Rivendell-esq fat bike

[Joe D.]

Hello Rivendell aficionados! The short version: I’d like some advice on picking a fat bike (4-5” wide tires) that shares similar ride characteristics with the current crop of Rivendell long chainstay-long wheelbase bikes (e.g. Clem, Atlantis, Platy, Gus/Susie).

The long version: I’m in the market for a full-on fat bike, with true 4-5 inch wide tires. I live in Montana and my previous winter riding with studded 3 inch tires just wasn’t enough. We’re a one car family, so in addition to riding on winter trails or snowy forest service roads for fun, I’ll use the bike for groceries and errands as well. And as much as I’d love an Atlantis or Platy for dirt roads, bike camping, and light trail use, the more economical choice would be to get a set of 29 inch wheels for a fat bike and run 2.8 or 3 inch tires in non-snow season for an all year off-road bike. Hence the importance of making a good choice now.

How I came to desire a Rivendell-esq fat bike: A friend in another state got a 2019 Clem and raves about the comfy, stable ride with the long  chain stays/wheelbase. But the real kicker was when I got a Yuba Mundo Lux cargo bike (https://yubabikes.com/cargobikestore/yuba-mundo-lux/) for hauling my two kids around. The swept back bars get me sitting upright, and the crazy long chainstay (753mm) and wheelbase (1410) make 150lb loads totally manageable. It’s like a Cadillac. Since the Yuba, I’ve vowed that all my bikes will be long and upright. Fortunately upright stems and swept back bars can take care of the upright part for near any bike, so that leaves chainstay/wheelbase length as the big question for a fat bike.

For reference, scroll down here (https://bikeinsights.com/compare?geometries=5d1ae74763bde8001707cf36,5e1faf637f17da00170c6e28,) and you can see the chainstay/wheelbase lengths on the Clem and Atlantis, both ~550mm for chainstays and ~1235mm for wheelbase. For fat bikes, consider these two models (https://bikeinsights.com/compare?geometries=5ff009522655ff0017c6e96a,61c0a2add559210021256cf2,). The Wyatt can actually have a longer wheelbase than the Rivendells with its sliding dropouts (1250 max wheelbase). But its chainstay is only 465, still long-ish for mountain bikes but not near what a Riv or cargo bike is. It achieves that with a slack head tube angle that pushes the front tire way out front.

Alternatively, the Giant fat bike in the link has a similar max chainstay length as the Wyatt (460mm) but a shorter wheelbase (1170mm), leading to a more centered position on the bike. I’m unable to find any fat bikes with the combination of long chainstay/wheelbase that the Rivendell’s have.

Any tips on which bike, and which geometry approach in general, would get me closest to the Rivendell/cargo bike-like comfort and ride quality? Other fat bikes? For simplicities sake, I guess don’t evaluate factors other than geometry, like frame material. For what it’s worth, there are very few chromoly fat bikes.

(Sorry for the length! I appreciate anyone getting into such a bike-nerdy discussion)

- Joe

[Mr. Ray]

Just find a bike with chainstays that can accommodate 4.5" tires.  Long wheelbase is not necessary since the volume of the tires would be your "comfort and suspension".

[Slin]

Joe - Have you taken a look at fat tire cargo bikes like the Surly Big Fat Dummy? Or the Salsa Blackborow? I don't have experience with either, but maybe they could be options to fit your use case?

S

[Coal Bee Rye Anne]

I forgot the Blackborow was redesigned as a cargo long tail... I was never in the market for such a thing but did initially have a slight interest in the v1 Blackborow with the dinglespeed build: https://www.salsacycles.com/bikes/2015_blackborow_ds

Here's a TI fat bike from Bearclaw with 463 chainstays, over 1000 wheelbase across all sizes and 1177 WB/66cm toptube at my XL size which rivals the 66 or 67cm TT of my Clem H, though angles of 73/70.5  definitely differ than 72.5/72.5 of my Clem.  No experience with fat bikes or Bearclaw in general but recall coming across some other Bearclaw models online and that they had a fat-fat tired model. https://bearclawbicycleco.com/frank-titanium-fat-bike/

[Coal Bee Rye Anne]

There's also the updated Crust Scapegoat/bot which takes up to 26x4" through 29x3"

https://crustbikes.com/collections/frames/products/scapegoat

[Brian Turner]

Speaking of Riv-esque? How about the Tanglefoot Bull Thistle? Pricey and extravagant for sure, but it sure is lovely. It's made by my buddy Alex Meade, too.

