BB30 and seat mast thoughts, also hoodie update

First, quick news: Brent thinks the hoodies will be ready in about 2 weeks (much faster than I thought) and we're doing an XXL size (it's been added as an option to the paypal link).

Now, on to BB30:

I got a great question from Steve about the BB30 bottom bracket/crank system and integrated seat masts - both of which he wanted to know if I'd do.

I rudely said, "no," and Steve followed up with (being much more polite than he had to) - "Why?"

Long boring rambling follows. You've been warned.

Steve -

Sure thing. The whole point of BB30 is that you can do the final alignment of the BB shell (as the bearings are press-fit) AFTER the frame is built. This solves a MAJOR problem for building with carbon fiber, since the shell has to be bonded into the frame, and the threads can't be re-cut afterwards to be in alignment. The BB30 solves this problem by using an aluminum shell with a lot of extra material, then having the final boring of the bearing surface cut after the frame is finished - allowing the BB bearing alignment to be done after everything else is done. That's huge for building carbon bikes, and cuts a load of cost. And it's a bit lighter, since you're replacing a pretty thick aluminum shell (plus bearing cups) with just the shell.

Fast forward to steel - alignment can be checked at every stage of the process and kept correct, since the frame is built in pieces (I do alignment checks at 6 different points in the process). So there's no alignment advantage.

And the shell is much different - instead of a 1 3/4" aluminum shell, we use a 1 1/2" steel one - which weighs about 85 grams for a 68mm (pre threaded) model. An equivalent BB30 shell in steel (you can look it up at Paragon) weighs 140g. Even after subtracting the weight of the bearing cups (about 30g) you end up with a heavier setup. The BB30 axle is a tiny bit bigger, so in theory it's stiffer - but I don't hear anyone complaining about how stiff their external bearing cranks are, so I can pretty confidently say that the extra stiffness isn't useful (or even noticeable outside of a laboratory) unless you weigh 400 pounds or something.

Another downside is corrosion - if you get water into the shell, either the shell or the bearing races can get nice and corroded, and lock themselves together. You can grease the crap out of everything and prevent this, of course, but if something does start rusting - that's the end of the frame, since you can't easily machine the bearing seat *smaller* again.

So bottom line is that BB30, for steel, is heavier and has some major downsides. It's also a huge pain to build with, since you've got to put the ENTIRE FRAME in a milling machine and use a boring head to machine the bearing seats when you're finished. Screw it up, even a tiny bit, and that's the END of the frame.

Great stuff for building carbon bikes in a mass production facility - I'm guessing that BB30 is saving manufacturers a nice chunk of change in costs. And it doesn't have any downsides for carbon or aluminum bikes, really. Weighs about the same, should perform fine.

But not steel, unfortunately.

The seat mast is likewise something that doesnt' end up making sense. If we assume we can use .049" 4130 cromoly for the mast, and it extends, say, 150mm above the toptube (a reasonable estimate for a normal non-compact road bike) then we've added 120g of steel to the frame (and that's being generous - you'd actually have to add more to make the seat tube/seatstay/toptube cluster strong enough - call it another 50g). So we're 170 over the normal frame weight. If we figure the seat clamp is 30g or so (I'
m being generous again - I bet it's more like 50g), we're at an even 200.

Contrast that to a standard collar (10-20g) and decent quality (WCS, Thomson Masterpiece) post that weighs 160-180. Best case scenario, we break even on weight. Worst case, we add 30-80g to the frame.

Second problem is corrosion. If we want to clamp the seat clamp to the steel, we either have to clamp on top of the powdercoat (slips, wears off and corrodes, etc) or to bare metal (corrodes). We could use 304 or 306 stainless to get around this problem, but that would need to be thicker to be strong enough - say .058" or so. So now the extra steel is 140g.

And I haven't even gotten into the downsides of the mast if you cut it too short, or decide you want to ride a different saddle and need to raise it, or decide you want to loan the bike to a friend, or (heaven forbid) sell it. Being stuck at one saddle height and then having to cut the mast down to go lower is, IMO, not very useful when you can move a conventional seatpost up and down as much as you want.

It just doesn't end up working out well. There's a reason most steel double triangle frames look pretty similar to each other - they just work well. In other materials, other configurations can be better, but not in steel, really.

Couple more for Ken

The bike is a pretty odd one - sort of a monstercross frame, but with Paragon sliders (for chainstay length adjustment) and a super-slack seat angle for Ken's weirdly long-femured self. Oh, and rack mounts, s-bends, all sorts of cable stops and guides, and S&S couplers. Not a light frame at all once all that stuff is welded and brazed on, but a very versatile one.
For those who are curious, the hose going into the top of the seat tube in the first photo is pumping argon into the frame while I weld the chainstays on. This has the effect of minimizing the distortion and oxidization of the back side of the weld inside the bottom bracket shell, which is nice because it help minimize the amount of thread chasing that's necessary. The shell itself isn't thin enough to need the backpurge, but bottom bracket taps aren't cheap - so I like to make them last as long as possible. 25 cents worth of argon on each frame has allowed me to still be using the same taps (after over 300 frames) without even sharpening the cutters.

Waltworks Hoodies!

Yes, they're finally being made. Here's the design that Brent at Twin6 just forwarded to me. I'm not sure why it shows up so pixelated, but the actual garment will look much sharper.

EDIT: The small dots are for spacing purposes for the printer and won't show up on the actual hoodie.

Cost will be $45, shipping included in the lower 48. I'm going to go ahead and put a pre-order paypal link here, but please be aware that there is not a firm delivery date yet, and I very much doubt that they'll be ready before the holidays.

