Erik's new Gus. Questions.

[Patrick Moore]

Erik: It just clicked: the bike I admired last night on the blog is yours. Congrats on the new baby; it looks lovely. They're not colors I'd choose for my bikes, but I must say that the orange and gold and silver and black go very well together.

I was particularly struck by 2 remarks: That the Gus takes much fatter tires than the 2.2 on the Atlantis, and that the Gus does very well on singletrack.

Just went to site: 2.8". Yours is 700C? How much clearance between outer knobs of 2.8 tire and stays? Might one cram in a true 80 mm tire? The minimum I want for the Monocog replacement is 3" with at very least 5 mm between outermost knob and inside of stay.

To own a 6th Rivendell would be wonderful, as long as it kept the signature Grant handling and feel, and fit my needs. I know that Grant's latest designs feature long and wide. Any thoughts on how well a Gus might do in conditions like these? 

Photos attached: 

1. Narrow ditchbank trail. This one is not by any means the narrowest and most sketchy; must not have saved any of trails crowded to 20" by ancient Cottonwood. with big roots trying to tip you into the ditch. I'd not use a very wide bar.

2. 4" deep sand.

I can plow through 4" sand standing, with great effort, and with radical downshift on the 61mm/19 psi-tire Matthews 1:1, and with similar effort, standing, in the single 65" gear with 71 mm tires at 15 psi psi on the Monocog. 80 mm at 12-13 psi should make it a doddle. All 700C.

Again, pretty baby.

Patrick Moore

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Patrick Moore

Alburquerque, Nuevo Mexico, Etats Unis d'Amerique, Orbis Terrarum

[Erik]

Well, that sand looks brutal!  As you noted, the max listed tire size on the Gus or Susie is 2.8, but I feel like that would be pushing it for a couple of reasons.  I'm running 29" x 2.5 Terravail Ehlines. They measure about 62mm without any weight on them on Cliffhanger rims, tubeless.  They have plenty of clearance on the sides (about 12mm on the front, a little less in the rear). I measured the distance between the inside of the chainstays and it looks like it's right about 80mm (I wasn't measuring with calipers!), so I don't think you could fit 3" tires (about 76mm) with any meaningful room to spare.  The forks have a little more clearance so maybe a slightly larger front tire would be possible.    

The bigger issue that I would see with trying to get even larger tires on the back is the bottom bracket width necessary to keep the chain off of the tire.  It would push the chainline out pretty far.  It's a 73mm shell and I'm running a 122 IRD bottom bracket with spacers.  Even with that and a chainline that is waaaay outboard, the chain runs pretty close to the tire in the 50t gear in the back.  I think that if I sized up even to the 2.8 I might have to switch up to a 127 BB, pushing the chainline out even further.  You almost need Boost spacing at that point to push the cassette further out in line with the front chainring.  Otherwise the front chainring is starting to line up with the smallest cog which makes for a terrible chainline.  That's my amateur opinion at any rate!  I'm sure someone on here has tried it or knows this better than I do.     

Otherwise, even with "just" 2.5 inch tires it's handled the terrain just fine and was easy to keep on track on multiple surfaces, including rocky sections and sections with lots of roots and loose gravel.  It was equally fine with all of it.  Sand, however, is another matter.  We don't have much of that on the trails in my area so I can't really speak to it.

I may try out a larger front tire soon and will happily report back.  I don't think I'm going to try a larger rear tire for the reasons above re: chainline.  

And thanks for the nod on the build!  Happy with all the shiny bits.  

Erik  

[Garth]

Patrick, I belive this has been pondered before with other Susie owners and I'm pretty sure 2.8 is the max for the rear while the front could take a 3.0. 80mm, would be a bit too wide. Suggestion!?! Contact Grant if you have not already. He would be able to tell you even "if" it were feasable given the chainline issues with tires over 2.8", and "if" it were "would" he even give the okay to have one made and sold to you as a "Rivendell" branded product. "If" he did ..... "then" you may wonder ... "why not disc brakes too" ?  ...... and that's where it all goes kaput ! ... das ist kaput !!!  (((( laughing ))).  Even so, the very widest rim brake rim I know of is a Ryde Andra 29.29ID/35OD and a cool 995 grams !  Not for the weight weenie. 

You know though .... when it comes to float, good float ..... forget about that 80mm !  How wide is "wide enough" ?  4" , 5 ", 10" ? 

