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  1. #1
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    First frame critique

    Hi folks longtime lurker, first time poster.

    I have been designing my first hardtail frame and would like you guys to have a look and advise.

    I have attached the file, hopefully will be viewable.

    Numbers are-

    Ha 66
    Sa 76
    Bb drop 50
    Cs 430
    Stl 410
    Htl 100

    I have a 170mm dropper that I have kind of designed the bike around, along with my short inside leg. I'm 5'6.

    Will use a 1 external headset to get 65 head angle.

    I look forward to some comments.

    Cheers
    Matt
    Attached Thumbnails Attached Thumbnails First frame critique-20181009_113027.jpg  


  2. #2
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    Why is the head tube so short? That's asking for trouble even if you're a pro. For a first build it's a terrible idea. Ditch the spacer under the stem and lengthen the head tube accordingly.

    Otherwise, looks like a normal long/low/slack sort of thing. Go for it.

    -Walt

  3. #3
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    Walt, thanks for the reply. Can you expand on why the headtube is too short?

    The spacer is an external headset cup.

    The jig il be using only goes to 66 and I would like 65 so the ec headset. Can't seem to get tapered headtubes in a favorable size. Also I'm really short so didn't want to have too high stack height hence the short htl.

  4. #4
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    It makes joining the top and down tubes more challenging. It also reduces the amount of weld/braze you can get into that joint and increases the load the down tube needs to take. It's certainty possible but for your first crack it would be wise to lengthen the head tube as much as possible, dare I say even at the expense of reducing fork travel.

  5. #5
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    Customfab explained it pretty well. The shorter the head tube, the more leverage the fork has on the top/bottom and the more likely it is to fail somewhere. I'd shoot for a minimum length, on your first frame, of 120mm. I'm 700+ frames in and I won't do shorter than about 110mm for anything that is going to get ridden hard offroad.

    At the very least, you should not be countermitering the toptube and downtube to each other. It can be done safely if it's done just right (I *still* refuse to do it though), but you're building frame #1. No way are you going to be able to do it right.

    If that's going to put your bars too high, use a Syntace flatforce stem + flatbar, or reduce fork travel/length (it looks like you're doing 150mm+ there, which is just silly on a hardtail anyway).

    -Walt

  6. #6
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    Also, you can just rotate the whole frame around the head tube to get to your 65deg if you want to. It will require a little bit of trig (or CAD) to figure out where everything needs to go, but it's totally doable.

    Then you can just use a 44mm ID head tube that is straight, which will make your life a lot easier.

    -Walt

  7. #7
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    There has to be a better way to get your 65* angle than a janky-ass offset headset cup. Modify the jig? Shim the head tube in the jig?

    Another vote for a taller head tube. Run flat bars and an inverted stem if ya gotsta. Also factor in that you have clearance for the controls to swing clear of the TT, although it looks like it should be fine in your drawing.

    If you're going to do a seat tube reinforcement like that be careful not to land it on/beyond the TT butt. Easy to do on a small frame. I would go without it, personally.

    Don't install the seat tube bosses, they'll interfere with your dropper.

    It looks like that cad is only half-done. The more you can complete the drawing the less opportunity for mistakes.




    edit- walt's suggestion to rotate the frame is the best solution.
    "Things that are complex are not useful, Things that are useful are simple."
    Mikhail Kalashnikov

  8. #8
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    Yes, good catch on the water bottle bosses. Leave those seat tube ones off.

    -Walt

  9. #9
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    Quote Originally Posted by Walt View Post
    Yes, good catch on the water bottle bosses. Leave those seat tube ones off.

    -Walt
    Could get some dem bottle studs, no?

    MS1019: Stainless Water Bottle Stud, M5 x .8
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  10. #10
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    Sure, but the frame is probably too compact for the ST cage to be usable anyway.

    -W

  11. #11
    pvd
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    You need a better print.

    The seat tube is too steep, head tube too steep, and bottom bracket crazy high (if 29")

    My wife is 5'6". This is her bike.