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[lucky...@gmail.com]

I just saw a lovely Tumbleweed Prospector on Tumbleweed’s IG set up as a fatbike with 26x4

On Dec 15, 2022, at 13:39, Brian Turner <brok...@gmail.com> wrote:



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[Justus G]

If this is in budget and ultimately meets your needs, my vote goes here.  Very Riv Style.  Wheelbase is not stated, but I see some length built into the ETT Geo and a 65mm rake fork with a low BB so should be agile in front end handling with a stable enough feel due to BB height and overall wheelbase.

As you can see I am a fan of this concept when the niche fills a need.  Attached is my 2016 Custom Clockwork Dirt Fat.  Mine was built for shredding tight twisty midwest trails so kept both front and rear center a little tighter and BB a little higher.  Same HTA as the Tumbleweed but my STA is a little steeper and less fork offset so more trail for strictly mountain biking use.  Mine is not a road fat in any way or a snow fat.

All threads benefit from Bike pics...

[CJ]

I've owned 5 different fat bikes over the last 10 years, and I love riding on snowy trails. In my opinion, you do not want long chainstays for that. Shorter chainstays make it easier to get traction and get up on top of the snow. Multiple time Iditabike winner, Mike Curiak, feels the same way, so I know I'm not alone in this opinion. If you want a four season fat bike, I'd recommend the Surly Wednesday. It rides great all year round, fits 4.6" tires for all but the deepest powder days, works great with 29x3" wheels, and doesn't have the super wide Q-factor of a full 5" tire fat bike. If you want max flotation, the Surly Ice Cream truck is a great choice with clearance for 5.05" Vee Snowshoe XL tires. 

Another thing, if you're in between sizes, you can size down for a more nimble ride (shorter front-center and overall wheelbase) or up for a more stable ride.

Chris

On Thursday, December 15, 2022 at 2:21:16 PM UTC-5 Joe D. wrote:

[Bob]

Joe,

The final iteration of Surly's Pugsley had 460 mm chainstays and accepted 4.8 in. tires "with drivetrain restrictions." It also had a 72° seat tube angle, which would feel a little more relaxed and Rivish than the steeper angles on MTBs these days.

The Tumbleweed Prospector and the Crust Scapegoat max out at 4.0 in. tires, I think, but have 73 mm bottom brackets for a more comfortable Q factor. (I ride a Pugsley, and have a limited tolerance for the 200 mm Q factor.)

If you go custom, Myth Cycles in Durango CO has the Chimera (https://mythcycles.com/bikes/chimera/). The listed geometry is shorter in chainstay and wheelbase than you want, evidently the design allows a narrower Q than usual for a fatbike while also accommodating 4.8 in. tires.

That Tanglefoot Bull Thistle, though… wow. They present it as a drop-bar-specific design, but the top tube and reach are long enough to work with an upright bar, I think. Limited to 4.0 in. tires, but the bottom bracket is 83 mm so the Q factor will be narrower than most fatbikes. The angles (ST 71°, HT 69.5°) rather Riv-like, and the lugs—the LUGS!

I'm curious to see how your quest plays out.

--

Bob

P.S. Maybe the most Rivesque fatbike would be an early Pugsley, when they still had cantilever studs and Large Marge rim-brake-compatible rims. (See Rivendell Reader 39 from 2007.)

[Joe D.]

Just wanted to say thanks for the insights everyone. I posted a longer reply a few days ago that still awaiting the moderator (I guess?) but I just wanted to say thanks in the meantime...

