Results 1 to 10 of 10

Thread: Stems

  1. #1
    pvd
    pvd is offline
    mtbr member
    Reputation: pvd's Avatar
    Join Date
    Jan 2006
    Posts
    2,807

  2. #2
    mtbr member
    Reputation:
    Join Date
    Sep 2005
    Posts
    557
    I see the issue already...they are all designed for 31.8 clamp diameters.

    I hate designing for a weaker bar material because marketing says I should.



    As for your true intent of the post...well thought out insight. One of the reasons I only use Thomson stems or build my own, accurate and consistent are key.

    I appreciate the repository of info you've accumulated and refer folks to it often, thanks.

    You've got too much brains to be wasting this much time on bikes Pete, it would be refreshing to see someone with so much knowledge putting it to good use, like teaching our kids. Wait a minute, you're already doing that too.

    Missed you at Nahbs this year, just wasn't the same hiking off to breakfast without your hung over arse.

    cheers,

    rody
    As requested by the MTBR gods, I am the voice of Groovy Cycleworks, check it out... http://www.groovycycleworks.com

  3. #3
    pvd
    pvd is offline
    mtbr member
    Reputation: pvd's Avatar
    Join Date
    Jan 2006
    Posts
    2,807
    I missed you more than NAHBS. Seriously. Next time.

  4. #4
    mtbr member
    Reputation:
    Join Date
    Dec 2012
    Posts
    77
    I find it amazing that +/-3mm is acceptable in a length tolerance. But then again, it's not an airplane...

  5. #5
    Moderator Moderator
    Reputation:
    Join Date
    Jan 2004
    Posts
    4,142
    Yeah, I'm unclear on what process could conceivably produce that much variance from item to item, whether it's forged/cast or machined. You'd expect variation well under 1mm, at least intuitively.

    But yes, it's not a satellite or a fusion reactor part, so the tolerances really don't need to be that good to get an acceptable result.

    Very interesting post, Pete.

    -Walt

    Quote Originally Posted by briderdt View Post
    I find it amazing that +/-3mm is acceptable in a length tolerance. But then again, it's not an airplane...
    Waltworks Custom Bicycles
    Park City, UT USA
    www.waltworks.com
    waltworks.blogspot.com

  6. #6
    Randomhead
    Reputation:
    Join Date
    Sep 2008
    Posts
    1,054
    yeah, hard to see how they could make them in such a way that there is that much variance between stems. I could see if the average was off that far from the drawing, but the scatter wasn't that big.

  7. #7
    pvd
    pvd is offline
    mtbr member
    Reputation: pvd's Avatar
    Join Date
    Jan 2006
    Posts
    2,807
    It's a 3D forging so the strut is rammed into the steerer binder during manufacturing. You see the evidence of this when you look inside the stem. It's also some dirty manufacturing for some comparatively cheap pieces. Also, when was the last time you saw a consumer QC a part?

  8. #8
    Who turned out the lights
    Reputation: Francis Buxton's Avatar
    Join Date
    Apr 2004
    Posts
    1,115
    Quote Originally Posted by pvd View Post
    It's a 3D forging so the strut is rammed into the steerer binder during manufacturing. You see the evidence of this when you look inside the stem. It's also some dirty manufacturing for some comparatively cheap pieces. Also, when was the last time you saw a consumer QC a part?
    Only when that consumer is you Pete. It's fun to have a guy like you involved and commenting. Always some good info.

  9. #9
    650b me
    Reputation: golden boy's Avatar
    Join Date
    Oct 2008
    Posts
    1,090
    Interesting post, Pete. Thanks.

    I'll add: I too see a lot of value in reverse engineering existing parts. You think you know a part from handling it and looking at it ad nauseum. Then you create a solid model of it and you learn a hell of a lot more.

  10. #10
    reading comprehension wat
    Reputation: dv8xin's Avatar
    Join Date
    Mar 2013
    Posts
    329
    I "QC'd" my parts! That doesn't involve referencing to a true-to-size draft, with alignment and deflection tests though.

    3D forging piqued my interest though. Can't really seem to find much through basic internet searching. There's some info from Cannondale and how they're advancing the technique that seemed interesting.

    What do you demand from a stem anyways? It's basic task is to connect your handlebars to the steerer, right? When I picked mine, I was under the impression that I simply wanted something light, yet strong and reliable for a stem, one that fit as far as length goes. Being able to clamp on my steerer and bar, without issues like slipping under loads found in biking when following bolt torque specs. Failing fit and slip tests would make me send it back... precision is another thing.
    I like to jump to conclusions, oversimplify, gossip, and participate in popularity polls.

Similar Threads

  1. why do some stems look like this
    By nauc in forum All Mountain
    Replies: 22
    Last Post: 07-04-2012, 06:04 PM
  2. UNO Stems?
    By Triaxtremec in forum Weight Weenies
    Replies: 4
    Last Post: 12-25-2011, 11:48 AM
  3. Carbon Stems vs Alloy Stems & Carbon Seat Post vs Alloy Seat Posts
    By torque29er in forum General Discussion
    Replies: 17
    Last Post: 12-05-2011, 10:01 AM
  4. LD Stems
    By CS2 in forum Vintage, Retro, Classic
    Replies: 16
    Last Post: 08-26-2011, 03:13 AM
  5. stems
    By Justin Credible in forum General Discussion
    Replies: 13
    Last Post: 07-09-2011, 05:52 PM

Posting Permissions

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