    PVD Glamorous Glennis | Peter Verdone Designs




  12. #12
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    Quote Originally Posted by pvd View Post
    The seat tube is too steep, head tube too steep,
    Have you tried a seat angle that steep? Steepest i've tried on a hardtail is 74.5*, which was mostly fine with 180mm cranks and aggravated my problem knee with 175mm cranks. In his print he's using a setback post, which i attributed to a poorly finished CAD...


    Looks like he's using the same head angle as your design, what's the difference you're picking up on?
    "Things that are complex are not useful, Things that are useful are simple."
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  13. #13
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    Thanks for all the comments.

    Here is a dodgy pic of the file with the numbers on. Obviously im terrible with computers and apologize.

    First frame critique-20181006_173056.jpg

    I should have stated in the first post that these are 650b wheels and a 150mm fork.

    I wont be putting bottle bosses on the seat tube due to the dropper, not sure why they are even on there (see above statement).

    Head angle will be 65 with a angleset so not really steep. What would you recommend PVD?

    The seat angle i have specced gets me (as far as i know) the correct reach with a 35mm stem. I realize it will be very arm heavy but surely il need that to get over the front?

    The bb height is 295 or 50mm drop with 650b.

    Cheers
    Matt

  14. #14
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    Quote Originally Posted by Walt View Post
    Sure, but the frame is probably too compact for the ST cage to be usable anyway.

    -W
    I'm 5' 6.6" and thirsty. If I can't have a hard tail with two water bottles, someone better break out their erasers.

    Never been a fan of the extra bike pipe from the top pipe to the seat pipe. Crotch clearance, crotch schmearance.

    Looks cool, but if I gotta wear a hydration pack? No bueno.
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  15. #15
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    Quote Originally Posted by pvd View Post
    You need a better print.

    The seat tube is too steep, head tube too steep, and bottom bracket crazy high (if 29")

    My wife is 5'6". This is her bike.

    PVD Glamorous Glennis | Peter Verdone Designs



    And she has two bottles. I can dig this.
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  16. #16
    pvd
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    Quote Originally Posted by littleskull99 View Post
    I wont be putting bottle bosses on the seat tube due to the dropper, not sure why they are even on there (see above statement).

    Head angle will be 65 with a angleset so not really steep. What would you recommend PVD?

    The seat angle i have specced gets me (as far as i know) the correct reach with a 35mm stem. I realize it will be very arm heavy but surely il need that to get over the front?
    I'm going to save you a lot of hassle, skip the angleset and design around 65 degrees.

    29" wheels should be manditory unless you have a real good reason for running other junk.

    Never design around an offset seatpost. Droppers don't have offsets. A good place to start for non-racers is 74-74.5 degrees of effective seat tube angle. More forward than that and you're going to hurt without good reason. If you are young, strong, and want to win races, you can go steeper. For normal older men, you'll die.

  17. #17
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    Pvd, the jig I will use only allows 66 so the target 65 will need an angleset to achieve. I'm not up on math so don't know how to design it for 65 using a 66 jig.
    The tyres (tires for you lot) I want to run are maxxis forecasters in 650b x 2.6 so od of around 29". Truth be told I have wheels and a fork ready to go so will use them. There will definitely be another frame after this one, maybe il get real and go 29".

    I have learned so much already just chewing through the numbers.

    It's strange also that I'm 5'6 and my bb to seat on all current bikes is 665mm, Seat centre to bar is 587mm but you're wife (same height) is 715mm and 630mm respectively. Who knew proportions could be so different.

    Il have a play with the seat angle, provided I can keep my seated reach the same then I'm OK changing it. Will this change the front centre?
    I'm still getting used to bike cad so playing with the drop down boxes to keep certain values the same and allow everything els to change.
    Thanks for the input!

  18. #18
    pvd
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    1. Fix the jig. You should be able to. Otherwise, just use 66 degrees. You're probably not ready for an angleset by what it sounds.
    2. Just build a proper 29er. Don't waste a build on shit wheels.
    3. Obviously, Your fit has issues. You should look into how you should be fitting a bike.

    This may help:

    https://www.peterverdone.com/bits-of...-framebuilder/

  19. #19
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    Thanks I think.

