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  1. #1
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    Appreciate comments!

    After a ~8 year hiatus i'm building another frame. I'll be working with someone with more fabrication experience this time, so i'm hoping that the process will go more smoothly, although my first two frames turned out alright. It will be fillet brazed and loosely based off my on-one 456, which i'm very fond of, it's just too small. I plan to use a 38 9/6/9 downtube, 31.8 9/6/9 TT, and a 1.5 steerer with a reinforcing ring. I'm 6'3, 215lbs, and not gentle.

    I'm pretty comfortable with my choices, but i appreciate others' insight.

    Appreciate comments!-fartmonster.jpg
    Photo is with 0 sag, a 130mm Lyrik rc2, and 26" wheels.
    Last edited by scottzg; 12-14-2016 at 04:59 PM.
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  2. #2
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    26" wheels? At 6'3"!?


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  3. #3
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    Quote Originally Posted by incubus View Post
    26" wheels? At 6'3"!?
    i've tried 24", but i prefer the superior rollover and traction characteristics of the big wheels.
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    Why not 27.5 or even 29?

  5. #5
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    Quote Originally Posted by restlessrider View Post
    Why not 27.5 or even 29?
    i have a very good newer fork and wheelset and a pile of new tubeless 26" tires. If i had to buy a fork/wheels i'd run 650b for future proofing, and if i wanted a 29er i'd trust someone else's design first. This design will accept 650b wheels and still be lower than my current hardtail.
    "Things that are complex are not useful, Things that are useful are simple."
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    Geometry/wheel size aside (a lot of which is personal preference so ride what you like), I'd probably go up in tube size to a 1/0.7/1mm down tube. You might look into a Paragon head tube rather than a straight tube + reinforcing rings. Also, I highly recommend the True Temper Cromag seat tube while you can still get 'em (1.6/0.8mm -- use it upside down from how it's shown on the Henry James site and it fits a 31.6 post perfectly) for ease of construction. It's a bit of an anchor, but one piece and you have to really cook it badly to ovalize it much unlike thinner seat tubes. And, hell, I'd probably consider a 1/0.7/1 top tube while your at it just for dent resistance.

  7. #7
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    Quote Originally Posted by Feldybikes View Post
    Geometry/wheel size aside (a lot of which is personal preference so ride what you like), I'd probably go up in tube size to a 1/0.7/1mm down tube. You might look into a Paragon head tube rather than a straight tube + reinforcing rings. Also, I highly recommend the True Temper Cromag seat tube while you can still get 'em (1.6/0.8mm -- use it upside down from how it's shown on the Henry James site and it fits a 31.6 post perfectly) for ease of construction. It's a bit of an anchor, but one piece and you have to really cook it badly to ovalize it much unlike thinner seat tubes. And, hell, I'd probably consider a 1/0.7/1 top tube while your at it just for dent resistance.
    Hmm, I appreciate the thoughts RE-tubing, i hadn't given 1/.7/1 a thought. Weight isn't really a huge issue for me. I definitely wouldn't mind a critique of my geometry choices, i'm not married to them. I was trying to keep the nimble-but-stable-enough feeling of the 456 while giving me more room in the cockpit, and i haven't been thrilled with how forward geo translates to hardtails.


    Thanks!
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  8. #8
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    Can't help you on the tubing side of it, but I'd suggest maybe for your "future proofing" that you use a dropout system the accepts different/replaceable ones so you don't have to compromise the chainstay length for 26" wheels so that 650B or 29" will work. Also know you know what you like, but curious what length stem you plan to run? Ask as I'm 6'2" with long arms to match my 35.25" inseam and my minimum Reach # is 450mm to use a 60-70mm stem and 785mm wide bar and would prefer a 460-470mm Reach to be able to run a shorter stem and maybe a bit more swept bar.
    One day your life will flash before your eyes, will it be worth watching??

  9. #9
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    Honestly, I don't think there's anything wrong with the bike design, it just looks short in the front end compared to what's fashionable nowadays. It's probably mostly that I'm used to looking at bikes with bigger wheels. (Hey everyone, remember when 29ers looked weird?) The head tube looks a little on the short side for 26" wheels even with the massive fork, but if you've got really long arms, then it makes sense.

