, then read this:

    www.63xc.com/scotn/metal.htm
    Last edited by meanwhile; 02-04-11 at 02:52 PM.

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    Team Water Andy_K's Avatar
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    Quote Originally Posted by meanwhile View Post
    As discussed many times before, this is garbage. The amount of cushioning that come from a frame is minute compared to the effects of tyres, and powertap experiments show that all frames transmit virtually all the power put into a bike. Ditto the idea that steel is the preferred choice for "soft" frames. The Crosscheck rides the way it does because of its geometry - even a slight increase in chainstay length will make a big difference to how a bike rides.
    Quote Originally Posted by meanwhile View Post
    It shows. Sorry, but the above is nonsense. Do you mean stiffer for the same weight? Or the same volume of material? If you specify equal weight, then will the alu tube have the same wall thickness or the same tube radius??? All these things change the relative stiffness of the two materials.

    In practice, given the world constraints on bike construction (the most important of which is the tendency of large thin walled tubes to dent, alu is the stiffer - in the sense that is the material that can be used to make a stiffer frame that is still practical.
    At the risk of starting a petty bickering session, these two posts seem to be in some tension with one another.

    I definitely agree that tires provide much, much more cushioning than the frame, but I don't know if I believe that it isn't possible to feel the difference between frames of two different materials using identical tires. Granted again, the design choices such as geometry and tubing size and shape probably play more of a role than the material as such, but as you point out in your second post, decisions about tubing shape and size are not independent of material choice. All of which leads me to think that I wasn't entirely wrong in my prior statement that "as a general rule, if you want to build a compliant bike, steel is the easiest place to start, and if you want to build a stiff bike aluminum is the easiest place to start."

    Also, the "powertap experiments" are measuring work over time and as such reflect the efficiency with which a frame acts as a spring, yes? So a stiff frame which flexes little and a compliant frame which flexes a lot but doesn't lose energy in the process will produce the nearly same power transfer, if I understand correctly, but that's something quite different from what it feels like to pedal either bike.

    Another thing I'd like to mention is that the materials discussion thus far has been focused on the frame, but the fork is also involved in ride comfort, and that's a piece that you can actually see flex in many circumstances. Obviously, the fork, being effectively a lever-arm, experience forces differently than the main triangles, but it's enough to convince me that frame construction (by which I mean, material + tubing shape, size, etc.) is not actually negligible.

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    Senior Member meanwhile's Avatar
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    Quote Originally Posted by Andy_K View Post
    At the risk of starting a petty bickering session, these two posts seem to be in some tension with one another.
    This is often the case when you try to understand somewhat complex physics and engineering without having read the boring tech stuff. Put simply -

    - Both steel and alu can be used to create ultra rigid or ultra stiff frames by the choice of appropriate tubing diameter and profile, but alu is more practical for ultra stiff bikes

    - Stiff frames won't provide the benefit that you expect unless, perhaps, you are an ultra powerful sprinter

    - A comfortable ride results much more from tyre pressure and tyre wall quality and frame geometry than a "supple" frame. The right tubing can have an influence, but it is small compared to 10mm on chainstays or 5mm on tyres. And "soft" tubing can be alu or steel.

    Regarding the first two points, Sean Kelly was one of the most powerful cyclists of all time. His Vitus (a 979?) had what was one of the least stiff frames ever to race - people called it "a wet noodle". And it was made of (narrow section) aluminium.

    The reasons that people don't understand this stuff are very simple: bike marketing departments fill the air with nonsense to get people to spend money and cycling journalists don't have engineering or physics degrees - or the spines needed to stand up against the ad sales manager.

    Another thing I'd like to mention is that the materials discussion thus far has been focused on the frame, but the fork is also involved in ride comfort, and that's a piece that you can actually see flex in many circumstances. Obviously, the fork, being effectively a lever-arm, experience forces differently than the main triangles, but it's enough to convince me that frame construction (by which I mean, material + tubing shape, size, etc.) is not actually negligible.
    Again, fork flex isn't the result of materials choice but of the combined effect of material and tubing cross section. A Crosscheck's thin section steel fork is springy and rigid. My old Kona Lavadome's straight steel fork defines rigidity.

    The main problem with using alu in forks is that it has a poor failure mode compared to steel - sometimes it snaps when steel would bend or dent. Given the consequences of a sudden fork failure, I think designers will be wary of creating flexy alu forks.
    Last edited by meanwhile; 02-05-11 at 07:12 PM.

  19. #19
    Senior Member Jumpinj98's Avatar
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    If you want a good all around frame, the cross check seems to get a lot of love from racers to commuters. I have a fuji and besides obviously liking the brand, the geometry is fantastic for commuting or racing. And if you want to talk about a cheap good frame for what your looking for, find a fuji. The bike snobs tend to over look them so they go very inexpensive on ebay!
    10 Fuji SL-1 Pro Sram

    09 Fuji Cross Comp with alpha q cx20 fork and slk canti brakes

    10 Fuji Tahoe 29er Pro

    07 Fuji Cross Pro -- Sold to a friend in need

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