Joe

[Patrick Moore]

Not to crowed Joe's questions, but this answers many of my questions about fatbikes too; and I didn't know that there are 3.25 and 3.5 650B tires. So thanks Keith for this detail. I've already found that no Riv can take full 3"/76 mm 700C tires, alas.

On Thu, Dec 15, 2022 at 7:06 PM iamkeith <keith...@gmail.com> wrote:

Joe,

before throwing in my 2 cents, I want to acknowledge that this is not really answering your questions but, instead, telling you to do something different.   I usually get annoyed when people answer a direct question with "you don't need that" but, in this case, my friend, I know enough about you and your bike-purchase-and-subsequent-regret habits to want to save you some hassle.  Others have already mentioned a couple of the ideas I was going to offer, but here it is with more explanation:

I haven't read through  your other ibob thread completely, but do understand that much of your interest comes from wanting to relieve wrist discomfort - especially on rough trails..  So this response is partly in consideration of that question.

"Novelty" concerns: I was a pretty early adopter of fat bikes. They're the only kind of bike I can even ride for fully 6 months of the year or more, due to the amount of snow where I live. (Along with northern Minnesota and Anchorage, my area - the sister communities of Teton County Idaho and Teton County Wyoming - were where much of the early fatbike development occurred.) For a number of years around 2010 or so, I rode a fat bike almost exclusively, all year. I liked it for it's back-to-basics, monster-truck, roll-over-anything simplicity. But, even for an retro-grouch like me who lives in a place where they make complete sense, that appeal eventually wore off and I now only ride it when no other bike will work. Most people who get fat bikes enjoy the novelty for an even shorter period of time. They eventually tire of the extra rolling resistance and steering compromises and increased q- factor and mechanical complications and weight. Then they quit riding them.

Tire Size considerations: Keep in mind that there have been HUGE advances in tire manufacturing and technology since (and because) 26" fat bike tires were invented - even though that wasn't all that long ago. 2008, maybe? Much of what made 26x4 tires work so well was their diameter, which was similar to the not-much-older 29er development. But, unless you really plan on riding in loose sand or deep snow most of the time, there is no longer any advantage to 4" tires. There are now some 650b semi-fat tires that give you almost all of the advantages of 26x4 with none of the problems. If you think about it, there's nothing more "rivendell-esqe" than 650b, right? They wouldn't even exist if it wasn't for Rivendell!

Regarding suspension and bounciness: The best thing about fat bikes is that they eliminate the need for suspension for most "normal" riding. But it takes a lot of effort to tune the tire pressure to really take advantage of this. Almost as much hassle as dealing with shock rebound rates and pressure settings, etc. on a true full-suspension bike. When you get tire pressure >just< right, you don't bounce at all, and you don't have funny steering or excessive rolling inefficiency. But the optimum pressure requirement changes depending on terrain and load, so you end up fussing with it a lot. (or giving up and getting frustrated with the ride qualities - a la the "novelty wearing off topic." ) The REALLY important thing to keep in mind here is that the bigger the tire volume / cross section, the more sensitive it is  to pressure adjustments, and the more you need to mess with it. So you're absolutely better off only getting as much tire as you really need! 4" is really overkill most of the time, now that there are intermediate options.

Geometry considerations (and Pugsley concern): You specifically asked about the Puglsey. I'll venture that is probably NOT the bike for you. I had a first generation pugsly at one point (with canti brakes!) . The thing about wrist pain - as you know from Grant teaching us - is that it's more of an issue of frame geometry than it is of tire plushness or vibrations and impacts being transferred through the bars. In particular, it comes from bikes with too-low handlebars and too-steep seat tubes angles and twitchy steering geometries, all conspiring to require you to put lots of your body weight on the handlebars. They may have gotten better since mine, but the thing about pretty much ALL surly bikes is that they have extremely short head tubes and stack heights. You can add 4" of stem spacers and a high-rise stem but, at some point, you're probably fighting the design intent of the bike.

