Cracked saddle Dogma F.

rublow
rublow Posts: 3
edited June 5 in Road general

Hi,

A few days ago I noticed that my Bjorn Setka saddle was cracked. One of the rails is broken. I contacted Bjorn, made a few phone calls and the answer from the manufacturer is that the reason for the failure is the sharp edge of the seatpost clamp. It was mounted with the correct torque on a brand new Pinarello Dogma F titanium seatpost clamp.


I am very interested in your opinion. There are only a few posts on various forums that mention this as one of the possible causes. However, the Dogma F with 3D printed titanium clamp has been on the market for over 3 years, so if this were the case I would expect to see more posts like this.

I would be grateful for any suggestions, hints.

Comments

  • MidlandsGrimpeur2
    MidlandsGrimpeur2 Posts: 1,530

    Sharp alloy clamped to carbon will most likely cut into the carbon and leave visible scoring. That rail has frayed and broken clean through. Nobody can say for certain but I would say it is clamping force. That is not to suggest you have overtorqued it, the recommended clamping torque might be too high.

    Looking at the rail, that carbon looks like it has voids in the carbon. It is obviously a very lightweight saddle (guessing it is 3D printed?). My personal view is that if you use super lightweight carbon parts, you do run the risk of parts not having the same durability of something more heavyweight.

    Unfortunately, trying to ascertain exactly what caused this would be very difficult.

  • rublow
    rublow Posts: 3

    Thanks @MidlandsGrimpeur2 . It is a 3d printed titanium clamp, and to be fair I always tighten 1-2Nm less than max torque and adjust if it moves.

    My theory is that there are so many Dogmas with this solution, that someone else will also report the issue with sharp titanium against carbon rails.

  • ugo.santalucia
    ugo.santalucia Posts: 28,300

    get another one, one of those 99g Dodici saddles from Ali3xpress, they are great and cost 15 quid

    left the forum March 2023
  • trevor.hall12
    trevor.hall12 Posts: 440

    Having the metal on carbon really gives them an out .

    Ss suggested above with matches like this you start low and adjust torque if needed .

  • ugo.santalucia
    ugo.santalucia Posts: 28,300

    saddles break, I broke a Fizik and a Selke Italia with metal rails.

    I don’t get the point of spending 350 quid on a saddle. Ali Express is littered with copies and with carbon saddles that weigh 100g or less and cost peanuts. They are broadly fine, I have two and they have not broken yet.

    I am under no illusion, they will eventually break. If you want a forever saddle, the 100g market is not the one to look at, whether is fancy Western made or Chinese.

    left the forum March 2023
  • sungod
    sungod Posts: 16,766

    is the mark on the rail where the edge of the clamp was?


    if so, it seems to be away from the break and matches the position in your second image, without a higher resolution image all around the break it's impossible to tell if the break is actually on the edge of the clamp

    as mentioned above, it looks like there're voids in the cf, also, the rails look like just longitudinal fibre with no reinforcement in/around the clamping area


    fwiw i've used an ax lightness leaf saddle for c. 10 years, still vividly remember hitting a surprise pothole so hard that i was stunned by the jarring impact up through the saddle, but it was undamaged

    it weighs c. 78g, over 50g less than the setka

    ax lightness have been around c. 25 years, they produce composites for many other industries too, including for f1

    ax make the leaf's rails like this...


    my bike - faster than god's and twice as shiny
  • daniel_b
    daniel_b Posts: 11,659

    I've had a number of saddles with carbon rails in metal clamps, though the clamps are of the Ritchey WCS type, and as far as I am aware have no sharp edges - you also have to buy different clamps based on the profile of your saddle rail, be them round, or oval etc.

    On the Fizik Ariones, genuine ones, they put a small amount of some kind of wrap around the rails, fakes on ebay are easy to spot as they weigh more and have none of the wrap.

    I presume Fizik add the wrap to help protect the rails from this kind of issue.

    The noises as you get up towards the correct nm are rather disquieting to put it mildly, but I have had no issues with them.


    I also had a Berk saddle, which had no wrap and is mega light, this had no wrap and made nasty noises as it was tightened up to the required 12nm 😬

    A friend locally bought the exact same saddle, and the rails had no issues, but there must have a been a manufacturing issue as the actual saddles developed tiny cracks in the weave - we both contacted Berk individually, and he was super quick at offering us a total replacement at zero cost, which we have accepted, though I have not gotten around to fitting the new saddle yet, it just has a Arione on there currently.


    I am not familiar with the brand of saddle you have used, but can see the price is significant.

    I'm a little surprised that they haven't offered to effect a repair for you at the very minimum, as then at least if it is definitely not compatible with your bike/seat clamp, you could sell it on to try and recoup some of the outlay for a new saddle.

    Felt F70 05 (Turbo)
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  • trevor.hall12
    trevor.hall12 Posts: 440

    That pic shows exactly the opposite to my eye ,the first mark is exactly where the break is .