Buellster

it would be on the rear dropouts.
if your unsure about wether it's a good idea that tells me I should be too haha
maybe Pclamps or another workaround then...

Buellster

I just wanna say I love the direction this thread has gone! Seeing all the projects and what not is a real treat!

gugie 

My experience is the opposite. I think people load bikes less heavily when touring vs BITD. Part of it is lighter equipment - lighter tents, sleeping bags, cooking gear, etc. I have a Rip Van Winkle life with bikes, rode and toured a lot in my youth, stopped when wife, house, and kids sucked up my time, and now I'm back restarting my youth. Personally I know I carry signficantly less gear weight, and only use steel racks where in my youth aluminum was the choice, and I've broken aluminum ones in the past, always near the eyelet.

SJX426 

Frame builders have a choice of brazing with silver or brass. Brass requires a higher temperature flame. Home builders like silver because the equipment requirements and the lower temperature. Lower temperature has less of an impact on the frame material. Both are acceptable. The issue is the cost of the silver rod. This is much like soldering but with much different temperatures and rod material. A bunch of metallurgy considerations.
The strength is not in the silver material but in the bond of the joint, hence the flux to ensure good bond between dissimilar materials.. Silver can be used to fill.

If you want some interesting information about frame building, go over to the frame building forum. Lots of really good info there.

gugie 

Two people I really respect with years of experience, so you can see there can be a difference of opinion. I am a mere Padawan here. Doug's solution perhaps "goes the extra mile"

This is one of those areas that would be worthly of a university project. You could have an experienced frame builder do several sets each of simulated dropout braze-ons, and do destructive testing with equipment to measure forces. Back this up with some FEA, determine the failure mechanisms for each method. My retirement plan includes upping my torchwork time. My wife and I plan on being in an area that has a University with a good engineering project, this is the type of project I'd love to be involved with. Published results would help guide framebuilders worldwide in best known methods.

Cynikal 

To clarify, to common filler we call "silver" is usually 56% silver which does not build up well but has great capillary action (filling lugs and what not). There are other silver fillers like 50n or 46% silver that can build up like brass (bronze). These are what stainless fillet brazed bikes are generally built with. Search for Kirk frames for some amazing examples.

Salamandrine 

I'd imagine it always varied by individual, then as now. Now that you point it out, the ultra light crowd seems to have had a lot of influence in bike camping as well as backpacking. Still, there are those that pack everything: a laptop, a phone, a GPS, a camp seat, etc.

I definitely rode a lot from junior high through high school, but didn't try bike touring until summers while in college. I never broke anything, but I didn't do *that* much of it. The most epic one for me was about 24 days, IIRC.

For sure much of my own camping gear is lighter than the vintage stuff, but even BITD you could find light gear, if sufficiently motivated. Down bags were always light. Hoop tents were light, if you even bothered with a tent. Water purifier? What's that? Actually I think tents have been going backwards the last couple decades, but that's pretty OT. In general though, yeah, gear was heavier. I did have one buddy who rode across the country on his Trek 720, and he had and used one of those Optimus suitcase stoves. It was hilarious. Must have weighed like 8 lbs.*

EDIT * Ha, I looked it up and they only weighed 28oz full. They looked like they weighed 8 lbs.

scarlson 

Ha, I love all of this post. My adolescence up until high school was mostly touring in the summers - if I can remember correctly probably a year on the road in total. We were definitely in the *heavy* camp. We rode over Gotthard Pass with a set of pétanque (French bocce) balls. I broke two Blackburn lowriders in six months, along with one Blackburn rear and a Trek fastback seat stay. Lawn games aside, I agree about tents. I do remember one time camping near the aptly-named Siren, WI, where tornadoes passed within a few miles of our camp and I was lying on my back with my feet in the air to support the roof of our not-so-aptly-named Windy Pass Bullfrog tent which was collapsing in the gale. These new ones with the hubs between poles are over-engineered, which probably makes them durable but definitely makes them heavy!