Similarly and, as CJ noted, many accomplished snow bike racers prefer short chainstays, and it's probably valid.. to a point. I've had that same conversation with Mike Curiak and Jay Petervary. The think to keep in mind is that these are extremely fit riders who have the strength to shift their weight fore and aft as needed, as a technique for staying on top of the snow. AND they're riding in the iditarod, for christ's sake. For most of us mortals - and for someone who's not really even riding on snow - that's much less important. The thing about longer chainstays, within reason and as you know, is that they allow you to sit more upright without un-weighting the steering and becoming twitchy. This might all be moot, because not much of the industry thinks like Rivendell.

Possible options: In summary, I'm saying look at geometry first, and tire size second. And think 'less is more." I just can't imagine you being happy with 4" tires in the long run. Bontrager makes a 650b by 3.5ish tire. (hodaq) Better yet, Duro makes a 650b x 3.25. (crux) There are even a few 650b x 3 tires, too (teravail corronado, surly knard) This leads to a vastly  different set of bike options, several of which I was going to suggest and were mentioned.  A couple of these actually have close Rivendell associations and lineage: Tumbleweed; Analog/Tanglefoot; Soma. The VO polyvalent might work too. Or a stooge Scrambler. All of these will fit more than enough tire, but I don't actually know all of the geometry details so you'll want to study closely. You want tall stack height, low bottom bracket, slack seat tube. To me, that's what makes a Rivendell fit so well and is what you're really asking. Use the Bike Insights tool.

Actual Rivendell Option: The Gus/Susie takes a pretty decent size tire too - but you've been there and know that and are probably looking for more than 2.8 tires. The availability of rims makes it hard to fully take advantage of even those, in my opinion, for the "squishy" tire effect you seem to be after. The thing about those bikes too, (in my experience) is that the geometry isn't actually all that "rivendell-esqe." They're meant to be decent mountain bikes, so the bottom bracket feels high to me. That's probably the case with some of the others mentioned.... but its more expected. Especially the tumbleweed prospector, which is intended to take a suspension fork. The stooge is low for sure.  Still, I can't help thinking that, if you got it set up right, it wouldn't do exactly what you're after.

My own hands-down recommendation: Again, already mentioned by others. I've said it a few times, but one of the best damn bikes I've ever owned is my gen 2 Crust Scapegoat. Ugly-as-sin paint job, but absolutely perfect geometry to me. It's what I'd want if doing a custom. It'll take a 26x4 tire with some compromises, but I set mine up with 650b x 3.25, 3x drivetrain with reasonable q factor, full fenders. Unfortunately, they just changed it. It got longer chainstays - which is probably good - but it also got a higher bottom bracket, shorter top tube and maybe steeper seat tube - which may or may not be good. The combination of the shorter top tube and longer chainstays probably allows you to still sit more upright than typical bikes. Still worth looking at and might work well for you - you know enough about what fits you. If not, you could look for a gen 2 used.

[Joe D.]

Thanks all. What great insight! I can’t believe that Bearclaw… a titanium drop-bar fat bike! I did recently learn about the Salsa Blackborow, but that really seems fully into cargo bike territory, with chainstays and wheelbase over 100mm longer than the Rivs. I know they designed it to be more sporty that something like the Big Fat Dummy though.

I really like that link to Mike C’s thoughts about fatbike design. It helped me realize what I’m trying to accomplish, which is not necessarily what he’s after. If I can’t ride any trails in winter it’s not a huge bummer, but I want to be able to cruise all over town for errands and go for longer rides on the dirt roads out of town. But these are all either intermittently plowed or at least trafficked roads. So mostly packed snow but occasionally 1-3” of fresh or churned stuff from cars.

I currently have studded 2” tires to get around town and I’m not enjoying it. On totally packed snow and ice it’s fine, but any kind of fluff makes it squirrly. Last winter I spent time riding a friends bike with 27.5 x 3 studded tires from 45NRTH. That was a much better setup than my current 2” studs. I think I could enjoy the riding I described above for the vast majority of the winter we get with that 27.5 x 3 setup. I just figured I’d go full fat, which nowadays seems to be 4.5 to 5”. But as Keith points out, there are definite down sides. (I see his post in my email but not in the thread…) I’ve only been on a fatbike briefly and am planning on renting one for some more real world experimenting.

