Rat Trap Pass Project - A frame for one of my brothers.

[John Clay]

I built a 26x1.5 (McClure tire?) before Compass had it's own line of tires and the stellar RTP tire. It's a nice bike and my middle brother loves it but he rode my RTP bike recently and it was pretty clear that he wanted one; what's a good little brother to do, so a new project began. Being the most difficult and time consuming tube to get right, it's always a relief to finish the top tube.

For my money and my height the RTP is a better 650b than the actual 650bs. He doesn't want fenders but it will be equipped for them anyway. He's not going to ride at night so it probably won't get a slip-ring unless I do it just for the extra practice and opportunity for refinement of the process.

I'm using the RH BB shell and Rossman/RH bent chainstays so I shouldn't have to do quite as much blacksmithing as was necessary with mine.

John Clay

Tallahassee, Florida

[Weston Hein]

Looking good John! I really like the RTP even though I'm on a bigger frame at 6'2"- definitely maintains a more road bike feel to me. Do you have a fork crown picked out for this build?

[Mark Bulgier]

Here's my semi-annual plea to include the tire size, not just the pass names.  I must have some kind of mental block or cognitive decline because I just can't seem to memorize them.  I've had to refer to the Compass/RH website probably 2 dozen times (no joke) over the years, every time someone talks about their tires without listing the size.  You know the size, and it's only a few keystrokes to type it in.  Have pity on us poor "pass memorizers".

I was especially thrown this time because I thought I knew what he meant -- I remembered it was "the wide one", and this being the 650b list, I "knew" it must be the wide/smooth 650.  Only the inscrutable phrase "a better 650b than the actual 650bs" made me doubt that and sent me once again to the website.  Surprise!

All that aside -- thanks John for documenting your frame projects like this, very fun to follow along.

Mark B in Seattle

[John Clay]

Looking good John! I really like the RTP even though I'm on a bigger frame at 6'2"- definitely maintains a more road bike feel to me. Do you have a fork crown picked out for this build?

Weston Hein

Thanks Weston. If I was that tall I’d be on the SBH (650b x 48). Crown will be Long Shen LC22C. I've used a bunch of them; nice crown.

I should be empathetic to the memory thing but I threw a slider. Shame on me! 26” x 54mm (50 actual, on my rims). I hop on my 650b x 42 (40 actual) Baby Shoe Pass and it’s superbe on asphalt, very, very nice on hardpack and good enough on the sandy road that I have to use to get out of the ‘hood; then I hop on my 26” x 54 and it’s – just – better, at everything. If I was racing/serious randoneuring on nearly impeccable asphalt, then I’d maybe prefer the BSP. Maybe. But the instant it’s real world asphalt with joints, cracks and other discontinuities, hardpack or softer dirt/sand surfaces the RTP is very much more capable, confident, comfortable and efficient. Functionally, for me, it’s a better 650b than the BSP. If it gives anything up on asphalt I can’t detect it.

Glad you’re enjoying the project “ride”.

John

[Ian A]

John

Thank you for sharing the build process and please keep updating as it goes along.

In terms of the 559x54mm RH Rat Trap Pass tires, what pressure do you run them at? I have Maxxis DTH on my 559 converted rSogn and 584x40mm GB Hetres on my other rSogn and I feel the DTH are somewhat sluggish against the Hetres. But, I suspect part of the reason for that is I'm not finding the pressure sweet spot.

IanA Alberta Canada

[John Clay]

I'm 160# ready to ride and my RTP pressure is typically 25 psi. That's a pretty good compromise for the surfaces I encounter on an outing. For asphalt a bit more, I've recorded as much as 32 in my log; for sand closer to 20. Those pressures were measured with a Grade B indicator...+- 2% in my measurement range. 

[David Cummings]

Yeah, another RTP build - subscribed!

David “RTP until I die” in MT

PS - are you interested in adopting me? I’m housebroken and don’t chew on furniture.

[Floyd Tiny]

Ever since I put RTP's on one of my bikes I find it harder to switch bikes. The Rat Trap Pass tires are fantastic ! I weigh 157 lbs and was riding them at about 27 psi (grade B or C gauge). I've started riding them at slightly lower pressures. The other day I rode some rough off camber gravel roads at about 17 psi (tubeless) and the traction, comfort and feel was superb. I was able to corner much faster, with confidence and comfort. 

FB in Columbia County NY

John- I've been following you on Flickr and enjoy seeing pictures of your wonderful bikes- I'm looking forward to this one !

John Clay

Tallahassee, Florida

[John Clay]

This is my second RTP frame. For reference the first one was for me and photos are here: https://www.flickr.com/photos/21624415@N04/albums/72157671170583438

I used a standard (Long Shen) BB shell and straight ROR stays. A LOT of blacksmithing and metal movement were required but I really couldn't be happier with the result. 