    If you really prefer 26" wheels, then go for it. If you're just doing it because you happen to own those parts already then I'd at least give it another thought. I know I've fallen into "trap" of building a frame around the parts that were living in my basement, rather than the parts I'd ideally like to have and some part of me usually regrets it. Stuff costs money, but when you factor the time that goes into building your own frame, it's worth it for me to invest in what I want. This doesn't mean XTR Di2 everything, but if I, say, really wanted a thru axle, I wouldn't build to a QR just because I had a QR wheel. (Or at least I would try not to do that )

    As far as future proofing goes, I don't think Lynx has a bad idea with the dropouts. OTOH, a 27.5 fork will fit a 26" wheel and I think it'll be a long time (if ever) before you can't get quality 26" rims and tires. Sure, you might not be able to get the newest everything, but there will be something decent.

  10. #10
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    As drawn, the frame is way too small for you. You should be looking into front centers in the 840mm range.

    ....then there are all of the other problems.

  11. #11
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    Quote Originally Posted by Feldybikes View Post
    If you really prefer 26" wheels, then go for it. If you're just doing it because you happen to own those parts already then I'd at least give it another thought. I know I've fallen into "trap" of building a frame around the parts that were living in my basement, rather than the parts I'd ideally like to have and some part of me usually regrets it. Stuff costs money, but when you factor the time that goes into building your own frame, it's worth it for me to invest in what I want.
    I agree with this. A frame is a decent bit of work any way you slice it. Build exactly what you want.

    The drawing looks great. The only thing I notice is that I like a steeper seat tube angle, but I know this is personal preference. Post up pictures when you're building it!

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    emm, i would recommend 29" wheels, front center 840, why the tiny wheels? if u are 5'8" or taller I would suggest 27.5" OR 29"r and if you want bigger tire's like 3" then once you ride them you will understand why folks like them, they are some fun! go big or go home, or do the 0lD scLool, but try them out and make an informed decision. You don't know what you don't know.

  13. #13
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    Quote Originally Posted by pvd View Post
    As drawn, the frame is way too small for you. You should be looking into front centers in the 840mm range.

    ....then there are all of the other problems.
    Quote Originally Posted by LyNx View Post
    Can't help you on the tubing side of it, but I'd suggest maybe for your "future proofing" that you use a dropout system the accepts different/replaceable ones so you don't have to compromise the chainstay length for 26" wheels so that 650B or 29" will work. Also know you know what you like, but curious what length stem you plan to run? Ask as I'm 6'2" with long arms to match my 35.25" inseam and my minimum Reach # is 450mm to use a 60-70mm stem and 785mm wide bar and would prefer a 460-470mm Reach to be able to run a shorter stem and maybe a bit more swept bar.
    Quote Originally Posted by Feldybikes View Post
    Honestly, I don't think there's anything wrong with the bike design, it just looks short in the front end compared to what's fashionable nowadays. It's probably mostly that I'm used to looking at bikes with bigger wheels. (Hey everyone, remember when 29ers looked weird?) The head tube looks a little on the short side for 26" wheels even with the massive fork, but if you've got really long arms, then it makes sense.

    If you really prefer 26" wheels, then go for it. If you're just doing it because you happen to own those parts already then I'd at least give it another thought. I know I've fallen into "trap" of building a frame around the parts that were living in my basement, rather than the parts I'd ideally like to have and some part of me usually regrets it. Stuff costs money, but when you factor the time that goes into building your own frame, it's worth it for me to invest in what I want. This doesn't mean XTR Di2 everything, but if I, say, really wanted a thru axle, I wouldn't build to a QR just because I had a QR wheel. (Or at least I would try not to do that )

    As far as future proofing goes, I don't think Lynx has a bad idea with the dropouts. OTOH, a 27.5 fork will fit a 26" wheel and I think it'll be a long time (if ever) before you can't get quality 26" rims and tires. Sure, you might not be able to get the newest everything, but there will be something decent.
    Quote Originally Posted by Erichimedes View Post
    I agree with this. A frame is a decent bit of work any way you slice it. Build exactly what you want.

