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  1. #1
    pvd
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    A nice comfy road bike.

    Last edited by pvd; 01-18-2013 at 07:16 AM.

  2. #2
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    Care to elaborate on the headtube and driveside chainstay?
    Slowly slipping to retrogrouchyness

  3. #3
    pvd
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    Segmented drive side on OX Platnum chainstays. Super lateral stiffness. Custom bent.

    IS41/EC44 tapered headtube brings the HT diameter down to 1.500" for improved astetics over 'beer can' headtubes.

    Seatstays are bent very slightly.

    BB86 bottom bracket.




  4. #4
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    Quote Originally Posted by pvd View Post
    Segmented drive side on OX Platnum chainstays. Super lateral stiffness. Custom bent.
    Very interesting. Are you just creating a butt joint where the tubes are joined end-2-end or is there some sort of internal support? I really like the way this looks, do you have any concerns about strength for this type of joint.

    Quote Originally Posted by pvd View Post
    IS41/EC44 tapered headtube brings the HT diameter down to 1.500" for improved astetics over 'beer can' headtubes.
    Very nice!
    Mark Farnsworth, Raleigh, NC
    http://farnsworthbikes.com

  5. #5
    pvd
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    No concerns. Years ago we debated this technique on this forum. I've done some destructive testing since and belive using proper technique it's an extremely stiff and strong solution.

  6. #6
    Nemophilist
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    Quote Originally Posted by pvd View Post
    ... using proper technique...
    Hmmm;

    I would imagine that many people would consider any butt-welded joint in a tube to be verboten. That being inferior to an uninterrupted tube for reasons of strength. I would further imagine that your conversation at that time included such opinions. Seems like a pretty simple job on the face of it, but I'd be interested to hear some of the points you would list under the heading of "proper technique" for such tube joinery?
    Most people ply the Well Trodden Path. A few seek a different way, and leave a Trail behind.
    - John Hajny, a.k.a. TrailMaker

  7. #7
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    Peter -- curious on the front-end geometry here. Your saddle position is very close to my own for road riding, but I'd want another 50mm or so to the bars... Anyway, my curiosity centers on the fairly low trail, with a middling-short stem. For me, I'd have close to 50% of my weight on the front wheel (okay, my CG is 14cm in front of the saddle nose, however that works out on this overall geometry). Not sure where yours lies, but it just seems that short trail + higher percentage of weight on front wheel = not as comfy. Of course this is coming from some one with "book learnin" on frame geometry, and riding experience on about 15 frames or so...

  8. #8
    pvd
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    I've been meaning to do a weighing on this bike. It should be close to 45%F/55%R as I'm a little on the heavy side. That was measured a few bikes ago and saddles have changed a lot since then (I've tried to compensate for that). I do need to measure again though.

    Lots of modern seats have longer noses so going by setback is a mistake. You need to base position on the sitting bones. Thus, an older saddle will be 260mm and a fairly centered sitz location. A WTB Silverado is 280 but the nose is extended 20mm not the sitz location. This Cutter saddle is "285mm" with an additional 5mm of nose extention. The point, don't use setback unless all the saddles are the same. Fyi, I'm only running the Cutter as I had it as a donation and didn't want to buy another Silverado for financial reasons. The Siverado is more comfortable.

    WTB Products Saddles Racing Devo
    WTB Products Saddles Racing Silverado
    Cutter Bikes Racing Saddle

    I show mechaical trail. Ground trail would be 57mm. It would go up a mm or two by slacking the head tube to 73 degrees.

    The bike rides great. The best road bike I've done yet. I'm actually as stretched out as much as I can stand with my toes grazing the wheel. My belly and comfort wont let me go lower. I may move the saddle forward a few mm.
    Last edited by pvd; 01-15-2013 at 03:55 PM.

  9. #9
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    Did you run out of head tube stock?

  10. #10
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    Quote Originally Posted by customfab View Post
    Did you run out of head tube stock?

    Interpreted as what's with the 25 stem
    Slowly slipping to retrogrouchyness

  11. #11
    pvd
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    What's wrong with a 25 stem on a road bike?

    **see update on website.

  12. #12
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    Well, it's an odd choice for a from scratch frame. Why not a longer head tube?
    Slowly slipping to retrogrouchyness

  13. #13
    pvd
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    Is the head tube not long enough to allow the bearings to support the front end loads? Is that what you are saying?

  14. #14
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    Nope, from a headset bearing perspective we could all probably due with 30mm headtubes. Especially with the bearings you're using.

    The question is why use a 25 stem when a few cm longer headtube would achieve the same bar position with a lower rise stem? Question applies doubly when you turn your own tapered headtube for looks (and it does look like a very nice tube!).

    You prefer the look of the stem vs a longer headtube/higher toptube? Or something els ?

    I only continue to ask because you quite obviously don't do things in a just because manner.
    Slowly slipping to retrogrouchyness

  15. #15
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    Quote Originally Posted by pvd View Post
    What's wrong with a 25 stem on a road bike?

    **see update on website.
    Everything. You built this bike just for you, with all kinds of custom touches, JUST FOR YOU. Why on earth could you not have added another 2cm of head tube to get rid of that god awful stem. That bike looks like it was built for somebody else and your trying to force it to fit you.

