Toyo Atlantis Double Crank question

[Cead Nardie-Warner]

Has anyone here ever put a Velo Orange double on a Toyo Atlantis? Did the manufacturer recommended 118mm BB spindle clear those luscious chain stays?

I'm a novice, and this is my first DIY frame-up build. So, y'all are my first stop in trying to avoid buying a new crank.

[Garth]

Spefically which VO crank with which rings are you referring to ? There are two models with different BCD's. That version of Atlantis has very bowed and non-dimpled stays just like my Bombadil and you just can't fit any sized double on there. These frames are not meant for double road cranks with straight arms. VO's suggested BB length would be for "average road frames", but the very bowed Atlantis and Bomba chainstay shape is not that. You run into a double whammy of clearance issues, of both rings and arms. Fitting cranks on these frames is really a case by case hands-deal, you won't know precisely until you're doing it. You may end up with such a long BB that the chainline is overly wide and or the arms end up wider than you like. If you're gonna try anyways, have a 118, 124 and 127 BB on hand, with some spacers for the driveside if needed. The most common to use are .5mm, 1mm and 2mm. 

Otherwise something like a New Albion GS double crank may fit better, with 46/30 rings and 94mm BCD. The sugggest BB sizes start at 110mm, so even if you have to go up a 113/115mm, you won't end up overly wide in chainline or tread width. It's not blingy silver for sure, but least it doesn't have the wonky hidden 5th arm like the other Sugino made versions. 

[Patrick Moore]

Garth is right that straight-arm cranks are meant for narrow-stayed frames. I did get a TA Pro 5 Vis to work on a very wide-stayed mountain bike (it fit 60 mm tires + fenders, comfortably) by using a custom 145 mm Phil and installing the big ring in the middle position for a “1X + granny” setup. The Q was 160 mm IIRC, about that of a 7 speed XT crank on 122 mm spindle, and it worked well, especially as there now was very ample room between big ring and crank arm for the fd cage.

I’m going to try again, this time with the Monocog 29er frame and 38 t inner using early DA crank and 130 mm spindle for a single speed setup; we’ll see.

But yes, be prepared to use a very long spindle and be limited to very small rings on the inside.

On Sat, Dec 14, 2024 at 5:37 AM Garth <gart...@gmail.com> wrote:

Spefically which VO crank with which rings are you referring to ? There are two models with different BCD's. That version of Atlantis has very bowed and non-dimpled stays just like my Bombadil and you just can't fit any sized double on there. These frames are not meant for double road cranks with straight arms. VO's suggested BB length would be for "average road frames", but the very bowed Atlantis and Bomba chainstay shape is not that. You run into a double whammy of clearance issues, of both rings and arms. Fitting cranks on these frames is really a case by case hands-deal, you won't know precisely until you're doing it. You may end up with such a long BB that the chainline is overly wide and or the arms end up wider than you like. If you're gonna try anyways, have a 118, 124 and 127 BB on hand, with some spacers for the driveside if needed. The most common to use are .5mm, 1mm and 2mm. 

Otherwise something like a New Albion GS double crank may fit better, with 46/30 rings and 94mm BCD. The sugggest BB sizes start at 110mm, so even if you have to go up a 113/115mm, you won't end up overly wide in chainline or tread width. It's not blingy silver for sure, but least it doesn't have the wonky hidden 5th arm like the other Sugino made versions. 

--

Patrick Moore

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

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[Garth]

For reference I measure the chainline of my Andel RSC6 triple 110 BCD crankset with 24/36/44 rings. 46mm. That's the center of the seat tube to the center of the middle ring, as this is a triple. If I left off the 24 and called it a double, then the chainline would be measured between the two rings, and on my crank with it's 8sp spacing of some 6.something mm, that would make say a minimum of a 49mm chainline for a double. That would require a long spindle for a double crank just so the 36t ring clears. Mine is as close as I be with a few mm to spare. Even then, wimpy derailleur springs can let the chain sag over bumpy terrain and suck itself in between the frame and ring. Not the end of the world but no fun and gouges the tube. A 34t ring would offer a little more leeway. I've used a 50t big ring on mine and it was no issue. It's the innermost rings that are limiting. No larger than a 36t for a reasonable double. My best guess is a 127mm cartridge would be minimum for it to work, given it follows the Shinao/Tange offset dimensions per give size.

[Cead Nardie-Warner]

Thank you all for your responses. I just went ahead with getting a used triple. Works great. HMU if you want to buy a VO double :)