    The drawing looks great. The only thing I notice is that I like a steeper seat tube angle, but I know this is personal preference. Post up pictures when you're building it!
    Quote Originally Posted by afwalker View Post
    emm, i would recommend 29" wheels, front center 840, why the tiny wheels? if u are 5'8" or taller I would suggest 27.5" OR 29"r and if you want bigger tire's like 3" then once you ride them you will understand why folks like them, they are some fun! go big or go home, or do the 0lD scLool, but try them out and make an informed decision. You don't know what you don't know.

    It's interesting to read so many comments regarding my short reach. My last frame i built, in 2010, had a 675mm reach and 800mm FC. I used horizontal drops cuz at the time nobody was doing anything like that and i could have between 410-435mm chainstay (i settled on 435). 290mm unsagged BB. It was seriously fast, but i didn't really like it that much; by the time i was going a speed where it was happy i was wishing i had suspension back there. It was kinda tricky to jump off anything with a lip, too. I replaced it with the bike i'm riding now, the 456 that i mocked up below, and was thrilled. I really like this frame a lot, it's just a bit too short, and i never ever tap the pedals on rocks.

    Appreciate comments!-456e2.jpg

    I was sticking with the 26" cuz i hardly see a difference between it and 650b, and i've never ridden a 29er or plus bike i've been totally jazzed on. It might just be familiarity, i don't know. I've made some alterations based off consensus, i just don't wanna deviate super far from a bike i really like. I expect to use a 60mm stem, but if 50 or 70 are better... i have plenty to play around with. I'm using a 70 on the 456.

    Appreciate comments!-version2.jpg

    I don't want this to be my last frame build, i've had my jig and O/A set up gathering dust and it feels good to use them again.

    Thanks again!
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  14. #14
    pvd
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    I can't, in any way, understand:

    1. Why you didn't move to 29er wheels 10 years ago.
    2. Why you are riding such a tiny bike.

    I'm 5'10 and my bike completely dwarfs your bike here. Its like it's 1998 and the past 18 years never happened. Even your cockpit looks crazy.

    What happens when we forget what we thought we knew. | Peter Verdone Designs


  15. #15
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    Quote Originally Posted by pvd View Post
    I can't, in any way, understand:

    1. Why you didn't move to 29er wheels 10 years ago.
    2. Why you are riding such a tiny bike.

    I'm 5'10 and my bike completely dwarfs your bike here. Its like it's 1998 and the past 18 years never happened. Even your cockpit looks crazy.

    What happens when we forget what we thought we knew. | Peter Verdone Designs

    It's interesting to read so many comments regarding my short reach. My last frame i built, in 2010, had a 675mm reach and 800mm FC. I used horizontal drops cuz at the time nobody was doing anything like that and i could have between 410-435mm chainstay (i settled on 435). 290mm unsagged BB. It was seriously fast, but i didn't really like it that much; by the time i was going a speed where it was happy i was wishing i had suspension back there. It was kinda tricky to jump off anything with a lip, too. I replaced it with the bike i'm riding now, the 456 that i mocked up below, and was thrilled. I really like this frame a lot, it's just a bit too short, and i never ever tap the pedals on rocks.
    "Things that are complex are not useful, Things that are useful are simple."
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  16. #16
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    You repeated it, but I'm fairly certain you meant a 475mm Reach and not 675mm ;-) As I said, you know what you like, unless of course you have never tried anything different, which seems you have, so go by what you like and want, not what someone else tells you need

    Quote Originally Posted by scottzg View Post
    It's interesting to read so many comments regarding my short reach. My last frame i built, in 2010, had a 675mm reach and 800mm FC. I used horizontal drops cuz at the time nobody was doing anything like that and i could have between 410-435mm chainstay (i settled on 435). 290mm unsagged BB. It was seriously fast, but i didn't really like it that much; by the time i was going a speed where it was happy i was wishing i had suspension back there. It was kinda tricky to jump off anything with a lip, too. I replaced it with the bike i'm riding now, the 456 that i mocked up below, and was thrilled. I really like this frame a lot, it's just a bit too short, and i never ever tap the pedals on rocks.
    One day your life will flash before your eyes, will it be worth watching??

