Jobst on short chainstays

[iamkeith]

I was daydreaming about a bike project and looking for information about some old IGHs this memorial day morning, and stumbled on a google group thread from 1991 in which Jobst Brandt participated. I thought this off-topic comment about chainstay length was interesting. Echoes everything Rivendell (or vice versa, given the chronology), but it is the first time I've heard the 'drafting' component of the racer-driven designs explained.

jobst_b...@hp1900.desk.hp.com

K---- C----- writes:

> Try as I might, I just cannot for the life of me figure out how short
> chainstays are going to help climbing. Someone enlighten me before I go
> nuts with this one!!

That's simple.  Short chainstays help you do wheelies if the hill gets
steep.  It's this kind of thinking that brought us bike with so little
tire clearance that a one inch cross section damn near scrapes the fork
crown and requires letting the air out of the rear tire for removal.

I think someone noticed that the fastest road bikes are the ones
ridden by TTT riders.  These bikes are the shortest road bikes and
therefore, short bikes are fast.  The trouble is, they are short to
allow four riders to draft as close together as possible, not because
a short bike is inherently fast.  This concept seems to have escaped
the advocates of short bikes.  They use terms like " they're
rsponsive" amd "accelerate quickly".  What can you say to such a
claim?  It is so patently unfounded that a response is difficult to
construct without being argumetative without just playing stupid.

Bicycle lore is great, and shave those legs before climbing hills.

jobst_...@hplabs.hp.com


R.I.P., Jobst.

[hugh flynn]

I picked up a gloriously long-stayed  Appalloooooosa around the time the new Atlantis was announced (with requisite hew and cry over its new long stays), and can only comment that I still don’t get the objections. I’m no faster or slower on the Appa than on any other bike I own (climbing or otherwise), but can attest that I massively enjoy steep on and off-road descents on this Cadillac of a ride more than on any of my shorter stayed bikes. 

Not suggesting it’s a massive night and day difference by any means, just that I FEEL like the Appaloosa is somewhat more shure-footed. If that has nothing to do with the long stays, well, at least I can report that I have yet to find anything to be unhappy about with the bike (and much to be VERY happy about).

Hugh “long stays seem nice so far” Flynn

Newburyport, MA

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Hugh Flynn
Newburyport, MA

[Jeremy Till]

Further comments by Jobst on chainstay length can be found here: 

http://yarchive.net/bike/frame_dimensions.html

http://yarchive.net/bike/short_chainstays.html

A couple of good quotes: 

For road bikes in the range that is available, the longer the
chainstays the better the bike handles in all but 10mph turns.

and: 

Chainstay length is primarily a comfort effect of sitting directly
over the rear wheel or not. Secondarily, a short wheelbase makes
weight transfer on braking less advantageous and least of all steering
motions more disruptive to straight line riding.

 

In the frame dimensions thread Jobst also says that when he was speccing his custom frames, he would basically have the builders (Tom Ritchey and Peter Johnson) leave the chainstays as long as possible, which I would guess put them somewhere around 45cm or more, so long for a traditional road or touring bike but not into the territory that Grant has pioneered, mainly because I don't think chainstays that long were available from tube manufacturers.  Pictures of his Peter Johnson show that there was clearly more than adequate space behind the seat tube for a frame pump:

http://bikecult.com/works/archive/04bicycles/pjohnsonJB04.html

I wonder what Jobst would have made of Grant's recent designs.  

I ride my long chainstay bike (Clem) mainly as a MTB and I would say all of this holds true for off-road riding as well, where you are far more likely to encounter grades of 10% or more, and the bikes ability to keep the front wheel down while going up without significant body english feels like a real boon.  On the way down, it feels stable and like it has a huge "sweet spot" where I am well balanced between the wheels.  

[John Hawrylak]

I suggest 45cm chain stays were the longest ones commercially used since the 1970's since normal front ring was 52t, largest cog 34T (for touring & hills) and standard chain lengths were packaged at 116L, the value using the standard formula 2*Lstay +(Fl +Rl)/4 +1, for a 45cm stay.

Longer stays would require longer chains, so perhaps the manufacturers thought 45cm was long enough.

Most JoeyA riders have commented on the need for chains > 116L.

If specing a bike now with a 42T front (100gi, 11T small rear) and 34T large rear, 116L chain requires a Stay length of <= 48.3cm using the chain length formula.

John Hawrylak

Woodstown NJ

[Patrick Moore]

I recall reading that when Jobst had his frames made, he told the builders not to trim the stays at all. 

I just looked again at the wonderful photo on the Jobst calendar of his 1958 Cinelli road racing bike: it has stays even Rivendell would be proud of.

[Garth]

  Sure !  When I had a custom sport/touring frame made in '99, that's 1999 for all the why2k kiddies.... I requested along with 62cm tt as long of stays as I could get which was 18"(close enough to call it a 46cm). The tubeset was from Reynolds 531ST. He made them shorter when I received the frame and when I discovered it at home and called him he checked the original order and indeed they were supposed to be 18", so he redid the frame. He mentioned it was about the last full set of stays he could get from Reynolds in 531.  

