Dropper post

Andsar
Andsar Posts: 3
edited June 2018 in MTB beginners
Hi all, I’m new to all of this biking and have just purchased a hard trail. I have just gone to change the handle bars and have noticed that the stem to the forks doesn’t come to the top of the headset and is only being clamped by the bottom bolt, any advise please

Comments

  • JGTR
    JGTR Posts: 1,404
    The steerer tube should stop just below the top of the stem and be clamped by both bolts. If not:

    1. The steerer is too short for your bike, in which case you’ll need to replace the fork.

    2. There are too many spacers under the stem, in which case remove them.

    Was it new or second hand? Pictures would also be very helpful
  • cougie
    cougie Posts: 22,512
    Dropper post ??
  • steve_sordy
    steve_sordy Posts: 2,453
    Presumably you test rode the bike and liked the riding position? Well, having to remove spacers under the stem and make the bar/stem safe will drop the height of the bars. You can compensate for that with a riser bar, but I guess that you have already bought your bar.

    If there are no spacers under the stem, then the seller has sold you a dangerous bike and you should demand your money back. It doesn't matter whether he knew about it or not.

    Even if there are spacers under the stem and you can make it safe, he has still sold you a dangerous bike and he could still be made to take the bike back. But you might like it and be happy to keep it. But you MUST fix that stem issue.

    I would ask yourself, "if he has faked something as dangerous as this, what else has he done?" Has this bike been assembled from a collection of stolen parts?
  • apreading
    apreading Posts: 4,535
    You dont say if the bike was new or second hand?

    Why are you changing the bars already?

    How far below the top of the stem is the top of the steerer tube? Its meant to be a little below but not much and certainly not below the top bolt - you make it sound like it is REALLY short but we cant be sure.
  • larkim
    larkim Posts: 2,485
    The stem is supposed to be about 2-3mm short when clamped over the tube in the forks, is it not?

    See the pick on the parktools website https://www.parktool.com/blog/repair-he ... and-sizing

    This may or may not be what you're asking!! A bit more than 3mm will be OK, but I wouldn't want to suggest how far that tolerance should be.

    If it's a new bike, back to the shop if you've got any concerns.
    2015 Canyon Nerve AL 6.0 (son #1's)
    2011 Specialized Hardrock Sport Disc (son #4s)
    2013 Decathlon Triban 3 (red) (mine)
    2019 Hoy Bonaly 26" Disc (son #2s)
    2018 Voodoo Bizango (mine)
    2018 Voodoo Maji (wife's)
  • The Rookie
    The Rookie Posts: 27,812
    larkim wrote:
    A bit more than 3mm will be OK, but I wouldn't want to suggest how far that tolerance should be.
    As a rule of thumb as long as the steerer ends above the centreline of the top most bolt it won't cause an issue (metal steerers that is, a carbon steerer will usually need a bung and must have a spacer above the stem).
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • 02gf74
    02gf74 Posts: 1,171
    The Rookie wrote:
    larkim wrote:
    a carbon steerer will usually need a bung and must have a spacer above the stem).

    Carbon steerer have bung instead of the star fangled nut.

    I have 4 bike with car on steerer, the bungs differ a bit in design but none of them need a spacer between stem and to cap.
  • Andsar
    Andsar Posts: 3
    Cheers all for the replies, yes the bike was second hand and the original folks had been changed and rockshoks put on but the stem is to short for the bike, looks like I will have to buy new folks
  • larkim
    larkim Posts: 2,485
    Sounds like a second hand pair of forks already cut down were added to the bike (or they cocked up the installation and cut too short) - shame, hope that hasn't turned a 2nd hand bargain into a "wish I'd never bothered"!

    How far off the top is it? Would a shallower (I'm sure there's a better term!) stem solve the issue, would certainly be a cheaper solution.

    Edit: low stack height I think is the correct term? Or perhaps find a stem with only a single bolt, they do exist.
    2015 Canyon Nerve AL 6.0 (son #1's)
    2011 Specialized Hardrock Sport Disc (son #4s)
    2013 Decathlon Triban 3 (red) (mine)
    2019 Hoy Bonaly 26" Disc (son #2s)
    2018 Voodoo Bizango (mine)
    2018 Voodoo Maji (wife's)
  • The Rookie
    The Rookie Posts: 27,812
    02GF74 wrote:
    The Rookie wrote:
    larkim wrote:
    a carbon steerer will usually need a bung and must have a spacer above the stem).

    Carbon steerer have bung instead of the star fangled nut.

    I have 4 bike with car on steerer, the bungs differ a bit in design but none of them need a spacer between stem and to cap.
    RS recommend it on their carbon steerer forks as do most road bike manufacturers, maybe you don't think it needs it but......
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • trek_dan
    trek_dan Posts: 1,366
    You could try and get a zero stack top headset cup too (I'm assuming one isn't already fitted)
  • 02gf74
    02gf74 Posts: 1,171
    The Rookie wrote:
    02GF74 wrote:
    The Rookie wrote:
    larkim wrote:
    a carbon steerer will usually need a bung and must have a spacer above the stem).

    Carbon steerer have bung instead of the star fangled nut.

    I have 4 bike with car on steerer, the bungs differ a bit in design but none of them need a spacer between stem and to cap.
    RS recommend it on their carbon steerer forks as do most road bike manufacturers, maybe you don't think it needs it but......


    Just checked the RS1 manual and the only reason I can see the use of a spacer above the stem is that the instructions state to cut the steerer flush with the top of the stem.... which if measured and cut correctly should not be required.

    I've been riding 2 bikes (road and mtb) with carbon steerers without the top spacer and have had no any issues whatsover nor can I see that it makes a jot of difference, each to their own I guess, so yes, I don't think it needs it.

    Definitive anware would be to ping SRAM an eamil.

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