Hi, I picked up a claud butler dalesman frame, to replace a frame I broke a chainstay on, from ebay. Before I set about prepairing it, could someone take a look at some rust on the chainstays and let me know if they think it's worth doing or not ? As received : http://www.phase7.org/stuff/P1011420.JPG after wire brush http://www.phase7.org/stuff/P1011434.JPG
Also, I checked the alignment of the frame rear stays using sheldon browns method using a piece of string tied from the drops to the head tube and got measurements of 33mm and 37mm which I figure is close enough. But the seat stays are clearly a little bent : http://www.phase7.org/stuff/P1011428.JPG will this cause a problem do you think ? The other one is bent slightly outwards.
And, I used 700x38 tyres that are very deep, anybody know a way to deal with clearances like these ? Will I have to by shallower tyres ? http://www.phase7.org/stuff/P1011403.JPG
Half of me says it's worth working on, the other half says it's a dog. Any help appreciated.
On Nov 6, 1:10 pm, "anern" <a...@anern.anern> wrote:
> Cross post from uk.rec.cycling
> Hi, > I picked up a claud butler dalesman frame, to replace a frame I broke a > chainstay on, from ebay. Before I set about prepairing it, could someone > take a look at some rust on the chainstays and let me know if they think > it's worth doing or not ? > As received :http://www.phase7.org/stuff/P1011420.JPG > after wire brushhttp://www.phase7.org/stuff/P1011434.JPG
Looks nasty, but usable. The chainstay bridge isn't critical stuff and it doesn't look to be going anywhere.
> Also, I checked the alignment of the frame rear stays using sheldon browns > method using a piece of string tied from the drops to the head tube and got > measurements of 33mm and 37mm which I figure is close enough.
That's a bit much. Clamp a wheel in there and check again.
> But the seat > stays are clearly a little bent :http://www.phase7.org/stuff/P1011428.JPG > will this cause a problem do you think ? The other one is bent slightly > outwards.
You're going to want to cold set these stays to fit whatever hub width you settle on. Have a shop align the drops--it's doable with a wrench, but far faster and more accurate with DO alignment tools.
> And, I used 700x38 tyres that are very deep, anybody know a way to deal with > clearances like these ? Will I have to by shallower tyres ?http://www.phase7.org/stuff/P1011403.JPG
> Half of me says it's worth working on, the other half says it's a dog. Any > help appreciated.
If it fits, and you like the thing, go for it. The cost of a powdercoat for a fresh start and a new commodity frame on Fleabay are probably not too far apart, though.
On Fri, 6 Nov 2009 19:10:30 -0000, "anern" <a...@anern.anern> wrote: >Cross post from uk.rec.cycling
>Hi, > I picked up a claud butler dalesman frame, to replace a frame I broke a >chainstay on, from ebay. Before I set about prepairing it, could someone >take a look at some rust on the chainstays and let me know if they think >it's worth doing or not ? >As received : >http://www.phase7.org/stuff/P1011420.JPG >after wire brush >http://www.phase7.org/stuff/P1011434.JPG
>Also, I checked the alignment of the frame rear stays using sheldon browns >method using a piece of string tied from the drops to the head tube and got >measurements of 33mm and 37mm which I figure is close enough. But the seat >stays are clearly a little bent : >http://www.phase7.org/stuff/P1011428.JPG >will this cause a problem do you think ? The other one is bent slightly >outwards.
>And, I used 700x38 tyres that are very deep, anybody know a way to deal with >clearances like these ? Will I have to by shallower tyres ? >http://www.phase7.org/stuff/P1011403.JPG
>Half of me says it's worth working on, the other half says it's a dog. Any >help appreciated.
Hi Bruce, my amateur opinion is yes, it's a bit of a dog, but an interesting and potentially lovable mutt. Looking inside the seat tube and bottom bracket, what's the internal rust situation? If it isn't bad, then I'd be inclined to go ahead.
I would attempt to straighten that rear end out. Sooner or later you'll want to sit up hands off. Be nice if the bike rode straight. If the stuff is too weak or rotten to withstand that you'd rather know now.
I've ridden with narrow clearances like that without any more trouble than needing to let the air out to get the tire past the brake blocks. The rear is usually tigher than the fork. Be sure to check that. Of course it all depends on how true and reliable your wheels are.
