Viewing 22 posts - 1 through 22 (of 22 total)
  • DIY – Direct Mount Stem Reach Plate!! Help…
  • alexxx
    Free Member

    I’m trying to extend the bar reach on my downhill bike.. offset anglesets can only get 3/4mm so thats not suitable.

    I think a plate of aluminium or steel would be the best bet to bolt into the current direct mount holes on the top crown and then have 4 new +10mm offset threads for the stem to screw into..

    My mate is cadding up the design for me… just wondering if anyone has thoughts on where to get this made… if it should be 2 bits of metal or 1 piece with a hole for the steerer… how thick it needs to be so I can counter sink the topcrown bolts, what type of metal or grade ect ect…

    Any thoughts appreciated!

    northernmatt
    Full Member

    I’m sure I’ve seen something like this on one of the DH bike check things over on Pinkbike but I’ve just had a look and can’t find it.

    I’m sure it was a one piece thing and looked to be around 8-10mm thick and looked exactly as you describe.

    thepodge
    Free Member

    when you say “bar reach” do you just mean you want a longer stem?

    I’d have a chat to Burgtec they already do direct mount stems and direct mount spacers plus have been known to do custom products.

    as for thickness so you could countersink it, your CAD mate should be able to do that, if they cant you might as well just scribble it on a fag packet as the CAD file will be little more use.

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    stevied
    Free Member

    If you want to send me a drawing I’ll have a look for you 😉

    steve_dees at hotmail.com

    STATO
    Free Member

    If your steerer is long enough just put a normal stem on it. s/h crown and steerer are cheap enough for a trial, or you might even manage a swap with someone for no cost if your current crown is in good condition.

    honourablegeorge
    Full Member

    Sounds like a really ropey way to get to a longer stem.

    Just get this in 60mm – it will give you an extra 10mm reach

    http://www.chainreactioncycles.com/truvativ-holzfeller-direct-mount-stem/rp-prod71769

    alexxx
    Free Member

    Thanks guys I’ll reply in more detail later but basically a 60mm stem wont cut it, my current one is 55mm or 50mm as its adjustable… so i like that fact that if I got a 10mm spacer then I can choose to run 65mm or 60mm.

    I’m sure I should be able to get the plate for less than £40. so worth me having the flexibility unless you can see a 65mm direct mount stem?

    The steerer is too short for a normal stem sadly.

    thepodge
    Free Member

    As above Truativ do a 60mm direct mount but I think thats the longest

    alexxx
    Free Member
    stevied
    Free Member

    Looks simple enough to make..

    SirHC
    Full Member

    There is one thing CAD’ing something up, I would wan’t to FEA the design, at the very least some hand calculations to assess a suitable design and material.

    If you are having to fit a 50mm+ stem, would suggest your frame is too small.

    alexxx
    Free Member

    The frame is too small but it only needs 5-10mm and we’re all good.. it’s a bit boutique so it’s staying with this mod in place!

    Anyone here able to suggest or stress test a design for me?

    legend
    Free Member

    Do you think a 65mm stem on a DH bike is going to feel good?

    alexxx
    Free Member

    You mean in regards to slowing the steering down? I think it’ll be just fine I may end up running it at 60mm but I want the option to try 65mm

    thisisnotaspoon
    Free Member

    Anyone here able to suggest or stress test a design for me?

    I’m sure I should be able to get the plate for less than £40.

    How much do you think ‘engineering’ costs.

    I suspect you’re barking up the wrong tree if you think
    a) this will be cheaper than just buying a new stem.
    b) this will be cheaper than a new boutique frame (if you wanted it CAD’d properly, FEA done and the part machined by CNC)

    Even if you did it manually on a mill (it’d take longer to CAD and program a machine to do it) it’s still probably an hours work for someone (at say, £100/hour by the time they’ve covered overheads).

    Kudos to anyone that helps you out with it, but I’d suggest they’re putting their time and effort into helping you save a small amount of cash buying a new stem.

    alexxx
    Free Member

    I’m going to try it in steel or with steel helicoil in aluminium myself if I can’t get it done for a price I deem worth the punt.

    There are no 65mm stems… so it’s going to be cheaper than buying something that doesn’t exist!

    I don’t want FEA doing or being made by CNC.. I want a good old “yeah that should be fine” or “hell no” from someone who knows enough to take an educated guess… ie it’ll be over engineered by making sure the bolts are the same size and there is a lot of thickness in the spacer to satisfy any worries.

    for legend:

    gregs stem

    spev
    Full Member

    Works components reach adjustment headsets are 5 to 7mm long depending on type, combined with a truvativ 60mm stem surely that’s long enough?
    What frame is it?

    andyl
    Free Member

    Layback seat post?

    What headset and steerer have you got? Superstar are doing some new offset ones to extend reach. Pretty sure I saw one on one of the german bike stores the other day too.

    Lower sweep, wider bars?

    All of which would be far more sensible than sticking a long stem on the kind of bike that needs a direct mount.

    shortyj15
    Full Member

    I could do some FEA on it but it won’t be til Sunday. Email me at iainjagger@Gmail.com if you want

    brant
    Free Member

    There is a lot of plate thickness. But there are some areas where cross section is very thin.
    Instead of counterbore for bolts I would consider using a spacer to lift the new stem above them.
    Those front holes are very close to each other (the counter bore and the new threaded hole).

    shortyj15
    Full Member

    I agree with brant there are areas where there is little material.

    jivehoneyjive
    Free Member

    Lose the counterbores, gain your face!!

    Material wise 7075 Alu is the obvious choice.

Viewing 22 posts - 1 through 22 (of 22 total)

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