This time around I'm more fully documenting the modifications, procedures and dimensions required to make everything fit properly so subsequent builds will be easier and more certain. This time I'm using the Rene Herse BB shell (wider angle between spigots) and pre-bent ROR chainstays rather than modifying standard parts as I did last time. I knew that this wouldn't be plug and play but I figured that the RH parts would start closer to the terminus and make the journey a bit easier. Today's documentation shows the starting points with the RH parts as well as the ending points of the prototypes I made last time. Photos start here: 

https://www.flickr.com/photos/21624415@N04/50033702516/in/album-72157714479460956/

I'm not sure if I'll fill the stays for bending but if I do, I think I'll use Wood's Metal instead of sand. I'll have to wreck (or maybe not) a stay in order to make the determination. The shell spigots will require the same approach as before (cutting, bending, grinding), but a little less of it I hope. One major key is the thickness of the outside spigot root; that is a very stiff location; I'm not certain but I don't think that grinding the ID will get me there satisfactorily. One warning for others that may want to try this, if my single "at bat" is any indication: Simply inserting bending bars and leaning on them will only wreck the shell.

John Clay

Tallahassee, Florida

On Wednesday, May 27, 2020 at 6:25:43 PM UTC-4, John Clay wrote:

[John Clay]

Here’s the RTP frame after completing all the brazing and machining work. It turned out well; oodles of tire clearance. Prior to brazing I discovered that I got more bend than I wanted but I was able to unwind it....carefully.

I ended up using a mixture of paraffin and sand as the filler for the chainstay bending operation. I don’t know if was necessary to bend such thick walls but I wasn’t going to find out the hard way. I’m going to make a wooden fit/no-fit pattern for the entire CS shape going forward; that will be a better way to navigate the task than working from my sketch. I also need to do some more work on my mandrel. Getting the necessary tire clearance isn’t the only challenge; getting the end-to-end bend path precisely as desired is tricky for my very basic tooling.

I'll fit the crank, dimple for the small ring if worthwhile, ream the ST, slot it, and then it's paint prep time.

Gasflux C04 rod + Allesandro Rizzato pressed lugs ( https://www.flickr.com/photos/21624415@N04/albums/72157674363530101 ), RH BB and chainstays. Even with the RH BB shell and CS there was still a lot of blacksmithing.

More fabrication photos here (and I'll load more soon): https://www.flickr.com/photos/21624415@N04/albums/72157714479460956

This photo shows the "more than I wanted" stage.

John Clay

Tallahassee, Florida

On Wednesday, May 27, 2020 at 6:25:43 PM UTC-4, John Clay wrote:

[David Cummings]

I’d love to see the “dimple for the small chainring” process. I just had to adjust an adjustable Sugino AT BB as far to the drive side as possible to fit a 45/24 Sugino RT crank without hitting the chain stay.

David “enquiring minds want to know” in MT

[Mark Bulgier]

David Cummings wrote:

> I just had to adjust an adjustable Sugino AT BB as far to the drive side as possible to fit a 45/24 Sugino RT crank without hitting the chain stay.

Hmm, 24t being a pretty small ring, most frames I'm familiar with will clear with no indent.  What frame is this, and what crank? (Sorry I don't know what an "RT" is).  Do you know what the chain-line was before the adjustment you made?  I can't help but think this could just be a case of too-short right end on the spindle. 

I'm willfully ignorant about these "29er" bikes with the seat tube curved to allow the chainstays to be shorter, so this could well be another case of me being out of touch with the 3rd millennium.

Mark B

[David Cummings]

Mark,

I was mistaken - it’s a much larger 26t chain ring.

The Sugino RT is very similar to the Ofmega Mistral - kind of looks like the weapon in Krull (another awesome product of the 80’s! X)

The frame is a 2015 Elephant NFE. It’s got room for 26x2.2” tires, but a narrow Q factor of ~155mm is tough with a double (my triple with only the inner two chainrings). I could go slightly narrower with a 1X, but I can’t bring myself to do that to such a classy steel bike. That and I don’t have such a drivetrain...

Sent from Dave's rockin' iPhone

[John Clay]

As the result of a request to build one of these for an IBob guy, I just realized that I'd made this comment ( Being the most difficult and time consuming tube to get right, it's always a relief to finish the top tube. ) without proper context; the TT is the most critical to cope and fit but the chainstays are vastly more difficult to reshape correctly and well....unless you've built a machine that can reliably knock them out, which would be a pretty substantial undertaking particularly for a hobby or low production builder.

Now if Hahn would modify the NC program used to make the plug'n'play BSP chainstay dies, and Jan would sell the results as well as have Long Shen make a BB shell with CS sockets that are out-of-the-box-suitable, no blacksmithing required, for the RTP/SBH tires then building superior RTP/SBH frames would be, to understate the task, a hell of a lot easier and well within reach for the serious hobbiest or pro...and the customers who want one. Just saying. As it is, it is a gynormous amount of work.