For me the go / no-go decision could depend on whether I needed to buy stuff to complete the build. If all your old stuff fits (maybe with the exception of the tires) there's not much reason to not try it out. All you'll lose is an afternoon of bike building and some cables. But if it takes a new bottom bracket, headset and seatpost, etc, it's probably not worth the investment.
I'm pretty sure I wouldn't be spending much on paint for it. There are few places where I think rattle cans are a good idea. This could be one of them.
On 6 Nov, 19:10, "anern" <a...@anern.anern> wrote:
> Cross post from uk.rec.cycling
> Hi, > I picked up a claud butler dalesman frame, to replace a frame I broke a > chainstay on, from ebay. Before I set about prepairing it, could someone > take a look at some rust on the chainstays and let me know if they think > it's worth doing or not ? > As received :http://www.phase7.org/stuff/P1011420.JPG > after wire brushhttp://www.phase7.org/stuff/P1011434.JPG
Looks good. Take a 3oz or 4oz hammer and lightly tap along the tube holding the hammer so that it bounces (lightly). If you can get it to ring with every tap (1" interval) then the tubes are still good. You can smooth it up a little more if you use emery cloth strip. Best to try to scrounge it as a whole roll is expensive for such a small job. You wont need to use filler, a filler primer will sort out the pits you have left.
> Also, I checked the alignment of the frame rear stays using sheldon browns > method using a piece of string tied from the drops to the head tube and got > measurements of 33mm and 37mm which I figure is close enough. But the seat > stays are clearly a little bent :http://www.phase7.org/stuff/P1011428.JPG > will this cause a problem do you think ? The other one is bent slightly > outwards.
If the wider side is to the right then you could leave it as is and adjust a multiple sprocket rear wheel rim to centre on the bike frame rather than centred between frame ends. But you'll need to remember this if you ever wish to use another wheel. It looks like the seat stay has been splayed to take a wider axle. This is not a problem, you can use it at this width, go wider or narrower. Bestto choose your rear wheel before painting to allow for any changes necessary to accept your chosen axle.
> And, I used 700x38 tyres that are very deep, anybody know a way to deal with > clearances like these ? Will I have to by shallower tyres ?http://www.phase7.org/stuff/P1011403.JPG
Close. possibly too close. You should know after a months use. You'll likely find that the rear wont even accept this width. It should certainly accept a 32mm tyre in the back if not a 35mm.
> Half of me says it's worth working on, the other half says it's a dog. Any > help appreciated.
Looks good to me. If the headset is firm, seat pin clamp intact and the bottom bracket isn't spread then go ahead. Emery cloth strip is the easiest preparation material.
>Looks nasty, but usable. The chainstay bridge isn't critical stuff and >it doesn't look to be going anywhere.
It's 531 tubing which I understand is quite thin - also it's going to be a working bike - shopping, commuting, weekends. It's not just surface rust either, the tubes are pitted.
>> Also, I checked the alignment of the frame rear stays using sheldon >> browns >> method using a piece of string tied from the drops to the head tube and >> got >> measurements of 33mm and 37mm which I figure is close enough.
>That's a bit much. Clamp a wheel in there and check again.
Did that, same result. Once the bike is assembled, does anything (other than the rear wheel) need to be removed to set the rear triangles ? There seems like alot to do and I'm trying to defer stuff.
>If it fits, and you like the thing, go for it. The cost of a >powdercoat for a fresh start and a new commodity frame on Fleabay are >probably not too far apart, though.
Can I ask what you mean by a 'commodity frame' ? I've been looking for a new touring frame but I'm only aware of branded frames like the Surly LHT.
> Hi Bruce, my amateur opinion is yes, it's a bit of a dog, but an > interesting and > potentially lovable mutt. Looking inside the seat tube and bottom bracket, > what's the internal rust situation? If it isn't bad, then I'd be inclined > to go > ahead.
Seat tube and BB are good. But it's going to be a working bike, used for shopping and stuff so needs to be structurally sound. I have to say this is the fourth frame in what is essentialy the same bike. Two others breaking tubes and one accident with a seat stay and a pannier.
> I would attempt to straighten that rear end out. Sooner or later you'll > want to > sit up hands off. Be nice if the bike rode straight. If the stuff is too > weak or > rotten to withstand that you'd rather know now.
I'm trying to leave this for a bit. As long is it isn't going to collapse.
