Raiden

I have an old semi-rare aluminum (7005) mountain bike that I love; however, it lacks a disc tab on the rear of the bike. I live close to a handful of both well-known and slightly-less-than well-known framebuilders (I'm just outside of Boston), but researching all of their websites shows that they all only work with steel, Ti, and carbon fiber. I haven't called any of them personally.

Am I seeing a lack of aluminum framebuilding simply because of the lack of demand for boutique aluminum framesets, or is it because of some sort of difficulty regarding working with aluminum? If a shop mostly works with steel, has the equipment for aluminum, but rarely works with aluminum, would it be risky to take the bike to them?

Additionally, are there some sort of certifications I should look for in a framebuilder? Obviously, reputation counts- a shop like Seven or IF is likely to do a good job, but I feel like I'm probably looking for a builder that's a little less high-profile, but still better than some-yahoo-with-welding-equipment-and-a-nice-website.

Anyway, I know its a tiny operation, but the frame is more or less irreplaceable, and I'm hoping to find my way to the best chances of getting a quality job done to it. Any advice is welcome, thanks.

Scooper

Member ftwelder, Frank, is in Vermont and builds high end aluminum frames. Maybe he'll chime in, or you could try sending him a PM.

unterhausen

there aren't too many people working on aluminum for the simple reason that there are nice aluminum frames coming into the country for little more than U.S. framebuilders have to pay for a single tube. And most work on an aluminum frame requires heat treating, which is expensive on a one-off basis

Davet

I think SpookyBikes is in your neighborhood. They're pretty much all aluminum. https://www.spookybikes.com

Waves77

Tsunami Bikes in AZ also does custom alu. Maybe they'd be able to help you.

unterhausen

ftwelder is the welder @spooky

fietsbob

They make Fishing and recreational Boats out of aluminum too, if it's welding you need,
someone in Mass or RI has to fix them.

ftwelder

I am the frank the welder mentioned above. I repair a lot of aluminum frames and do a lot of aluminum fabrication.


IMG_3648 by frankthewelder, on Flickr

NoReg

Weld Porn!!! Nice welding, FT.

Those braces look pretty stylized. The one on the top is new to me, interesting way of avoiding the effects of heat on the tubing, along the main axis.

Scooper

What happened to the OP?

Raiden

Sorry, he disappeared for a minute. Thanks for the replies, guys

Just wanted to get this out of the way- this is really not what I'm looking for. I have friends who have welded aluminum, including bikes, however, I would never let any of them near MY bike

Frank- nice to meet you- expect a PM.

In the meantime, I'd love to hear from anyone else with suggestions on a place in the greater Boston area. Thanks again.

ftwelder

The OP wanted to attach a disc brake mount on an existing frame with track drops. The position of the caliper would cause the wheel to scoot when the brake was applied. The whole drop could be replaced with a low mount but it's 7005 and machining a whole new drop would be very costly. I told him I can't help him but gave him some info on a guy who builds aluminum bikes in the Boston area.

The aluminum frame you are looking at weighs five pounds and with a 6" travel fork is nearly unbreakable. I can't explain what the gussets do. They often appear on bikes I make. I know they need them because I know the frame would fail without them though I have not built any without the gussets. I could draw a picture with colored pencils that explains it but there are lots of engineers around here so I will spare myself the embarrassment and let someone explain it who can verbalize their mechanical thoughts better.

DannoXYZ 

Nice welds Frank! Looks like that frame can get run over by a tank and be unharmed!

Yes, that's why many motorcycles have their rear-brakes mounted below the swingarm. Applying the brake would force the axle forward which would then push the axle-adjuster bracket into the end of the dropout slots (which is closed anyway). Some swingarms have adjuster bolts inside the slots ahead of the axle. This is cleaner and more compact, but it requires you to remove the axle to turn the adjusters.

