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  1. #1
    Senior Member shortshorts's Avatar
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    Cyclocross / Touring geometry switch-a-roo ???

    How important is a frames geometry?

    I'm going to get a new frameset to build up for my commuter, and I'm choosing between a cyclocross bike & a touring bike.
    I know I can't change the wheelbase & bottom bracket height, but everything else is pretty much adjustable right?

    There are options like setback seatposts, moving a saddle forward/backward in the seatpost clamp, all sorts of stems with varying rise & length...

    Can't I pretty much make one type of bike fit like the other just by moving my saddle around and maybe swapping a stem?

  2. #2
    Randomhead
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    Just to be clear, you are considering buying commercially available off the shelf frames or having a framebuilder make you a frame?

    Front triangles are not all that different between different styles of bikes and the differences should be small enough that stem swapping should be able to get you in the right position

  3. #3
    Senior Member shortshorts's Avatar
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    I was trying to decide between a Surly Cross Check frameset that I would build up myself, or a custom built cyclocross frameset. The Surly is a bit heavy for my tastes, so if I'm going to pull the trigger & go custom, I wanted to make sure I'd be able to have the best of both worlds down the road.

  4. #4
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    True touring bike = longer wheelbase + slacker angles + stiffer tubeset -----> All the better to safely carry significant front and rear loads.
    Cyclocross = geometry not too different from a roadie + a little higher BB + canti-posts (although discs are coming up fast).

    Dunno know about you, but I don't need to carry significant front and rear loads, and opted for a cyclocross rig (Gunnar Crosshairs) for my commuter. Marginally more sluggish in handling than my better road rigs, but I'm running rear racks, with a cargo bag and weatherproof panniers, fenders, dyno hub, and 32x700 tires. All that carp would make most any rig a less lively.

    If you are looking at a Surly Cross Check, you should also check Soma Double Cross. They even have a newer version for discs brakes, which is a nice option if you are running all weather. Higher up the food chain is the Gunnar Crosshairs, although I'm on mine simply because I found a really sweet deal on a used one. Nice frame though. For a relatively modest upcharge, Gunnar will make you one to measure. Stock or custom, they are made in Waterford, WI, by a company run by Richard Schwinn, (yes, related to that family) which I think is pretty cool.

  5. #5
    Senior Member GrayJay's Avatar
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    You could likely produce similar biomechanical fit on either a touring or CX frame by adjusting saddle position and stem, but the ride & handeling quailities are more or less determined by the frame design and are somewhat unadjustable. A CX frame is most often a comprimize to optimize nimble handeling and positioning for producing explosive busts of power, not necessarily the most comfortable fit for a long, extended ride. Touring bikes are a compromize designed around comfortably being capable of carrying a lot of extra weight for a long time and producing stable handeling while doing so. Unless your are indending to CX race or loaded tour, dont rule out a traditional road bike which is largely optimized for nimble handling and a long range comfortable position.

    Head tube angle is not a great predictor of the intention of the frame and will likely not limit its use. Most loaded touring frame will have same 72-73 range of HTA that you would find for most CX bikes. While not typical of most production CX bikes, some of the slackest HTA used by any road/touring/CX bike are found on the race winning focus mare CX bike, 70.5-71 HTA depending on frame size; http://www.focus-bikes.com/us/en_us/...es-cx-1-1.html Same CX frame also uses a fairly low BB (70mm of drop, more road like).
    Big difference for the front end would be that the loaded touring bike will have more fork rake, less fork trail (<56mm) for lighter steering while front loaded, the CX bike forks will have less rake, more trail (56-65mm) for more steering stability on rough surface.

    Chainstay length is probably the one factor that will most reliably differentiate a CX frame from a touring frame. A CX bike will have medium length CS and wheelbase for somewhat quick handeling while a touring bike will have long CS for heel clearance with panniers and long CS/wheelbase for stable tracking ride.

  6. #6
    Wrench Savant balindamood's Avatar
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    FWIW, if you go to the Vintage-Trek.com website, you will find that the 1990 Trek 520 (touring) and the 7x0 hybrids used the same frame geometry (just different tubes). I do not know if I would "recommend" this approach. I am just point out that corporate America has made similar compromises in the past. They (Trek) did not make a CX bike back then.
    "Where you come from is gone;
    where you are headed weren't never there;
    and where you are ain't no good unless you can get away from it."

  7. #7
    Senior Member shortshorts's Avatar
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    As far as geometry, aren't a cyclocross bike & a road bike pretty much the exact same thing?
    I thought a cyclocross just has clearance for wider tires & cantilever brakes?

  8. #8
    Senior Member GrayJay's Avatar
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    Quote Originally Posted by shortshorts View Post
    As far as geometry, aren't a cyclocross bike & a road bike pretty much the exact same thing?
    I thought a cyclocross just has clearance for wider tires & cantilever brakes?
    I would look for a road bike to more often have a slightly slacker seat tube angle & perhaps slightly longer top tube for a more comfortable position, shorter chainstays, less fork trail for better road handling. Many (but not all) CX bikes will also have a high bottom bracket , a lower BB will give you slightly more standover height and a riding position with slightly lower center of gravity (more stable). Road bike sidepull brakes give better braking if you dont need the clearance of cantilevers.

  9. #9
    coprolite fietsbob's Avatar
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    The 'cockpit' fit is about your body proportions , and the posture
    you prefer to be in most of the time, while you ride the bike.

    Both are trying to be a fit for the average body, and someone
    designs what they think will sell well.. 71~73 degrees .. is not a big range..
    fork trail is the other dimension to vary..

    Cross = carrying the bike , up steep run-ups and lifting it over barriers..
    so the specs are presumably about Light. and not digging a pedal in the hill,
    riding an off camber slope ..

    touring You have a load being carried, and the panniers on the rack in back
    not being so close you hit them with your feet, needs longer chainstays.
    so a touring bike, to handle the load on it, uses a thicker tube for the main triangle.

    to cloud the waters,, further commuter bikes are being sold, with V or cantilever brakes
    so the fender mounting has room over a decent sized tire.
    Last edited by fietsbob; 12-05-11 at 05:45 PM.

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