> For me the go / no-go decision could depend on whether I needed to buy > stuff to > complete the build. If all your old stuff fits (maybe with the exception > of the > tires) there's not much reason to not try it out. All you'll lose is an > afternoon of bike building and some cables. But if it takes a new bottom > bracket, headset and seatpost, etc, it's probably not worth the > investment.
It'll need new brakes but I've been planing to get some of these for a while so that's not prob. They'll go on a new frame when I finally get one and I've only got callipers at the moment. I'll need new tyres is all which might mean the ones on there go to waste (pity cos they're really long lasting). Also not sure about the headset stack height but might be able to fiddle that.
> I'm pretty sure I wouldn't be spending much on paint for it. There are few > places where I think rattle cans are a good idea. This could be one of > them.
I was just going to wire brush and then apply two coats of hamerite red oxide to seal it.
> Looks good. Take a 3oz or 4oz hammer and lightly tap along the tube > holding the hammer so that it bounces (lightly). If you can get it to > ring with every tap (1" interval) then the tubes are still good. You > can smooth it up a little more if you use emery cloth strip. Best to > try to scrounge it as a whole roll is expensive for such a small job. > You wont need to use filler, a filler primer will sort out the pits > you have left.
It sounds OK when I tap it. This is to be a working bike, my only real concern was weather the pitted tubes (they are 531) would affect structural integrity. It's not just surface rust. I'll be using it for heavy shopping.
> Looks good to me. If the headset is firm, seat pin clamp intact and > the bottom bracket isn't spread then go ahead. Emery cloth strip is > the easiest preparation material.
I'm going to give it a go, though I'm just going to wire brush it and apply hamerite red oxide.
> >Looks nasty, but usable. The chainstay bridge isn't critical stuff and > >it doesn't look to be going anywhere.
> It's 531 tubing which I understand is quite thin - also it's going to be a > working bike - shopping, commuting, weekends. It's not just surface rust > either, the tubes are pitted.
If those tubes broke, you're not likely to have a magnificent accident. Rattle can it and ride it. I'd give it away and get a cheap aluminum frame for a "working" bike, as long as it held the components the correct distances from my appendages.
> >> Also, I checked the alignment of the frame rear stays using sheldon > >> browns > >> method using a piece of string tied from the drops to the head tube and > >> got > >> measurements of 33mm and 37mm which I figure is close enough.
> >That's a bit much. Clamp a wheel in there and check again.
> Did that, same result. Once the bike is assembled, does anything (other than > the rear wheel) need to be removed to set the rear triangles ? There seems > like alot to do and I'm trying to defer stuff.
Correct, all you need to do to align the rear is to pull the wheel and have a party with a 2x4 board.
> >If it fits, and you like the thing, go for it. The cost of a > >powdercoat for a fresh start and a new commodity frame on Fleabay are > >probably not too far apart, though.
> Can I ask what you mean by a 'commodity frame' ? I've been looking for a new > touring frame but I'm only aware of branded frames like the Surly LHT.
The Surly *is* a commodity frame, IMHO, weld up in Asia by unfeeling robots, just like everything else--but you get Surly stickers and some sort of cachet--if you wear the matching hat. That said--the LHT is a great deal as a complete bike.
On Sat, 7 Nov 2009 16:05:12 -0000, "anern" <a...@anern.anern> wrote:
>> Hi Bruce, my amateur opinion is yes, it's a bit of a dog, but an >> interesting and >> potentially lovable mutt. Looking inside the seat tube and bottom bracket, >> what's the internal rust situation? If it isn't bad, then I'd be inclined >> to go >> ahead.
>Seat tube and BB are good. But it's going to be a working bike, used for >shopping and stuff so needs to be structurally sound. I have to say this is >the fourth frame in what is essentialy the same bike. Two others breaking >tubes and one accident with a seat stay and a pannier.
>> I would attempt to straighten that rear end out. Sooner or later you'll >> want to >> sit up hands off. Be nice if the bike rode straight. If the stuff is too >> weak or >> rotten to withstand that you'd rather know now.
>I'm trying to leave this for a bit. As long is it isn't going to collapse.
>> For me the go / no-go decision could depend on whether I needed to buy >> stuff to >> complete the build. If all your old stuff fits (maybe with the exception >> of the >> tires) there's not much reason to not try it out. All you'll lose is an >> afternoon of bike building and some cables. But if it takes a new bottom >> bracket, headset and seatpost, etc, it's probably not worth the >> investment.
