Jmclay

The title pretty much encapsulates my current project; a randonneur all-road enduro for the 559x54 Rat Trap Pass tire. Fenders, electrical slip-ring on the steerer/brass brush in the down lug, in support of rinko and concealed power delivery to the taillight, and a rack for a large front bag...or a stack of pizzas. Aside from a last bit of final checking the main triangle is ready to be brazed.



Project photos here: https://www.flickr.com/photos/216244...57671170583438

John Clay
Tallahassee, Florida

Cl904

brian3069

subscribed

Classtime 

Lascauxcaveman 

Aye-yi-yi; dis gone be good!

Andy_K 

This isn't the first bike I've seen designed around those tires. I'll be interested to see how yours ends up comparing to the one @gugie built.

Jmclay

Except for the tires/wheels and brakes (canti) it's pretty much a carbon copy of the 650b x 42 Baby Shoe Pass frame I built. Since the OD of the BSP and RTP tires are within a mm or two (as measured in my shop) I didn't even have to adjust the main frame fixture. The chainstays will probably get a little more sophisticated treatment in order to clear the 60-62 mm fenders cleanly and with adequate daylight between. Fabrication photo album of the 650b, here: https://www.flickr.com/photos/216244...15273680/page1

650b x 42 BSP frame. Internal wiring + slip-ring in the HT for power to the taillight. The frame has the essential rinko details built in though I haven't modified the rear fender or other bolt on stuff to support it. The rack I built also houses the wiring in the right side strut.

Jmclay

I built the main frame fixture though I outsourced the machined parts to Joe Bringheli. Dummy axles by Anvil. It's just a basic flat plate unit made from a piece of 1" thick aluminum plate I found at the scrap yard. I designed it to adjust exactly the way I think of frame design: The axles are horizontal datum, BB drop is an offset from that, WB is measured off the vertical datum going through the horizontally fixed BB location, angles or set back measured off of that as well.

Sir_Name 

Watching with interest.

gugie 

I follow John's flickr site, he does a lot of cool stuff. His slip ring design (all internal wiring from fork through frame) is very interesting. Since he's posted it on the interwebs, I'll link to it here. I haven't seen any other detailed posts on how to do this, there's a lot of thought and planning that goes into this design.

As @Andy_K pointed out, I built a frame around RTP tires when I took the UBI framebuilding class. John's been doing this a lot longer than I have, and I already see things I would do differently if I were to make another one. He's bending his own chainstays - I came to the conclusion that if I didn't want Rivendell Clem Smith Jr. length chainstays, one needs S-bends to get around the need for fat tires and chainring/crank arm clearance.

Do yourself a favor and go through his flickr album on this bike. It's pretty cool watching him solve the myriad problems that one comes up with when designing a "outside the envelope" bike frame.

Cyclist0108

As much a slobbering fan of Compass tires that I am, I never considered building a bike around the tires.

Having said that, you need a cover for that electrical outlet in the wall.

gugie 

With the plethora of tire sizes out there, it's become a thing.
Oh, and note that John has a fire extinguisher next to that outlet. Safety Third!

DiegoFrogs

Super cool!

How reliable do you think the carbon brushes will be? It seems like they will be difficult to replace...

I have some experience with carbon brushes in an industrial application, but I was flexing them only in one direction at a low contact angle. I typically got about 500-800 km before they wore down or the pin became loose from its assembly and I had to implement some daily sanity checks to ensure they were behaving properly. I get that the rotation of the fork is practically negligible, but maybe the back-and-forth flexing of the brush will be a problem.

Jmclay

Thank you for the kind words Mark! The lack of a lathe and proper tube bending equipment, aside from rack-sized stuff, forces some of the "creativity". Once I braze up the main triangle I'm going to pause to consider incorporating the simple mandrel I made ( it does three bends, photos here: https://www.flickr.com/photos/216244...posted-public/ and https://www.flickr.com/photos/216244...posted-public/ ) into a machine with a proper bending roller and clamping block. The side that does the gentle bend does a fine job on ROR stays for a 42mm wide tire + crimpless fenders ( https://www.flickr.com/photos/216244...posted-public/ ) but I'm not sure it will be adequate for the RTP + fenders. I'm working on shop-bent S-stays. The only attempt so far was with the unrefined mandrel, just to see what might be possible with an absolute minimum of tooling....building tooling takes a lot of time. The answer is "I'm not sure" ( https://www.flickr.com/photos/216244...posted-public/ ). The mandrel is much refined now (there were large voids where it mattered, they've been filled and shaped) so I'll try it again, on 22mm round tubing stock and see if I'm willing to risk a set of stays.

