Yeah, just at a high cadence when I'm going really fast. Other than that, no bobbing at all. I just stripped the screw in my saddle so I need to go buy another before I can ride so I'm pretty pissed about that. The thing would not budge for the life of me.

sux dood. If you have access to a dremel, you could make a new slot in the screw..

And I tend to 'bob' going fast downhill too. But I've found that it helps to tense up my legs and stand slightly to get a more fluid motion. Or maybe this just means that I need some better **** for my bike, lol.

Yeah and I still haven't done anything about it, mainly because of the current 30 degree weather outside and me having no motivation to even get outside to drive and get a new screw. Yeah, I'm currently attempting to get a Fizik Arione for cheaper than it's retail price, I read A LOT of good reviews about it and I've read so many good things about it on here. I need a little more comfort than the San Marco...

Have you fitted yourself? If not, get your gf/so/bf/wife/husband/neighbor/parent to help. Take your shoes off and stand against a wall on a hard floor. Take a hardcover book about one or two inches thick and shove it up hard against your pubic bone such that it feels you are almost lifted from the floor and then mark the wall at the top edge of the book. Measure that height. Then multiply that number by .883 and that is your saddle height measured to the center along the seat post. Set your saddle there to begin with. Set the nose of the saddle tilted slightly to noticeably upward. If you have standard drop bars now get in the drops and look down at your bar, it should cover the front axle (this is not always true). If it does not you need adjustment fore or aft on the saddle.

If you are bobbing, your saddle is too high. Saddle height must be set to your stature, not for style points for having seat post showing. If you cannot achieve a good aero position in the drops with that saddle height (.883XPBH) then your frame is to big which prevents the proper 3 to 5 inch saddle to stem drop. The bigger you are, the longer your arms, the more drop you may need to get a good areo position. Little people may not need as much drop, heck, they can just get deeper bars.

Most of the above is a trial and error, the PBH X .883 is not, it is darn close to exact!

ive got ariones all around.

Of course I miss out on a bid for a super cheap new Arione on ebay. Oh well, I'll just spend $100 on the newest one that's out now. I'm hoping the fact that the San Marco is shaped the way is part of the problem and that once I get this Arione, it'll at least help in the comfort department. I've been reading from a lot of people here that my saddle is too high, but like I've previously said, my knee pain has gone away with the height I'm at now. I guess once I get my new saddle and move it forward and I'm still bobbing then I have no other choice but to move it back down. Oh, conflict...

You're just "spinning out" at high speed. Practice and you'll be able to handle higher rpms but there's a limit for everyone.

Seriously, try the fit calculator or go to a reputable bike shop and get fitted. THEN you can see about a saddle. If you aren't properly fitted to your bike you will never find a comfortable saddle.

I've currently got five rideable bikes with five different saddles and they all work for me. I've no doubt the Unicanitor NOS I bought for my Pinarello build will work just fine, too.

I used to have that san marco ponza saddle too. I found it quite comfortable. Play with the position before splashing out cash on a new saddle.

"Guess and check" with $100 saddles seems like a good way to spend a lot of money and still not be comfortable.

Might be a good idea to find an LBS that lets you test ride saddles.

FWIW: I ride this on my geared bike - https://www.roadbikereview.com/mfr/pe...2_2509crx.aspx
I rarely ride my geared bike less than 30 miles, and for a low-profile seat this one is pretty comfortable in the long haul. Did a century this past weekend with no trouble... really feels good once you get settled in around mile 15-20.

Also helps that it won't break the bank at $50 MSRP (and Performance has some sales going on you can probably get it cheaper).