We get some cool “fan photos” e-mailed to us now and then, but this experimental elevated chain stay 29″er is just too interesting to keep under wraps. So, after getting owner approval, we are bringing it to you readers to show some radical ideas at work here.
This is reader “AW”‘s custom rig #1. (Number 2 with refinements is already in the works!) AW sent in his e-mail to us that the following were his goals for this unusual rig.
1- Short chain stays
2- Loads of mud clearance
3- Single speed/hub geared or normal geared capabilities
The chain stays are a super-short 410mm in length. Head angle is 71*, and the virtual seat angle is 73*, but AW tells us that the fork used here is “30mm too short”, so with his preferred fork length the angles would be slacker. The bottom bracket height on this is 300mm as it sits. AW tells us that the Continental Mountain King has 10mm of clearance between it and any part of the frame.
So “goal” number one and number two are met, but what about #3?
AW designed the drop out with a three bolt configuration and claims it has 20mm of adjustment with the single speed/belt drive set up. Of course, internally geared hubs could also be accommodated with this drop out. AW says that the derailleur hanger drop out simply bolts on with no provisions for adjustment.
AW says the frame is “a bit heavy” and the bottom bracket stiffness is not to his liking, so another prototype is already in the works. This one served to test his ideas for himself, and was manufactured in China.
Comments? Suggestions? (As far as we know, this is a personal project for AW, and no mass sales of this bike were indicated to us, nor implied)
OH my, that is pretty cool. Sorta looks like a Mrazek.
Pretty cool rear dropout.
Looks like an updated version of the Nashiki alien from the early 90’s.
http://www.mombat.org/1990_Nishiki_Alien.htm
Rear dropout design is most elegant. Only posible with elevated chainstays….
Can understand the BB stiffness issues. Not much holding it in place.
Very cool regardless!
I love seeing other people’s experiments.
The flex in elevated chainstays is always a problem. If he can come up with a way to minimise it then he’s on a winner because elevated chainstays have several practical advantages.
His chain adjustment solution is neat.
Looks like a “sawyer with high pants”! Interesting…
I assume that belt drives are problem?
@yogi: I assume you meant, “belt drive is no problem”? It isn’t an issue with this design as far as getting the belt on there, but it might be from a flexing stand point. That said, the new Center Track is said to help greatly with that.
I raced an Alpinestars Titanium bike with elevated chainstays back in the day. It too had a lot of BB flex, but it climbed like a scalded monkey. Very interested to see AW’s v2.0.
GT – Curious what you mean re: the centertrack improving the belt situation. Care to elaborate?
Ya know, utilizing a BB30, 83mm, or some form of oversized bb in combination with an ovalized seat tube could help mitigate those flex issues.
Elevated, super short stays are intriguing, especially if the flex and durability issues were taken care of.
Los
Love the Elevated Chainstays Design.
I own a Mantis Valkirie. 😉 I’d like to see this design with 29ers because i believe it’s the real way to have a really short chainstays without problems.
I can only imagine what a brand like Santa, Ibis, Niner, can do if they will use their knowledge in carbon fiber and design taste….
I really like to see a nice and well enginereed 29er with elevated chainstays.
To prevent some flex i believe AW will have to work more on the chainstays (for me, they are to high and too straight) that not on the front part of the frame. Take a look at some of the Richard Cunningham design http://mombat.org/Mantis.htm
Hope to see more news! Good luck and good work to AW.
Well thanks for the comments, currently the bike has slightly more bb flex than my Ragley TD-1 ,, I have only ridden it ” around the block ” but it seems quick and agile ,
AW, you have solved the one big problem I have with elevated chainstay bikes – the look. Some may like their looks, but most elevated chainstay bikes are pretty ugly in my book. But this one works for me. Keep it up.
OMG I want one!
Cool!
410 would be short even for a 26er 🙂
Why not add a 3rd chain stay to the non-drive side? It could be nearly in the traditional location, and on the NDS side theres’ no front derailleur/chainring clearance issues to worry about.
Another solution might be a heavily ovalized seat tube that is as wide as the stays to help with lateral flex, or just a gusset between the seat stays, chainstays, and BB shell.
Either way, fun stuff.
GT-Yup that is what I meant. Jimmythefly-neat idea! How thick are the chainstays? Are they welded at the seat tube? KOOL………..
22mm chain and seat stays chainstays are attached
To the the seat tube via a sheet gusset but maybe
Something more 3d would help
The problem here (and with all elevated chainstay bikes) is that you’ve taken what was a truss junction and hung it out on a tiny little fin.
Using a standard non-dirve side chainstay will help, but it’s going to have to be really heavy since it’ll be seeing a dozen times the stress of a pair of chainstays.
Alternatively, lower the down tube so it no longer instersects with the BB shell, and box in the entire area between the elevated stays and the BB. Actually, you’d be best off just making the biggest, widest box there that you could and welding the seat and down tubes to the box. I don’t think it would look very attractive, though.
Elevated stays came up a couple weeks ago on the MTBR framebuilding forum. Summation: once you add enough material to keep them from (a) breaking, and (b) flexing all over the place, they’re not really worth it. Carbon may very well change that argument….
@Jim in SF: Center Track technology supposedly allows for more “belt line” variances than current belts will tolerate. So, for a frame with some torsional flex, for instance, a Center Track belt will stay on the pulleys, and not ratchet as easily. Also, it helps prevent the belt from “walking” off a pulley.
I am also told that Center Track will require less belt tension, so there seems to be a benefit in terms of designs that have a small degree of flex, like steel bikes, or perhaps this design at some point.
GT-Seems you have great faith that the Center Track Technology will solve most of the problem with belts………we will see..
@yogi: Don’t confuse my reporting with confidence in the system. 😉 I am only relaying what I’ve been told by Gates. We hope to be on a Center Track equipped bike in a month or so. Stay tuned…..
Very interesting! I ran a UK made Ozone CO2 (Bigfoot Smokestone) for a couple of years and 8k miles in the mid 90s on the muddy South Downs here in Blighty. The mud clearance gain was tremendous compared to what was around at the time, but the limit became heel clearance. Climbing performance/traction was great but somewhat wheelie prone on the short wheelbase – also a bit skittish downhill. Also had a 1 1/4 headset – those were the days. Just needed a 29″ wheel……… Good luck in your quest AW.
The need for a front derailleur mount position is crippling the potential of this bike.
The chainstay could be more or less in line with the top of the chain otherwise and enable a much stiffer frame (for an Elevated CS).
The elevated chainstay is the answer to a lot of possibilities – just need to get it stiff enough. The short chainstay that is possible with this destroys one 26er argument against 29ers.
Let’s see what else – SS, Alfine/Rohloff, belt drive. 🙂
BMac you have a good point there i could then lower the chainstays to make it stiffer,
on that point i havent run a front mech on any of my bikes for , maybe 5 years
Looks like the answer to the question nobody asked.
“Looks like the answer to the question nobody asked.”
We’d still be riding Penny Farthings if we all thought like that. I have heard the same said about 29ers too.
Read the article again – this is an experiment. The next version is on the way.
I remember elevated chainstays from back in the day, they went away for a reason.