>It'll need new brakes but I've been planing to get some of these for a while >so that's not prob. They'll go on a new frame when I finally get one and >I've only got callipers at the moment. I'll need new tyres is all which >might mean the ones on there go to waste (pity cos they're really long >lasting). Also not sure about the headset stack height but might be able to >fiddle that.
>> I'm pretty sure I wouldn't be spending much on paint for it. There are few >> places where I think rattle cans are a good idea. This could be one of >> them.
>I was just going to wire brush and then apply two coats of hamerite red >oxide to seal it.
That sounds sensible enough to me. Yeah, 531 has been done thin, but often not super thin. If the inside was as rusted as the outside, I'd worry more. Even if a chainstay does fail down the road those are rarely accident causing. The frame just goes lame and you soft pedal home.
My thinking on resetting the stays is it's potentially destructive, best to do that before much other work goes into it.
Sounds like this will be a perfectly suitable member of the succession of beater bikes you describe.
On 7 Nov, 16:10, "anern" <a...@anern.anern> wrote:
> It sounds OK when I tap it. This is to be a working bike, my only real > concern was weather the pitted tubes (they are 531) would affect structural > integrity. It's not just surface rust. I'll be using it for heavy shopping.
Make sure that your luggage is loaded centrally through the wheel axles not the main triangle.
> I'm going to give it a go, though I'm just going to wire brush it and apply > hamerite red oxide.
I think you may need to get pitting in the chainstays filled with some braze, if not replaced. I've just reminded myself about your weight. I think that the pitting will cause stress risers that may be sufficient to cause a relatively low cycle fatigue failure should you use high pedal force.
From an earlier posting of yours you said "Hi, I bought this tyre 3 yrs ago and it has done about 12K miles. " Worked out, its probably your wheel has a good radial stiffness for your load. I got a bunch of tubulars years back and they still haven't worn halfway despite probably up to 5000 miles on some. I thought it was due to the tubulars renowned wear qualities, but see it now as a function of the radial stiffness of the rim following a little insight into the Rudge-Whitworth research laboratories conclusions. So you will be using that same rear wheel, wont you?
>> It sounds OK when I tap it. This is to be a working bike, my only real >> concern was weather the pitted tubes (they are 531) would affect >> structural >> integrity. It's not just surface rust. I'll be using it for heavy >> shopping.
> Make sure that your luggage is loaded centrally through the wheel > axles not the main triangle.
I have a very long rack, the panniers are mounted as far back as I get get them (Otherwise my feet catch them) But the hooks are far apart. I reckon most of the weight sits on the axles.
>> I'm going to give it a go, though I'm just going to wire brush it and >> apply >> hamerite red oxide.
> I think you may need to get pitting in the chainstays filled with some > braze, if not replaced. I've just reminded myself about your weight. > I think that the pitting will cause stress risers that may be > sufficient to cause a relatively low cycle fatigue failure should you > use high pedal force.
> From an earlier posting of yours you said "Hi, I bought this tyre 3 > yrs ago and it has done about 12K miles. " > Worked out, its probably your wheel has a good radial stiffness for > your load. I got a bunch of tubulars years back and they still > haven't worn halfway despite probably up to 5000 miles on some. I > thought it was due to the tubulars renowned wear qualities, but see it > now as a function of the radial stiffness of the rim following a > little insight into the Rudge-Whitworth research laboratories > conclusions. So you will be using that same rear wheel, wont you?
It's the same rear wheel, built by me and very tight. Are you saying that the stiffness could transmit shock to the frame ? This is why I use big tyres, so they take the hammering rather than the frame. I don't think any metal work of any kind is cost effective. If I think it's going to fail I'll return it - I paid £50 for it and it was sold as structurally sound. I still use the Bontranger tyres despite my moaning - they seem to exceed most peoples expectations for longjevity, hold the road well (when worn in), and I never get puctures. I'll have to switch to Marathons now though because of the clearances of the frame. There may be another problem now with the forks - I put it in another post. Thanks everyone for all the input, it's been very informative.
I just started examining the forks more closely and there's somthing loose rattleing about inside - I guess a bit of detatched rust. Does this ring any alarm bells with anyone ? The forks have two holes drilled in each leg, one at the top and one at the bottom, on the inside - for ventilation ? The one at the top looks perfectly located for receiving water from the the tyre.