I’m thinking about a few different scenarios. Of course budget plays a role, and I only see one new bike coming in the foreseeable future.

1) Buy a Rivendell! Makes sense if I’m excited a bout the geometry and ride feel. I guess the Gus/Susie for max tire clearance (2.8”) and then I’d stud the tires myself. Or a Clem and then buy the available 29 x 2.6” studded tires.
Pros: it’s a Riv! Which is really what I’m most excited for.
Cons: not the biggest tires, certainly not compared to a fat bike but not even compared to option 2. But perhaps it’s fine for my winter riding?

2) Get a Rivendell-inspired off-road bike   that has even more tire clearance than Gus/Susie, but isn’t full fat. Many good choices given already like the tumbleweed prospector and crust scapegoat. I’d throw the Jones LWB in there too.
Pros: Theoretically better snow performance than #1 since there are bigger tires, like a 29 x 3.25 Duro Crux for the Jones that I could stud, but still regular bike feel compared to a full fat.
Cons: Although they’re making design choices with a nod towards Riv, they’re not a Rivendell! Also, still some compromise in snow performance compared to option 3, but doable 95% of winter, and more enjoyable the rest of the year?

3) Full fat. Realize that I’ll probably want either option 1 or 2 eventually anyway, so just get whatever cheap used fat bike is available. Those are often either old pugsleys or salsa mukluks for 700-800. And then eventually, like 7-10 years from now at some celebratory moment, by a classic Riv like an Atlantis or Appaloosa that can handle most of my April-October dirt riding.
Pros: Maximum snow performance. Cheap initial cost, although new fat bike tires are expensive.
Cons: I’m waiting a while for a bike I really want from option 1 or 2.

Options 1 and 2 seem nice because other than the cargo bike, my personal bikes are two $100 specials from Craigslist: a late 80s schwinn with 40mm tires and an early 90s steel MTB with 2.3” knobbies. I enjoy the heck out of both but would expect options 1 and 2 would be more enjoyable for the dirt roads/easy single track/bikepacking I enjoy doing.

On Thursday, December 15, 2022 at 6:12:33 PM UTC-7 rcook...@gmail.com wrote:

[Patrick Moore]

Bob: Do you know how low a Q you can get on the Prospector, Scapegoat, Chimera and Bull Thistle, particularly with a single speed drivetrain (if any accept a ss drivetrain)? I've stayed away from Pugsleys etc because of the Q but if one can be built as a ss with a Q of no more than 160 I'd be very interested for our local sandy trails. As it is, I've been thinking of a 29er+ replacement for my Monocog 29er on which the rear 71 mm WTB ranger rubs the stays in corners but fat would be even better if the Q could be sorted. 

Thanks.

[Bob]

Patrick,

I do not, sorry to say. Would like to have those data myself. Anyone here have a Prospector, a caliper, and a few minutes to take measurements?

--

Bob

[Joe Bernard]

For the record I'm not the OP, which is why Keith deleted the post you're replying to. Fortunately his info was helpful anyway, but Joe B. who started a fatbike thread on internet-bob is not Joe D. who started this one! 

[Hoch in ut]

I’ve owned a number of fat bikes. One I thought was the most Riv-esque was the Ritchey Commando. I don’t think they make them anymore. But you may be able to find a used one. They rode fantastic. Chainstays were relatively long. 

Regarding chainstays, it was just fine in snow. Mike C’s point of short stays has some merit, but remember it’s just one guy’s opinion. He’s also said in the past that rigid and hard tail bikes were useless and full-suspension was the only way to go. I wholeheartedly disagreed with that. 

If you ever meet him, ask what he thinks of lugged steel rigid frames with rim brakes! 

Don’t put much weight of what he or others say. Go test it out for yourself. 