  17. #17
    pvd
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    Looking at your "prints" forces me to question your design and fit method when you say what you have. I'm sure if you look deeper into how to measure and change variables of you design you will be able to understand the improvements a few of us are talking about.

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    Something funny about framebuilding is that there are a lot of builders who can't fathom why anyone would build a bike that's not exactly the same as what they build. I guess it's why a lot of us got into building in the first place. But it's also the reason there's such a great wide variety of handbuilt bikes out there.

    Sounds like you've really paid attention to what you like in front center, so go with it and tell us how it works out. And post pictures!

  19. #19
    pvd
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    Quote Originally Posted by Erichimedes View Post
    Something funny about framebuilding...
    This is more about pointing out that someone adding two and two and coming up with five might have to do some studying.

  20. #20
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    Quote Originally Posted by LyNx View Post
    You repeated it, but I'm fairly certain you meant a 475mm Reach and not 675mm ;-) As I said, you know what you like, unless of course you have never tried anything different, which seems you have, so go by what you like and want, not what someone else tells you need
    Yeah, you're right. 472mm reach, 675mm effective top tube. Reach wasn't a thing back then.
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  21. #21
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    Front triangle done. Merry Christmas!
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  22. #22
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    Sweet Don't forget to document and post up pics, as you go if you have time, I'm sure I'm not the only one interested in seeing this being built

    Quote Originally Posted by scottzg View Post
    Front triangle done. Merry Christmas!
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  23. #23
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    Rear triangle done. Got some filing to do. Wish i was a better brazer... the front triangle is always easier.



    Appreciate comments!-mtbrbraze1.jpg
    "Things that are complex are not useful, Things that are useful are simple."
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  24. #24
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    Looks pretty decent, but biggest thing is that the welds are good and strong, wish I could braze and build my own frames. Curious what experience you had before you gave building your own frames a go, any? Asked a local welding shop down here about doing it, even brazing steel and they kept telling me that despite their welders being good they'd need to have lots of scrap to practice on first.

    Quote Originally Posted by scottzg View Post
    Rear triangle done. Got some filing to do. Wish i was a better brazer... the front triangle is always easier.



    Click image for larger version. 

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  25. #25
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    Quote Originally Posted by LyNx View Post
    Looks pretty decent, but biggest thing is that the welds are good and strong, wish I could braze and build my own frames. Curious what experience you had before you gave building your own frames a go, any? Asked a local welding shop down here about doing it, even brazing steel and they kept telling me that despite their welders being good they'd need to have lots of scrap to practice on first.
    This is my 3rd frame, i had 0 metal working experience before i built the 1st one and i taught myself. Not recommended, although i rode #2 about 1500 miles and neither of them failed. I didn't particulary intend to build any more after #2, but i had the free time and an opportunity to work with someone more much experienced. Each frame has taken me about 40 hours to make; it's just for fun. If i had a way to cut mitres faster and a chainstay jig it would go a lot faster.

    Having a welding shop build a frame doesn't sound like a good plan. It's not so hard to weld (although my tig experience is minimal) it's holding the tubes in place, checking alignment, getting all the tubes mitered properly, etc etc etc. Who would be responsible if you specced the wrong tube? Commission a pro; what they offer is cheap when you consider the value of expertise and the right tools. I wish i had spent the money up front and gone to a frame building school.
    Last edited by scottzg; 01-08-2017 at 11:44 AM.
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  26. #26
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    Ah, OK, sounds a lot like me and teaching myself a number of different things throughout life, just requires a lot of patience and time and research.

    No such thing as a professional bike/frame builder down here in the Caribbean or frame building school, best I could achieve is a welding class at the polytechnic. I also figured that sorting the jigs would actually be the really hard part, but after that once you get the mitre thing sorted and some good practice welding/brazing thin tubes it should be doable.

