Plus-size 29er build

[jon_norstog]

I sold the prototype Elk Hunter expedition bike and was kind of thinking about what I learned. I thought that that lightweight, high volume tires would be the thing for that kind of riding and this, it turns out, is the year of plus size. I've been chipping away on this build for a month. The racks are not on yet, but you can see the basic bike. The new, lightweight "Plus-size" tires are just what I was waiting for on this bike. These are Surly 26" x 3" "Knards." This is mostly an oxy-acetylene welded build. I used kinda obsolete stuff - 83.5mm bottom bracket shell and 150mm rear axle spacing. It's old downhill stuff I had kicking around. The frame is designed to take a 29" x 3.0" tire, but I don't have the wheels or the fork yet, so I'm using this old 4-cross/downhill stuff for now. I have a Marzocchi Shiver fork I can run if I change out that front hub.

I made the dropouts from 1' x .058" cro-moly tubing with a grade-8 extra thick washer behind. I brazed in a 12 x 1.5 mm nut to receive the hub thru-axle, and hogged out a forged dropout to make the derailleur hanger. Work in progress. elk_4.jpgelk_1.jpgelk_2.jpgelk_3.jpg

[AnthonyLubetski]

I really like this. Hoping to do something similar this winter.

[jon_norstog]

OOPS! The nut was a 12 x 1.75mm. No edit feature on this site or I would have corrected the mistake. BTW, those Shimano 150mm thru axles are getting scarce as hen''s teeth.

jn

[Amaro Bikes]

Hi Jon

Please don't take this messagge as any negative or bad vibed words, but quite the opposite, trying to help you as much as possible.

I'm not sure what's your intention when posting this pictures, if you're looking for some opinions or just showing your work, but if you accept my humble suggestion, I would certainly put some more time on getting a bit of welding/brazing skills before building complete frames, specially if you're actually selling them as you did with the expedition prototype.

I hope you get this comment as it's, at least is what I would love others to do whenever they see me doing something wrong

Cheers

[jon_norstog]

Well, Amaro, thank you for your comment. You probably have never seen oxy-acetylene welded chrome-moly tubing before. I'm the only 'builder in the US, maybe the world using this method. I learned from an old guy who worked in the aircraft plaNTS around WWII. You may know that the US built about 250,000 planes during that conflict. Every last one of them had subassemblies or framing made of chrome-moly tubing and every last one of them was OA welded. Mostly by women. Yeah, it looks like somebody put it on a grill.

All I can say is I've built hundreds of bikes over the last 18 yeaRS and have had exactly one of them come back broken.

My intention in showing the pictures was to show them. the dropouts, especially, might be of interest to builders. The new thing for mountain bikes is the "boost" spec. which I will probably succumb to once I've wrung out this prototype. The bike has yet to have the racks welded on, and of course clean-up and paint. Also I need to get the forks and wheels for the 29" setup. I'll post more later.

jn

"Thursday"

[Nate Zukas]

Just for fun I read about OA welding then tried it tonight on some scrap. That shit ain't easy!

[Amaro Bikes]

You're right Jon, I do not know much about OA welding, and you do have some experience. sorry if I did bother you, my bad

[bambuko]

...You probably have never seen oxy-acetylene welded chrome-moly tubing before...

I have seen plenty of gas welded airframes and the welds looked a lot better than yours

... I'm the only 'builder in the US, maybe the world using this method...

You mean bicycle builder?

From your webpage:

...Thursday is also a master of the forgotten art of gas-welding chrome moly steel...

Clearly you are a master of understatement

...every last one of them was OA welded. Mostly by women...

male chauvinist

...Yeah, it looks like somebody put it on a grill...

no... your welds look a lot worse than that

...I've built hundreds of bikes over the last 18 yeaRS and have had exactly one of them come back broken...

All I can say (as a pilot) that I would hesitate to fly anything with welds looking like the ones on your photos...
Maybe not so much of an issue for the bicycle

...My intention in showing the pictures was to show them. the dropouts, especially, might be of interest to builders...

Yes, I liked them - thank you.

[crumpton]

Chris, if you speak to your airplane mechanics like you just spoke to Jon, god save you and your passengers.

[Yokeiseasy]

Chris, No amount of smiley faces will make personal attacks OK.

I'm glad you shared these pictures, Jon.

[Will Neide]

Only thing I know about OA Welding is it isn't easy.

Just curious, why choose OA welding over brazing?

[edoz]

If you have issue with his work, at least be polite about it. If you want to be a dick, MTBR is that way >>>

[e-RICHIE]

I have to put on my Admin cap here and agree with the posts above as well as with the notifications received about the tone of Chris' reply to Jon. In short, it crosses the line of community standards. Let's not let it happen again. Thanks.

[Mike Mcdermid]

[QUOTE=bambuko;732924]

male chauvinist

/QUOTE]

No its actually a FACT my grandma could oxy acetylene weld and she made bombs for the war effort

SHEESH this is why this forums gone to shit...

