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A nice comfy road bike.

8K views 66 replies 25 participants last post by  Walt 
#1 · (Edited)
#4 ·
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.

IS41/EC44 tapered headtube brings the HT diameter down to 1.500" for improved astetics over 'beer can' headtubes.
Very nice!
 
#6 ·
... 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?
 
#7 ·
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 · (Edited)
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.
 
#15 ·
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.
 
#14 ·
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.
 
#16 ·
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/Pythagoras#Pythagorean_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?
 
#40 · (Edited)
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/Pythagoras#Pythagorean_theorem.
If you're going to be pedantic you could at least spell it right. The Pythagorean theorem is about calculating the sides of right triangles. It doesn't justify your stem choice - you picked the stem rise first and drew a straight line to your steerer tube at that given angle. You're not using the wisdom of the ancients or doing any sort of mathematical optimization here.

The smaller triangles in the frame make it stiffer geometrically, allowing for smaller diameter tubes to acheive the same desired stiffness.
Moving the top tube closer to the down tube along the head tube increases the leverage the fork the fork has on the frame. And one could argue that you're adding flex back with the longer stem.

I don't have a problem with it though, I think the bike is very PVD and fits his style and 'terroir'.
 
#18 ·
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.
 
#24 ·
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?
 
#22 ·
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 ·
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.
 
#25 ·
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.
 
#29 ·
Functionality vrs Style

When I first saw the design and picture, I originally dismissed this bike as an ugly effort from a person who should know better. You know, steep sloping top-tube and riser bar stem as pointed out above. However, Peter is smaller than I am, and I have used various means of reducing the size of a bike visually to look not so big.

I understand the rationale, and also can see the view of the 'conventional look' that is contemporary. Is Peter's bike marketable? It would probably be an orphan sitting in the back corner of a display in a bike shop. But, he clearly built it for himself, with a spec suitable for his application, and any builder would do this for his client as a one-off, given the brief received. I just wouldn't publish it........critical public and all.

By the way, there are huge weight savings to be had reducing mass at the head tube by keeping it short. I have done the numbers on a frame that would have needed a 240mm HT to be used to comply with convention. I halved the length to 120mm, steerer stem also halved, which is heavier than the HT and constructed a triangular stem/bar 1 piece that looked much more elegant and saved 300grams in the process, sorry, no picture The seat tube and seat stays were also reduced in length giving an over-all weight of 1750g for a Columbus Zona tubed frame.

Eric
 
#30 ·
Hey Peter, I'm with you on the riser stem. All my customs (one Paul Barkley and two TiCycles, all Softrides) were designed with a riser stem in mind for the very reasons you cited. I might lessen the rise a little bit, but my position is pretty settled after 35 years of saddle time. +10, or even +15, is no affront to my sense of style, but any means.
 
#35 ·
For most people a road bike should have a sloping top tube. For a long time the sport clung to level top tubes but right now pretty much all the top of the line road bikes have sloping top tubes.

Stems are similar. In time sloping stems will become as normal as sloping top tubes. Basically unless you need a super low position a level stem does not make much sense. I expect that eventually the top pros will be on sloping stems in the larger sizes for all the reasons that PVD mentioned plus it lowers the front end of the bike for better aerodynamic profile in the context of a thinner stem for the raised bit vs the big fat head tube. The bikes are also lighter using this approach.

Great job on the bike BTW.
 
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