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Sloping frame

Discussion in 'General Discussion' started by gmason, Jul 19, 2007.

  1. gmason

    gmason Warming-Up

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    Just been asked by a friend who is considering buying a road bike what is the reason for sloping frames?
    He's looking at a Merckx Gara and it is available in both classic and sloping framesets. My only answer is weight and stiffness - anybody got a more mind-blowing answer?

    G
     
  2. WhiteGiant

    WhiteGiant Maximum Pace

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    Sloping...

    I have a Giant, obviously with a sloping tube; and I've asked many people "how is it different?".
    I've heard various answers, but the two most common ones were:

    1. The flat top-tube is more aerodynamic, but the physics/engineering of the sloping tube is actually much stronger.
    With a seat-tube at roughly 72 degrees, the weight that is pushed towards the rear wheel is more evenly compensated for with a sloping tube.
    The flat top pulls too hard on the top of the Head-tube, while also putting extra stress on the rear triangle.
    2. The main reason that some manufacturers have stuck with the flat, is mainly because the old retro (steel-frames) were all made like that - and a lot of people still like that look.
    Steel frames were made like that because before computer-design allowed frames to be made within fractions of millimeters, the flat-tube was the easiest way to calculate tube lengths all around.
    ie. It was never an exact science.

    Companies like "Trek" for example, still want to keep that "retro-flat" look, but now they have the advantage of computers, so there's not so much of a difference (they just make the top-tube joints stronger).
    Weight changes are minimal - your talking about 1 inch of extra carbon on the bike - almost nothing.
    Aerodynamically, it can make a difference in a Time-Trial.
    Even mainly "sloping" manufacturers make their TT-Bikes with an almost flat top-tube.

    Basically, I think it's mostly aesthetic, so you can choose "flat" or "sloping" without too much difference in performance.
    It just depends what look you're after.
    Personally, I still love the look of the flat-top, but after having ridden my "sloping" Giant for over 10,000km, it's kind of starting to grow on me a bit.

    Any other opinions out there are most welcome.
    T
     
  3. kiwisimon

    kiwisimon Maximum Pace

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    I'll add my two cents worth.
    Compact frames are the invention of a marketer (GIANT)who discovered that customers will buy a small frame and extend the seat tube and stem beyond what was the established norm. So instead of builing 8 frame sizes they can now get away with building 3 or 4.
    The argument about the down tube pulling on the top tube and such is highly unlikely unless frames are being built without seat stays these days. The strength of a welded joint comes from the contact areas of the joint , not the angle of it. Strength of the frame may come into it as shorter tubes are more rigid thn longer ones but this is countered by having longerr extended seat posts etc,
    as Travis said it comes down to rider preference, I prefer man sized frames:p1: and I have an excuse for being so slow up the hills, " hey my bike weighs more" never mind the engine.
     
  4. WhiteGiant

    WhiteGiant Maximum Pace

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    Saddle stems...

    Thank you Simon, for the extra information.
    It really was great.
    For the record though, I already have one of the longest carbon seat-stems on the market, and it's at its limit - Nearly 20cm sticking out of the frame itself.
    That said, I do find the Giant "compact" frame much easier to get into a bike-bag than my old steel-framed "Mobius" (That had a flat top-tube; and the size is 61cm from crank to the top the seat-tube).
    Besides that, my "Giant" happens to be 3kg lighter than the old steel beast.
    Where do you think I'm gonna put my money?
    T
     
  5. TODO R CASPELL

    TODO R CASPELL Maximum Pace

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    A fist full of seatpost.

    I will take my top tube flat thank you. I think it is another case of MT bike technology going road. Like the ahead set. Next look for disc brakes on road bikes. Also is true they have to make less frame sizes, small medium and large. HEY just like MT bikes ! I ride a 63 cm and don't like 2 feet of seat pin showing and my bars a foot lower. I am not racing here. What's the old standard ? A fist full of seat post. TODO
     
  6. m o b

    m o b Speeding Up

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    Disc Brakes on Road Bikes

    "The future is already here - it is just not equally distributed" - one of my favourite quotes; this one from William Gibson. And of course there are already disc brakes on road bikes : http://www.canyon.com/_en/technology/project68.html

    I think that this is a wonderful idea. Besides my Cervelo road bike I ride a Cannondale Bad Boy Ultra hybrid bike, MTB frame, 700 x 23C tires, front suspension (mainly shut off) and Hayes hydraulic brakes in the front and rear. The braking performance is so much better than on my Cervelo and this is the reason why I prefer the Bad Boy when riding in the city.