    1. What is fixing the jig? And when will I be ready for an angleset? Lol.

    2. I don't have 1000 to buy a wheelset, tyres and a new fork so will use what I have.

    3. My fit may have issues but that's why I'm here asking for help/advise. You have just shot me down on a few points and not really added any real info. You're article is nice but certainly doesn't help me with bike fit. Just more do and don't.

    I'm not having a go at you peter but you haven't really helped.

    Can you link me to an article that does help with bike fit. One with dimensions and numbers?

  20. #20
    pvd
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    You will want to learn this before you build a frame.

  21. #21
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    ..?

  22. #22
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    lol use ctrl+printscreen to screencap. Or use Snip, which you can find by typing it in to the windows search box.

    Quote Originally Posted by littleskull99 View Post

    The seat angle i have specced gets me (as far as i know) the correct reach with a 35mm stem. I realize it will be very arm heavy but surely il need that to get over the front?
    I don't understand the logic here. If the correct reach requires an awful seat angle (not saying it is, but it's not my preference) then how is it the correct reach?




    Quote Originally Posted by littleskull99 View Post
    Pvd, the jig I will use only allows 66 so the target 65 will need an angleset to achieve. I'm not up on math so don't know how to design it for 65 using a 66 jig.
    You don't need to do any math. Using bikecad- lock the frame dimensions and plug in a fork length that gives you a 66* head angle. It will be roughly 20mm shorter than your actual fork axle-crown. Voila.


    Anglesets are garbage, it's criminal to design a frame that requires one.
    "Things that are complex are not useful, Things that are useful are simple."
    Mikhail Kalashnikov

  23. #23
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    Quote Originally Posted by pvd View Post
    2. Just build a proper 29er. Don't waste a build on shit wheels.
    I totally disagree. Funnest bike I rode was a 27.5+ bike and my daily is a 29er. Especially since you already have wheels and a fork - it would be a *shit* idea to waste money on something if you already have something else that will work.

  24. #24
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    Littleskull99, putting a bike design out here in cyberland can be daunting, and due to strong views held by many on how it will come out as they see it can leave you in confused land.
    Can you build a decent bike on 27.5"? - of course you can. Water bottles, well I dislike them and use a Camelpac, but thats just me, ignore my viewpoint. Seat Tube angle, big deal. find where your seat should be and place the seat stem cradle to clamp the seat in the middle of the seat rails, the angle will be whatever. You will not die. Have you ridden any bikes with 65-66 degree head angles to find a preference? You are correct in observing the positional differences between yourself and PVD's Wife. Don't copy his design. Your body proportions are likely to be very different.

    I would recomend that you measure yourself up and understand your own body shape.
    Eg: short legs, long back, average arm length for your height, or whatever you actually are, then design from there. You are looking at building especially for yourself, so this is bespoke to you, it is part of why you build for yourself. This is not a mass market bike so take the time to understand yourself, then you won't need to stand trial to battle for your convictions. We are meant to help you here, but it can sometimes get a little murky and this is not helping you.

    Can you modify the jig to get the extra HT angle?
    With what has been discussed about head tube length being a preferred120mm, this will be easier to do on 27.5mm than what PVD has done with his design at 95mm for 29".

    Not everything will work out in an easy one off answer. You've got to work through so absorb the good, throw out the bad and revise what you're working on.
    I spend 200 hours on paper details and a 100hrs building when I want to really nail it.
    Its ony time, but you learn alot - OK?

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    If I don't make an attempt, how will I know if it will work?

  25. #25
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    To adjust the head tube angle/frame geometry such that it will work on your jig:

    * Draw the frame up full size on paper with the 65 degree HTA.*
    * Revise the horizon line to 1 degree off such that the HTA is now 66 degrees.*
    * Re-measure the stack/reach/STA/etc to the new horizon line and build that on your jig.

    No trig involved.

    * Edited because I swapped the HTA numbers...

  26. #26
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    Thanks everyone again for the replies.

    I am going to have a play on bikecad with the seat angle and relax it slightly to 74/75 as everyone recommends. This will change either my bar to saddle or the reach bb to bar.

    I'm not going to copy anyone else's design as it will not fit me. Not my style anyway, I'd rather learn and understand for myself.

