# Who wants to talk me into, or out of, elevated chainstays?



## Walt (Jan 23, 2004)

So for those of you (all of you, I'm sure) who regularly read my insipid blog, I've got some belt drive stuff sitting around waiting for a frame to put it on. Long story short, there's no way to fit the "chainring" onto any of my existing bikes as a retrofit, so I'm contemplating building myself a new bike.

With that said, the ring is HUGE (46t, about 1cm wide, run on the outer ring position of any 4-arm crank). For all practical purposes, it's like running a 46t ring on the middle position of your cranks, with a nice narrow BB spindle. In short, it's a huge PITA if (like me) you want 29" wheels, relatively short chainstays, and enough room to squeeze in an actual mountain bike tire (in my case, 2.1" is big enough). The Spot Longboards that I've seen all use 18.5"+ rear ends and (IMO) overmanipulated driveside stays to solve the tire/stay/ring clearance problems, but that's not a solution that appeals to me, since I feel like I'd be giving away a lot, geometry-wise. Chains work pretty good, after all. 

So briefly, I'm thinking about elevated chainstays. I can kill 2 birds with one stone, methinks - no need to break the dropouts or stays to get the belt installed, and no need to worry about chainstay clearance for the ring or tire. I could even do only a driveside elevated stay if I wanted extra cool points...

But I look around at old Nishiki Aliens and AlpineStars and they're hideous, and look heavy and complicated and annoying to build. Should I go ahead and bite the bullet and do it? If so, who's seen a cool elevated chainstay (hardtail) frame or bike that might be more inspiring? Should I do it or not?

Thoughts?

-Walt


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## scooter916 (Jan 2, 2006)

you could alays retro fit an old frame with an S&S coupler on the seat stay, thats how Greg over at Patrick Cycles is doing my frame


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## Schmucker (Aug 23, 2007)

scooter916 said:


> you could alays retro fit an old frame with an S&S coupler on the seat stay, thats how Greg over at Patrick Cycles is doing my frame


Except that doesn't solve any of problems except for how to install the belt.

I'd probably do some sort of vertically curved stays that went up past the seat tube and connected at the downtube. Although you apparently don't do curved tubes, so that's probably out. The problem you're going to run into is more sway in the bottom bracket, but an extra wide ovalized downtube or seat tube might solve that.

A few pics of some I found
Some Nishikis
https://www.neebu.net/~khuon/albums/nishiki/nishiki_fan_Ariel.jpg
https://farm4.static.flickr.com/3142/2471471631_3555913500.jpg?v=0
Probably more your style
https://www.matuzmaster.hu/_userfiles/image/2007-09-15-retro-rocky-mountain/1222-big.jpg
This wouldn't be bad if the little tube that goes from the BB to the downtube/chainstay was given a curve and the ends of the stays curved down.
https://img.2dehands.be/f/view/21312639-minerva-mountainbike-te-koop.jpg

And screw the belt, go shaft!
https://farm2.static.flickr.com/1210/653062024_eacf4fb753_o.jpg

Or make a custom hub and only have a non-drive stay. It'd be like a Lefty, but for the rear!


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## vulture (Jan 13, 2004)

*cooks bros*

A friend of mine had an old cooks brothers drive side only elevated chainststay. With the belt drive being single speed or internal hub you could bring the stay quite low ( no front der) and brace it nicely. Special problem. It will be interesting to see if belt drive bikes will be like elevated chainstay bikes 15 yrs from now, curiosities. 
good luck tho.


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## smudge (Jan 12, 2004)

Drive side elevated stay. Do it. 

I *really* want to like CD but wow, what a pain. I was looking at the belt length/gear ratio/cs length matrix the other day...at least they give us decent drawings.


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## pvd (Jan 4, 2006)

I think that you should instead take a more realistic use for belt drive systems on bikes. They are not good for performance applications.

Due to the tension that must be maintained constantly on the system, the freehub is loaded a lot during freewheeling. This will destroy all but the finest hubs in short order. I talked to the folks at Gates and Spot that did the testing and development on their system. They confirmed that all of their testing was done on King hubs, not XT or Deore level components. I would have run a lot of test time on lower level parts in harsh conditions.

This load during freewheeling also creates something I call freewheel braking. Go to the local skatepark and watch a bmx kid with one of those overly tensioned chains. Note how fast they coast down when not pedaling. The load on the freewheel creates a lot of drag at the interfaces. Not good if you plan on going fast.

The gearing choices also limit chainstay length and ratio selection. Only a few options exist, leaving you SOL if you don't like what they got.

For these reasons and the issues you mention I relegate a belt drive bike to only be used for local cruiser applications or train/bus bikes. I love the idea of them, but they are really only useful in the low performance applications.


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## Walt (Jan 23, 2004)

*Couple questions*

Is it a mountain bike? If so, how is he making the drive cog/chainring fit without hitting the chainstay?

Getting the belt on isn't the problem for me. Tire/chainring/chainstay clearance is.