Anyways ... I have enough room with 35mm tires no fenders to nave my pump behind the seat tube. It handles like a racing bike, the same as I was used to but with much longer stays :)  It handles distinctly different from the Riv way. I've not ridden what people call "low trail" handling , but back then no one used such terms, it was what it was.  When I hop on the Bomba it takes me a while to get used to it's handling, most notable out of the saddle it just feels goofy. Likewise so does the Franklin after riding the Bomba.  For high speed maneuvering, the Franklin feels most natural to me, responding to every rider input of hands and body, the Bomba I still have to remind myself to "sit back and let it go".

[Lester Lammers]

I agree 100%. There is a lot of bike folklore out there. You won't be able to make a sharp U turn as easily but so what?

[Eamon Nordquist]

1983 Trek 720's and 850's had 47 and 48.5 cm stays, respectively. I suspect those were the maximum length you could get. Great riding bikes. I think most people would objectively consider those long chainstays, and that's about in the range of the current Waterford Atlantis. I doubt Jobst's stays were any longer than that.

Now, if one has reasons to find stays well into the 50's too long for their purposes, that doesn't necessarily make you a long chainstay denier who insists on 42-43 cm stays. I bet the very looong Riv's do ride great, but I do hope all the Taiwan bikes don't go to that extreme. That doesn't mean not making long bikes, but hopefully still keeping a Taiwan made option that can tour, without having chainstays well into the 50-60 cm range.

Eamon
Seattle

[iamkeith]

You guys are correct.  I didn't consider the context of Jobst's comments, and what length of stays were even available in that era.  Obviously, as those of you who were even more familiar with his contributions and philosophy than me realized, he was pretty outspoken about this too.   The lightbulb for me was the idea that the ultra-short stays preference came about by trying to emulate a "team" of riders who worked in a tightly-grouped paceline pack, drafting each other.   Too bad someone didn't make the argument that the REALLY fast riders - the ones who could be competitive on their own merits and without the team - were better off with a more stable bike in which more of their exertion was transmitted into forward motion instead of some of it being necessary to keep a wobbly, twitchy bike pointed straight.  Like a speed skate vs a figure skate.

But I don't really know what I'm talking about here, because I've always been a non-racer type bike enthusiast in addition to mostly mountain biking.     All I know is that every time I get used to a longer chainstay, I lose all interest in riding my old, shorter bikes that I once thought I'd keep forever.  Since I very rarely do group road rides, I couldn't understand why so many people are so resistant to them - until now.   The weight and 'quickness' arguments are so evident in their fallacy.   Twitchy might 'feel' the same as quick but a cycle computer tells you it's not, and all anyone has to do is try it.

I'm sure there's a limit to what length makes sense, but I'm personally looking forward to finding it.  I too wonder what Jobst would have thought about Rivendell's new chainstays.  I'm sure people will get their wish of some models being retained that don't quite push that limit and that stay well short of the 50s.  Looking at the new geometry chart again just now I see that, as their designs are updated and production moved, SOME of the models (Atlantis) seem to moving completely toward proportional chainstays which increase incrementally with the frame size, with other models (Homer)  less so - at least for now.  Interesting that the newer Roadini is proportional AND mostly intended as a go-fast.  I'm guessing the bottom bracket shell casting complication is the difference?

[Bill Lindsay]

Eamon said "I do hope all the Taiwan bikes don't go to that extreme"

That could mean one of two things

A.  I hope that ZERO Taiwan-made Rivendell models have a chainstay length of >50cm in any framesize

B.  I hope that there remain one or more Taiwan-made Rivendell models that are touring capable with a chainstay length of <50cm in my size

The wording of Eamon's comment sounds like A, but I think he meant more like B. 

Bill Lindsay

El Cerrito, CA

[Eamon Nordquist]

Bill, I definitely meant option B!

Eamon

[Metin Uz]

One thing to note is that Jobst rode a very large frame, 64cm or maybe taller. So shorter chainstays had him sitting over the rear wheel. We all experience our own reality, and generalize from there. I remember Brian Baylis claiming that Colnago's rode significantly better than other Italian frames in 50cm or smaller sizes. Perhaps most designs were (are) based on 56cm, than extrapolated.

--Metin

[hugh flynn]

I’m still interested in the answers to “how long is too long?” and “what are the drawbacks to long, as long as it’s not too long?”

My recent Appaloosa experience only confirms (for me at least) that Riv long doesn’t seem to be too long.

Hugh “long in the tooth” Flynn

Newburyport, MA

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[Garth]

Here is a person who extended the chainstays 25cm. of a donor mtb into a long tail cargo bike .  Pretty cool ! 

 http://www.steves-workshop.co.uk/vehicles/cargobike/cargobikeindex.htm

Of course ... many cargo bikes have very long chainstays .  The only on-road differences I suppose would be getting used to the different cornering of a very long wheelbase. 

[Mark in Beacon]

I suppose at some point if you made them really really really long, you'd be in danger of the front of the bike running into the back of the bike. But this is probably only a theoretical problem. Just remember what the good Duchess of Windsor said, "You can never have too many Rivs, and chainstays can never be too long." (I may be paraphrasing somewhat.)

So long,

Mark "the long and the short of it" Roland