Advertise on Bikeforums.net



User Tag List

Results 1 to 7 of 7
  1. #1
    Junior Member
    Join Date
    Feb 2013
    Location
    Alabama
    My Bikes
    Volae Club, Cannondale Jekyll, Orbea Opal, Rans F5, Diamondback Mtb, Murray Eliminator, Haro BMX, and more....
    Posts
    19
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Question on stays

    Hi! First post on this forum here. The talent is amazing here. I ride a recumbent much like the one pictured here. I am wanting to build one like it for a friend and am going to build out of 4130. My question is on the stays going to the rear wheel. Will it be strong enough if I do a good tight job of fitting them and then fillet braze? It seems like there will be a lot of pressure on the weld because there isn't really much triangulation with the seat stays. Any hints or tips on this?md_11club.jpg

  2. #2
    Andrew R Stewart Andrew R Stewart's Avatar
    Join Date
    Feb 2012
    Location
    Rochester, NY
    My Bikes
    Stewart S&S coupled sport tourer, Stewart Sunday light, Stewart Commuting, Stewart Touring, Co Motion Tandem, Stewart 3-Spd, Stewart Track, Fuji Finest, Raleigh Pro, Trek Cycle Cross, Mongoose tomac ATB, GT Bravado ATB, JCP Folder
    Posts
    2,954
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Assuming good brazing (enough flow to establish an internal fillet, proper sized external fillet) and proper finishing (no undercutting of the tube) it will be a tube selection question. So if the tube choice is up to the task and you do a good job brazing and filing it will be OK. The difference in strength between a weld and a braze depends on how well each is done, not which is done.

    But this design relies on the beam strength of the tubing. Adding some triangulation would increase the stiffness and reduce the need for a high beam strength. I have worked on many recumbent with this type of main frame/stays construction and still don't like them from a design standpoint. I understand why this simple design is used compared to a truss one (like a P-38) but I don't like it. Andy.

  3. #3
    Randomhead
    Join Date
    Aug 2008
    Location
    Happy Valley, Pennsylvania
    Posts
    12,383
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I would have a really long miter between the main tube and the stays.

  4. #4
    Senior Member
    Join Date
    Sep 2006
    Location
    Aurora, CO
    My Bikes
    2005 Performer Toscana, 2000 Kona Hoo-Ha, RANS Rocket
    Posts
    419
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    The seatstays on a recumbent don't have to be an integral part of the frame. Instead you can bolt them onto the dropouts or tabs on the chainstays if there's enough metal there to provide strength. On many bents, the primary job of the seatstays is to support the seat and adjust seat angle, and they don't contribute much to frame rigidity. BUT, it really depends on your frame design.

  5. #5
    Randomhead
    Join Date
    Aug 2008
    Location
    Happy Valley, Pennsylvania
    Posts
    12,383
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I believe the question was regarding the joint between the boom tube and the chain stays. I had the same initial reaction to the question because he mentions the lack of support from the seat stays.

  6. #6
    Junior Member
    Join Date
    Feb 2013
    Location
    Alabama
    My Bikes
    Volae Club, Cannondale Jekyll, Orbea Opal, Rans F5, Diamondback Mtb, Murray Eliminator, Haro BMX, and more....
    Posts
    19
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Yes I don't think the seat stays add much strength.

  7. #7
    Randomhead
    Join Date
    Aug 2008
    Location
    Happy Valley, Pennsylvania
    Posts
    12,383
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    hopefully the seat stays reduce the load on the main tube by transferring it directly to the rear axle

Posting Permissions

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