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#31
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The one thing that couldn't go wrong, did go wrong.
On Sun, 14 Aug 2005 22:19:01 GMT, Blair P. Houghton wrote:
Dennis P. Harris wrote: On Sat, 13 Aug 2005 06:53:01 GMT in rec.bicycles.tech, Blair P. Houghton wrote: But I've got enough practice with mechanicals to know that theory don't mean **** when you're standing there with a broken widget in your hand. it's steel. it's not going to break. ...said the designers of the Tacoma Narrows bridge. if you want to be gentle, use a long bolt, several large washers, and a couple of nuts and spred it gently by increasing the distance between two nuts on the inside of the dropouts until you have the width you need. you keep obsessing about this frame. steel frams bend quite easily, especially for the small distance that you're discussing, 6 to 8 mm. it's almost impossible to damage a steel frame by gently spreading the rear dropouts. How do I guarantee that the lugs won't separate from the frame at the welds under this non-designed stress; how do I ensure that the two stays move outward the same distance; and how do I know the bar on which the brake is mounted won't break from one stay or the other? Because they aren't welded, they are brazed. It is a stress for which the frame was designed - when it was designed and brazed together it was with the understanding that alignment by cold setting would almost surely be needed. We know it is safe because it is done all the time. All that having been said, it's your bike and you get to decide how to make it do what you want. Apparently you'll have to do something clever in the rear shifting department to get the gearing you want without spreading the frame. Perhaps an 8 of 9 arrangement. Ron |
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#32
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The one thing that couldn't go wrong, did go wrong.
Dennis P. Harris writes:
But I've got enough practice with mechanicals to know that theory don't mean **** when you're standing there with a broken widget in your hand. It's steel. It's not going to break. If you want to be gentle, use a long bolt, several large washers, and a couple of nuts and spread it gently by increasing the distance between two nuts on the inside of the dropouts until you have the width you need. You keep obsessing about this frame. Steel frames bend quite easily, especially for the small distance that you're discussing, 6 to 8 mm. It's almost impossible to damage a steel frame by gently spreading the rear dropouts. As was already mentioned by Andrew Muzi, who runs a bicycle shop where this is a common procedu Lay your frame without wheel flat on the ground. Put your foot on the frame end. Lift the other one with both hands until it stays at 130mm. Go ride. Sometime when it's convenient, have the alignment checked. To which I added: Let me add to that to place your foot at the brake bridge of the side on the floor and pull up on the dropout that is upward with care, noting when spacing has increased by half the required distance. Then repeat on the other side. Overshoot isn't good. The reason this more complex procedure is advisable is that just pulling the dropouts apart will cause an asymmetric spread, the two rear triangles not being identical. By placing ones foot on the downside seatstay at the brake bridge, while bending the other, assures that only the up-side will bend, it receiving the greater bending moment. Doing this one half at a time and measuring carefully will assure that the frame has symmetry afterwards. Since this is a steel frame, there is no hazard of breaking, especially with the small bends required to make the necessary change. At this point the dropouts are no longer parallel (if they ever were) but the angle is smaller than you want to know about. There are special tools for making that alignment: http://www.parktool.com/tools/FFG_1.shtml Jobst Brandt Jobst Brandt |
#33
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The one thing that couldn't go wrong, did go wrong.
wrote:
Blair P. Houghton writes: I'd rather find the right axle or find out it's not possible to find one, first. It's not the axle but the width of hub and freewheel that defines frame spacing. Define "axle". I'm defining it as the parts of the wheel that don't rotate; they include the part that mates with the inner surface of the lug. That is the part that defines the spacing. If it's a two-piece affair, one on either side of the hub, then yes, the hub would have to be replaced entirely. But the wrench at my LBS implied it would be an axle change, not a hub change. Changing the hub would not be a simple thing, if the aero spokes Neuvation used are not compatible with someone else's hubs, because they don't appear to make anything other than 130mm. In this case, repacking the bearings is much the less-stressful solution. Or, rearrange the deck chairs as the ship sinks. What does this have to do with the OP's frame width adjustment? I'm the OP. Changing axles requires repacking bearings. Unless you have magic axles without bearings. --Blair "I'm not emotionally attached to the axle." |
#34
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The one thing that couldn't go wrong, did go wrong.
Blair P. Houghton wrote:
Changing axles requires repacking bearings. Unless you have magic axles without bearings. May I suggest a look at the Neuvation hub technical sheet? Your hubs have sealed bearings; no need to repack them when you change the axle. http://www.neuvationcycling.com/pdf/...icalsheets.pdf Of course, I'd just re-space the frame and there'd be no need to change the axle. |
#35
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The one thing that couldn't go wrong, did go wrong.
wrote: Blair P. Houghton wrote: Changing axles requires repacking bearings. Unless you have magic axles without bearings. May I suggest a look at the Neuvation hub technical sheet? Your hubs have sealed bearings; no need to repack them when you change the axle. http://www.neuvationcycling.com/pdf/...icalsheets.pdf Of course, I'd just re-space the frame and there'd be no need to change the axle. Just found Sheldon's excellent instructions for frame spacing, including photos: http://www.sheldonbrown.com/frame-spacing.html It's not that risky, even for a vintage Holdworth (my first real road bike was a Holdsworth. Great bike, but it shimmied no-hands at 17 and 35 mph.) |
#37
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The one thing that couldn't go wrong, did go wrong.