-Walt



scooter916 said:


> you could alays retro fit an old frame with an S&S coupler on the seat stay, thats how Greg over at Patrick Cycles is doing my frame


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## toddre (Mar 1, 2004)

Bring back the Alien !!!:thumbsup: 
If anything for sh**s and giggles. I bet with a well thought out design, you could keep the weight down. Or maybe go with an assymetrical set-up?


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## Walt (Jan 23, 2004)

*Good points*

P -

I've also thought along those lines, simply because it seems to me that every solution available to make the darn things work will also cause a bevy of annoying problems.

To whit:
-Since the belt drive system is only about 30-60g lighter (not including chaintugs) than a conventional singlespeed drivetrain, all the extra frame bits for an elevated chainstay frame are going to end up making this bike quite a bit heavier than my chain drive bike. 
-Chainstay lengths are fixed to the available cogs/belts that are out there, and I don't particularly like what I see. I could wait for more selection, I guess.
-I'm not a huge fan of running super-high tension, though to be fair, I've yet to hear about anyone having problems with a hub blowing up. As far as I can see, the bikes coast downhill just fine. 
-I can't run my favorite 2x2 setup (38/34 in front, 20/16 in the rear) which is pretty crucial for the ~10 mile paved rides to the trailheads around here. No way I'm putting a Rohloff on.

Maybe the solution is to just do a townie type bike with offroad capability and test the belt out that way. Long chainstays? No problem. Heavy? Who cares? If the thing just blows me away, I could build another more XC oriented frame down the road...

-Walt



pvd said:


> I think that you should instead take a more realistic use for belt drive systems on bikes. They are not good for performance applications.
> 
> Due to the tension that must be maintained constantly on the system, the freehub is loaded a lot during freewheeling. This will destroy all but the finest hubs in short order. I talked to the folks at Gates and Spot that did the testing and development on their system. They confirmed that all of their testing was done on King hubs, not XT or Deore level components. I would have run a lot of test time on lower level parts in harsh conditions.
> 
> ...


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## Thylacine (Feb 29, 2004)

Damn, how did I miss this thread?

Some obvious design shortcommings here, but it's always stuck in my mind (probably due moreso to the paint)


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## Baulz (Sep 16, 2005)

Thylacine said:


> Damn, how did I miss this thread?
> 
> Some obvious design shortcommings here, but it's always stuck in my mind (probably due moreso to the paint)


Rocky Mountain made a similar frame in 1995, the suzi q.

I always thought it was pretty cool looking, but kinda pointless.

http://www.mtb-kataloge.de/Bikekataloge/PDF/Rocky_Mountain/1995.pdf page 4-5


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## itsdoable (Jan 6, 2004)

Baulz said:


> Rocky Mountain made a similar frame in 1995, the suzi q.
> 
> I always thought it was pretty cool looking, but kinda pointless...


If you rode the west coast shore trails back then with the available equipment, you were treated to a cacophony of clanking chain on chainstay. The Suzi (and Cirrus) were quiet.

I've always liked asymmetric elevated chainstays.


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## swift (Apr 3, 2007)

itsdoable said:


> I've always liked asymmetric elevated chainstays.


Word! :thumbsup:

I like the I-horse implementation on their FS rigs.


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## itsdoable (Jan 6, 2004)

pvd said:


> ...Due to the tension that must be maintained constantly on the system, the freehub is loaded a lot during freewheeling. This will destroy all but the finest hubs in short order....


I'm not sure I agree with this, the load on the bearings from belt tension is similar to, or less than the load on the bearings from pedaling, especially climbing. Granted the freewheel takes a static load during pedaling (and Shimano freehubs are designed accordingly), the hub & crank bearings are designed to take that load, as are most cartridge bearing freehubs. I think the biggest issue is run-out tolerance on the freehubs and cranks, the belt system cannot tolerate run-out. This means higher tolerance parts, or belt wheels with some run-out adjustment to handle standard bike parts - which leads to maintenance and set-up issues.

All that said, I'd like to run one and see how they hold up though our winter (chain maintenance is a pain).


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## TgMN (Aug 22, 2006)

Newb frame builder here. Just finished frame number one and was thinking about a elevated chainstay 29er for #2. Not sure I understand the attraction of the asymmetric approach though. Once you've added the necessary structure to elevate one side, the added weight in extra chain stay length to elevate the other side has to be pretty negligible. Asymmetry just seems like it begs to cause weird handling issues under heavy pedaling loads or impacts. Your thoughts?


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## Thylacine (Feb 29, 2004)

Weird handling issues? Like what?

Asymetric makes sense because it makes the rear end substantially stiffer. You're only raising the stay to avoid the chain, so what reason is there to elevate the non-drive side apart from looks?

There's many non-elevated examples of asymmetry if you look in the suspension world.


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## vulture (Jan 13, 2004)

*the cooks was like this*



Thylacine said:


> Damn, how did I miss this thread?
> 
> Some obvious design shortcommings here, but it's always stuck in my mind (probably due moreso to the paint)


With a unicrown fork blade for chainstay. It could be way farther down the seat tube to be stiffer. Sometimes the old cooks would rub the tire pretty bad on the non drive stay, but it had terrible clearance.


