Results 1 to 21 of 21
  1. #1
    mtbr member
    Reputation:
    Join Date
    Jun 2014
    Posts
    9

    Stem troubles- NEED HELP/SUGGESTIONS !

    Hi guys. Just recently bought a new stem to match my handlebars - Crank Brothers Cobolt 2, but I've struck a problem.

    The gap between the stem and steerer tube is 13mm, and from what i've read the recommended gap should be no bigger than 5mm. The steerer is shortish (about 187mm) so i'm running no spacers with the stem.

    I managed to screw on the top cap into the star nut with the stem on, but only JUST (couple of turns in), though i don't think that would be overly safe.

    Problem i noticed was the height of the new stem, its (45mm), compared to my previous OEM 30mm stem with a 5mm spacer which gave me the perfect 2-3mm gap.

    Is there a way around this without having to buy another stem? Such as a longer top cap bolt? I've looked everywhere for a 35mm stack height stem with a 31.8mm bar clamp with 90-110mm stem length (I ride XC), but no luck.

    I have found a few 40mm stack height stems, which will bring it down to a 8mm gap, but is that still too much of a gap?

    Last thing i want is my stem/fork coming loose while doing 35km/h down a run.

    Any suggestions or help on this would be greatly appreciated guys

    Regards,

    Benjamin.

  2. #2
    mtbr member
    Reputation: J.B. Weld's Avatar
    Join Date
    Aug 2012
    Posts
    2,482
    The top cap bolt doesn't matter because it's only for adjustment but the pinch bolts on the stem both need to be in full contact with the steer tube, and with 13mm of your stem above it I doubt that your top bolt is pinching anything but air. You either need a stem that matches the dimensions of your old one or a longer steer tube.

  3. #3
    mtbr member
    Reputation:
    Join Date
    Nov 2011
    Posts
    2,309
    You could look at a new headset with a shorter stack height.

  4. #4
    mtbr member
    Reputation:
    Join Date
    Jul 2012
    Posts
    101
    This might work for you. I think it's discontinued, so there aren't a lot of sizes still available. 35mm stack height. There was a thread on bikeforums.com questioning if it was safe for use on carbon steerer tubes, but if your steerer is aluminum/alloy that concern(if it is even a valid concern) shouldn't matter.

    FSA OS-115 Stem | Chain Reaction Cycles

    FSA Os-115 Mtb Threadless Mountain Bike Stem (069302018603) at CambriaBike.com

  5. #5
    mtbr member
    Reputation:
    Join Date
    Jun 2014
    Posts
    9
    Thanks for the input guys. That FSA stem.might be the pick Geralt, though I found another with a better stem length (prefer 90 over 110). The stack is 38mm, so it brings the gap down to 6mm. Wouldn't i still be pushing the limits?

    wiggle.com.au | Race Face Evolve MTB Stem | Oversize Stems

  6. #6
    mtbr member
    Reputation:
    Join Date
    Jan 2012
    Posts
    5,341
    Get a longer cap bolt, you need that threaded all the way through the star nut.
    Now think about it. even with the pinch bolts loose, how can the fork come out?
    It's impossible. There is no danger related to that. With the pinch bolts loose you can't get the bars to come off the steerer either. Impossible also. The only thing you need them for, safety-wise, is to maintain the orientation of the bars perpendicular to the wheel. I've run with the stem setup like you have it. No problem, and as you can see, I thought about it just like you are. Through very rocky terrain with crashes. Never a problem.

  7. #7
    mtbr member
    Reputation:
    Join Date
    Jun 2014
    Posts
    9
    You have a point there eb. Here's a couple pics of my situation. So the top bolt definitely doesn't line up with the steerer.




  8. #8
    mtbr member
    Reputation: J.B. Weld's Avatar
    Join Date
    Aug 2012
    Posts
    2,482
    Quote Originally Posted by eb1888 View Post
    Get a longer cap bolt, you need that threaded all the way through the star nut.
    Now think about it. even with the pinch bolts loose, how can the fork come out?
    It's impossible. There is no danger related to that. With the pinch bolts loose you can't get the bars to come off the steerer either. Impossible also. The only thing you need them for, safety-wise, is to maintain the orientation of the bars perpendicular to the wheel. I've run with the stem setup like you have it. No problem, and as you can see, I thought about it just like you are. Through very rocky terrain with crashes. Never a problem.

    That is poor advice IMO. The cap bolt is designed to preload the headset bearing and nothing else. The star fangled nut inside the steer tube is in no way structural and is not designed to handle any load. The stem pinch bolts are what secure the stem to the steer tube, once those are torqued it would be totally safe to remove the cap bolt and ride.

    cripadger- I don't often say this but I think that setup is completely unsafe, get a different stem.

  9. #9
    mtbr member
    Reputation:
    Join Date
    Jun 2014
    Posts
    9
    True! The gap from the top of the steerer to the centre of the top stem bolt is 7mm.

  10. #10
    No Clue Crew
    Reputation:
    Join Date
    Apr 2005
    Posts
    3,943
    Do what you like, but there is no way I'd ride that bike on the trail. Both pinch bolts need to be clamping the steerer.