Hah ... even enough never seems enough does it ?  There's always that nagging "what would a little more feel like" ?  Even that would never be enough 'till you take full flight, as that is our Nature ..... Boundlessless, The Infinite !  If We were not already So, we could not even play a finite game of "follow the trails". 

Whatever "the situation" ... a good laugh is always in order.  Like riding a road bike through the sand and sinking over the rims...... oops !  Riding a road bike a on a mtb trail .... Hi-Yo Silver !  

No joke ! My Franklin custom is the best handling offroad/trail bike I've ever ridden. It's as-if I've played "let's box myself into wider tires are better" ! Better than what ? When ? How ? Where ? For Who ?  An honest inquisition reveals but a circle of relatives all leading to where it begins and ends, all-at-once. How facinating !  

[lconley]

The solution to wider tires on the rear while maintaining tire clearance and chain angle is a narrower cassette with spacers on the inner side - the 7 speeds that Rivendell and Soma sell.

Note also that long chainstays keep the chain angle smaller than with the same chainring and cog offset on a shorter chainstay bike.

Laing

On Wednesday, May 25, 2022 at 1:28:49 AM UTC-4 Erik wrote:

[Joe Mullins]

Hey Erik,

I’m building my large Susie with the same 2.5” Terravail Tires but I’ll be using Riv’s 13-42 7-speed so that I have room to fit a bigger tire in the back if I decide to do so and because why not? I’d be happy to measure the distance between the chain and tire once built so we can compare and we can both get an idea of how going either way affects it. At first I was going to wait for the new 7-speed hubs that Riv is working on but decided that going with a 9-speed hub and spacers gives me more options.

Joe

On May 25, 2022, at 5:16 AM, lconley <lco...@brph.com> wrote:

The solution to wider tires on the rear while maintaining tire clearance and chain angle is a narrower cassette with spacers on the inner side - the 7 speeds that Rivendell and Soma sell.

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[Patrick Moore]

Thanks, Erik and others. Garth, come to think of it, I think that I did ask this before -- more Ralph Wiggumry. Oh well.

And I would prefer disc brakes, tho' that's not a deal breaker.

Also, any Monocog replacement would be a single speed, or perhaps use a hub gear -- typical wide range 3 speed or perhaps a 2 speed kickback; but probably just a simple single speed.

The dealbreaker tho' is 76 mm tires with 5 mm clearance on each side, so 86 mm between stays at tire level.

Garth, I find that an extra cm of width and corresponding 5 psi or so drop in pressure makes a huge difference when negotiating sand. 60 mm at 19 psi is much better than 50 mm at 23 psi, but 71-2 mm at 13-15 psi is even better, and 76mm+ I daresay would improve things further. 

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Patrick Moore

Alburquerque, Nuevo Mexico, Etats Unis d'Amerique, Orbis Terrarum

[iamkeith]

I think I responded to the question last time, but just in case:

I have my 1st run, size L Susie set up with 29x2.8 tires, measuring at least 74mm  on 42mm rims, with a 3x9 drivetrain.   My tires don't have huge knobs, but there are no absolutely no clearance or interference issues anywhere, in any gear.   By far the biggest constraint is the height of the fork crown.   If it was higher, I could and would put fenders on the bike, too.   

If I can find a 2.6 tire that I like, I will eventually switch to those.  I want fenders,.  And the 2.8 tires are fine on dirt but have a little too much self-steer on hard surfaces.

[larson....@gmail.com]

Hey Eric,

Enjoy your Instagram site. How well do you think Gus would work as an allroad/mixed terrain bike with tires like the 700x55 Antelope Hill or 2.2” Fleecer Ridge? Giving thought to the ATB/one bike solution and am thinking about the possibilities. Somebody on the forum speculated that the Gus could possibly be an Atlantis/Jones LWB mix. Thank you and happy riding.

Randy in Wisconsin

[Patrick Moore]

Thanks again, Keith. I want to hold out for true 3"/76 mm tires and 5 mm clearance at all 4 stays, and from such research as I've done, the Krampus and one other off-shelf bike which I forget -- in my archive -- should allow this with a =/< 160 mm Q, which is the goal (again, single speed), as also of course would a custom.

To view this discussion on the web visit https://groups.google.com/d/msgid/rbw-owners-bunch/4c084692-104a-48c1-83c9-d87dff482caen%40googlegroups.com.

