1.5" to 1 1/8th 'tapered' steerer tube on a fork

dyls
dyls Posts: 64
edited January 2009 in MTB workshop & tech
How does this actually work if I want to change the forks? Because different bike sizes will have different headtube lengths.

I've got on of those Specialized forks (120mm) on my Stumpjumper carbon.

Comments

  • supersonic
    supersonic Posts: 82,708
    The taper is from the bottom of the steerer, which quickly turns into a standard steerer so you cut as normal.

    If you want to change to a standard 1.125 fork you will need adaptor cups for the headset.
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  • nicklouse
    nicklouse Posts: 50,673
    well you could buy a 1.5 to 1 1/8th reducer headset and a 1 1/8th headset and use half of each.

    But it does depend on what the headset fittings are.


    Also there are a few aftermarket forks coming out with the dual headset sizing.
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  • dyls
    dyls Posts: 64
    Thanks.

    Noticed that Fox now do the tapered steeret tubes for their 2009 forks.
  • dave_hill
    dave_hill Posts: 3,877
    I really don't understand the thinking behind tapered headsets at all.

    I mean, I know that a 1,5" bearing will take a higher load than a 1.125", but how much weight are you actually saving by having one of each instead of just two 1.5"?

    And it just introduces a third, unnecessary type of steerer tube. Surely it would be easier to sleeve down a 1.5" bearing and fit that to a standard 1.125" steerer? Or fit a larger crown race.

    I had considered a Trek Remedy as a possible replacement for the Giant this year, but the tapered head tube (and the ABP setup) really put me off.
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  • supersonic
    supersonic Posts: 82,708
    It is not really about the bearing loading or wear (though a nice side effect): it is there to increase the stiffness of the steerer at this critical point (and the crown). This stiffness is not so essential at the top of it therefore the taper is introduced.

    Waht's wrong with the APB?!
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  • dave_hill
    dave_hill Posts: 3,877
    supersonic wrote:
    It is not really about the bearing loading or wear (though a nice side effect): it is there to increase the stiffness of the steerer at this critical point (and the crown). This stiffness is not so essential at the top of it therefore the taper is introduced.

    Looking at it from a manufacturing/supply point of view, it introduces more parts than are needed and if you want extra stiffness, why not just have the smae diameter along the whole length? I still don't think it makes sense.
    supersonic wrote:
    Waht's wrong with the APB?!

    They break (no pun intended). Plus its more of a faff to remove the rear wheel.
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  • supersonic
    supersonic Posts: 82,708
    The stiffness is only needed at this part of the steerer. This is why 1.5 was born, so we could have longer travel single crown forks. RS 1.5 steerers are stiffer and lighter than the heavily reinforced 1.125 versions, though overall system weight for the 1.5 due to heavier headset is a little higher.

    The taper reduces the weight further for the top headset assembly, and stem, and the frame a little as the 1.5 is simply not needed here. So with this system you get a lighter, stronger and stiffer set up than a constant diameter steerer.

    It does introduce more parts, but headsets will soon be sold with a 1.5 bottom cup and race, and 1.125 top cups and bearings so hardly an issue.
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  • dave_hill
    dave_hill Posts: 3,877
    Bah. Yet another example of the industry foisting unnecessary (and unproven) "technology" on us, in an attempt to "solve" a "problem" that probably doesn't exist outside of a computer.

    Right, I'm off down the manufactory on my hobby-horse to smash power-looms...
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  • supersonic
    supersonic Posts: 82,708
    SHould have seen manitous original Millenium test reslts when they tried a standard XC steerer on a LT fork - it flexed FOUR INCHES backwards under braking! This is why they went to 1.5 very early on a lot of forks. No doubt 1.5 works in this area, and at less weight (than a beefed up 1.125)
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  • dave_hill
    dave_hill Posts: 3,877
    It just seems odd to me that we've had 1.125" steerers for how long? 20 years? ANd 1.5" steerers for how long?

    And then somebody (Who? Who comes up with these ideas?? I have hundreds of ridiculous ideas every day, why can't I get paid for them???) suddenly decides that neither one is any good on it's own, we need a combination.

    BOLLOCKS!!

    If it's such an obvious probem, why has it taken so long to surface and for somebody to do anything about it? It's just a marketing fad, and like everything else the gullible will suck it all up, forcing the rest of the industy and ultimately the cash-spending punters to toe their line.

    Makes me wonder how I never managed to kill myself by loosing control of those noodley frames with 1" headsets we used to ride back in the day...
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