Raiden

With respect, is that all theory and opinion, or based on actually seeing a bicycles of that design fail? I'm familiar with the concepts about torque that you guys are expressing, but I've also put many thousand miles on my daily commuter/touring bike, which is equipped with disc brakes on track ends- using QR levers even- without incident. Its a Cotic Roadrat- https://i56.tinypic.com/vyqkid.jpg.

The bike I'm trying to have modified is a Bianchi BASS- the BASS was an early '90s singlespeed design- after about 2002, Bianchi updated them all to disc brakes (on the DISS, GUSS, WUSS, SISS, etc., and some cyclocross bikes such as the Roger). I'd love to have one of those models, but finding one at a reasonable price, in my size, not beat to hell, and (as a low priority) in a color that I like has been difficult (I've even engaged in- and lost- a bidding war on some guy's lawn when two of us answered his craigslist ad at the same time.)

Some others, for reference:
https://www.cotic.co.uk/product/roadrat
https://surlybikes.com/frames/1x1_frame/
https://surlybikes.com/frames/karate_monkey_frame/
https://www.on-one.co.uk/i/q/FROO26IN...-frame-2nd-gen
The Bianchi bikes are probably all on Bikepedia- there was one model per year for about ten years starting around '97.

Brakes on a racing motorcycle need to stop a ~500 pound object (with a 200HP motor) that's moving 200mph. My brakes need to stop a ~200-pound object (with a 1/4HP motor) moving 20 mph (on a good day). I don't know how many RPM a motorcycle wheel is spinning at at 200mph or how much one weighs, but I'm assuming its energy is a distant multiple of the the forces a bicycle wheel puts on its brake caliper.

Anyway, I'm not arguing the point; I'm simply surprised by the brief, dogmatic replies.

ftwelder

Yes, I have seen them fail and also know plenty of people who have no issue with that type of modification. I have made 2000+ custom frames and so try to avoid problems.

DannoXYZ 

Well, I've worked on thousands of disc brakes during my 10-years at a shop. For the most part, 99% of them work great. It's just the rare case when someone forgets to tighten an QR or something breaks and the overhead caliper design has no built-in safety margin to deal with it. The ONLY ones I've seen failures that caused injury were of this type (other than rider-induced crashes).

With a caliper under the chainstay and track ends, you can even leave the QR completely loose and braking-action will just shove it forward into the closed end rather than out the back. I always strive for the design that works 100% of the time, even when there's a failure somewhere. Just because some boutique manufacturers didn't do their engineering background, doesn't mean they're crap, just that it may only be 99% effective. Do you want to be the person with the 1% situation that had a problem?

fietsbob

Yea But its on the other side of the wheel.. drivechain on the left..

seen people get sensible and put the caliper on the front of the right fork blade too .

the fact is that the disc wants to walk out of the dropout on the usual behind the left blade mount.

and will press more firmly into the dropout when its on the right

as the Torque center shifts to the brake pads when you hit the brakes..

DannoXYZ 

Doesn't matter if the brake is on the left or right side of the bike.

PaPa

Not to be argumentative, but...

I don't entirely agree. Yes, if some bozo forgets to cinch-down the QR, the wheel can longitudially shift in the dropouts. But it isn't as detrimantal as it first appears. Why?...

Because 80-85% of the braking is done with the front wheel - and when the front brake is applied, the CoM shifts forward, effectively unloading the rear wheel. I probably wouldn't recommend the upper caliper installation on a heavily rear biased and loaded touring bike, but I see no problems on a MTB or road machine.

ftwelder

With all due respect, I didn't suggest it couldn't be done. I simply said I wasn't offering to do it. Have I seen rear wheels slip?, yes. Aluminum frames wear much more quickly than steel frames. As you make necessary chain adjustments you create indents in the frame that the wheel can return to easier than an original location.

I don't make too many assumptions about one's use of a machine. Perhaps he only rides this bike with an ice cream cone in his hand and I am being grossly over cautious. I see a large amount of leverage being generated by a 700C wheel against a point 3" from the axle and depending on the hub/fastener, a very modest amount of material to support the load.