Highly bridged photos of the process, here: https://www.flickr.com/photos/21624415@N04/50054038212/in/album-72157714479460956/

John

[Ford Bailey]

Would you consider fillet brazing the chain stay/ BB joint ? Would that be easier ?

Ford in Ghent NY

On Sep 22, 2020, at 9:26 AM, John Clay <nice.c...@gmail.com> wrote:



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John Clay

Tallahassee, Florida

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[Hahn Rossman]

John-

Thanks for the nice words and subtle hint. It's on the list to make a rat trap/switchback hill version of that chainstay. Do you ( or anybody else) have some clear criteria for what they are looking for?

Something like:

1. clearance for a 62mm fender

2. RH cranks with a x size inner ring

3. absolutely has to be round, not oval.

4. ???

I think that as the stay gets more and more compressed between the chainrings and the tire/fender it becomes less and less important to use a round chainstay, except that I really like the RH bottom bracket shell. 

I'm also considering making some socket bending bars out of heat treated 17-4 or something equally amazing to help with tweaking those sockets. Holler if you want one.

Hahn "the list is long"Rossman

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[John Clay]

Yes and maybe yes, respectively. Jamie mentioned that some of the early MTB builders simply sawed off the CS spigots back in the day; that would certainly simplify that aspect and I may well try it. Using a CS socketless shell is certainly a possibility as well.

John Clay

Tallahassee, Florida

--

John

[John Clay]

Hahn,

Glad you saw the hint! Get cracking!

Good clearance for a 62mm fender + at least two mm of daylight on each side is a good target. I can send you a tracing of the stay contours on the two RTP bikes I've built and sketch in the slight changes that I think would improve things. I favor the results of my first RTP frame; I over bent the ones on the second, and spread the CS spigots a bit more than I wanted too, and the bend radius was a little larger than I was after. I was able to correct things but the result wasn't as svelte as the first. It turned out to be OK as my brother wants extra clearance for knobbies and is used to a larger crank tread than most of us want but it made me realize that I need to do more work with my tooling and procedures to reliably get what I'm after...or get hi tech help!

I figure that spindle length can be used to make it all work, even if Q suffers. I figure a max inner ring of 30t. Without a dent and with a spindle change, I'd have a 143mm tread on my RTP frame (the first one).

I'm partial to round sockets but the stays will end up as ROR and with the right die the ovalization can be optimized for clearance without going overboard on the ovalization. Given all of that I don't see a benefit to oval stays.

Thanks for the offer but I have some bending bars. What I discovered the hard way was that you can't, well I certainly couldn't, just bend the sockets to the degree necessary; that screwed up the shell at the threads. I used the bars for sure but I also cut the spigots and moved the resulting elements individually, and did a lot of grinding. You can see it on mine starting here: https://www.flickr.com/photos/21624415@N04/44991553602/in/album-72157671170583438/

And on the second one, starting here: https://www.flickr.com/photos/21624415@N04/50050898488/in/album-72157714479460956/

PM me if you want kick this around some more and thanks!

John

--

John

[John Clay]

Finished, back from the painter:

https://www.flickr.com/photos/21624415@N04/50646297017/in/dateposted/

https://www.flickr.com/photos/21624415@N04/50667001756/in/dateposted/

https://www.flickr.com/photos/21624415@N04/50646297947/in/photostream/

John Clay

Tallahassee, Florida

[Ian A]

Just a fantastic project all round. The colour is well chosen and the whole premise of the bike is superb.  I really appreciate the graphics too. 

Please post more photos when it is built up and let us know how it rides. 

IanA Alberta Canada

[Steve Chan]

   Can't wait to see it all built up! Should be great with the new Humptulips tires (when they come out).

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[David Cummings]

Agreed - can't wait to see it with HTPs (Humptulips Pass?)

David in MT

[fordb...@gmail.com]

Wonderful inspiring project. Nice work on the bottom bracket and chain stays. Thank you for sharing your methods !

I was able to order a pair of Humptulips tires yesterday ! I got the tan extra lights. I can't wait...

Ford in Ghent, NY

[John Clay]

Thanks everybody! I'm pretty happy with the results. Build-up will probably be delayed until after X-mas but I'll post pics.

John

[John Clay]

Mounted RTPs (endurance casing) on one of my brother's new RTP bike today. With Sun Rhyno Lite rims it was 52mm wide at 25 psi. My RTP (standard casing) is 49mm on Sun CR18 rims. It's finished; I'll have to take some pics. He's a very happy camper.

John Clay

Tallahassee, Florida

[John P]

OT but out of curiosity's sake have you seen this CL listing?

https://sfbay.craigslist.org/eby/bik/d/lafayette-custom-randonneur-57cm/7322321229.html

-John

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