[VertigoCycles]

... The new thing for mountain bikes is the "boost" spec. which I will probably succumb to once I've wrung out this prototype.

jn

"Thursday"

Thanks for sharing the pics, Jon, and for giving us all a little education.

If you're not already aware of it, check out the options for a 157mm back end. It's replaced the 150 that you seem to be a fan of and has advantages...namely a shoulder on the dropouts that the hub sits in when you screw in, or bolt in the axle. You can still use your 83mm shells since all the critical working parts are in the same space as on the 150mm axles.

[jon_norstog]

Only thing I know about OA Welding is it isn't easy.

Just curious, why choose OA welding over brazing?

The thinner the tube, the tougher it is. Smaller the tube, ditto. I was building BMX bikes, fillet brazing, back in the '90s. A lot of tifers did not understand fillet brazing and wanted none of it. About that time I met Jim Bedeaux, an Albuquerque gunsmith who had worked in the California aircraft plants after his WWII Marine Corps service in the Pacific. He was interested in the bikes, I showed him some frames, he asked why I didn't weld them. I said I didn't know you could weld chrome moly with OA. He said it's easy! And gave me a demonstration. Well it isn't all that easy but I stuck with it. All my BMX, slalom, 4X and extreme riding bikes are welded. One of them broke, I had THAT client, the one who weighs 160 pounds and snaps off a set of XTR cranks the same day he puts them on.

Another advantage of OA welding, and this is why I'm using it on cargo and expedition bikes, is that you can weld OR braze to modify or repair the frame. With bronze, once you've brazed a joint you are stuck with with it from then on.

My welds look better in person than they do under the harsh and unforgiving eye of digital photography. But that's not too important. I file them some to find any places that might have cooled too fast and gotten brittle. The most important thing, to me is to get thorough penetrATion, which basically wiped out that beautiful miter you did. The weld has to hold. Mine do.

Chris: no harm. no foul.

jn

[Will Neide]

The thinner the tube, the tougher it is. Smaller the tube, ditto. I was building BMX bikes, fillet brazing, back in the '90s. A lot of tifers did not understand fillet brazing and wanted none of it. About that time I met Jim Bedeaux, an Albuquerque gunsmith who had worked in the California aircraft plants after his WWII Marine Corps service in the Pacific. He was interested in the bikes, I showed him some frames, he asked why I didn't weld them. I said I didn't know you could weld chrome moly with OA. He said it's easy! And gave me a demonstration. Well it isn't all that easy but I stuck with it. All my BMX, slalom, 4X and extreme riding bikes are welded. One of them broke, I had THAT client, the one who weighs 160 pounds and snaps off a set of XTR cranks the same day he puts them on.

Another advantage of OA welding, and this is why I'm using it on cargo and expedition bikes, is that you can weld OR braze to modify or repair the frame. With bronze, once you've brazed a joint you are stuck with with it from then on.

My welds look better in person than they do under the harsh and unforgiving eye of digital photography. But that's not too important. I file them some to find any places that might have cooled too fast and gotten brittle. The most important thing, to me is to get thorough penetrATion, which basically wiped out that beautiful miter you did. The weld has to hold. Mine do.

Chris: no harm. no foul.

jn

I'm kind of fascinated by this. Not because I want to make frames this way, just seems like a cool skill set to have in the back pocket for fixing other random stuff I have lying around (my neighbor has a habit of smashing his tractor deck into stuff and then asking me to fix it). Any pointers? Thanks!

[jon_norstog]

...
If you're not already aware of it, check out the options for a 157mm back end. It's replaced the 150 that you seem to be a fan of and has advantages...namely a shoulder on the dropouts that the hub sits in when you screw in, or bolt in the axle. You can still use your 83mm shells since all the critical working parts are in the same space as on the 150mm axles.

Oh yeah, Vertigo, thanks for the tip. I did check the new DH standard out. I was hoping to finish the build quick enough to make elk hunting season in Idaho. I looked at the new standard dropouts Paragon was selling and decided to just make my own and use up that old DH stuff that's been cluttering up the shop. For a client I would definitely go with the 157mm - unless they wanted to use the horizontal dropout/sliding derailleur mount setup a' la early Shimao Saint.

X

[jon_norstog]

I'm kind of fascinated by this. Not because I want to make frames this way, just seems like a cool skill set to have in the back pocket for fixing other random stuff I have lying around (my neighbor has a habit of smashing his tractor deck into stuff and then asking me to fix it). Any pointers? Thanks!

Will, use a perfectly neutral flame, until you get sharp enough to gauge just that little bit of reducing flame that makes the welds flow nicely without carburizing and embrittling the metal. On bicycles I use an aircraft rod that I get from Aircraft Spruce. Ordinary repairs you can use the cheap stuff. The flame shouldn't be too soft or too hard. Practice on scrap tubing first. Heat the molten bead, not the tubing - let the molten metal eat its way in like lava devouring a hawaiian village.

Good luck!

jn

"Thursday"

[bambuko]

...Chris: no harm. no foul.
jn

The tone of my reply was un-necessarily confrontational.
Please accept my apologies.