grizzly907la

I have an old Shogun metal frame (tested it on a magnet.) It says "Cro Mo." Can I weld on drop outs for disc brakes and for a front rack on the fork? Thanks!

guy153

Yes. But if the fork is a spindly road fork it might not be a good idea. What sort of bike is it?

JohnDThompson 

Chrome-molybdenum steel is weldable, but I'd be reluctant to put disc brake mounts onto a fork that was not designed to handle disc brake loads. Fork failure is a significant concern, and can be deadly. Rack mounts could be ok, but unless you're skilled at welding thin-wall steel, you'd be better off brazing them in place.

If you really want a front disc brake and rack mounts, the easiest and safest option would be to replace the current fork with one designed for disc brakes and a rack.

grizzly907la

It's a Road bike frame. I got it with the frame, though I am not adverse to replacing the forks its needed.

guy153

If it's a road fork I would replace it. A fork failure can really put a crimp on your whole day. The rear triangle should be OK to add a caliper mount. Some bikes seem to also use a small bridge tube between the chainstay and seatstay on the side with the caliper so could consider also adding one of those although I doubt it's really necessary.

bulgie 

'nuff said?

-Mark B in Seattle

grizzly907la

yikes!

David Tollefson

I don't understand why ANYone would put that kind of a disc brake mount on any fork blade. At the very least use a Willets style. And that only on fork blades designed for disc brake use.

hsuBM

A good caliper, good cable housing, good lever, KS salmon pads, and a good alloy rim are as good as the best disc brake in all conditions.

“But you’ll wear the rim out braking in the mud”

if there’s mud, you should be at home drinking cocoa instead of rutting up the trails.

recommended: TRP caliper & H Plus Son rims.

grizzly907la

I won't do it, after looking at those pictures and will instead get a fork that has a disc brake mount on it. I'm new to building bicycles, and that's why I posted the question.

Trakhak

The Shogun probably has a 1" headset and would need a fork to match (versus the 1 1/8" headset dimension that mostly superseded the earlier size a number of years ago). People here who know about disc-compatible forks (unlike me) can advise you.

grizzly907la

I'll keep that in mind. I might keep it as is and use brakes that are compatible with it. I want to build it out as a poor mans touring bike, though I have others bikes that could be repurposed to fit that role.

bulgie 

For touring, best thing you can do to an old Shogun road bike is 650b conversion. It does mean buying or building new wheels, so not really the "poor man's" way to go, but it's still one of the cheaper ways to get yourself a totally new bike. I mean same old Shogun but it will be transformed. You can probably fit a 38 mm tire in back, sometimes a 42, which is just so much better you'll never go back to skinny tires. For one thing it opens up a whole new world of unpaved roads, that are technically possible but unpleasant/impractical with skinny tires.

For the front, you just need a fork with 1" steerer and wide enough for a nice fat tire. The existing Shogun fork is probably not going to cut it.

If you can live without disc, then consider a fork with canti/V-brake studs. Soma has their Champs-Elysees touring fork in 1" 650b on sale for $160, but also offer 10% off with the checkout code thankful10 which brings it down to $144. All chrome, really nicely polished, nice-looking investment cast crown that takes real wide tires, excellent workmanship. It has a lot of offset (rake) which makes for a low-trail bike, which is controversial, but I think most experts agree it's excellent for a loaded-touring bike, if you put a lot of weight up front. Weight on the front doesn't make the frame wiggle, so it doesn't need an oversized rigid frame, just get a good front rack that's stiff enough not to wiggle and you're good for full camping loads completely over the front wheel.

The Soma has a threadless 1" steerer, but that's no too hard to deal with, there are headsets available, and you can use most any 1-1/8" stem, with a shim. Just get a headset with a 26.4 mm crown race — the other modern alternative is 27.0 (JIS standard), which will not fit the Soma.

Just spitballin'. Me, I like canti brakes, but I am old, so don't listen to me.

Mark B in Seattle

grizzly907la

Would the 650 b's fit into the triangle without rubbing? I'll post a pic of the frame.