    Quote Originally Posted by scottzg View Post
    This is my 3rd frame, i had 0 metal working experience before i built the 1st one and i taught myself. Not recommended, although i rode #2 about 1500 miles and neither of them failed. I didn't particulary intend to build any more after #2, but i had the free time and an opportunity to work with someone more much experienced. Each frame has taken me about 40 hours to make; it's just for fun. If i had a way to cut mitres faster and a chainstay jig it would go a lot faster.

    Having a welding shop build a frame doesn't sound like a good plan. It's not so hard to weld (although my tig experience is minimal) it's holding the tubes in place, checking alignment, getting all the tubes mitered properly, etc etc etc. Who would be responsible if you specced the wrong tube? Commission a pro; what they offer is cheap when you consider the value of expertise and the right tools. I wish i had spent the money up front and gone to a frame building school.
    One day your life will flash before your eyes, will it be worth watching??

  27. #27
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    Quote Originally Posted by LyNx View Post
    Ah, OK, sounds a lot like me and teaching myself a number of different things throughout life, just requires a lot of patience and time and research.

    No such thing as a professional bike/frame builder down here in the Caribbean or frame building school, best I could achieve is a welding class at the polytechnic. I also figured that sorting the jigs would actually be the really hard part, but after that once you get the mitre thing sorted and some good practice welding/brazing thin tubes it should be doable.
    Don't teach yourself. Working under an experienced frame builder was 100% the impetus for this frame, and it is considerably better than my previous attempts, despite putting by far the least effort in to it. If you can't find a mentor don't do it.

    Dave Bohm teaches a 2 week frame building program in tuscon, az. I hear there's awesome riding in tuscon, and i know there's some sweet trails outside phoenix and especially sedona. If i was a mtb nut in barbados i'd find a way to take a winter month off and attend frame building school and road trip. Acquiring a good custom frame costs $2k no matter what, why not spend a little more and have some real guidance and awesome riding?
    Last edited by scottzg; 01-09-2017 at 12:57 AM.
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    I have ~300 miles on this bike, so i guess i'll comment on the design myself.

    I'm over all happy with the frame and expect to ride it about 2 years before i feel inclined to build another one. I'm using a 130mm pike rct3 with 3 (4?) volume spacers. Short travel with lots of ramp-up seems to work best for me.

    Despite the fairly large tube diameters i have no trouble flexing the front triangle. This is most easily seen if i manual and twist the bars- i can get an inch of deflection. For contrast- my transition suppressor defects slightly, my friends' carbon santa cruzes don't move at all, and my road bike and my mom's bike path bike move just a touch. This phenomenon doesn't seem to really matter, but when i land nose-first in to a corner i can see the front end deflect. My friend just built a similar frame with the same tube set, but he's 5" shorter (5'10) and i can't get his frame to twist laterally nearly as much.

    I wish i had made the chainstays longer, like 430 rather than 425. Climbing it's pretty darn good and it's only when i'm tired that i forget to lean forward a bit for the steepest climbs and it gets light, which i kinda like ordinarily. Descending i can get too far back hanging off my arms and the front end gets too light, and for lipped jumps it's occasionally tricky to time them right. So... another 5mm or so of chainstay would let me be a little bit lazier and that would make it faster and more intuitive.

    I did not use the heavier seat tube feldybikes suggested, but i wish i had. Although my seat tube only took about 3 minutes of honing it was clear that there was a ton of deformation going on in that area. I don't think it matters, knock on wood.

    I used bolt-on cable guides from an older scalpel, which attached to water bottle bosses. They work well, but it ended up being as expensive as premium zip tie guides and if (heaven forbid) i lose a guide it will be a huge pain in the butt.


    I spaced the water bottle bosses before i set the tube diameters in bikecad. Whoops! Fortunately i had a blackburn stainless cage that was mounted high and doesn't show the mistake.
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  29. #29
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    An inch I can't imagine that feels too good when , as you say you land nose first into a corner/turn or just a bit squirrely. Any ideas as to why so much, especially as your friends doesn't seem to exhibit any?
    One day your life will flash before your eyes, will it be worth watching??

