Info on "scalloped" seat tube

[Gsinill]

I assume the purpose is to accommodate a geo with short chain stays?
Or was this common during a certain era, for specific builders, more stiffness etc.?
Just curious to educated myself...
BTW, I borrowed "scalloped" from Cannondale's Synapse, since its ST has a similar shape and was the only thing I could find.

[vjp]

Yes, for a short wheelbase, like a crit bike.

[wallymann]

the legendary/notorious Rigi:

http://www.bikecult.com/works/archive/04bicycles/rigiPDSstb.JPG

[Dr Luxurious]

Wow, Rigi!
Haven't seen/heard that in a loooong while.
I wanted one of those pretty badly back in the day just for the funky factor.
I wonder how those ride?

[ultraman6970]

Seen that in some french manufacturers, generally custom made stuff for pros. The reason IMO is to make a good climbing bike. The back of the bike gets stiffer, easier to climb.

No idea about a criterium bike with this feature. could work tho.

[Ken Robb]

my experience: all else being equal (never is) shorter chainstays= rougher ride and twitchier handling which isn't what I want in a bike. The proverbial "crit racer" might like a bike like that. Any advantage short chainstays might add for climbing would probably be offset by crappy handling in fast descents for me and only skinny tires would fit.

[ntb1001]

I remember waaay back in the day...around '81, I knew a guy who custom built his own frame and he made the chain stays so short he couldn't install the rear wheel with air in the tire, it would hit the seat tube...he had to install it flat then fill it with air. I don't
think it would've very good in a race if you needed a wheel change.

[El Chaba]

I assume the purpose is to accommodate a geo with short chain stays?
Or was this common during a certain era, for specific builders, more stiffness etc.?
Just curious to educated myself...
BTW, I borrowed "scalloped" from Cannondale's Synapse, since its ST has a similar shape and was the only thing I could find.

That arrangement looks exactly like a Denti that I bought back in the mid 80's. Despite the short stays, it handled and rode very well as it seemed to be sorted to accommodate the short back end (center of balance shifted forward over the front wheel). My Denti was made with a combination of Columbus SL and SLX. The indented tubes were SL. Incidentally, you could change the rear wheel with the tire inflated with no hassle...

[spacemen3]

Mino Denti definitely liked short wheelbases, and I don't recall seeing a CBT Italia that didn't have the scalloped seattube. Here's my CBT Italia Dream frame that I'll eventually get around to building.

[Gsinill]

Mino Denti? Now this all makes sense ;)

On a serious note: thanks all for your input and educating me.

Mino Denti definitely liked short wheelbases, and I don't recall seeing a CBT Italia that didn't have the scalloped seattube. Here's my CBT Italia Dream frame that I'll eventually get around to building.

[El Chaba]

Mino Denti definitely liked short wheelbases, and I don't recall seeing a CBT Italia that didn't have the scalloped seattube. Here's my CBT Italia Dream frame that I'll eventually get around to building.

NICE frame....

[spacemen3]

Thanks! I believe BiemmeZeta was another Italian maker that scalloped their seattubes.

http://forums.thepaceline.net/showpost.php?p=1495181

http://farm7.staticflickr.com/6136/6037041454_3216fd46b1_b.jpg

[abalone]

I had a bike once with super short chainstays. The tube set was a True Temper with a curved seat tube. The bike felt extra snappy especially when out of the saddle and the rear wheel always felt firmly planted and better underneath me when sprinting too. So, I'd say the biggest perceptible difference, and even then it's still a slight perceptible difference... The biggest perceptible difference was felt when out of the saddle. It actually felt more balanced because I think when you stand up your body weight shifts more forward, so having the rear wheel further forward helps to alleviate any rear wheel skipping if you are leaning too far forward. Anyway, if you are leaning so far forward on the bike that the rear wheel skips a bit, then you are leaning too far forward. But anyways, you get the idea. With the rear wheel more forward it just felt more stable when I was standing When climbing or sprinting.

Sitting down though, I really didn't notice that much more of a difference compared to my other longer chainstay roadbikes. I didn't really seem to notice a benefit or disadvantage on handling either. I thought it looked kinda cool, but I can't say one way or another if the handling was better or worse. I really couldn't tell when seated really any difference compared try other road bikes.