Anyway, with my jumble of hand-me-downs (usually heavy stuff because heavy stuff lasts long enough to hand down) and cheap new stuff (usually heavy because it's cheap), I struggle keeping the load down these days, even on a short trip. Luckily I have nice Nitto racks and 48 spoke wheels on my Ron Cooper to support it all, purchased and built out of post-traumatic stress from all the touring breakdowns I suffered in my teens.

USAZorro

My reflexive response is "yes". That said, I have an offering to the discourse.

I do not understand there to be a difference in strength between "factory" mounts and "after-market" mounts. If, for example, I were to have after-the-fact attachment points added by someone competent, I would trust them as much as I would an attachment that was there as the result of building the frame. Is there a difference?

Andy_K 

Have I told you the story about the physicist, the engineer, and the mathematician who were asked to prove that you can boil water on a stove top? The physicist went about documenting the specific heat of water and the metal used in the pot, applying Boyle's law, etc. The engineer requested specifications on the BTU capacity of the stove, the range of ambient temperatures in the room, the purity of the water, and so on before providing a set of constraints within which the water would boil. The mathematician poured a pot of water, put it on the stove, and said, "QED!"

That's kind of how I see this problem. There's a saying among programmers -- "has" proves "can". So while an engineer may be interested to find out why the eyelet sometimes breaks off, I'm satisfied just to know that it can.

Last ride 76 

Thank you for your response. I have posted in that forum occasionally and read it regularly. That was my understanding, based on a comment by some guy named Dave Moulton regarding brazing materials. I may have, as I said, misunderstood what he wrote. Many decades ago I did some basic brass brazing on a bike, (frame add-ons) bitd, as well as some silversmithing, and blacksmithing... my long-ago repaired Ron Cooper is already on a few threads. I'll try to find the reference and post.
Best, Eric

Last ride 76 

Thanks for that clarification. I had read the positives about "silver" in the first part, and knew that there are various brazing mixes, but that was it. Thx, lots to know, Best, Eric

P!N20

Glad this thread didn't come up before I carted my kids on a rear mounted seat connected to brazed on eyelets for about seven years.

JohnDThompson 

If you have a choice, by all means mount the rack on the integral eyelets and the mudguards on the brazed-on eyelets. But if your choice is between a hardware store P-clamp and a brazed-on eyelet, I'd trust the brazed-on eyelet to handle load better.

gugie 

I was thinking the same. P-clamps can fail, screws can loosen, etc. If you could Pareto rack failures, I'd think that brazed-on eyelets on dropouts wouldn't be the #1 cause. That doesn't mean we shouldn't use that as an excuse to go with the strongest method available.

These are things I think of when putting torch to frame - what's the best way I can do this? I'd like to think I'm making small improvements every time.

gugie 

Excellent point, I usually keep a roll of 56% and 50% to use around depending on the application. Brian Chapman uses 30% silver for rear stainless dropouts, something I'd like to try.

gugie 

Just 5 years ago a buddy of mine and I were on a 6 day trip north of SF. We were coming down Highway 1 and stopped for lunch around Stewart's Point when a bike pulled in going south. It was diffiult to see the bike behind all the gear he was carrying. One item of interest was a cast iron skillet. He said he found it on the side of the road and couldn't resist.

BTW, a 24 day tour is a fantasy dream for me! It's long enough to forget that your other life doesn't exist, and you're new daily reality is riding a bike over hill and dale. Would love to sit down and share a beer and hear your stories of that tour.

Doug Fattic 

If you were to attach a long rod to an eyelet that is originally part of a steel dropout, it would take a lot of bending force to break it off. In fact it probably won’t break but bend because it is all the same metal. If you were to do the same experiment with eyelets that were brazed onto a dropout, you would discover that it takes less force to break off an eyelet. If you could somehow measure the amount of force used before it would break, you would find out that eyelets brazed with bronze it would take more force than if it was brazed with 56% silver. There are other silver based brazing materials that would take more force to break than the 56% but not as much force as it would if brass is used.

