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Sloping top tubes. Pros, Cons?(24 posts)

Sloping top tubes. Pros, Cons?Patrick
Nov 21, 2001 6:33 PM
Our cycling team has just worked out a deal with a frame company that offers the standard road frame and also a sloping top tube frame. The sloping top tube frame is lighter but I do not have enough information about them to make an educated decision. Any information would be greatly appreciated. Thanks.
re: Sloping top tubes. Pros, Cons?cool
Nov 21, 2001 6:46 PM
Pros- look cool, lighter frame, stiffer

Cons- butt-ugly, bike weighs the same when everything considered, need long potentially flexy seatpost
Flexy seatpost?wes
Nov 21, 2001 9:29 PM
I keep seeing references to "long flexy seatposts" in these threads about compact/sloping top tube frames.

Just voicing my opinion here, but the seatpost is rarely a point of flex. If you notice any bike frame, the area around the joint of the seat tube and top tube are never reinforced other than the standard butting.

The flex in a frame is aroung the bottom bracket where you will see many externally butted tubes and often ovalized tubes to compensate for the extra stress there. Also, the top tube and the down tube where they meet the head tube is an area for stress.

Let's also think about mountain bikes for a second (God forbid). We're basically talking about the same type of design. Mountain bikes perform very well with sometimes HUGE posts.

Somewhere in one of these boards there is a thread about the best cycling myths. "Flexy seatposts" should be added to this. Anyone who has ever complained about a flexy seatpost should just get a nice beefy aluminum post.
A little flex is good...no?Little Pooter
Nov 22, 2001 5:18 AM
As far as seat posts go, isn't a little flex a good thing to take the edge off of rough roads? It doesn't take anything away from the handling of the bike because the BB and frame are still stiff for sprinting etc, but the slight vertical give of the seatpost could really add some comfort to a stiff frame. Just a thought.

BTW, I ride a Giant compact frame, with carbon aero post.
A little flex is good...no?REMan
Nov 22, 2001 12:58 PM
I agree. I ride a Specialized Allez Comp with a sloping top tube. The little bit of flex in the Ritchey seat post is welcome as this bike has a very stiff rear triangle.
re: Sloping top tubes. Pros, Cons?Dutchy
Nov 21, 2001 7:20 PM
I can't see any cons with these frames. If there was a down side, pro teams
like team ONCE wouldn't use them. I haven't ridden one, my brother has one
and he thinks it's fantastic. The only problem is the trend factor, in 5 years
they won't be trendy any more and every bike will have traditional geometry
so the bike will definitely show it's age. But this won't be a problem for
sponsored team like yours.

CHEERS.
RE: Trendy sloping toptubesBicycle Bill
Nov 22, 2001 3:02 AM
Dutchy,

You and a few others say that slopinr toptubes are just a fad and will pass in time. I disagree, sloping toptubes have been well received by the public and the pros, they're here to stay. Some retrogrouch friends of mine poo-pooed indexed shifting some years ago, remember "shifting for dummies" they were also late to go clipless "heavier and I know how to loosen a strap when I need to" STI "oh my god there are cables hanging out all over the place and what happens when you crash? you'll break both your shifter and brake and they're heavier" Get the drift? Or do I have to tell you what they said about mountain bikes?
lolgtx
Nov 22, 2001 10:33 AM
exactly right. I said all of those things--'cept with clipless. I went for that right away (1986?) cause it solved my cold/numb feet problem (hmmm, I guess two Alfreda Binda straps per foot will stop blood flow). I still haven't gotten STI (I'm actually hoping to skip it altogether--my guess is that Shimano is working on something pretty crazy for the next version of Dura Ace) and have reservations about threadless for road bikes (makes sense for mtbs, or if you want a carbon steerer). But compact makes sense to me cause I also ride mtbs. I'm sure horizontal top tubes will look very old school in just a few years.
Some things improve riding others don'tDutchy
Nov 22, 2001 3:09 PM
I don't have any problem with these frames, like I said my brother has one that I helped
him choose. Things like STI levers, clipless pedals are revolutionary they actually make
a real difference, there's no argument there. But no one can actually say sloping top tubes make
a difference, that's why there's always this debate. I just feel that sloping top tubes will
eventually go the way of Y frame bikes and softride bikes. The standard geometry
has been so well proven it will take something extremely different to change conventional wisdom.

It's just an opinion, and I'm no retro-grouch.

CHEERS.
Some things improve riding others don'tBicycle Bill
Nov 22, 2001 7:04 PM
Sorry Dutchy, I didn't mean to stereotype you. I actually expected you to compare compact frames with those out of round chainrings Shimano thought we needed a few years ago, what were they called again? Oh yeah, bio-pace. I think compacts will be around longer, not because they are better but because they look good to the owner. I recently bought a new Serotta Legend Ti and speced a sloping TT on it. This replaced another Legend Ti with conventional geometry. Having ridden the same bike in both styles I will say that it is only style, both bikes ride the same, except the compact fits better, well I guess it is better than.
RE: Trendy sloping toptubescyclepath
Nov 26, 2001 6:42 PM
Bravo!!!!!!
need more info nmCT1
Nov 21, 2001 8:29 PM
Go with the compact frame.nigel
Nov 21, 2001 8:59 PM
I'll probably get bashed for this by half of the board. I'vebeen thrilled with my Giant TCR, however, and feel its acceleration and lively handling frequently on rides. GREAT for hills with its stiffness, and I understand that compacts are great for crits as well with their usually shorter wheelbases and faster handling.