    I've had bikes with head angles ranging from 68 to 63 and like the way a slack bike feels at speed. I didn't want to go dh slack as I feel it wouldn't suit a 150mm fork hardtail.

    I realise that everyone has a different idea of what the ideal bike is and my bike will probably only be my ideal (if I achieve it first time).

    Il post the revised design up once I've played about with it.

  27. #27
    pvd
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    It's not the head angle that you are liking. Start by learning that.

  28. #28
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    What is it then peter?

  29. #29
    pvd
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    Your journey begins here.

  30. #30
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    OK peter I'm tired of you're cryptic bullshit. If you aren't going to help, please stop posting in my thread.

  31. #31
    pvd
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    Haven't I given you a huge amount of help already and a valuable resource to draw from? I have about 30 pages on my site that you could learn from...if you chose to. I can't learn for you.

  32. #32
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    First frame critique

    Quote Originally Posted by littleskull99 View Post
    Thanks everyone again for the replies.

    I am going to have a play on bikecad with the seat angle and relax it slightly to 74/75 as everyone recommends. This will change either my bar to saddle or the reach bb to bar.

    I'm not going to copy anyone else's design as it will not fit me. Not my style anyway, I'd rather learn and understand for myself.

    I've had bikes with head angles ranging from 68 to 63 and like the way a slack bike feels at speed. I didn't want to go dh slack as I feel it wouldn't suit a 150mm fork hardtail.

    I realise that everyone has a different idea of what the ideal bike is and my bike will probably only be my ideal (if I achieve it first time).

    Il post the revised design up once I've played about with it.
    Id be careful about changing your geo figures based on what someone else thinks is good geometry. Theres no peer reviewed scientific evidence to prove what the perfect geometry is, its just what works for you. Take your seat angle for example I love steep seat angles and have yet to ride a bike other than mine and think this is steep enough. I currently have a Nimble 9 set up with a 120 fork and a -2deg angleset in this configuration with the seat I am using in the position it is on the rails I am at about 76.8deg unsagged thats with 165mm cranks. Steep or not that works for me on the trails I ride most of the time. Its still a compromise though. If I were riding mostly flatter terrain Id probably want it a bit slacker but not much and it is easily accommodated within the adjustment of the seat rail length.

    As has been expressed geo choices are all a compromise. Finding the right compromises for you is all that matters. PVDs bikes are awesome in their pushing of the envelope of what is possible for long front centres combined with super long forks on hardtails but honestly Id hate that type of bike on my local trails. If all I rode were fireroads up manufactured downhill runs down Id probably dig it.
    Last edited by geraldooka; 1 Week Ago at 10:15 AM.
    Michael

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  33. #33
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    Quote Originally Posted by littleskull99 View Post
    OK peter I'm tired of you're cryptic bullshit. If you aren't going to help, please stop posting in my thread.
    Since you're new here, I'm going to let you in on a little secret. Having Peter show up and tell you your ideas are dumb is like a rite of passage for this forum. No one knows why this is, but it has been this way for a long time. Congratulations; don't let it bother you.

  34. #34
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    Yeah, just learn what you can from the folks here who are, erm, blunt, and let the rest just roll off you. It happens to everyone. Your bike will be super fun, and it doesn't have to be perfect on your first try. Half the fun is building stuff just to see how it'll ride, right?

    -Walt

  35. #35
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    Quote Originally Posted by littleskull99 View Post
    What is it then peter?
    front-center.
    "Things that are complex are not useful, Things that are useful are simple."
    Mikhail Kalashnikov

  36. #36
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    I say this all the time, but I'll say it again: bikes are like surfboards. There are surfboards that are easier/harder to ride in certain conditions, and that will allow you to more easily do certain things. But all sorts of surfboards can be "ideal" to give you the *feeling* you want out of your experience - like jumping onto a big ass wave on a skimboard and just trying to stay up? Cool. Want to ride a rigid singlespeed on techgnar chunder, or a 6" travel trail bike on smooth stuff? Cool.

    There is not a "right" or "wrong" surfboard, or bike, if it works for you and makes you smile, and what someone else says is the "right" thing might not be any fun at all.

    -Walt

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