Blair P. Houghton writes:
I'd rather find the right axle or find out it's not possible to find one, first. It's not the axle but the width of hub and freewheel that defines frame spacing. Define "axle". The shaft on which the hub turns. It's jam nut-to-jam nut width can be arbitrarily long but the hub and specifically the FW width prescribe what that dimension must be. I have axles of various lengths for wider dropout spacing from 120 to 135mm because that is what bicycle shops stock but my dropouts are 120 because I use an old ultra-6 SunTour new winner pro freewheel. I'm defining it as the parts of the wheel that don't rotate; they include the part that mates with the inner surface of the lug. That is the part that defines the spacing. So what? If it's a two-piece affair, one on either side of the hub, then yes, the hub would have to be replaced entirely. But the wrench at my LBS implied it would be an axle change, not a hub change. Why do would you want to change the axle if it fits in the hub and freewheel? Changing the hub would not be a simple thing, if the aero spokes Neuvation used are not compatible with someone else's hubs, because they don't appear to make anything other than 130mm. Just re-space the rear dropouts the way everybody else did as hub spacings grew with increasing number of gears. In this case, repacking the bearings is much the less-stressful solution. Or, rearrange the deck chairs as the ship sinks. What does this have to do with the OP's frame width adjustment? I'm the OP. Yes? Changing axles requires repacking bearings. Unless you have magic axles without bearings. I think you speak a different mechanical component language than I. I don't understand what you mean by that. Are we talking about dropout width or bearing maintenance. I missed the connection. Jobst Brandt |
#38
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The one thing that couldn't go wrong, did go wrong.
Blair P. Houghton wrote: I've got plenty of experience with mechanicals. Enough to know these two significant things: when you stress old metal, it doesn't behave the way new metal does; Sorry, I disagree, unless there's something special going on, like severe corrosion. you can't bend two pieces of metal exactly the same, and the two sides of the rear triangle are two pieces of metal that need to be bent exactly the same. Here's how I did it last time (just a couple months ago): The bike was a beautiful old Trek touring bike, Reynolds 531, in perfect condition. I was doing some work on it for a friend, and found the bike shop hadn't respaced the frame to fit the new hub. I phoned the owner, explained the problem and said "Do you want me to fix it?" She said yes. I left the bike in the workstand, got two blocks of wood and one longer two-by-four, used the two-by-four to pry the dropouts further apart by putting pressure on the wood blocks. I used trial and error to get the exact 130mm spacing. The force was applied evenly and simultaneously to the inside of both dropouts. The frame passed a quick string alignment check, and the frame rode perfectly straight when it was all done. It all took 15 minutes or less. There's also the fact that we're talking about one kind of metal encased in another (the Campy lugs ... Was that supposed to be dropouts? ... are hardened and the surrounding material is not) and once the stays are widened the lug area has to be realigned, which threatens to split the join between these dissimilar metals. I don't know about any differences between Campy dropouts and Trek dropouts, but there was absolutely no problem realigning the Trek dropoouts, or the ones on my old Raleigh when I did this, or any other bike I know of. Besides, I doubt the brazed area of a dropout would be hardened after brazing. You're probably getting it thoroughly annealed as you're brazing it. Really. Seriously. You're making a mountain out of a molehill. But if you really like your mountain, you're free to keep it. Nobody's forcing you to perform an easy fix for an irritating problem. - Frank Krygowski |
#39
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The one thing that couldn't go wrong, did go wrong.
Blair P. Houghton wrote: my Holdsworth. I see the following relevant points: 1. A large body of practical experience says you should be able to spread the frame no problem, if you do it carefully as described. 2. It's your Holdsworth and your hub, for you to do as you determine and to take responsibility for. I object to anyone ordering you around and telling you what to do, instead of merely explaining or even insisting what you can do without problem. 3. Isn't replacing an axle less strenuous than spreading a frame? Assuming everything else fits. 4. What's wrong with an original five, or was it six or seven, speed freewheel with no change? You have a classic Holdsworth, why not leave it with the original configuration on classic wheels and sell the new ones on eBay? I don't see any advantage to a modern wheel with its extreme dish. Who needs so many gears? Who needs so much aero, unless you are racing? The weight need not be any better.. |
#40
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The one thing that couldn't go wrong, did go wrong.
John Forrest Tomlinson wrote:
On Sun, 14 Aug 2005 22:14:27 GMT, Blair P. Houghton wrote: Vee wrote: Blair P. Houghton wrote: But I've got enough practice with mechanicals to know that theory don't mean **** when you're standing there with a broken widget in your hand. Others have been polite, but that hasn't worked, so he you're being stupid about this. The best solution is to respace your Holdsworth. Others have been polite because there is more than one solution, and I've told you I don't want to break my Holdsworth. It's extremely unlikely to break, as the many examples presented have shown. If you want to ignore them, fine, but it's irrational. It's not irrational, it's cautious. It's not their bike and their dares aren't going to make me try something that risky. You've got a non-problem with your bike you want to make into a problem. Too bad. It's a real problem and I'm looking for a less risky solution. --Blair "Too bad." |
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