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Thread: cyclo fit

  1. #1
    Senior Member Vlaam4ever's Avatar
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    cyclo fit

    I'm not sure what a good fitting cyclo cross bike feels like. I'm seriously considering picking up a new or used Cyclocross bike for next fall race season. I've only been riding road for the past 15 years with more or less fast group rides. so I know a what I need to be comfortable on my road bike. but now sure how this translates to cross. I've gotten some poor guidance from the first two bike shops I visited and thought I'd check in here before looking at used bikes.

    In case it matters: I ride a 55.5 cm top tube with a 100mm stem. I have quite a bit of saddle to bar drop and am very comfortable this way. I've heard I may want to consider a more compact and upright bike fit to make it easier to get on and off the bike and also so it is more maneuverable. So does this mean I should find a ride that is short in the top tube? Should I be shopping for 54's instead.

    As an aside: I picked up a Motobecane Fanthom UNO as a commuter bike in size 54 with a 130mm stem. it feel a bit small but is totally fine for commuting and bar hopping duty. Not sure I could get this one into race form without redoing all the fit pieces. So, I'm looking for a real cross bike (with gears) to tear up the Georgia CX circuit this fall.
    20?? Motobecane Fantom Cross UNO, 2008 Giant TCR Advanced, 2000 Trek 2300, 1995 Giant ATX 760

  2. #2
    coprolite fietsbob's Avatar
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    buy a copy of Simon Burney cyclocross book < google that << [now in 3rd edition]
    read it, and figure it out .. maybe with a few test rides in the shop.

    http://www.competitivecyclist.com/za...LCULATOR_INTRO

    I have a 57x57 bike myself, Re its fit, .. show very little seatpost, I'm old and dont compete.
    9.5 stem level with saddle,

    have an RB1 road bike thats a 56x56.5.. im an old tourist rider.
    Last edited by fietsbob; 06-10-13 at 09:48 AM.

  3. #3
    Senior Member Vlaam4ever's Avatar
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    Thanks for the book advice. I put it on my amazon list to pick up this week. I'll revisit the shops after reading about fit. I dont see jumping on and off my road bike as a great idea in its current fit. I may loose some some precious cargo.

    I was highly discouraged after visiting my first bike shop and being told that my "fit should the same as your roadbike, more or less, most people just lower their saddle a bit so they dont rack themselves. Why dont you take a 56 around the parking lot. "
    20?? Motobecane Fantom Cross UNO, 2008 Giant TCR Advanced, 2000 Trek 2300, 1995 Giant ATX 760

  4. #4
    Team Water Andy_K's Avatar
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    There are two different things at issue here. For comfort, a CX bike and a road bike have exactly the same fit issues. If you've got your road bike set up for comfort and you set your CX bike up like that then it will be comfortable.

    The other issue is geometry. You aren't going to find a CX bike with exactly the geometry of your road bike, so probably that's not what your LBS was saying. Things like tube angles and chain stay length are chosen for you once you choose a specific CX bike, but they have little to do with fit. Once you choose the CX bike, the geometry issue is behind you and you're looking for fit in choosing the size. There are certain things you can do like modifying the bar and seat height, but those are minor tweaks.

    I don't think the advice you got from the LBS is all that bad. The saddle position relative to the bottom bracket determines your power output and so you probably want that pretty close to what you'd want on a road bike. You spend a lot of time riding just above the saddle in CX to let the bike move, which is why you might lower the saddle a bit. You probably want the bars a bit higher than you would with a road bike, but the head tube length mostly makes that happen. Top tube length is still a function of your body proportions, but you might want less reach than you would on a road bike because handling is usually more important than aerodynamics. You want a little more standover clearance than you would for a road bike for those times when you don't manage to stay in the saddle, but the compact geometry of a CX bike usually takes care of that for you.

    So at the end of the day, the best thing to do is guess which size you need then ride it a bit to see how it feels.

    BTW, Simon Burney says, "If you already own a road bike and it fits you comfortably, then go for the same sizing."