As someone else noted, they're purported to be stiffer, which makes a bunch of sense since the triangles (particularly the rear one) are tighter--shorter tubes equal stiffer rides. You've already said that it's lighter than the trad frame.

Often comes down to looks. I happen to think they're beautiful, but others hate them. I can't see sponsored riders balking about riding a paid-for compact frame, though; it's a tool to them. If it's lighter, tighter, and stiffer (more efficient), they're likely to do just as well if not better than on a trad design.

My two cents.

Nige
two advantagesgtx
Nov 21, 2001 10:15 PM
not weight or stiffness

1) might be easier for some people to get a good fit, because it eliminates the standover issues

2) easier to clamp into the repair stand--this is actually the biggest advantage as far as I'm concerned. This is especially good if you have snazzy decals or super lightweight tubing.

BTW, I never hear any mtbers complaining about "flexy" seatposts. Compact is here to stay.
one moregtx
Nov 21, 2001 10:20 PM
slightly lower center of gravity. I'm quite sure my next road bike will be compact.
easier to get a good fit?diggler
Nov 22, 2001 5:49 AM
when they typically come in only 4 sizes?! bawhahaahaaahahaaahahahahaha!!!!!!!!!!!!!!
easier to get a good fit?gtx
Nov 22, 2001 9:12 AM
typically? You mean Giant, right? Serotta, Litespeed, etc., come in the same number of sizes.
happy with minegrandemamou
Nov 22, 2001 5:32 AM
My frame came in more sizes than SML. I was probably able to get a better fit. The only real con in my opinion other than sizing is looks. I'm a certifiable retro grouch people were shocked when I showed up with an AL, compact frame. The look is like fungus it kind of grows on you. Many traditionalist hate the way they look. I think it's here to stay. I remember many people screaming at welded frames. How many lugged steel frames out there now? There are a few but not many.

The only real pro is it's flickability. Maybe has something to do with the lower center of gravity. I love it when the road turns twisty. A little flick right or left and hang on. Really nice attribute in a crit. I'm not an engineer so maybe someone could chime in and explain the "feeling"
frames should fit...C-40
Nov 22, 2001 8:41 AM
without resorting to high rise stems of extreme length (long or short) or lots of head tube spacers.

If the sloping frame is only available in limited sizes, fit problems are more likely.

With many of the Al frames exhibiting extreme stiffness with traditional geometry, what's the point in making a frame even stiffer? Frames that are too stiff can be difficult to handle if the road gets rough. An overly stiff frame can slow your average speed if you repeatedly quit pedaling to get your butt off the saddle.

The weight savings is virtually zero, once you factor in the heavier and longer seat post required.

The long torsoed rider may find a stock sloping top tube frame that has sufficient standover clearance and top tube length that can otherwise be obtained only with a custom.
frames should fit...tr
Nov 22, 2001 11:44 AM
couldn't have said it better.
"what's the sense..." <=== actually, a LOTCT1
Nov 23, 2001 7:23 AM
"With many of the Al frames exhibiting extreme stiffness with traditional geometry, what's the point in making a frame even stiffer? Frames that are too stiff can be difficult to handle if the road gets rough. An overly stiff frame can slow your average speed if you repeatedly quit pedaling to get your butt off the saddle. "

----------------------------------------------------------

Actually, the percieved "roughness" of a STT frame has VERY little to do with the angle of the TT. Case in point is my TCR ONCE frame which is MUCH-MUCH more smoother than my ex caad5 (straight TT) frame . In fact the TCR is downright "comfy".... and yes the BB is quite stiff on this bike.

That being said, STT frames are not for everyone. I actually don't like the way they look. When I'm on the road I don't want to be a mtb wanker. LOL.

YMMV
JohnG
apples and oranges again.....C-40
Nov 23, 2001 8:56 AM
A valid comparison would be between a sloping TT and traditional model made with the same tubes, by the same manufacturer. To compare frames with entirely different tube sets is meaningless. There's no way to distinguish what differences in construction contribute to each frame's ride and handling characteristics. If your Giant TCR was built from the same tubing, but with traditional geometry it should ride even smoother.

My point is that too much stiffness can be a bad thing, regardless of the frame's design. The tight rear triangle created by the sloping TT gemometry is credited with increasing stiffness.

At 135lbs, I've ridden a lot of bikes with excessively stiff frames. The handling of these bikes definitely suffered anytime the road got a little rough. My C-40 handles the same type of pavement much better and has all the BB stiffness that I need.
huh???CT1
Nov 24, 2001 1:01 PM
"The tight rear triangle created by the sloping TT gemometry is credited with increasing stiffness. "

Actually, the "layed down" seat stays soften the rear end due to the increased angle and forces on the seat stay. Draw a force diagram and you will see why this is so.

STT by itself MAKES NO DIFFERENCE TO ride quality. Ride quality has more to due with specific tube material than anything else.

JohnG
huh???paper warrtor
Nov 24, 2001 1:38 PM
I know nothing of force diagrams but if you are right wouldn't compact frames be stiffer and smoother riding at the same time even if the "flexy seatpost" is a myth?