K2 / Proflex Riders Group
General => Tech Forum => Topic started by: DugB on March 16, 2010, 11:26:39 am
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As the line says, I'm going to look at a cheap 857 frame for sale locally today...anyone interested in getting it in trade for a Large (857, 957)? Keep in mind that the Way Big 857 seems to have the taller headtube, which wont likely work with the spare Carbon Crosslink I have.
Just wondering...
- Doug
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I wish I were tall. :(
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LOL, I'm not that tall but have long legs...which makes finding the right bike a bit of a hassle. If it's right for my leg length than the frame is probably too long for me...if it's right for my body then it's probably too low which means a 330mm seat post and leaning way over (usually what happens on PFs). My Way Big 4000 is probably the only bike I have where the seat is close to being at the same height as the handlebars. I was actually excited about this 857 frame until I realized the head tube was like that on my 4000 (taller than the standard size).
- Doug
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You set the seat level with the bars? How tall are you Doug and whats your leg length? Im 6'2" and a 35" leg and have managed on a large 857 and 4000 with (i think) a 120mm stem fine.
Chris
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Ok, good and bad on this frame (Terry, I hope you're listening)...though it has seen very little use, the bozo who installed the headset cracked the top and bottom of the headtube. Is this even something that can be rewelded?
On the plus side the pivots, quad rings, swingarm, shock and strut are all nice. It has a BB and seatpost clamp...all together. And not counting the front triangle, possibly just worth the $50 I paid. Rather a disappointment, though, especially since I didn't see the cracks until I was home.
- Doug :-/
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Must shed a tear for a fallen Proflex.
Thunderchild
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Yes, it's a bummer, but the fault made me go and check all the other frames I have and luckily I found no issues with them. I think someone just forced in this headset, but what made me nervous was that never in the past did I consider that the press-fit of a headset might be too tight...which I assume was the same mistake made by the PO of this frame.
To the welders in the group...is this even an area of the frame that can be reliably repaired? Each of the cracks goes a little beyond the initial thicker/reinforced area of the headtube into the thinner area. Other than that the frame is perfect, and looks barely ridden. This error might have occurred with the installation of the initial headset, but if not certainly the second.
Anyone want to experiment with repairing it? It's yours for the cost of shipping ($20?).
- Doug :-)
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Cracks eh?
Good news is the the 857 frame is 7005, and does not need reheat treat after weld. The 957s are 6061 and fussier to repair without heat treat.
The ones I have done need to have the crack beveled out with a steel headset cup left in. Then welded, headset cup removed, cleaned and welded then blended on the inside. And then I would suggest bonding in a deep cup headset.
(Sidenote on this. I am a firm believer in DeepCup headsets. I run an FSA Orbit Extreme in my 957 which has an elongated(loose)fit. And an Acros AH-07 in my Oz.)
Terry
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Hey Terry, here's a question for you: if you were going to repair a cracked headtube weld, could you just replace the headtube with a OnePointFive-compatible headtube? That would let you use the Lefty fork. :drool:
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So Terry, any interest in taking this on? ;-)
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Hey Terry, here's a question for you: if you were going to repair a cracked headtube weld, could you just replace the headtube with a OnePointFive-compatible headtube? That would let you use the Lefty fork. :drool:
hmmm I know where your coming from but I recon repairing and replacing are two completely different things.
Chris
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I know that replacing a head tube on an aluminum frame can be done as I have had a Ventana head tube replaced, so I would imagine that a 1.5" head tube could be added to the frame for a "small uptick" as they say.
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So Terry, any interest in taking this on? ;-)
Sure, no problem. I may as well make an insert for it, as I usually use an old steel bearing cup.
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Hey Terry, here's a question for you: if you were going to repair a cracked headtube weld, could you just replace the headtube with a OnePointFive-compatible headtube? That would let you use the Lefty fork. :drool:
hmmm I know where your coming from but I recon repairing and replacing are two completely different things.
Chris
I agree. Two different things, but very possible. The hardest part would be sourcing a 7005 headtube. And I think most headtubes have to be reamed and faced afterward. That would run into some bucks. I thought I read a thread on the retroboys site about adapting lefties to standard headtubes. That would be the direction I would turn to.
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Dont hold me to this but i think lefty's fit the older 1992/3/4 frames with just shy of 1"1/2 headtubes...(i think??)
If so it might be poss to pick up one of these off of ebay fairly cheap....or has someone got a spare there willing to contribute to a good cause..
Anybody got a frame stripped to measure up??
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Well, I was speculating on the use of a Lefty fork, but honestly I don't know how comfortable I'd be with using one on a regular basis; The HeadShok design is intriguing, but the Lefty also introduces continuous side-loading and torsional-loading on the needle bearings, because all of the forces affecting the wheel are handled by a mechanism that isn't in-line with the wheel. There has to be additional flex and premature wear as a result of that. There's a reason the two-legged telescoping fork is in nearly-universal use; it's a simple, well-balanced design that doesn't pose any unconventional problems in its implementation.
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Sweet, Terry! If you PM me your mailing address I'll pop the frame in the mail.
Like I said, if you're interested in it for yourself the offer is there.
If you don't mind repairing it for my use at least let me give you something in return (cash, parts?). Also, if you need to use a specific headset when doing the repair let me know your preference and I can order one and have it shipped to you, or can reimburse you if you know of one locally.
If, when you receive the frame you think the damage is too severe for a reliable repair just let me know. The cracks don't seem that severe, but that's to my untrained eye.
Thanks again!
- Doug :-)