On 8 Nov, 10:06, "anern" <a...@anern.anern> wrote:
> I just started examining the forks more closely and there's somthing loose > rattleing about inside - I guess a bit of detatched rust. Does this ring any > alarm bells with anyone ? The forks have two holes drilled in each leg, one > at the top and one at the bottom, on the inside - for ventilation ? The one > at the top looks perfectly located for receiving water from the the tyre.
> Cheers, > Bruce.
One hole is necessary in a fork blade to allow for braze penetration during maunufacture. Two holes aid the flushing out of the flux which would otherwise encourage corrosion. It is possible that a crumb of flux still remains and is rattling around. It's nothing to worry about and if it bothers you, they can sometimes be broken up by striking the forks at the ends so that they sound. I've only ever done this with the fork blade assembly in my hand held by the steerer. What I did was to strike the blade end on a table top and tip the blades about the horizontal so that the flux was bouncing around making most noise. It can sometimes take a while to breakit up. The dust will tip out of the vent holes as your doing it. It could be rust, considering the rear tubes' condition. Flux is usually white or cream and rust will be red or pink as a dust.
If there is no rust ejected after breaking up the rattling object, then you do not need to worry about the little holes. In which case, you should leave them as they are. Altering the ventilation properties may cause rusting despite it appearing to be correct to close the holes up. You can thin down some wax and swill that around the fork blades to seal the internal surface from atmospheric effects. Never worried me but if you keep your bike in a humid area or outside by open ground then condensation will form inside the tubes and some protection should be used.
On Sun, 8 Nov 2009 10:06:11 -0000, "anern" <a...@anern.anern> wrote: >I just started examining the forks more closely and there's somthing loose >rattleing about inside - I guess a bit of detatched rust. Does this ring any >alarm bells with anyone ? The forks have two holes drilled in each leg, one >at the top and one at the bottom, on the inside - for ventilation ? The one >at the top looks perfectly located for receiving water from the the tyre.
Holes in tubes are necessary during brazing to let out hot air and gases. Otherwise pressure builds up and splurts* the braze out of the joint.
As for what's in there, no telling. IME, captured loose rust sounds like sand. You could shake it down to the bottom of the leg and squirt some glue or something in to capture it.
*That might not be the exact word used in the trade.
> On 8 Nov, 10:06, "anern" <a...@anern.anern> wrote: >> I just started examining the forks more closely and there's somthing >> loose >> rattleing about inside - I guess a bit of detatched rust. Does this ring >> any >> alarm bells with anyone ? The forks have two holes drilled in each leg, >> one >> at the top and one at the bottom, on the inside - for ventilation ? The >> one >> at the top looks perfectly located for receiving water from the the tyre.
>> Cheers, >> Bruce.
> One hole is necessary in a fork blade to allow for braze penetration > during maunufacture. Two holes aid the flushing out of the flux which > would otherwise encourage corrosion. It is possible that a crumb of > flux still remains and is rattling around. It's nothing to worry > about and if it bothers you, they can sometimes be broken up by > striking the forks at the ends so that they sound. I've only ever > done this with the fork blade assembly in my hand held by the > steerer. What I did was to strike the blade end on a table top and > tip the blades about the horizontal so that the flux was bouncing > around making most noise. It can sometimes take a while to breakit > up. The dust will tip out of the vent holes as your doing it. It > could be rust, considering the rear tubes' condition. Flux is usually > white or cream and rust will be red or pink as a dust.
> If there is no rust ejected after breaking up the rattling object, > then you do not need to worry about the little holes. In which case, > you should leave them as they are. Altering the ventilation > properties may cause rusting despite it appearing to be correct to > close the holes up. You can thin down some wax and swill that around > the fork blades to seal the internal surface from atmospheric > effects. Never worried me but if you keep your bike in a humid area > or outside by open ground then condensation will form inside the tubes > and some protection should be used.
Thanks, thats reassuring, I'm going to go ahead and build it (Cross fingers).
On 8 Nov, 14:44, RonSonic <ronso...@tampabay.rr.com> wrote:
> Holes in tubes are necessary during brazing to let out hot air and gases. > Otherwise pressure builds up and splurts* the braze out of the joint.
To be accurate, the venting holes are not necessary for the brazing process (but helpful) they are there to prevent a fall in internal pressure when a closed vessel cools following brazing, collapsing the walls of the vessel. It may be more appropriate to drill a fork crown after brazing it and before brazing the ends than to braze the ends, drill the forks then braze the crown. The top of the fork crown would then NEED filling.
