User Tag List

Results 1 to 12 of 12

Thread: V brake post extender

  1. #1
    Join Date
    Jan 2009
    Posts
    5,305
    Post Thanks / Like
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)

    Default V brake post extender

    Would you trust a post extender like this, used to bring a 700 C frame down to 650 B wheel size?
    Elevn V-Brake Post Extender at Dan's Comp
     

  2. #2
    Join Date
    Oct 2012
    Location
    Puyallup, WA
    Posts
    3,585
    Post Thanks / Like
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)

    Default Re: V brake post extender

    Though not shown, I'd imagine there's a tab that slots into one of the spring holes in the post base to keep the extender from rotating. I'm sure it works fine. I've never been a fan of canti's, so it's not something I would do, but it'd at least be a decent temporary fix.
    DT

    http://www.mjolnircycles.com/

    Some are born to move the world to live their fantasies...

    "the fun outweighs the suck, and the suck hasn't killed me yet." -- chasea

    "Sometimes, as good as it feels to speak out, silence is the only way to rise above the morass. The high road is generally a quiet route." -- echelon_john

  3. #3
    Join Date
    Sep 2012
    Location
    Oakland CA
    Posts
    344
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Default Re: V brake post extender

    I wouldn't put that on one of my bikes, but it probably won't explode or anything.
    Nash Taylor - Oakland CA

  4. #4
    Join Date
    Jan 2009
    Posts
    5,305
    Post Thanks / Like
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)

    Default Re: V brake post extender

    The shear on that little pin is what I'm afraid of. Things are steep here in places.
     

  5. #5
    Join Date
    May 2011
    Location
    North Shore, MA
    Posts
    1,658
    Post Thanks / Like
    Mentioned
    7 Post(s)
    Tagged
    0 Thread(s)

    Default Re: V brake post extender

    I used something like it a few years back. I put 700c wheels on my Bontrager Race mountain bike. I used a Sinz adapter, but not with v-brakes. I tried a few canto’s, and found Gravity Research and Avids worked best, as you could slide the brake holder up. Some “fixed” canti’s would not work properly.

    Sinz Brake Post Extender at J&R Bicycles

    gravtrail sinz.JPG
     

  6. #6
    Join Date
    May 2011
    Location
    North Shore, MA
    Posts
    1,658
    Post Thanks / Like
    Mentioned
    7 Post(s)
    Tagged
    0 Thread(s)

    Default Re: V brake post extender

    Overall, it worked, ok for cantis, but v-brakes put more force on the post. I actually raced a couple of cross races with this bike, just for the heck of it. Had fun with it actually. It’s now back to a 26’ drop bar rigid mountain bike. And my Stigmata cross bike just sat in the basement, slowly shaking it’s head, mutering…”you idiot”…

    biketable.JPG
     

  7. #7
    Join Date
    Aug 2010
    Location
    W Mass
    Posts
    11,455
    Post Thanks / Like
    Mentioned
    8 Post(s)
    Tagged
    1 Thread(s)

    Default Re: V brake post extender

    I wouldn't do it. Those spring holes are not designed to react the braking force, just the return springs which are not mission-critical.

    Unless you also used them with one of these:

    Trod Harland, Physical Educator

    Not everything that is faced can be changed, but nothing can be changed until it is faced. James Baldwin

  8. #8
    Join Date
    May 2011
    Location
    North Shore, MA
    Posts
    1,658
    Post Thanks / Like
    Mentioned
    7 Post(s)
    Tagged
    0 Thread(s)

    Default Re: V brake post extender

    Todd, the small pin aligns the adapter, and keeps it from spinning, but when the adapter mounting bolt it TIGHT, it won’t move, so I don’t believe anything is transferred to the pin. I was on a curious mission, to see if I could do it.

    Overall, it worked for me, but honestly, if this was my main bike and was going to be used hard, I wouldn’t feel 100%. And not with v-brakes. Those adapters may work well for small wheel BMX bikes (as intended), but the measurement is not perfect for 26” to 700c. My adjustable cant’s made it work on my frankenbike.

    Going down from 700c to 650 requires the adapters to be installed upside-down…and you want to use v-brakes, which put a lot of leverage on any mount. So to answer the op’s original question, it might work, as mentioned above as a temp fix or experiment, but i wouldn’t plan on it as a full time solution.
     

  9. #9
    Join Date
    Jan 2009
    Posts
    5,305
    Post Thanks / Like
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)

    Default Re: V brake post extender

    Really braking force is independent of wheel diameter in this (rim brake) application not?
    edit : My friends try to talk me into a gravel grinder but I've got two good cycle cross bikes sitting in the basement that I would love to try with 650 B 42 mm tires and be done with that.
     

  10. #10
    Join Date
    Sep 2012
    Location
    Oakland CA
    Posts
    344
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Default Re: V brake post extender

    I think you should do it and keep us posted. There are others around the internet who have done this on mtn bikes even. The more I think about it, the more it kinda grows on me. It works with removable post braze ons so the adaptor replaces and is bolted onto the frame mount, not just the post. Drop bolts for canti brakes. Sounds like something Sheldon Brown would try out.
    Nash Taylor - Oakland CA

  11. #11
    Join Date
    May 2011
    Location
    North Shore, MA
    Posts
    1,658
    Post Thanks / Like
    Mentioned
    7 Post(s)
    Tagged
    0 Thread(s)

    Default Re: V brake post extender

    Quote Originally Posted by rabo View Post
    Really braking force is independent of wheel diameter in this (rim brake) application not?
    edit : My friends try to talk me into a gravel grinder but I've got two good cycle cross bikes sitting in the basement that I would love to try with 650 B 42 mm tires and be done with that.
    I may not have been clear about the wheel diameter part. The adapters OP posted, and I used are for BMX bikes. My Bonty mountain bike is built for 26 rims. Using the adapters allowed me to use a 700c rim. But, the ratio of “lift” the bmx part give did not allow me to use a canti that did not have a large range of vertical pad adjustment. I tried a bunch of canti’s I had lying about, and for example, the Suntour cx pro did not have enough adjustment to work. See photo. I’m just not sure using this part to lower the post will make the rim brake you plan on using align properly.

    I eventually used Avid try-aligns in the end, taller brake than the Gravity’s pictured. The taller brakes were stronger. I also replaced those philips head with proper allen bolts.

    suntour.JPG
     

  12. #12
    Join Date
    Jan 2009
    Posts
    5,305
    Post Thanks / Like
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)

    Default Re: V brake post extender

    What I mean is the the brake force (tire to road) is the same with a 16" or 29" wheel (if using the same rim brakes).
     

Similar Threads

  1. Can a 2nd Di2 junction box be used as a wire extender?
    By Dallas Tex in forum VSalon Pro-Bicycle Tech
    Replies: 2
    Last Post: 07-28-2015, 03:34 PM
  2. Valve extender length help plz
    By tronstein in forum VSalon Pro-Bicycle Tech
    Replies: 1
    Last Post: 06-03-2011, 09:50 AM
  3. Tubular Valve Extender
    By false_aesthetic in forum General Discussion
    Replies: 9
    Last Post: 04-27-2011, 12:24 PM

Tags for this Thread

Bookmarks

Bookmarks

Posting Permissions

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