  16. #16
    pvd
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    The reason that I turn this question around is that folks seem to have an 'idea' that a rise stem is a bad thing. I see it all the time, folks with 50mm of spacers so that they can run level stems. Where is the sense in that? Where is the basis folks use for stem selection? Looks. They want it to look the way they are used to. You are right that I do everything for a reason. As my head tube is perfectly adequate to handle the needs of the loads and bearings there is no reason for it to be any longer than it is. Then it's all about placing the handlebar. Simple enough. In engineering we use a little trick we like to call 'a straight line'. An aquantance of mine came up with that a while ago. His name was Pythagoris.http://en.wikipedia.org/wiki/Pythago...gorean_theorem.

    It's funny that I see the exact sentimate in mountain bike builds. As you may know, I build up a bike with a rise stem and flat bars on all my bikes, even all mountain type bikes. Why run a 90 degree stem and rise bars when you can do the exact same thing directly with a stem and flats? Also givin that flat bars are lighter, stronger, and cheaper than rise bars it leads to the question; Why would you not do it the way I do?

    There's even more reasons. It's a lighter setup as there is less steerer and spacer. The mass of the bike is lower than standard. The smaller triangles in the frame make it stiffer geometrically, allowing for smaller diameter tubes to acheive the same desired stiffness. I also get a lot of body room over the bike and space when porting the bike into my house, up stairs, and into the godawful bike trays on the Golden Gate Transit buses I take to work.

    So. I've given a few good reasons why I do it my way. I invite you folks to come up with a compelling reason for a longer head tube and flatter stem. I looks like garbage when you think like an engineer. The worst reason in the world is "that's how we've always done it". So....why?

  17. #17
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    If your in the business of educating cyclists about what's better that's great. If your in the business of actually making bikes that people want to buy you might want to change your tune.

  18. #18
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    Quote Originally Posted by customfab View Post
    If your in the business of educating cyclists about what's better that's great. If your in the business of actually making bikes that people want to buy you might want to change your tune.
    Peter has always said he doesn't want to sell anything so it's a non-issue I suppose. I like the work PVD does for sure and see his points on the stem thing but it just looks weird to me. He's right though, 95% anyway. I dock him the 5% because you can't get most stems in the rises that he uses but then he always finds a stem that will work.

    Nice looking bike, Peter! What size tires are those? I couldn't find that in your description anywhere unless I just overlooked it.

  19. #19
    pvd
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    Why would I want to make a bike that a novice was interested in buying? Iwould I waste my time building commodities. I'm designing and building progressive bicycles. Have you read my wiki? Anybody can just copy old junk or techniques. My style is based on true learning.

  20. #20
    pvd
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    The tires are heavy Continental Gatorskin 25c. Most of my road riding is commuting so a light tire isn't worth it. On my FBR I use the 28c version for more aggressive riding.

  21. #21
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    Quote Originally Posted by pvd View Post
    The tires are heavy Continental Gatorskin 25c. Most of my road riding is commuting so a light tire isn't worth it. On my FBR I use the 28c version for more aggressive riding.
    I like the Gatorskins. I'm sure it rides nicely.

  22. #22
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    I don't mind the stem. I, personally might have used a 10 degree rise stem by adding maybe 100 of head tube above the TT, but I like where the TT is positioned for easy on/off of the bike. It's all about what your goal for the bike is and what your personal preferences are.

    I think the bike looks good and the head tube blends very well into the rest of the bike.

  23. #23
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    Hey;

    Conventions are useful for those to whom it does not occur to think.

    Ask yourself why riser stems are frowned upon by so many? If the only thing you can come up with is "that they look funny"... aaah-k. I pronounce it po-TAY-to.
    Most people ply the Well Trodden Path. A few seek a different way, and leave a Trail behind.
    - John Hajny, a.k.a. TrailMaker

  24. #24
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    Quote Originally Posted by pvd View Post
    Why would I want to make a bike that a novice was interested in buying? Iwould I waste my time building commodities. I'm designing and building progressive bicycles. Have you read my wiki? Anybody can just copy old junk or techniques. My style is based on true learning.
    I never said anything about a novice buying your bike. If anything they would be more apt to buy it because they are less likely to realize it's bucking the norm. The more avid a rider gets the more they attach themselves to tradition.

    I could tolerate your wacky stem if they were possible to get as quality parts. Last I check no stem manufacture makes anything in that steep of a rise past entry level parts. That alone is enough reason to ditch it. Have you actually done the math to show how much better your slightly more compact front triangle is, how much lighter your setup is. Or are you just throwing out generalized claims like the big bike manufactures do?

    Steep rise stems are around in limited supply to get fat people on hybryds more comfortable. Is that what your bike is about?

  25. #25
    pvd
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    I find that Ritchey, Salsa, and Profile make perfectly good stems**. They cost very little, they are light, and they are strong. Why would you pay more? I see lots of people with $200+ stems that don't fit them but they are stuck with as they've invested so much in. Also, these expensive stems aren't much lighter or stronger. Why do you think this is so important?

    **Provided the steerer clamp faces have been squared on a lathe.

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