On 8 Nov, 10:01, "anern" <a...@anern.anern> wrote:
> I have a very long rack, the panniers are mounted as far back as I get get > them (Otherwise my feet catch them) But the hooks are far apart. I reckon > most of the weight sits on the axles.
Good, that'll mean no additional loading for the chain stays.
> > I think you may need to get pitting in the chainstays filled with some > > braze, if not replaced. I've just reminded myself about your weight. > > I think that the pitting will cause stress risers that may be > > sufficient to cause a relatively low cycle fatigue failure should you > > use high pedal force.
Even fillling with tinmans, electrical or plumbers (for copper) solder will benefit by reducing the stress risers caused by the corrosion.
> > Worked out, its probably your wheel has a good radial stiffness for > > your load. I got a bunch of tubulars years back and they still > > haven't worn halfway despite probably up to 5000 miles on some. I > > thought it was due to the tubulars renowned wear qualities, but see it > > now as a function of the radial stiffness of the rim following a > > little insight into the Rudge-Whitworth research laboratories > > conclusions. So you will be using that same rear wheel, wont you? > It's the same rear wheel, built by me and very tight. Are you saying that > the stiffness could transmit shock to the frame ?
It does.
I was connecting radial flexibility with long tyre life. It seems I misunderstood the press article, upon re-reading, it seams that the increased mileage was due to heat transmission from the tyre to the rim. This was for motor cars, not bicycles, which do not usually suffer from overheating tyres.
>This is why I use big > tyres, so they take the hammering rather than the frame.
You can make your wheels disperse some of that shock energy by slackening the spokes until the bottom spoke becomes loose at full loading. This permits the rim to work as a beam in its lower section, rather than a solid disc.
>I don't think any > metal work of any kind is cost effective. If I think it's going to fail I'll > return it - I paid £50 for it and it was sold as structurally sound.
As long as there are no holes in it, then it is. I just think you should do something to help the fight against it failing perhaps in a year or two.
> I still > use the Bontranger tyres despite my moaning - they seem to exceed most > peoples expectations for longjevity, hold the road well (when worn in), and > I never get puctures.
I seem to recall that your rear tyre mileage was exceptional for that model tyre compared to other peoples experience with it.
> I'll have to switch to Marathons now though because of > the clearances of the frame. There may be another problem now with the > forks - I put it in another post. Thanks everyone for all the input, it's > been very informative.
>> Holes in tubes are necessary during brazing to let out hot air and gases. >> Otherwise pressure builds up and splurts* the braze out of the joint.
>To be accurate, the venting holes are not necessary for the brazing >process (but helpful) they are there to prevent a fall in internal >pressure when a closed vessel cools following brazing, collapsing the >walls of the vessel.
One atmo will not collapse a fork leg, ATMO. And yes, the vents are necessary. There is nothing but capillary action (and sometimes the least bit of gravity) pulling the braze into the joint, any positive pressure will defeat that.
> It may be more appropriate to drill a fork crown >after brazing it and before brazing the ends than to braze the ends, >drill the forks then braze the crown. The top of the fork crown would >then NEED filling.
Or just drill the damn leg before mounting and brazing it, as has been done by the entire industry in the century or so of bicycle production. That puts the vent on the inside face of the fork, doesn't require filling and works in a way that has not required improvement in the eyes of the guys who actually build this stuff.
On 8 Nov, 16:22, RonSonic <ronso...@tampabay.rr.com> wrote:
> One atmo will not collapse a fork leg, ATMO. And yes, the vents are necessary. > There is nothing but capillary action (and sometimes the least bit of gravity) > pulling the braze into the joint, any positive pressure will defeat that.
If you feed the joint from the inside using granular spelter mixed in with your flux then the joint can be finished with the minimum of applied heat so avoiding overbrazing and fork leg enbrittlement. It also results in a cleaner fork assembly which may require very little clean up time. The tube is vented if the ends have not been fitted.
"positive pressure will defeat that" What of the positive pressure of the molten braze, don't you think this has a much greater bearing on advancement of the braze front than any slight variation in gas pressure. The air is at a much lower pressure than molten metal.
> > It may be more appropriate to drill a fork crown > >after brazing it and before brazing the ends than to braze the ends, > >drill the forks then braze the crown. The top of the fork crown would > >then NEED filling. > Or just drill the damn leg before mounting and brazing it, as has been done by > the entire industry in the century or so of bicycle production.