  30. #30
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    Quote Originally Posted by LyNx View Post
    An inch I can't imagine that feels too good when , as you say you land nose first into a corner/turn or just a bit squirrely. Any ideas as to why so much, especially as your friends doesn't seem to exhibit any?
    I have no idea! it's really weird. I think mine twists more because my reach is longer and my high seat post gives me more leverage. his might move almost as much while descending...?

    it doesn't feel bad riding it, but it's noticeable. Other people aren't able to twist it like I can, I don't know anyone else as big as me.

    I've had frames with similar front end deflection but fore and aft, and that was horrible.


    maybe next frame I'll do rivendell style double top tubes.
    "Things that are complex are not useful, Things that are useful are simple."
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  31. #31
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    But but but... how can you be happy on this bike, when PVD said it was completely no good, but couldn't specify why? Clearly, you just *think* you're having fun, but actually not.

    How about some pictures?

    Quote Originally Posted by scottzg View Post
    I have ~300 miles on this bike, so i guess i'll comment on the design myself.

    I'm over all happy with the frame and expect to ride it about 2 years before i feel inclined to build another one. I'm using a 130mm pike rct3 with 3 (4?) volume spacers. Short travel with lots of ramp-up seems to work best for me.

    Despite the fairly large tube diameters i have no trouble flexing the front triangle. This is most easily seen if i manual and twist the bars- i can get an inch of deflection. For contrast- my transition suppressor defects slightly, my friends' carbon santa cruzes don't move at all, and my road bike and my mom's bike path bike move just a touch. This phenomenon doesn't seem to really matter, but when i land nose-first in to a corner i can see the front end deflect. My friend just built a similar frame with the same tube set, but he's 5" shorter (5'10) and i can't get his frame to twist laterally nearly as much.

    I wish i had made the chainstays longer, like 430 rather than 425. Climbing it's pretty darn good and it's only when i'm tired that i forget to lean forward a bit for the steepest climbs and it gets light, which i kinda like ordinarily. Descending i can get too far back hanging off my arms and the front end gets too light, and for lipped jumps it's occasionally tricky to time them right. So... another 5mm or so of chainstay would let me be a little bit lazier and that would make it faster and more intuitive.

    I did not use the heavier seat tube feldybikes suggested, but i wish i had. Although my seat tube only took about 3 minutes of honing it was clear that there was a ton of deformation going on in that area. I don't think it matters, knock on wood.

    I used bolt-on cable guides from an older scalpel, which attached to water bottle bosses. They work well, but it ended up being as expensive as premium zip tie guides and if (heaven forbid) i lose a guide it will be a huge pain in the butt.


    I spaced the water bottle bosses before i set the tube diameters in bikecad. Whoops! Fortunately i had a blackburn stainless cage that was mounted high and doesn't show the mistake.

  32. #32
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    Quote Originally Posted by seat_boy View Post
    But but but... how can you be happy on this bike, when PVD said it was completely no good, but couldn't specify why? Clearly, you just *think* you're having fun, but actually not.

    How about some pictures?
    PVD has his ideas on what makes a good hardtail and i have mine. That's ok, i appreciate his insight even if he's negative.

    To be honest i'd enjoy riding it even if it was a flaming sack of crap- you learn a lot riding meticulously designed crappy bikes.





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  33. #33
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    Quote Originally Posted by scottzg View Post
    After a ~8 year hiatus i'm building another frame. I'll be working with someone with more fabrication experience this time, so i'm hoping that the process will go more smoothly, although my first two frames turned out alright. It will be fillet brazed and loosely based off my on-one 456, which i'm very fond of, it's just too small. I plan to use a 38 9/6/9 downtube, 31.8 9/6/9 TT, and a 1.5 steerer with a reinforcing ring. I'm 6'3, 215lbs, and not gentle.

    I'm pretty comfortable with my choices, but i appreciate others' insight.

    Click image for larger version. 