EDIT: Brent is estimating 2 weeks until T6 has them, so probably 3 until I have them. No promises, though.

They will also be available direct from Twin6, probably for a bit higher price, for those who don't want to preorder.

Size

Unisex Small $45.00 Unisex Medium $45.00 Unisex Large $45.00 Unisex XL $45.00 Unisex XXL $45.00

Few random shots for Ken

...while I wait for the right downtube to show up (smallish CX frame + S&S couplers + needs to be stiff = special tube order). Not much to see yet, here's the seat tube/BB shell and a shot of the dropout/chainstay joint. A lot of builders will use nickel silver to braze these in, but I think TIG is more secure (and I'm better at it) so I do it that way.
Also note that I've used a nylon brush on the ST/BB to make it easier to see what's going on. The normal weld discoloration makes it a little tricky to take clear photos.

Yes!

I am on cloud 9. Now I have a reason to care about the Washington Wizards.

I really wish he could get signed by a good team, though. It was a lot of fun to watch him play in Denver.

The reason 'cross and fancy drivetrain parts don't mix

Thanks to Chuck D for the photo. I always laugh when I see cyclocross bikes with Record, or Dura-Ace, or Red. Unless you're a sponsored pro, that's just advertising that you either A) don't race, or B) have more money than sense.

200 is in the bag... I think

I managed 6 reps of 185# on the benchpress today. I'll try 195# on Tuesday, but I think at least 1 rep of 200 is probably in the bag... meaning that I will have finally accomplished *last winter's* goal.

File under: pathetic skinny bike racer boasting.

You rock, Thomson, or, I am SO important!

I'm a huge fan of Thomson seatposts and stems, for a variety of reasons -
-Made in the USA by people who get paid decently and probably enjoy their work.
-Largely indestructible, reasonably light, pretty trick looking.
-Well engineered and easy to install/use.

So I was pretty upset when my supplier of OEM bike parts, Security Bicycle in New York stopped carrying Thomson. To be fair, they mostly supply road bike stuff (that's where the money is - there are a lot of people who seem to think nothing of dropping $2k+ on a wheelset for their roadbike) and Thomson doesn't make trick carbon fiber doodads. Then again, I see plenty of Thomson posts and stems (including the ones that I ride) that are 10+ years old and still working just fine. I'll take 10 years of honest service over a couple of grams any day.

Long story short, I called Thomson and they immediately gave me a manufacturer-direct OEM account. So now I've got a reliable source for all things Thomson, and I even can *lower* prices for their posts and stems. Since I'm not a retail shop, they're only available to *new* frame customers, of course. If you're curious about pricing, drop me a line and I'd be happy to quote you for whatever build (with or without Thomson stuff) suits your fancy.

Not that I'm complaining, but 6 or 7 years ago when I would try to get accounts with various companies, I'd spend *weeks* (if not months) submitting paperwork, begging via email/fax/phone, and so on. Now apparently I can just randomly call people, tell them who I am, and I'm good to go. Weird.

Jefe's TA fork

I get a lot of questions about 20mm through axle forks (rigid ones, that, is). Here are some thoughts and a few photos of Jefe's fork before it went off to powdercoat.

-I really think through axles are mandatory for any fork over about 100mm of travel, especially for big folks and especially on 29ers. The difference is really night and day. That's suspension forks, of course. For rigid forks, most people won't notice a huge difference in the ride - rigid setups are already really laterally stiff, even with a standard 9mm QR axle. For big or aggro riders, or folks who really want the ultimate in steering precision, though, there's no argument from me that this is the stiffest setup you can get, short of doing a rigid fork with a TA AND a 1.5" steerer.

-It's a lot of work to build the dropouts and attach them. Really small stuff (ie, pinch bolt dropouts for 20mm axles) is always a pain. It probably takes me an extra 2-3 hours of work to do a TA fork versus a standard dropout model. Consequently, they cost an extra $100. Not cheap. Probably only worth it if you're a serious snob or have a *really* fancy TA front wheel you want to swap back and forth from a suspension fork.

-The actual build process is the same as for a standard fork, but I cut off the bottoms of the fork blades at a 35 degree angle, cut a piece of .065" 4130 sheet to fit, fusion weld, and file smooth, then make a 7/8" miter for the actual dropout, which is made from (you guessed it) 7/8" 4130 tubing and a seat binder. I like to use the seat binders because the M5 bolts are a lot harder to strip or screw up than the M4s you find on a lot of stem clamps and such. The dropout has to be welded in *really* carefully (and mitered perfectly) to keep the fork in alignment and make sure the axle will fit smoothly and securely when installing the wheel. It's much, much touchier than doing a standard DO fork.

-Weight is about identical to using standard dropouts. There's probably a 10g or so difference one way or the other, depending on what 9mm configuration you compare to, but for all practical purposes, the weight is the same.

So anyway, I build a decent number of these, and I'm happy to do them in any configuration you can dream up, as always.

Rumors of my demise...

...have been greatly exaggerated. From Hassan:

"Funny enough, went out to Bachelor St. last night and someone had raked! It was kind of like fantasy land. Really weird.

More odd however, was my learning that you have 'gone out of business'. In the parking lot, while we were getting ready, a couple bikers returned and started packing up. One of em', lights blazing, came up and explained how cool my 'vintage' bike was. My buddy John explained to him that it was pretty much brand new. The guy then went on to explain how that we were wrong because, 'they went out of business a while ago'. My only thought was of you handing Pele and Snickers pink slips, ranging a for rent sign on the garage, and walking off into the sunset. It's ok, you can always just poach apple trees.

Regardless, please accept my condolences.

Pure comedy."