It's a project for sure. I would like to go with it because its a steel frame, and from what I understand, its a good idea to go with a steel frame when it comes to touring. I'm appreciative that you "rambled," because it gives me a good insight on what needs to be done.

bulgie 

Brief (?) primer on 650b conversions of 700c road bikes:
650b wheels will (pretty much) always fit in any 700c frame with the same tire width, because the 650b rims are smaller. You don't want the same tire size though, you want wider, which is the whole point of 650b conversion. Chainstays diverge as you go back from the BB toward the dropouts, so at the point where the widest part of the tire comes close to the chainstays, you almost always have more room at the 650b size than you did with 700c. The only exceptions would be some really strange shaping on the stays, which I can pretty much guarantee your Shogun doesn't have.

So we know you can go at least a little wider on the tire if you go 650b, the question is just how much wider. This can be measured before you commit to buying new wheels and tires, but there's no substitute for actually mounting the tire and looking. Especially with knobby tires, where the widest point on the tire might be unpredictable without having the tire in hand and inflated. But typical road tires are pretty much predictably round-shaped, and the widest point on the tire shouldn't be too hard to determine, just do the math.

Lots of 700c road bikes fit a 38 mm 650b. A real tight frame might be limited to 32 or 35 mm, but 38 is more likely, and frames with indented ("fluted" or "dimpled") chainstays often can fit a 42 mm tire. This is good to know before proceeding because it's not worth buying new wheels and tires if you're going to be limited to 32 mm tires, that would suck, and it would lower your bottom bracket height by a lot. (Whether that's too much is a matter of taste; some people like a low BB.)

One good way to know what tire will fit is to buy the Rossman Cycles Tire Checker. It's $25 but pretty well worth it IMHO, especially if you will use it more than once. Probably worth it even for a single use, for the peace of mind before you go ordering your 650b wheels and tires. It simulates the width and position of 26", 650b, and 700c tires that are anywhere from 23 to 54 mm wide. It's just a few laser-cut hunks of plastic, but pretty ingenious. You put an axle in the dropouts and hook the gauge over that, then choose which tire you want to check, and mount the "dummy" tire of that width in the appropriate slot, in this case 650b.

The magical thing about 42 mm 650b tires is they give the same theoretical radius as a 700c wheel with a 23 mm tire. So if that's what you're switching from, your BB won't hardly lower at all. I said theoretical radius because it doesn't account for the increased squish you get from a fatter tire run at a lower pressure, so your BB will actually be a couple mm lower. But still well into the normal height range, unless your bike was already dangerously low with the 700c wheels.

Last thing I'll talk about is increasing chainstay clearance by indenting. That's an advanced topic that deserves a thread all its own (and I bet there are multiple threads on it already, tho I haven't looked). Suffice it to say, if you're handy with tools, you can definitely make a 42 mm tire fit that Shogun if you're willing to make indents. Though again, check it out before proceeding, because there's a chance the frame fits 42 mm tires already, no extra indenting needed. That's mostly the case on frames that came with the chainstays already indented. My old Follis road racer was made for skinny sew-ups but it fts 650b x 42 easily. It has Reynolds 531 stays that came already indented by the Reynolds factory. Lots of bikes used those same indented 531 stays, and they pretty much all fit 42 mm tires right outta the box.

Indented stays became unfashionable for racing frames after about the mid-1970s, so this is mostly true of older racing frames. Indents stuck around longer on touring frames, never went away completely, and are common nowadays because of the increased interest in fatter tires.

Mark B in Seattle

grizzly907la

Thanks for the primer!!! That was very informative and useful. I got the link for the tire fit gauge bookmarked. I also understand that 27.5 wheels are about the same size as 700c's. My hybrid bike (another touring bike candidate,) is running 700x45c tires at the moment, though I'll probably change them out for 40's or 38's, because the 45's have little clearance between the chain stay. On slight adjustment on the skewers will cause them to rub. I got some ideas now, and thus a rough game plan once I sand the frame down, remove the rust and paint. I'm going to build it out regardless if I use it as a touring bike, road bike etc...I like building things and giving old useless things, new life.