The original question “do you trust a brazed on eyelet” suggests an all or nothing situation. It will last or it won’t. The answer really has to be under what circumstances? There is not a black and white answer. As you can see now it really depends on the chances of enough force being applied to the brazed-on eyelet that might exceed its yield strength. I provided an example of a loaded rack tipping over that did exceed what a properly brazed-on eyelet could withstand. Of course that is an unusual circumstance but it can happen. As a professional builder I have to assume that a customer does not understand the differences between the strength of a brazed-on eyelet and one forged as part of the dropout and they might blame me if a brazed one breaks and then expect me to fix it for free. That fix might include disassembling the bike, rebrazing the eyelet, repainting the area and then putting everything back together again. That can be a several hundred dollar repair that I want to avoid. And I can avoid the problem by attaching a rear rack with a different kind of braze-on. So this is why the answer is not black and white but rather it depends.

branko_76 

The derailleur hanger of this abandoned bike was lopped off by some genius and I would like to have someone restore the dropout. Can it be done and can it be trusted?

Bad Lag

I am going to sell this bike but I recommend you not ride it in case something bad happens, I don't want to be sued.

Blackburn used to sell rear rack attachments for frames without eyelets. They fit thru the opening of the dropout, so "in" rather than "on" the dropout. They are removable, if you ever take off the rack.

P-clamps rotate. P-clamps scratch.

scarlson 

Yes. That one's been done quite a bit, I believe. You can also probably save the paintjob, if you wrap the stays and upper "web" of the dropout with wet rags or clay.

Here's a thread on exactly this topic:
https://www.bikeforums.net/classic-v...-hanger-2.html

branko_76 

Thanks for the link. I'm going to strip and repaint the frame.

unterhausen

When I taught engineering design a couple of years ago, a project cost $3000. I can use a fatigue machine, but I'm not sure that's really the failure mode that builders worry about. I think that probably just hitting a brazed on mount with a hammer and looking for cracks in a microscope would be as good of a test as anything. Just to qualify that, I am totally against that kind of testing for most brazing. I have seen some incredibly inept brazing survive such a test. I have my suspicions about eyelets that fail. I suppose I should do some destructive testing of my work. Not sure where you would publish it,maybe in an open source journal.

Just to be clear, we are talking about eyelets like the ones that come on dropouts. Just about every other kind of rack attachment is beyond safe. I'm pretty sure the difference between built-in and brazed on is ductility. It's also not too hard to braze something like an eyelet and not get full penetration with complete bonding in the center. At least that's my working theory on why people have had brazed on eyelets fail.

USAZorro

Thanks, Doug. I hadn't been thinking of the dropouts, and what you've explained makes perfect sense.

gugie 

QUOTE=unterhausen;21590823]When I taught engineering design a couple of years ago, a project cost $3000. I can use a fatigue machine, but I'm not sure that's really the failure mode that builders worry about. I think that probably just hitting a brazed on mount with a hammer and looking for cracks in a microscope would be as good of a test as anything. Just to qualify that, I am totally against that kind of testing for most brazing. I have seen some incredibly inept brazing survive such a test. I have my suspicions about eyelets that fail. I suppose I should do some destructive testing of my work. Not sure where you would publish it,maybe in an open source journal.

Just to be clear, we are talking about eyelets like the ones that come on dropouts. Just about every other kind of rack attachment is beyond safe. I'm pretty sure the difference between built-in and brazed on is ductility. It's also not too hard to braze something like an eyelet and not get full penetration with complete bonding in the center. At least that's my working theory on why people have had brazed on eyelets fail.[/QUOTE]

I was thinking this would be an undergraduate project, mechanical engineering curricula usually has a lab class, often with an "open" experiment at the end for the student to design. Publishing might be limited to Bike Forums!

I agree that almost all brazed on bit failures are due to incomplete penetration, leaving a stress riser.