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  1. #26
    Senior Member JeffOYB's Avatar
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    Quote Originally Posted by bobotech View Post
    Out of curiosity, are you a professional racer? Just wondering what the big deal about 1 pound is. To me generally a light bike is anything about 22-23 pounds or less with pedals and saddle. Under 19 is an ultralight to me. I vaguely remember weighing my TCX frame/fork and it was something like 4 pounds and a couple of ounces on the scale at the bike co-op i work at.

    If you want something lighter, just pony up the cash. It seems to me that once you get to lighter weight frames, the lighter the weight, the more they cost or the weaker they are or both. So sure your TCR is lighter than the TCX but apples and oranges. If you want a cheap very light cross frame, you will probably end up with something weak. If you want a light strong cross frame, figure heavier than a similar road frame since as far as I can tell, they are designed to handle much more abuse than a typical road frame.

    road vs cyclocross frames=apples and oranges
    Since you ask, I confess that I'm really Sven Nys posting secretively (until now). I'm pretty sure a bike is a bike for the most part. I don't see any CX frame-maker saying "reinforced here and here to survive the rigors of cross." Cross has been done using roadbikes for over a century. Ride a heavier frame if ya like, tho. But my policy is the more weight I can easily shed, the better. I'm not talking about getting carried away or spending any excess at all. I just have a hunch that a 25-30% heavier frame isn't needed. The TCR isn't either a pricey or bad frame -- so cheap'n'light are totally doable. I just want someone to gimme a CX frame like the TCR only with some clearance. ...Then I'll just put a Trek sticker on it and win the next World's!
    Jeff Potter
    http://OutYourBackDoor.com
    for indie outdoor culture & DIY adventure
    bikes, boats, skis 'n' more ... 2000+ articles since 1994!

  2. #27
    Senior Member JeffOYB's Avatar
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    PS: In short, it looks like CX frames are heavier than road frames these days by a large percent. 1 lb doesn't mean much to many, it seems, but I call it, oh, about a 28% weight increase with no detailed explanation of why/where the weight is needed. Frame hype has many details but not this, apparently.

    I note that in the 80's/90's that CX bikes were mostly roadbikes or CX specific bikes that weighed the same or LESS than road bikes. I don't recall any rationale for heavier. Also, I do strongly note that CX courses are often much smoother and easier nowadays. Lastly, back then a fat CX tire was 28 and absorbed LESS shock, yet these light frames did fine. Today's CX frames fit up to 35mm -- very cushy. Well, maybe roadframes these days are made so much more fragile that CX frames have to weigh more due to mystery reinforcement. Is it well known where the extra pound-worth of material must go or a frame will break in normal CX usage?
    Jeff Potter
    http://OutYourBackDoor.com
    for indie outdoor culture & DIY adventure
    bikes, boats, skis 'n' more ... 2000+ articles since 1994!

  3. #28
    Senior Member Kopsis's Avatar
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    Material plays a big role. I'd wager that in the 80's/90's most CX bikes were steel. You're looking for aluminum and that has a radically different fatigue life. Al can handle very little flexing before the material fatigues and cracks. No matter how tame your CX courses are, the dynamic load stress on the frame from riding high speeds on bumpy surfaces is significantly higher than riding on the road (though when it comes to Michigan roads, the difference may not be as great as elsewhere ). The only way to prevent aluminum fatigue failures is to keep it from flexing. The way to do that is add material. Note that fat tires don't change the magnitude of the low frequency forces on the frame, they just filter some of the high frequency content.

    Now, it's possible that a smaller rider on a well groomed course could get by with a lighter alloy frame and not push it into the fatigue range, but the big brands don't build for the 5th percentile. What you describe is a custom tailored frame, so you're going to have to go to a custom builder and pony up a bit more than a $200 ebay price tag. When it comes to alloy frames: strong, light, cheap ... pick any two.

  4. #29
    Senior Member
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    Quote Originally Posted by JeffOYB View Post
    PS: In short, it looks like CX frames are heavier than road frames these days by a large percent. 1 lb doesn't mean much to many, it seems, but I call it, oh, about a 28% weight increase with no detailed explanation of why/where the weight is needed. Frame hype has many details but not this, apparently.
    I would look at it completely different. That 1 pound equals more of a 5 percent difference in the bike's weight, not 28 percent. Look at the overall end sum of the final product, not the individual pieces. In the end, just how much of a difference is that going to make for your race. Maybe lose an extra pound or two in body weight, free overall riding weight loss. For everyday riding and amateur riding, 5 percent probably really doesn't mean all that much. Heck, if you take your weight into consideration with the bike weight, your one pound difference probably is more like .5 percent difference (175lb person+25lb bike). And I agree with the other poster, steel is much more forgiving than aluminum so you could get away more in the eighties. Just spend the money, it doesn't appear that you are going to find a cheap light cross frame that you desire so spend a few hundred or more for a light cheap strong frame. Won't be cheap but it might have the characteristics that you desire.
    "When dealing with stuff like this consider that this is a bicycle, not a spaceship." -- FBinNY

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