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## pvd (Jan 4, 2006)

itsdoable said:


> Granted the freewheel takes a static load during pedaling (and Shimano freehubs are designed accordingly), the hub & crank bearings are designed to take that load, as are most cartridge bearing freehubs.


Actually, given an ideal system, the bearings of the freewheel mechanism do not handle any load except while freewheeling. Under load the pawls take the entire load. This is of course in theory, but certianly a very minimum of drive loads will be shared by the bearings.


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## Thylacine (Feb 29, 2004)

My favourite Elevated Stay bike eva. A complete engineering nightmare, but a thing of beauty.


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## Schmitty (Sep 7, 2008)

Owned a few Mantis elevated and non bikes. Brave had an asym bike, and Alpinestars had some sym elevated frames. Elevated stays make for real short stays and mondo mud clearance (one of Richard's reasons for going that route). Bikes are asym by nature anyways... no strange handling dur to asymetry. The belt thing is hokey.


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## formulaone33 (Jul 20, 2008)

Ugh...center pull cantilever brakes! My hands hurt just looking at them.


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## fjyang (May 4, 2007)

Built this elevatd chainstay bike last year with a frame I got from e-discountbike.com. Slap it together with parts I have and it ride better then the price tag suggest. I think E-Stay bikes are simple and clean designs and elegant when done right. For a belt drive or 29er its time to bring it back with fresh new application.


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## eMcK (Aug 22, 2007)

That is something else.

It's been awhile, but I seem to remember the fork legs on Girvin/Noleen forks facing the other way.


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## TgMN (Aug 22, 2006)

Thylacine said:


> Weird handling issues? Like what?
> 
> Asymetric makes sense because it makes the rear end substantially stiffer. You're only raising the stay to avoid the chain, so what reason is there to elevate the non-drive side apart from looks?
> 
> There's many non-elevated examples of asymmetry if you look in the suspension world.


In an asymetric configuration there are going to be some loadings where the stiffness of the two sides are not the same, and under that load the wheel would twist sideways out of the plane of the main triangle.

Not sure if this is of any practical significance and your reply would imply that it is not.


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## toddre (Mar 1, 2004)

eMcK said:


> That is something else.
> 
> It's been awhile, but I seem to remember the fork legs on Girvin/Noleen forks facing the other way.


Yeah..they are...Look at the front brake..
I always thought the Noleen fork was an under rated fork for it's day... I bet it would be a fun 29er application


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## fjyang (May 4, 2007)

I reverse the fork legs on the Noleen/Girven Crosslinks so it have a leading instead of trailing profile. It rides fine and increased the wheelbase 1/2" from 42.5 to 43" so rides more stable. No problems with the brakes behind the fork, I've try but can't seem to hit anything (linkages) with the V-brakes behind the fork legs, so far so good. I though it might be a poor man's way of getting a Gary Fisher G2 geometry forks by reversing the Noleen fork legs. Its probably the only fork that allow you to do that.


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## Thylacine (Feb 29, 2004)

TgMN said:


> In an asymmetric configuration there are going to be some loadings where the stiffness of the two sides are not the same, and under that load the wheel would twist sideways out of the plane of the main triangle.
> 
> Not sure if this is of any practical significance and your reply would imply that it is not.


Mate, the forces are different regardless. You have the chain on one side, remember? Doesn't matter if the stay is elevated or not in that respect.

What does matter is that when you elevate the stay, the compressive forces of the chain are now not in line with the stay, so the stay has to be designed to counter this.

The forces are already assymetric, now however they're just more assymetric and you have to design the bike as such.

As I said, if you look at the suspension world, you'll see all the smart guys doing assymetrical stays, because they know it's stiffer and lighter that way. The 09 Turners, Ironhorses etc which do have elevated stays only have drive side elevated stays.


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## xy9ine (Feb 2, 2005)

always thought the yeti iteration was pretty cool:


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## w.king (May 27, 2008)

*Asymmetric chainstays for beltdrive*

Hello, here my 2c:

I´ve tried this constellation some years ago. 
Custommade frame - not the lightest (= weakest) AL-tubes, Rohloffhub, handmade front- and rearrings, 8m-belt (16mm!). The "beltline" was/is correct!

But...it doesn´t work well. 
I´m not a sprinter, but while climbing or starting - since little more momentum, the belt slips. 
Then I tensioned the belt so extrem, that the frame was constantly bent to the left (just a little)!!!
The belt still slips while normal hillclimbing!!! :madman:

I found out, that the elevated chain/belttube has been bent to the right side (and little bit upside). 
This means, front and rear ring are not in the same direction, and of course the virtuell chainstay length vary!

A chain could tolerate this, but a belt...:nono:

I´m sure, that the common frames work more/less in the same manner.
To use a extra big chainstay could help, but the weight?...
I remember a poster (don´t know the nick), who had the same idea. He uses(d) a Mrazek. 
What´s his experience?
Imo, the only solution is, to use a normal rear triangle.

-walt


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## pvd (Jan 4, 2006)

The new engineered systems will work far better than your home made system. Tension is an issue, but not as extreme as in your case.


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