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    Photo is with 0 sag, a 130mm Lyrik rc2, and 26" wheels.

    I wonder in light of the flex you are experiencing that in hindsight you had used a down tube that was not butted, of say 0.9mm. The design of your frame in quite compact and therefore less likely to flex than a more open, longer frame as suggested by PVD. A PVD design using your tube spec would likely have accentuated this problem, so a debate could start right here. Please don't, though. Won't help the OP. He asked for our thoughts at the beginning and we responded with geo/wheel size current thinking when we over looked his actual size/weight. The honesty of the result is enlightening and we should take note. I do not believe a double top tube is your answer though. Consider a 42mm DT and 35mm TT next time.

    Eric
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  34. #34
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    I agree with Eric, I think a 42 or 44.5mm down tube would really help for the next build.

  35. #35
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    Quote Originally Posted by Eric Malcolm View Post
    I wonder in light of the flex you are experiencing that in hindsight you had used a down tube that was not butted, of say 0.9mm. The design of your frame in quite compact and therefore less likely to flex than a more open, longer frame as suggested by PVD. A PVD design using your tube spec would likely have accentuated this problem, so a debate could start right here. Please don't, though. Won't help the OP. He asked for our thoughts at the beginning and we responded with geo/wheel size current thinking when we over looked his actual size/weight. The honesty of the result is enlightening and we should take note. I do not believe a double top tube is your answer though. Consider a 42mm DT and 35mm TT next time.

    Eric
    I used this design for my frame... it's not dramatically different though.

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    So, i've been under the impression that while a lot of factors influence how a frame rides, the DT has the greatest influence over how the frame sways under hard sloppy pedaling and (along with a bunch of other stuff) how the frame manages braking forces. In those regards this frame is great. The top tube, however, is mostly under compression/tension except when it's pushed sideways by forces that use the DT as a fulcrum, like me twisting the bars or loading up the front wheel in a crooked landing--- which is where i notice the flex. My impression is that a larger/stouter top tube would do the most to minimize the behavior. I don't know.

    Ultimately i'm not sure that this front end give is really a handicap; so far it's just interesting. As i mentioned, all the front end movement i've experienced in the past has been in the fore-aft direction and that's been awful, whereas this lateral deflection... not so much. Need to ride it more.
    "Things that are complex are not useful, Things that are useful are simple."
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  36. #36
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    One of the material variations I notice with butted tubing over straight gauge tube in a frame is the ability of the butted tube to flex, yet has a wonderful quality of 'snapping' immediately into alignment. I always marvel at that effect when riding. As to whether there is a positive or negative about this I guess is up to you the rider, as each rider style/riding enviroment will be specifically unique.

    I always used a ride slow - quick snap the h/bars left to right technique to induce a frame flex and observe the movement and how quickly the bike 'corrects' itself. I have never found a bike to be a complete noodle, but it is quite surprising how much a frame can move and whip back into line.

    Some thoughts for you that do contribute to this condition are: Butt lengths. Short thick sections leave a tube mostly as a thin walled tube which can flex more easily than a longer butt. Tube Diameter - if retaining a mostly thin wall section tube, increase the tube diameter as this increases resistance to flex. If the design requires longer TT and DT then again, watch the butt lengths in relation to tube diameter. Having short ST is good in the reduction in flex as is a short 115-125mm HT. MTB's are good, but road bikes with 180plus HT and 600mm ST in traditional 28.6mm tubing are very bendy. Thankfully, we can address these issues if we understand the dynamics. The down side or maybe the positive side to all of this is in the learning/experimenting which of course always involves making another frame!!!!!

    Happy riding.

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

  37. #37
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    Quote Originally Posted by scottzg View Post
    I have ~300 miles on this bike, so i guess i'll comment on the design myself.

    I'm over all happy with the frame and expect to ride it about 2 years before i feel inclined to build another one.
    Nice project and good for you! I can offer no educated advice on fit or size and very little experience but I went what feels right and all the measuring and current bikes I have really didn't mean much in trying to use as a template. Much has changed since my 91 Specialized and 03 Kona.
    At 5'10.75, 34 sleeve and 32 inseam, I'm right between this and that on almost everything.
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    I just did a rebuild on an old frame, taking the front end geometry from the last century into this century. Since it's a throwaway experiment I just grabbed whatever I had lying around in my stash, so it got the same tubing sizes - 38 DT and 31 TT.