    I tried to improve the braking performance of the Cervelo and consulted with Nagai-San from Positivo. Summary:

    Nagai-San:

    - An upgrade from Ultegra SL to Dura Ace will not substantially improve braking
    - Cleaning and polishing of the Al rims will neither
    - Standard Shimano brake pads for Dura Ace, Ultegra SL and 105 are the same

    Me :

    - I upgraded to Swiss Stop brake pads (very expensive) with almost no effect
    - Brake performance would substantially increase with me loosing weight

    I remember another thread about Koolstop brake pads, but after my experience I doubt that there will be much improvement.

    Any other good idea ?

    Let's wait until the distribution is more equal in the future.
     
  7. Phil

    Phil Maximum Pace

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    Musing on disc brakes...

    One thought: Have you changed your brake wiring recently? New cable might help.

    Don't see a future of plentiful road bike disc brakes... Weight is one problem, but the real issue is that the limiter on (dry) road bike braking is the skinny contact patch of the tire...I can skid my tires under heavy braking with regular calipers, so any braking power beyond that is superfluous. Going downhill the limiter is me going over the handlebars, which again I have enough braking power to achieve (untested supposition, so far.)

    Wet weather is a somewhat different case, but roadies don't like to get their bikes wet anyway :)

    Disc brakes make some sense on commuter/hybrid/city bikes though. A few cyclocross bikes come with disc brakes/disc brake mounts, but they're not UCI legal so it's only a few models that have them.
     
  8. maverick_1

    maverick_1 Warming-Up

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    hi mob..

    please tell us more about components setup on your Cervelo..
    it is a complete D/Ace setup? or mix of D/A, Ultegra?

    i'm currently on the Campy 10s Record, was previously using the D/Ace 10s approx 2yrs ago..
    found the brake calipers on the D/Ace to be very grippy and you really need to modulate the brakes well else it will go on full lock..
    as for the Campy 10s, it's not as powerful as the D/Ace.

    in addition to that, i've also switch from the stock D/Ace pads to Koolstop as well (i believe i got the wet/dry version- bi color pads)//not much of a difference comparing to the stock D/Ace pads.

    cheers
     
  9. m o b

    m o b Speeding Up

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    Cervelo Setup

    Hi Maverick,

    I have a Cervelo Team Soloist (2007 version) and basically all components are Shimano Ultegra SL (levers, brakes, derailers, chain, casette) with the exception of the crank set which is SRM Force 53/39 with a 172.5 mm crank.

    In addition I have Campaganolo Zonda wheels with Al rims mounted.
    My right lever is connected to the front brake.

    I wanted to improve braking performance, so I did the following :

    1. Replaced old with new Shimano brake pads (rear and front) - no effect
    This Type (http://www.excelsports.com/new.asp?...ura-Ace Brake Pads 7800 R55C2&vendorCode=SHIM), same for Dura Ace/Ultegra/105

    2. Readjusted and greases cables (some effect)

    3. Cleaned and polished Al rims of Campagnolo wheels (no effect)

    4. Replaced brake pads with Swiss Stops (no effect)
    See here: http://www.excelsports.com/new.asp?...ano 4pads&vendorCode=SWISSSTP&major=1&minor=8

    If you have any good idea, please let me know.
    Cheers.
     
  10. trad

    trad Speeding Up

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    SRAM brakes and brifters

    My current bike came with SRAM Force brifters and brakes and these things are POWERFUL. I've ridden 7700 variety DuraAce for a long time, and also have ridden 6600 Ultegra, and there's simply no comparison. Not sure if is the design inside the brifters or the brake calipers as the pads are not great and I cleaned/tried same wheels. Feel, modulation, power is very different and better - at least for this out of shape, middle aged fred/poseur. :cool:
     
  11. maverick_1

    maverick_1 Warming-Up

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    hi mob..

    im not so sure about the new Ultegra SL 10speed calipers though, haven't tried it before. nonetheless, comparing all the other brake calipers that i've used (Campy Record Skeleton 10s, Campy Chorus 10s, D/Ace 10s, Ultegra 9s), the D/Ace offers the best braking power. Even with the stock pads, you can easily lock the wheels if you're not careful enough modulating those levers.
    personally, i believe it all boils down to the caliper design (pads do have some effect but bottom line is the calipers itself)
    IMHO..the 7800 D/Ace calipers outperforms my current Record Skeleton brake calipers anytime.

    since you already stated that you've basically done whatever possible (cleaning of rims, polishing, brake pad change etc), my only recommendation is to try out the D/Ace calipers (7800 series):cool:

    keeping my fingers crossed, i hope this works for you!

    cheers
     

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