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  1. #1
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    Sudar's First Frame

    Just about ready to get started on putting my first frame together, so I thought I'd post up a drawing of what I am going to do. This bike will be fillet brazed mostly because I have a torch in my garage and I like the flowing look of brazed frames. I have access to a TIG welder at work, but it's an hour drive away and I don't want to haul my frame jig all over the world.

    I'm building this on an old (early nineties?) Henry James Universal Jig I picked up a couple years ago. I had never done any machining before, but it was pretty clear I was going to have to learn how in order to build modern frames on the old jig. I had to make a new fixture to hold tapered head tubes, a couple new tube saddle blocks to hold 35mm seat tubes, and machine an adapter to allow me to use Anvil dummy axles on the Henry James jig. Should be pretty cool.

    The frame is a 27.5 hardtail with a custom Paragon 44/49 headtube so I can use an Angleset and do a little experimenting. The other bits (dropouts, BB, brake mount) are all Paragon as well. The tubes are all Dedacciai Zero Uno from BikeFabSupply.com with the exception of the ST which came from Vari-Wall. I'm about 220 lbs geared up. I hope I chose wisely. Here are the specs:
    TT 35mm .8/.6.8
    DT 38mm .9/.5/.8
    ST 35mm 1.6/.85 - no seatpost insert required
    SS 19mm .7
    CS 15x30mm 1.0/.7

    I'm currently riding a V2 Evil Sovereign with a 150 fork and a Knolly Chilcotin 170F/160R. Both are 26ers and getting a little dated. I went back and forth between 27.5 and 29 for a long time, but 27.5 won because I didn't feel like the 29ers I had ridden were as flickable when things got rough and techy. One of the primary goals for this build was to fit a 200mm dropper. The Fall Line 200mm will fit, but I ended up with a Bike Yoke 185mm. Either way, it should still be able to be dirt jumped if the need arises. Which it will.

    The thinking behind the cut and welded seat tube are: I don't currently have proper bending dies for that size/wall thickness of tube, easy dropper cable routing and aesthetics. I have always been a fan of 2Souls Cycles.

    All the components for the bike build and all tubes are sitting in the garage ready to go. I haven't cut tube yet, so I can still make some minor tweaks to the geo. Let me know what you think. Never done this before, so I'd like some feedback. Not sure why the thumbnail is all black, but there is a pdf of a frame there if you click.
    Attached Thumbnails Attached Thumbnails Sudar's First Frame-bikeframe-layout1-2-.pdf  


  2. #2
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    Looks good to me. You're like 5'9 or so? That is going to make a very stiff frame. I'd use a smaller diameter TT in 9/6/9 for a little more flex and dent resistance.

    I'd also consider using paragon sliders (if you're comfortable with silver), nova mild steel sliders (if you would rather just TIG them in), or horizontal dropouts and a disk tab. On your first frame it can be super valuable to be able to shorten/lengthen the chainstays independently of other fit/handling variables. See how chainstay length can affect handling on it's own, dial in the handling, compensate for build mistakes, get your wheel as forward as possible... and i think those chainstays are too dang short. Especially combined with that STA, but i would struggle even in the attack position. The chainstay miters always seem to be the trickiest and i end up shaving a bit more stay off than i intended to get them perfect.

    Walt and PVD are/were selling curved seat tubes. I'd prefer them on a 1st build because i'd worry about cooking the DT/ST joint, or landing it on the butt, or something. Cutting and welding the thin wall section of the seat tube will fail eventually. I made mistakes on my first frames despite sweating the details, and a curved ST eliminates a spot to screw up. Steepening the STA a couple degrees would do the trick too, and would probably gel with the rest of the frame/build kit better.

    I'd drop the BB at least 10mm, possibly more.

    I won't be running another pike. They suck to service and i don't like the damping behavior.


    I'm not the final word of frame design by any stretch of the imagination, but i'm an expert at spouting opinions. Good luck with your first frame!
    "Things that are complex are not useful, Things that are useful are simple."
    Mikhail Kalashnikov

  3. #3
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    Couple thoughts:
    You may have a challenging time fitting the chainstay between the chainring and tire. Napkin math tells me you have roughly 19mm between them (if you're running a boost chainline and 2.4 tire), so try to have a plan for threading through that gap.

    I would also recommend a bent ST. With your dropper requirements, Walt's bent ST plus a collar welded to the top is probably your best option, I would think.

    I agree with scottzg, your TT is kinda huge. A 31.8 in 9/6/9 would probably be just right. I feel like your seatstays are kind of on the thin side, I might go with .8 wall.

    I think the geo looks great. Should be a killer trail bike.
    Myth Cycles handbuilt bike frames
    Durango, CO
    http://www.mythcycles.com

  4. #4
    pvd
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    The 643mm dimention should be removed from the print.