    I was expecting it to end up super stiff, but the bike is still surprisingly flexy. It is using almost the full length of a 29er DT, so maybe the extra length is canceling out the extra stiffness of the larger diameter tube.

  39. #39
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    Here's an article on tubing diameter, wall thickness, and flex that i thought was interesting.

    I Like Big Butts: Custom Framebuilding, tube size and butting
    "Things that are complex are not useful, Things that are useful are simple."
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    Since i'm commenting on my own design---

    i just spend a week at moab and rode this bike. We did ahab, porcupine rim, mag7/portal, and some other stuff, and visited st george on the way out and back. In that environment i regret sticking with 26" wheels; there's a lot of pokey stuff and chatter that bigger wheels handle better. Otherwise the bike performed fantastically. BB height was perfect- i clipped my pedals maybe 10 times total. The short rear end i complained about earlier was a boon when it came to hopping from rock to rock or those moab 90* transitions, and steep slickrock climbs were easily managed by just leaning forward (no need to choke up on the saddle) and pedaling smoothly. I was able to ride the whole week without being significantly more fatigued than i was on previous trips with a variety of 6" FS bikes. The torsionally flexy front triangle wasn't apparent because there aren't any berms or big doubles to whip on out in the desert. On the porc rim jeep trail i probably could open it up enough to take advantage of a longer FC, but good scanning and 'hardtail awareness' covered for it pretty well.

    This is half a comment saying that this bike was pretty well suited to moab riding, and half saying that a quality hardtail was ****ING FUN AS SHIT in moab, despite what i thought going in to it. Seriously, no more fatiguing than riding a 5-6" bike.



    I was not planning to ride this bike on the trip, but i found my 6" bike was cracked when i was prepping it for the trip.
    "Things that are complex are not useful, Things that are useful are simple."
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  41. #41
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    Hahaha. Appreciate the updates, interesting to hear you felt it didn't fatigue you any more than your FS. Never been there to ride, so not familiar with the actual trails, do they not have as much small chatter, which is what makes a HT sap more energy as you're constantly having to be off the saddle or did the frame actually provide enough compliance to not make that necessary?

    Quote Originally Posted by scottzg View Post
    Since i'm commenting on my own design---
    ...........This is half a comment saying that this bike was pretty well suited to moab riding, and half saying that a quality hardtail was ****ING FUN AS SHIT in moab, despite what i thought going in to it. Seriously, no more fatiguing than riding a 5-6" bike.



    I was not planning to ride this bike on the trip, but i found my 6" bike was cracked when i was prepping it for the trip.
    One day your life will flash before your eyes, will it be worth watching??

  42. #42
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    Quote Originally Posted by LyNx View Post
    Hahaha. Appreciate the updates, interesting to hear you felt it didn't fatigue you any more than your FS. Never been there to ride, so not familiar with the actual trails, do they not have as much small chatter, which is what makes a HT sap more energy as you're constantly having to be off the saddle or did the frame actually provide enough compliance to not make that necessary?
    I think the key was that i was the strongest rider in our group- i never had to really push my endurance unless i wanted to.


    I don't really think frame compliance is very important (everything flexes when you put it under me, so i don't have much of a perspective on 'too stiff'), but i have a TOTL fork and my cockpit set up is well suited to me. It took me a day to adapt my desert riding style to the hardtail, but after that it didn't really matter much, and it was easier in some ways. I thought the chatter was gonna kill me but it just didn't matter, even the high-speed jeep trail descents... didn't matter.


    Seth's bike hacks did a great video of porcupine rim, it's fun! I still had to take 2 runs at a couple features, despite having done it 4-5 times now.

    Last edited by scottzg; 04-15-2017 at 09:50 PM.
    "Things that are complex are not useful, Things that are useful are simple."
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