[Hoch in ut]

Make sure a 3” tire will be enough for you. I’ve ridden deep sand in southern Utah. 3” tires (Chupacabra and XR4) were ok. You’re still putting out a ton of wattage to keep going, especially on climbs. 

Nothing beats fat tires. 4” or bigger. Get yourself a fat bike with light carbon rims and fast rolling tires. 

[Ryan Frahm]

I’ll second what Hoch said. I don’t notice very much difference between a 2.6 and a true 3.0 in sand. 4” plus is all that has helped. 

[Patrick Moore]

Ryan and Hotch: Thanks, but a 3" tire, or rather rims and frame that allow full 3" plumpness of my WTB Rangers, labeled 3", is not a variable; I've long since worked out what I want, which is not a sand bike but a sand-capable all-rounder.

IME, which is extensive enough to make a considered judgment, the current 71 mm/2.8" at 13-15 floats better over such sand as pictured than 61 mm at 18-20, which in turn is better than 50 mm at 21-23 psi. And I want a tire that is not entirely disheartening on pavement.

OTOH, if I can find or commission a frame that with a ss drivetrain lets me use a 26 X 4" tire with a Q factor =/< 160 mm, and a 26 X 4" tire weighing less than 700 grams, I'll take them both, seriously; but I expect neither is possible. I'll be happy to be shown wrong.

(Sorry, Tarik.)

That sand was the worst, or almost the worst I ride in (there are a few patches deeper or longer which require me to walk, but I rarely ride on those stretches).

A 3" 700C tire at 13 psi or so is, for my all rounder but sand-biased riding needs, a good compromise, just as the earlier Matthews with 61 mm (450 gram) Big Ones is an excellent pavement biased bike that can handle 3" sand, perhaps even that pictured if I use the small-ring gears. The Monocog replacement would also be a more "just get on and ride" bike that I can use to "walk" the dog with -- tho I use all my freewheel bikes for this purpose on the appropriate terrains.

To view this discussion on the web visit https://groups.google.com/d/msgid/rbw-owners-bunch/65aad58a-62f6-44a3-80af-4a8aa1dcbfdfn%40googlegroups.com.

[Patrick Moore]

One more non-variable: a single 65" gear that is high enough to prevent making flatland, hard-surface cruising with 175 mm cranks hateful, but low enough (with the tires described) to make even shorter stretches of 4" sand, as well as the shorter hills, rideable, with effort.

[Ryan Frahm]

Tumbleweed Prospector frame? Then you’d be able to play around with the tire sizes! And selfishly, I get to see another sweet prospector build. Haha!

[Patrick Moore]

Ryan: Thank you! Perhaps this might work. 26 X 4 or 622 X 3. There's this for minimum 2 mm crank clearance per side:

But:

Crank clearance

Chainstay width is 140mm, crank arms must have 144mm inner width, 24mm spindle recommended

That leaves 16 mm total or 8 mm per arm for arm thickness. The WI Eno crank is with the Monocog at the LBS, but my Logic crank arms are 13.13 mm wide, and my TA Pro 5 Vis arms are 14.54 mm wide.

Let's say 26.5 mm: 144 + 26.5 mm (I know that 0.5 mm don't mean a thing practically) = over 170 -- well beyond the 160 mm limit to my Q factor comfort.

Oh well ...

Still, interesting to see that 26X4 and 28X3 are given as suitable alternatives.

On Sun, Jun 5, 2022 at 6:09 PM Ryan Frahm <fra...@gmail.com> wrote:

Tumbleweed Prospector frame? Then you’d be able to play around with the tire sizes! And selfishly, I get to see another sweet prospector build. Haha!

[Ryan Frahm]

Close! Well, Waltworks would be my next suggestion then. He is known for making narrow Q work with multiple tire sizes. Can’t wait to see what you end up with!

Side note, I did some riding around ABQ trails last thanksgiving. What an amazing area to ride! I had a blast with the limited time I had there between the family stuff. Didn’t even notice all the cactus needles in my tires till I got home! I really can’t imagine not being tubeless.

[iamkeith]

Too late.  Walt announced his retirement from framebuilding.  You waited too long, Patrick. (Me too.)

[Ryan Frahm]

Well shoot. I was hoping he’d have a few more years! I have finally started to figure out what I really wanted to have him build. I have been pretty interested in Mahall bikes as well. Some beautiful work!