[Ryan Frahm]

Mike has a lot of opinions. He builds excellent wheels. What he is looking for is not necessarily what a Rivendell rider might be looking for in a bike. He is an aggressive rider. If you are serious about a long chainstay fat bike, it might be worth checking out Mahall Bikeworks. It is custom so it won’t be cheap, but I’ve read some about him experimenting with Rivendell long stays on some adventure bikes that made me interested. It has been a while so the details are fuzzy to me, but I was very interested. He can even make it lugged!

[rlti...@gmail.com]

I just measured my Prospector with Rohloff and measured a Q of 185 mm. I could likely shave a few mm off with with a different crank.

Robert Tilley

San Diego, CA

Sent from my iPhone

On Dec 20, 2022, at 1:33 PM, Bob <rcook...@gmail.com> wrote:



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[Bob]

Thank you, Robert. 185 mm is good, considering the tire clearance of the Prospector.

--

Bob

[Tom Palmer]

I agree with Hoch- the Ritchey Commando is Riv-esque and rides very well. I have had several fat tire bikes from low end to high end and it just has the ride. Good tires help any fat bike in particular. Schwalbe Jumbo Jims in particular work for me. 

In keeping with the spirit of Joes' ask- a dual suspension mountain bike is smoother than a fat tire bike even with good tires and dialed pressure. 

I have some inflammation issues and the dually has allowed me to ride rough trails in comfort during the ride and feel good the next day also. 

Tom Palmer

Twin Lake, MI

[lconley]

For reference. I have a 1st generation (I believe) Crust Scapegoat. With a Sugino crank on a 122.5 x 73 Shimano bottom bracket, I get 180mm Q-factor. A narrower bottom bracket could be used but clearances would be diminished. I am currently running a 26x4.3 Surly Edna on the front and a 26x3.8 Surly Larry on the rear. I have another 26x4.3 Edna for the rear which fits, barely, but forces a wider bottom bracket if more than a single speed is desired. Drivetrain is a double single speed - either a 34x21 -> 47" gear or 38x18 -> 61" gear. The amount of adjustment in the swinging dropouts does not allow using the big-big or small-small combination. 

Clearances:

Drivetrain:

Laing

Delray Beach FL

On Thursday, December 15, 2022 at 2:21:16 PM UTC-5 Joe D. wrote:

[Patrick Moore]

Thanks, Bob. Others: If any of youse have this information, would be very glad to hear it. Thanks.

[Hoch in ut]

For reference, I built a Pugsley years ago with White Industries cranks and custom BB. The narrowest I could get the Q factor was 183mm. That is with about 2-3mm crank clearance. Much narrower than stock but definitely nowhere close to 160. 

[Patrick Moore]

Thanks Laing and Hoch. Once again, confirmed that fatbike Q is more than I care for.

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Patrick Moore

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[Zach Roeder]

I'm using a Shimano XTR M9125-1 with a Q of 174mm on my Rohloff Prospector (first generation). With short axle XTR SPD pedals, it feels like a 168mm q factor. I've tried several different cranks, and I think this is as narrow as you can go. And if you are a super strong rider, maybe there's the possibility of the crank hitting the chainstays?

Clearances are super tight everywhere with 26x4". I'm actually considering slightly wider q or smaller tires because I occasionally rub my legs on the tires on descents, and it hurts! I love how it pedals for long rides though. 

[Joe D.]

Thanks Zach! The Tumbleweed is definitely appealing, especially with a 29 x 3 dirt tire and 26 x 4 in winter.

I wonder if 26 x 4 with reasonably big rims (64mm or full 80mm) would work with a modified cassette, like the setup Crust bikes talk about here: https://www.tumblr.com/crustbikes/159521355676/the-stubby-cassette. I'd be fine with only 5-7 gears. And I think a Q factor closer to 180-185 would be ok. It sounds like it'd definitely be a no-go at your Q factor of 174.

Thanks!

[J G]

You guys have it right for ball parking limits based on something in the 26x~4" range based on my experience.