  11. #11
    Bro
    Bro is online now
    Where I do my thinking
    Reputation: Bro's Avatar
    Join Date
    Dec 2010
    Posts
    4,309
    How tall is the top dust cap on the headset? If you're willing to do a bit more headset maintenance, you can take that dust cap off to get yourself some more room to work with.
    I've made some bad decisions like taking the gears off my bike. So here's the warning: Do not as I say, nor as I do.

  12. #12
    mtbr member
    Reputation: J.B. Weld's Avatar
    Join Date
    Aug 2012
    Posts
    2,482
    Yikes, I didn't even see the second picture from the top! I wouldn't ride that around the parking lot.

  13. #13
    mtbr member
    Reputation:
    Join Date
    Jun 2014
    Posts
    9
    Ok so i've worked it out haha.

    I have 2 choices.

    The FSA stem which has a 35mm stack. It will give me the 3mm gap. Although 110mm length is a little long.

    The Raceface stem has a 38mm stack. The gap will then be 6mm, and it has the 90mm length i'm looking for.

    Pondering on this right now.

  14. #14
    mtbr member
    Reputation:
    Join Date
    Aug 2008
    Posts
    1,810
    It might be possible to take a milimeter or two off the stem top or bottom surface.

  15. #15
    mtbr member
    Reputation:
    Join Date
    Jan 2012
    Posts
    5,341
    I haven't done what I advised with an open design like yours.
    New Uno Ultralight 31 8 x 100mm for Road Bike Stem Black | eBay
    I've used these(with this graphics design) on several bikes. Light and reasonable price. Sell yours. You will be ok with this.

  16. #16
    mtbr member
    Reputation:
    Join Date
    Jul 2012
    Posts
    101

  17. #17
    mtbr member
    Reputation:
    Join Date
    Jun 2014
    Posts
    9
    Quote Originally Posted by eb1888 View Post
    I haven't done what I advised with an open design like yours.
    New Uno Ultralight 31 8 x 100mm for Road Bike Stem Black | eBay
    I've used these(with this graphics design) on several bikes. Light and reasonable price. Sell yours. You will be ok with this.
    What is the stack height on this? Will it cope with XC riding conditions?

    That one is on the money. That price though is hard to justify. Postage to where i live (Australia) is half the price of the stem itself.. it hurts

  18. #18
    mtbr member
    Reputation:
    Join Date
    Jun 2014
    Posts
    9
    Quote Originally Posted by rangeriderdave View Post
    It might be possible to take a milimeter or two off the stem top or bottom surface.
    I wouIdn't be ballsy enough to do that. I'm going to sell the stem. Put the funds towards the successor.

  19. #19
    mtbr member
    Reputation:
    Join Date
    Jul 2012
    Posts
    101
    Here ya go. 35 mm stack height, available in 90 mm length, relatively inexpensive, shipping to Australia not too bad.

    On-One Ultralight CNC Stem | On - One

  20. #20
    mtbr member
    Reputation:
    Join Date
    Jun 2014
    Posts
    9
    All good guys!

    New FSA OS 150 1 1 8" x 90mm x 31 8mm x 6 Stem White w Carbon Cap | eBay

    It'll give me the 3mm gap i'm after. Thanks for all your input guys, much appreciated

  21. #21
    mtbr member
    Reputation:
    Join Date
    Jan 2012
    Posts
    5,341
    Quote Originally Posted by cripadger View Post
    What is the stack height on this? Will it cope with XC riding conditions?
    ~39mm but more importantly the shipping to you is freeee.
    Sorry. More importantly it is a fully enclosed design which will grab the entire less than adequate remaining length of the steerer. More than enough clamping force for safety.
    And you can't see the problem anymore, so it's solved.
    I run it with Easton carbon bars and now a Bontrager RXL carbon 720/15 rise from china off ebay. Some really good hits haven't phased the Easton bars or stem at XC speeds. Tree hits included. None yet with the RXL.
    If you want 90mm I just ordered this--
    New Uno Ultralight 31 8 x 90mm for Road Bike Stem 103G | eBay
    I haven't tried the versions with different graphics, so no recommendation on those.

    Might be too late but there's a time dif.

Similar Threads

  1. Stem upgrade suggestions
    By cnitram in forum 29er Components
    Replies: 14
    Last Post: 07-08-2013, 07:50 AM
  2. Want to replace my handlebar and stem. Suggestions?
    By dhosinski in forum General Discussion
    Replies: 5
    Last Post: 06-04-2012, 09:09 AM
  3. Lightweight 50mm stem suggestions?
    By rusty904 in forum All Mountain
    Replies: 31
    Last Post: 05-15-2012, 07:15 AM
  4. Epic 29er - bar and stem suggestions
    By sbermhb in forum Specialized
    Replies: 6
    Last Post: 03-16-2012, 09:27 AM
  5. i need a new stubby stem. any suggestions?
    By LONO100 in forum Bike and Frame discussion
    Replies: 1
    Last Post: 01-16-2012, 07:18 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •