Atlantis vs Platypus?

[Peter Fray]

Hello folks, 

I think this question might have been broached before but I read Will's take in the recent newsletter (Platypus is his favourite ride) and the Atlantis releases next - headed over to the geometry chart to see how they really differ...or not?

I'm a 87 pbh so I compared the 55 Atlantis and the 55 Platypus, the similarities and differences - 

• HT angle - 70 vs 69.5
• ST angle - 72 for both
• ETT - 61 vs 61.5
• Chainstay - 53.5 vs 53
• BB drop - 80 for both
• Stack - 61.8 vs 60.3
• Reach - 40.8 vs 41.5
• Trail - ???

Seems to be very minor (insignificant?) differences. So would they ride similarly? Or is there something about the tubing that would make the Atlantis stouter (?) or more suitable for loads vs the Platypus? 

Thanks for helping me figure this out,

p

[DavidP]

Hi Peter,

Riv describes the Platypus as "like an Appaloosa or Atlantis, but with a step through frame", and as you note the geometry is pretty close, so I thnk it's safe to say they would ride very similarly. The step through fame of the Platypus does make it a bit less suited for heavy loads so it's also safe to say the Atlantis is stouter and more suitable for heavy loads. Riv says the Platypus is good for loads under 30lbs.

I'm 5'11" with the same PBH and ride a 60cm Platypus. One reason I went with the Platypus (besides the look of the frame) is the ability to size up for a longer reach without worrying about stand over, knowing that I wanted to use a big sweptback bar. This recent thread on Platypus sizing may be of interest: https://groups.google.com/g/rbw-owners-bunch/c/2HdGv21LE3E

-Dave

[Michael Connors]

Have you seen this video comparing the flex of Riv non-diamond frames?  https://theradavist.com/video-rivendell-the-string-test-for-bike-flex/

[Peter Fray]

Thanks, Dave and Michael.

I had not seen the video, thanks for sharing. Seems not much difference in flex except for the clem! I do question if this is noticeable for riders...

So I guess the choice comes down to whether you want to carry more load and whether you want a longer wheelbase!. (apart from considerations and preferences regarding the looks, style, and color)...

p

[Steve]

I did happen to see that string test video when it first appeared - but after well over a year of riding a Platypus (pavement and mildly chunky gravel) it was worth a revisit. My impression of the Platypus has been that it rolls over rough surfaces with just the right degree of supple aplomb.  Recognizing the multiple variables involved in producing that quality I'll add that I've been running 42mm RH slicks (w/ butyl tubes) at 35 - 42psi with a long, tall stem (100mm reach and 120mm  height) and a tall seat post (Nitto S83 at 130mm). My next set of tires will be 48s.

So, back to the question of ride quality of the Atlantis vs Platypus;  my thought is how the bike is set up (choice of tires, stem, bars, saddle and seat post)  is the determining factor.

Steve

[Mike Rossi]

I had 2.1 GK sk’s on my Platypus and the only clearance issue I noticed was that the Newbaums tape on my kickstand was 3mm from the tire. I wasn’t concerned with it, but one day while going for a “Leah dismount” I heard a repetitive “thud” sound. The tape was rubbing my tire. I’m about 150lbs during this time of year. I switched to 47’s and added fenders. I actually test fit some SKS fenders with the 2.1 tires and they were going to work. I had planned on cutting the front fender right before it went under the fork as that was the only clearance issue, but that “thud, thud, thud…” ruined that idea.

Mike

On Feb 11, 2025, at 10:20 AM, Steve <steve...@gmail.com> wrote:

I did happen to see that string test video when it first appeared - but after well over a year of riding a Platypus (pavement and mildly chunky gravel) it was worth a revisit. My impression of the Platypus has been that it rolls over rough surfaces with just the right degree of supple aplomb.  Recognizing the multiple variables involved in producing that quality I'll add that I've been running 42mm RH slicks (w/ butyl tubes) at 35 - 42psi with a long, tall stem (100mm reach and 120mm  height) and a tall seat post (Nitto S83 at 130mm). My next set of tires will be 48s.

So, back to the question of ride quality of the Atlantis vs Platypus;  my thought is how the bike is set up (choice of tires, stem, bars, saddle and seat post)  is the determining factor.

Steve

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On Tuesday, February 11, 2025 at 8:12:58 AM UTC-5 peter...@gmail.com wrote:

Thanks, Dave and Michael.

I had not seen the video, thanks for sharing. Seems not much difference in flex except for the clem! I do question if this is noticeable for riders...

So I guess the choice comes down to whether you want to carry more load and whether you want a longer wheelbase!. (apart from considerations and preferences regarding the looks, style, and color)...

p

Michael Connors schrieb am Samstag, 8. Februar 2025 um 21:50:03 UTC+5:30:

Have you seen this video comparing the flex of Riv non-diamond frames?  https://theradavist.com/video-rivendell-the-string-test-for-bike-flex/

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[Bill Lindsay]

"So I guess the choice comes down to whether you want to carry more load and whether you want a longer wheelbase!. (apart from considerations and preferences regarding the looks, style, and color)..."

I'd say it comes mainly down to what you can get and when.  If they were both available or you were infinitely patient, then go on looks.  If you think the both look great like I do, then for me it comes down to the extra bottle cage, if I'm ever doing long rides.  :)

Bill Lindsay

El Cerrito, CA

[Armand Kizirian]

I will seize this opportunity to take a break from my work and chime in. Platypus owner who will be replacing the frame with the upcoming Atlantis.

Why?

I've ridden my Platy nearly every day since I built it up about a year ago. I love everything about the ride. I'm in fact pleased to see the latest Atlantis differs so minimally. I will gladly take the slight increase in chainstay length too. Some of my reasons for the change:

• The step-thru is stylish, and I admit I'm spoiled with never throwing my leg over the saddle now. However, it has lost it's charm for me because
  • I miss having two bottles in the main triangle
    
  • Slight complaint, but when standing at a stop and trying to grab something out of my basket bag, there is no tube between my legs to straddle, and I need to use my forearms or elbows on the bar to not let it tip to one side. Or I try to bring my feet together and stain my pants with the chain.
    
  • I like running a custom half-frame bag with a custom top tube bag on my other bikes, would be great to have that for this bike.
• More tire clearance. Let's be clear, the Platypus has an abundance of tire clearance for it's intended purpose. But, we're in the golden days of tires right now. I want to be able to run a 55mm rene herse slick, with fenders, and have the ultimate in comfort, both on and off-road.
  
• Not really part of my decision making, but the Atlantis has the extra set of rack mounts on the seat stays for a mid-stay rack.
  

Overall, more in-line with my ideal all-rounder forever bike. Time will tell if the Atlantis feels any more stiff than the Platypus, I doubt I will perceive anything. I will weigh both frame/forks with just their headsets and see if there is a difference. The seat tube is a larger diameter on the Atlantis, taking the 27.2 seatpost. I imagine some of the tubing may be a bit more robust as well, as it's traditionally been advertised to be the option in the Riv line-up for a fully loaded tour. The Platypus is Will's (and many others) favorite because they cite it having it be the best all-rounder when mostly used on paved roads (a bit more sprightly, I'm assuming).

Either way, I'm sure I'll be pleased. Yes, my 55cm purple Platypus will be for sale, when I place the pre-order.

[Bill Lindsay]

"The seat tube is a larger diameter on the Atlantis, taking the 27.2 seatpost". 

Not exactly correct.  Same Outside diameter seat tube (28.6mm).  A Frame that takes a 27.2mm seat post has thinner wall thickness seat tube than one that takes a 26.8mm seat post.  

BL in EC

[Steve]

"A Frame that takes a 27.2mm seat post has thinner wall thickness seat tube than one that takes a 26.8mm seat post"  

Interesting observation Bill, and in keeping with my impression that the rear end of the Platypus is nicely responsive to vigorous input  on the pedals, belying its long chain stays. Given the unsupported height of the seat tube above the TT it makes sense that Riv would choose to make it a bit more stout.    

I get what Armand is saying though about the Atlantis. I've been thinking about it (or an Appaloosa) with naked 2.2" knobbies, but as a complement to my more road oriented Platypus. 

Steve in AVL

[Patrick Moore]

I’m curious about “replace” instead of “augment”? If 1 Rivendell is good, 2 must be better, no? Especially as you have ridden your Platypus daily since buying it a year ago — I foresee a tragic sale and everlasting regret.

That aside, I’ll be interested to hear how you find a new Atlantis compared to the (I hope, still owned) Platypus. If the 27.2 seatpost is large than that on the Platypus, that might indicate thinner tubing — a fatter post to fill the bigger hole made by the narrower walls.

Patrick Moore, thinking (out loud, forever) about buying a Clem as a poor man’s Platypus (or, as a beater Platypus).