    The bb is a bit high, the seat tube is too slack, the head tube isn't slack enough.

  5. #5
    pvd
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    Also, go with a 46mm offset fork.

  6. #6
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    I will get a smaller TT ordered. That decision was based on the TT of my Evil Sovereign.
    That will give me more room to build a fillet on the sides of the TT to ST joint. I was a little concerned about not having much of a fillet without an unsightly bulge when joining two tubes of the same diameter. I've been practicing my brazing on scrap tubing and that was one of the things I was worried about-- there wasn't much brass left where the sides of the fish mouth interesected tangent to the other tube.

    I'm having trouble finding S bend seat stays that are thicker than .7 mm. All the True Temper stuff is sold out and Columbus, Vari Wall and Dedacciai don't make anything thicker in an S bend. I need the S bend for heel clearance. Are the .7 mm walls really too thin?

    I'm pretty sure I can run a staight ST and forget the cut/weld if I steepen the ST angle as PVD suggested and move the rear wheel back 5 mm. This will also help with tire/chainring/CS clearance. I have other drawings I did not post where I did check those clearances. According to CAD I have 7 mm tire clearance and 4 mm chainring clearance and that's before any dimpling. More clearance is always welcome though.

    How low can I go on the BB? 300mm? I'm running 170mm cranks.

    PVD-- I'm curious about running a fork with more offset? Are you suggesting I shorten the trail with more offset and then slacken the HA to lengthen it out again? Not that I care to follow trends, but it seems like Transition and Whyte were going with less offset on their forks and then moving the riding position foward?

    Thank you for the suggestions. I will get a revised drawing posted up in a bit and some pics of my jig.

  7. #7
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    Quote Originally Posted by jsudar View Post
    I will get a smaller TT ordered. That decision was based on the TT of my Evil Sovereign.
    That will give me more room to build a fillet on the sides of the TT to ST joint. I was a little concerned about not having much of a fillet without an unsightly bulge when joining two tubes of the same diameter. I've been practicing my brazing on scrap tubing and that was one of the things I was worried about-- there wasn't much brass left where the sides of the fish mouth interesected tangent to the other tube.
    Do your miter, then ovalize the tube by using a vice and some wood blocks, then adjust the miter so it sits flush again. I finish it up by wrapping the other tube in sand paper and running it through the miter. Pretty easy; an extra 10 minutes once you've done a few. My current mtb frame has a 35mm 9/6/9 TT, and although i don't see it as a hindrance it's not really beneficial for me either. It's a girder and i'm glad i've unloaded the pike- the frame felt excessively stiff until i mounted up a more rigid, better damped fork. I'm somewhat heavier and significantly taller than you.

    Quote Originally Posted by jsudar View Post
    I'm having trouble finding S bend seat stays that are thicker than .7 mm. All the True Temper stuff is sold out and Columbus, Vari Wall and Dedacciai don't make anything thicker in an S bend. I need the S bend for heel clearance. Are the .7 mm walls really too thin?
    Here. I don't understand the need for S bend SSs for heel clearance, with 415mm stays you'd have to have hooves to not hit the dropouts. I might use .7mm stays, but erichimedes' input is more valuable than mine. A slightly thicker tube can be a godsend if your temp control sucks. Ask me how i know.


    Quote Originally Posted by jsudar View Post
    I'm pretty sure I can run a straight ST and forget the cut/weld if I steepen the ST angle as PVD suggested and move the rear wheel back 5 mm. This will also help with tire/chainring/CS clearance.
    Personally i would do this without hesitation. Seated steep climbing can only improve and i'd expect improved descending too unless you're quite short.

    Quote Originally Posted by jsudar View Post
    How low can I go on the BB? 300mm? I'm running 170mm cranks.
    For me and 175 cranks- 295 clipless, 305 flat pedals. No sag. Raise 10mm if riding in a rocky/desert environment, or somewhere where you're constantly pedaling to keep momentum. That's based on experimentation and might be totally off base for what most people want. No idea.

    Quote Originally Posted by jsudar View Post
    PVD-- I'm curious about running a fork with more offset? Are you suggesting I shorten the trail with more offset and then slacken the HA to lengthen it out again? Not that I care to follow trends, but it seems like Transition and Whyte were going with less offset on their forks and then moving the riding position forward?
    If you live somewhere with non-chop, high speed descents------- the only thing that matters is getting the longest front-center possible, then adjusting the rest of the bike so it climbs and handles right. Once you're fastest on a bike with the longest FC it takes a pretty tight/narrow/flat trail for that design to be a definite handicap. This is a place where terrain, fitness, rider skill/experience, etc make for a murky crystal ball and there's no simple answer and it can change as you do.

    Transition and Whyte are going after a bike with a somewhat more moderate FC that's very stable. Different goals. Maybe i've interpreted it all wrong.


    Quote Originally Posted by jsudar View Post
    Thank you for the suggestions. I will get a revised drawing posted up in a bit and some pics of my jig.
    Sweet!

    Maybe you're more talented than i am, but every ride i'm grateful that i used my first couple frames as geometry and tube set experiments. You can go buy a good frame from a hundred different manufacturers, but you have to go alone if you want to make fundamental compromises and amazing gains. So to a certain extent it's wise to build what you want, ride the result, and be candid. Go heavy on tube wall thickness and do what you want with tube diameter. Take framebuilder advice in aggregate and you'll get another 'safe' design that works well (hopefully) and you don't know the compromises that were made.

    With framebuilding... 'craft' advice is invaluable, 'art' advice is interesting.

    Don't take my advice. I'm a newbie and an idiot.
    "Things that are complex are not useful, Things that are useful are simple."
    Mikhail Kalashnikov

  8. #8
    pvd
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    The whole "high trail" trend is completely marketing hype.

    High Trail MTB | Peter Verdone Designs

  9. #9
    pvd
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    You keep referencing the Evil and Knolly bikes. Those are total shit bikes and really not anything you'd want to base your own build on.

    Here's my last mtb. I'm 5'10" and ride aggressive trail and pedal a lot. It currently has the fork set at 180mm. It's pretty dialed. Note the tube sizes.

    SR-71 Blackbird | Peter Verdone Designs

  10. #10
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    Quote Originally Posted by pvd View Post
    The whole "high trail" trend is completely marketing hype.

    High Trail MTB | Peter Verdone Designs
    I did find the 51mm offset 29er fork to be inferior to 44mm from a handling perspective.

    The 51mm fork tends to tuck under once the front wheel loses traction leading to a crash where the 44mm is save-able because it's easier to pull back. Perhaps a better athlete than I wouldn't notice this so much but for me it was a significant difference.

    I don't have a perfect explanation but it's a combination of the movement the wheel takes when it washes out and the quickness one can straighten the wheel and ride out the slide.

    I discovered this feeling on my own but went back and read some opinions of others and found they had the same thoughts.

    So there' more to it than just optimizing for front center unfortunately. I bought a whole new kashima upper for $250 to get the feeling right :/

  11. #11
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    I agree with you on the save-able perspective.
    Along with chainstay lengths, seat tube angles, headtube angles, front centres, fork offsets, they are variables and you know what you are comfortable with in your riding environment. So select what works for you.
    Generally, regardless of HT angle, a shorter offset will always produce a bike that requires more lean to steer rather than turning of the bars like its a steering wheel. The high trail figures produce bikes that tend to 'self steer' and track solidly in the straight ahead.
    With the wide bars now being used, leverage is available to overcome turning reluctance.
    It all depends on what you prefer in your bike.

    Your Build, You Choose.

    Good Luck

    Eric
    Last edited by Eric Malcolm; 1 Week Ago at 01:26 AM.
    If I don't make an attempt, how will I know if it will work?

  12. #12
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    Revisions

    Sorry for the long delay, but I was helping coach a junior development team with the NICA League. Got busy with all the end of season racing and other stuff.

    Here is an updated drawing. The changes are as follows: smaller diameter top tube (31.8, 9/6/9), thicker seat stays and and a straight seat tube. I decided I wanted more standover, so I reworked the top tube. The different butt profile of the new TT allowed for the brace and I'm really liking how the TT flows into the seat stays.

    As far as the geometry goes, I lengthened the chainstays a little bit (to 423mm) for better tire clearance and lowered the BB (302mm). The ST is now steeper (75) and the head angle is slackened to 65.5. I also stretched the front end out to make up for the steeper seat angle. I decided to go to a 150mm fork too.

    I'm feeling good about it. Hopefully I can start putting it together this weekend.
    Attached Thumbnails Attached Thumbnails Sudar's First Frame-bikeframe-layout1-3-.pdf  


  13. #13
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    Attached Thumbnail is too dark for me to read, but from your writtings to date, you appear to be goiing in the right design direction to have a rewarding ride.

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

  14. #14
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    I don't know why the thumbnail shows up black. If you click it, it's a .pdf of an AutoCAD drawing with a white background. Don't judge a pic by its thumbnail? IDK.

  15. #15
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    Looks awesome.
    "Things that are complex are not useful, Things that are useful are simple."
    Mikhail Kalashnikov

  16. #16
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    Looks like a pretty normal long/low/slack kinda bike. Not my personal cup of tea but most people love 'em. Build it and enjoy!

    -Walt

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