As stated before, my custom Clockwork Dirt Fat 1x (SqT White Industries Road Cranks w/76bcd spider & 1x ring) with narrow Deda stays has a Q of ~180mm and looking at the space needed for tire, space, stays (modern yokes giving a little more here when used), space and arms, 170mm was what I was thinking for theoretical minimum with a SS or Rohloff.  Sounds like Zach is confirming 168mm really pushes that limit.

[Joe D.]

Another question for you Crust Scapegoat owners... Crust released an updated version last Fall (https://crustbikes.com/products/scapegoat). Compared to the Tumbleweed Prospector,  the new Scapegoat has 1.5 degree steeper head tube angle, 1 degree slacker seat tube angle, and the wheelbase is 50mm shorter in size L (https://bikeinsights.com/compare?geometries=63613a1388731d001d710fb5,61bf4058e6ec02001cccd3cf,).  There's also the rocker/sliding dropouts of Scapegoat vs standard dropoust/EBB of the Prospector. And the Prospector's ability to run 135mm spaced wheels front and back vs Boost spacing of the Scapegoat.

The slacker head tube angle of the Prospector makes me think it'd handle singletrack better than the Scapegoat. Any merit to that? Any other ride differences you all imagine between the two?

[iamkeith]

I haven't fully read this thread, but have been tempted to discuss my Scapegoat.  I have the Gen 2 and, as I've stated in other threads, it is one of the best bikes I've ever owned.  I was slow to investigate or buy it - despite wanting the exact thing - because it is so ugly.  I finally jumped on one just before the pandemic hit, when Crust was moving, and had them on sale.  I had contemplated the Tumbleweed Prospector and a couple of other, similar bikes - including the Chumba Ursa and the Analog/Tanglefoot Moonshiner - before looking past the paint job, really studying the Scapegoat's geometry chart, and realizing it was just what I wanted.  

Unfortunately, the new version un-did most of what I sought out and like about my Gen 2 and made it different than other offerings.    It had a much lower BB, and a longer TT  than the new version.   The fact that the bb is now higher and the HT angle is now slacker than the Prospector (which is high in order to accommodate the squish of a suspension fork if so outfitted)   really tells me how much the Gen 3 has changed.  (Assuming that's accurate.) The top tube on the Gen 2 large was longer than the one on the Gen 3 XL.  The longer chainstay on the Gen 3 is probably good.  But unless someone actually owns the new Gen 3, I think it's going to be tough to get a good review. 

It really depends on what you want, but the prospector might once again be king of the hill for my tastes.   Unless you can find a Gen 2 Scapegoat - then get that!.  That's my suggestion anyway.  The stooge Scrambler has a great geometry too, but it still doesn't a have enough clearance for the rear tire.  The reason the Scapegoat works so well is that they used flat yoke plates on BOTH sides where the chainstays connect to the bb.

Regarding the chain tensioning options:  Owning bikes with: (1) an eccentric bb [a  Jones 29]; (2) sliding dropouts [my actual fatbike, a lynskey]; and (3) rocker dropouts [the Scapegoat], I'd say that the eccentric bb is my favorite in terms of hassle-free, set-it-and-forget it ease.   The only bad thing is that I position it with a rear bias to yield a longer front-center measurement (ideal for me) which means that the rear center / effective chainstay length gets shorter (bad).  The other two mechanisms allow you to lengthen the later measurement by itself (good).

In case you haven't shopped for off-the-shelf wheel sets lately, boost wheels are now easier to find and do help a tiny bit with drivetrain clearance.  The prospector is still 135 only because it works best with Rohloff.  

FWIW, I have my scapegoat set up with 27x3.25 wheels, 3x drivetrain and full fenders - not 26x4 wheels.

[Joe D.]

Thanks for those insights Keith! 

I came across the scapegoat V2 geometry chart (attached). Interesting comparison to the current version (at the bottom of this link: https://crustbikes.com/products/scapegoat). 

When I reached out to Crust they said the current chainstay measurement of 451mm is with the rocker dropouts all the way in, and you can get an additional 20mm by pushing them out. So size Large could then conceivably get a 471mm chanistay and 1130mm wheelbase.