I dont think it has. I think it MAY have been introduced to speed production throughput with assembly line work. I dont think it applies to the one man workstation.
> That puts the > vent on the inside face of the fork, doesn't require filling and works in a way > that has not required improvement in the eyes of the guys who actually build > this stuff.
And there are users who dont like to see the holes, so they require filling. Putting the hole on the outside of the blade or in the crown makes for easier filling. It also means the builder doesn't leave the holes unfilled due to failing to consult an order/prompt card before shutting off the gas or moving onto the next job. With the thinnest gauge of fork blades, it may be deemed undesirable to drill them even when filled later.
thirty-six wrote: > On 8 Nov, 10:01, "anern" <a...@anern.anern> wrote:
<snip>
>> This is why I use big >> tyres, so they take the hammering rather than the frame.
> You can make your wheels disperse some of that shock energy by > slackening the spokes until the bottom spoke becomes loose at full > loading. This permits the rim to work as a beam in its lower section, > rather than a solid disc.
Isn't this the exact mechanism that supposedly causes eventual spoke fatigue/breakage? I've never tried it, myself, but it just doesn't seem like a particularly good idea...
> >> This is why I use big > >> tyres, so they take the hammering rather than the frame.
> > You can make your wheels disperse some of that shock energy by > > slackening the spokes until the bottom spoke becomes loose at full > > loading. This permits the rim to work as a beam in its lower section, > > rather than a solid disc.
> Isn't this the exact mechanism that supposedly causes eventual spoke > fatigue/breakage? I've never tried it, myself, but it just doesn't seem > like a particularly good idea...
It's the method that the largest tension wheel manufacturer used a century ago. Spoke tension optimised for load to give the easiest running does not break spokes. So easier and more comfortable running with less fatigue to the rider and machine with no penalties, what is there not to like?
> >> This is why I use big > >> tyres, so they take the hammering rather than the frame.
> > You can make your wheels disperse some of that shock energy by > > slackening the spokes until the bottom spoke becomes loose at full > > loading. This permits the rim to work as a beam in its lower section, > > rather than a solid disc.
> Isn't this the exact mechanism that supposedly causes eventual spoke > fatigue/breakage? I've never tried it, myself, but it just doesn't seem > like a particularly good idea...
Wordy wordy wordy! You're playing the Trevor drinking game wrong!
> > >> This is why I use big > > >> tyres, so they take the hammering rather than the frame.
> > > You can make your wheels disperse some of that shock energy by > > > slackening the spokes until the bottom spoke becomes loose at full > > > loading. This permits the rim to work as a beam in its lower section, > > > rather than a solid disc.
> > Isn't this the exact mechanism that supposedly causes eventual spoke > > fatigue/breakage? I've never tried it, myself, but it just doesn't seem > > like a particularly good idea...
> It's the method that the largest tension wheel manufacturer used a > century ago. Spoke tension optimised for load to give the easiest > running does not break spokes. So easier and more comfortable running > with less fatigue to the rider and machine with no penalties, what is > there not to like?
> >> Holes in tubes are necessary during brazing to let out hot air and > >> gases. Otherwise pressure builds up and splurts* the braze out of > >> the joint.
> >To be accurate, the venting holes are not necessary for the brazing > >process (but helpful) they are there to prevent a fall in internal > >pressure when a closed vessel cools following brazing, collapsing > >the walls of the vessel.
> One atmo will not collapse a fork leg, ATMO.
Good grief, no. You wouldn't be able to ride a bike down the street without it catastrophically failing if 14.7 psi would cause it to collapse.
> And yes, the vents are necessary. There is nothing but capillary > action (and sometimes the least bit of gravity) pulling the braze > into the joint, any positive pressure will defeat that.
> > It may be more appropriate to drill a fork crown > >after brazing it and before brazing the ends than to braze the ends, > >drill the forks then braze the crown. The top of the fork crown > >would then NEED filling.
> Or just drill the damn leg before mounting and brazing it, as has > been done by the entire industry in the century or so of bicycle > production. That puts the vent on the inside face of the fork, > doesn't require filling and works in a way that has not required > improvement in the eyes of the guys who actually build this stuff.
And if you really dislike having the holes, a tiny dab of brass will close 'em up after the joints are finished.
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