I've been meaning to do that...and the door handle, for several years. I guess now I'm getting shamed into it.

It's on the way out, and I unlock the dead bolt when brazing.

Thanks! Carbon brushes: In the final analysis I had the same concerns and went with a brass brush on a copper ring. I always ask the folks I ride with to let me know if they see any odd behavior with the tail-light. No problems so far and I'm not the first to use that material paring for this job. I think it will work for the long haul.

Andy_K 

You just need more Kool Aid.

I talked to a guy at one of the Norther Cycles swap meets about some cool fleur-de-lis lugs he was selling. He said you have to be careful with things like this. He called it the doorknob effect -- you find a unique doorknob that you really like and you end up building a house to go with it. Obviously the same thing can happen with tires.

CliffordK

I like the thought process.

Buy the tires first... then build the frame.

I have a similar project in mind, but I've settled on the Surly Extraterrestrial tires. A bit wider, and perhaps tougher.

gugie 

I'm pretty sure that "guy" you talked to was Jeff Lyon.

Andy_K 

Oh, wow! I knew he was a frame builder. I had no idea he was Jeff Lyon. I guess I'm retro-actively honored to have met him.

This is one of the really cool things about Portland. I have randomly met people like Mark DiNucci, Mark Nobilette, and Jeff Lyon just hanging around bike shops without even knowing who they were when I started talking to them. It's weird how these world class frame builders are actual people too.

nlerner

Hey, I'm sure those folks are saying to each other, "Do you realize that we met THE Andy K?!"

John Oak

Good project!

DiegoFrogs

Which dynamo hub will you be using? I guess you have to limit yourself to those that ground to the axle...

Jmclay

Itcan happen in extreme cases but, ironically, the most vivid example that comes to my mind is that of skinny tire bikes patterned after professional racing bikes...the very bikes we've been consuming in the millions since the 70s. Bicycles made for specific tires, irrespective of fenders, that happen to come from the randonneur, all-road or gravel world can utilize a much wider range of tires. When I conceive of a bicycle the first question is what do I want it to do well...what's it for? Once that's framed then the next question is about tires; what type, size and which one(s); what range? Frame design follows that. The RTP frame that I, or anyone else, is building is capable of a wide range of sizes and types of tires. Saying that it's built for the RTP doesn't render it incapable of using lots of others.

It will probably get the hand-me-down Sanyo off of my BSP bike once I spring for a Schmidt gen-hub and Edlux headlight. But the axle doesn't have to be ground; a ground lead can be attached to a small threaded stud or other connector on the fork.

I've been riding my BSP and CX (Clement, MXP tire) bikes on the red clay plantation roads around here a pretty good bit. Unless it's wet I prefer the BSP bike; I really like my CX bike and I use it a lot but the reality is that the BSP bike is better, faster, more comfortable unless it gets sloppy...and I could put knobbies on it. The RTP bike will be even better...and I can put knobbies on it, too!

due ruote 

DiegoFrogs

I like the Sanyo on my touring bike, too. I bought mine thinking it was a cheap way to dip my toe into the waters of dynamo lighting, and haven't bothered to upgrade at all some 5 years later... Rather than upgrading and downcycling the wheel to my city bike, I just bought a super cheap Shimano-hubbed wheel for the city bike. I even contemplated building a 26" Sanyo wheel this year on vacation here at my family's house in the USA, but the front wheel is fine and a battery light makes more sense for 1 dark ride on it every year.

Bad Lag

It looks as if the tail light is completely obscured by the brake cable straddle thingie. It is staring right at it.