  5. #5
    Senior Member Vlaam4ever's Avatar
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    Quote Originally Posted by Andy_K View Post
    There are two different things at issue here. For comfort, a CX bike and a road bike have exactly the same fit issues. If you've got your road bike set up for comfort and you set your CX bike up like that then it will be comfortable.

    The other issue is geometry. You aren't going to find a CX bike with exactly the geometry of your road bike, so probably that's not what your LBS was saying. Things like tube angles and chain stay length are chosen for you once you choose a specific CX bike, but they have little to do with fit. Once you choose the CX bike, the geometry issue is behind you and you're looking for fit in choosing the size. There are certain things you can do like modifying the bar and seat height, but those are minor tweaks.

    I don't think the advice you got from the LBS is all that bad. The saddle position relative to the bottom bracket determines your power output and so you probably want that pretty close to what you'd want on a road bike. You spend a lot of time riding just above the saddle in CX to let the bike move, which is why you might lower the saddle a bit. You probably want the bars a bit higher than you would with a road bike, but the head tube length mostly makes that happen. Top tube length is still a function of your body proportions, but you might want less reach than you would on a road bike because handling is usually more important than aerodynamics. You want a little more standover clearance than you would for a road bike for those times when you don't manage to stay in the saddle, but the compact geometry of a CX bike usually takes care of that for you.

    So at the end of the day, the best thing to do is guess which size you need then ride it a bit to see how it feels.

    BTW, Simon Burney says, "If you already own a road bike and it fits you comfortably, then go for the same sizing."
    This is super helpful. thanks
    20?? Motobecane Fantom Cross UNO, 2008 Giant TCR Advanced, 2000 Trek 2300, 1995 Giant ATX 760

  6. #6
    Senior Member GrayJay's Avatar
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    All good advice from Andy. I would add that a bit higher handlebar position is definitly helpfull for CX, makes for much better off-road control than being too-low in a pure road position. If your bars are too low, you will also never get into the drops which is a usefull position for CX. Problem I see with getting a small fitting CX frame is that with a shorter headtube, the available bar position is also correspondingly lower (without a goofy looking upright stem, tall stack of spacers) so quickly limits ability to setup for a higher bar position, particularly when the seatpost is at long extension height to compensate for the frame being small.
    Once you get your dismount/remount technique down, standover clearance is very minimal consideration. However, if standover clearance is a big concern for you, look for a CX frame with a lower bottom bracket (like 70-75mm BB drop range) instead of a high BB style CX frame (55-60mm drop). Tradeoff is that you might have more off-camber pedal strikes with the lower BB but you gain standover. Going to a sloping TT can also gain clearance but makes it more difficult to shoulder the bike for run-ups.

  7. #7
    Senior Member Vlaam4ever's Avatar
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    I've spent the past few days looking for LBS'es to test Cross bikes. Nobody has them, excepte the Performance store that gave me better advice that I credited them for. I did talk to some knowledgeble sales folks and I have a small list of recommendations but I'll need to go to the store and order a bike based on recommendation and trust they will get it to fite.

    LBS 1 Carrries Trek Cannondale. Highly recommended the CAADX. pitch was that it essentially a CAAD10 built a to be used as a cross. I love the CAAD 10 so am putting this at the top the list for function and cost. I'm very disappointed on the color options but can live with it I suppose.

    LBS2 Carries Specialized Bianchi. High recommended a SORA version of the CRUX. The CRUX is a gorgeous bike and will suite me well for many years in Cross or commuting. It may be more bike that I need for this first go at cross, it's nearly out of my price range. I'llhave to order it soon to get on the waiting list for a 2014 version of the Sora model that is comming out late july... They do have 56cm 2012 expert Crux so I can at least get a feel for the bike sizing and what it can do, it is way out of my price range though.
    20?? Motobecane Fantom Cross UNO, 2008 Giant TCR Advanced, 2000 Trek 2300, 1995 Giant ATX 760

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