I am looking at buying a Cervelo Soloist Team and can fit either the 56 or 58.

Would you expect a smoother ride with the 56 (more carbon seatpost showing) or 58 (longer aluminum seat stays)?

I've been able to take a 56 out for a short test ride, but the shop is waiting for the 58 to come in. I want to take one out for a couple of hours to see how I feel on aluminum compared to my current steel bike, and want to pick the one with the smoothest ride, but I'm tired of waiting for the Cervelo to ship.

I wouldn't expect a particulary smooth ride from an Al frame with an aero downtube. I'd check out some other frames if smoothness is your primary consideration. Just my $.02

I'm not looking for a smooth ride necessarily, just trying to figure out if I should wait around to test a 58cm because it would be noticeably smoother with the longer seatstays vs the longer carbon seatpost on the 56

Probably no difference at all.

FWIW- that frame is not "smooth". Not even a little. Bigger tires (say 25mm's) may help.

If anything, I'd think that the 58 woulg give the smoother ride, due to the longer tubes. A longer tube of the same diamater and wall thickness will flex more. However, many manufacturers use slightly thicker tubes on larger sizes, and if that is the case with your particular bike, the 58 could use a beefier tube than the 56. With all that being said, I seriously doubt you could tell the difference in sizes as far as ride quality goes. A 58 will give yo7u a taller headtube and offer a higher handlebar position, assuming your saddle height would be the same for the 2. You would also more than likely use a shorter stem on the 58, as it will have a longer top tube. I personally don't like a lot of seatpost sticking out, as I can notice the flexing of the seatpost, and while it may smooth the ride a bit, it robs a significant amount of power, IMO. I have always ridden a 56, but recently decided to try a 58 for the higher headtube position and find that I like the larger size, despite the fact that I am 5'9". I feel more comfortable being higher up, but more stretched out. I don't have any top tube clearance at all, but it's not been a factor at all. I agree with JimNazium in that an Al frame with an areo downtube is probably not the best choice if you are concerned about ride quality. Wanna super smooth ride? Check out a Cannondale Synapse carbon. I've ridden carbon for years, starting with the Kestrel 4000 back in the mid 80's, and the Cdale Synapse is the smoothest riding bike I've ever swung a leg over. Of course ther are many good riding bikes, in fact Cervelos carbon bikes seem to be one of the more lusted after bikes around [ though not cheap]. Smooth carbon on a budget? Cannondale's 6-13 models can be had for a bargain these days, as thier new super bikes, the super six and system six are all the rage and prices have come way down on what was one of the top bikes in the world just a few years ago. A dealer with an 06 or 07 6-13 would probably cut a killer deal on one, or look on ebay, as many 6-13 owners are upgrading to the new six sisters and you could probably pick up a very nice used one for half of it's original price. Titanium is another frame material touted for it's smooth ride, and while it has taken a back seat to carbon in recent years, it is still a great material, and probably the best, if ride quality is your primary concern. Well, that's my opinion!

Not noticable either way, unless you go in with a pre-defined notion, then you'll feel that.

In the strictest technical sense, the larger size will be smoother, mostly as a result of a slightly longer wheelbase. Amount of seatpost showing matters not-at-all, and variations of triangle size an extraordinarily small amount.

I am looking at buying a Cervelo Soloist Team and can fit either the 56 or 58.

Would you expect a smoother ride with the 56 (more carbon seatpost showing) or 58 (longer aluminum seat stays)?

I've been able to take a 56 out for a short test ride, but the shop is waiting for the 58 to come in. I want to take one out for a couple of hours to see how I feel on aluminum compared to my current steel bike, and want to pick the one with the smoothest ride, but I'm tired of waiting for the Cervelo to ship.

I think many would agree in this forum that the "smooth ride" is greatly dictated by your wheelset, tire choice and tire pressure. The frame, especially an ALU frame, actually will counter react those positive forces. The key is finding the right blend of components to give you that smooth ride. Sometimes the best components for your riding style and preference are not mainstream.

I am looking at buying a Cervelo Soloist Team and can fit either the 56 or 58.

Would you expect a smoother ride with the 56 (more carbon seatpost showing) or 58 (longer aluminum seat stays)?

I've been able to take a 56 out for a short test ride, but the shop is waiting for the 58 to come in. I want to take one out for a couple of hours to see how I feel on aluminum compared to my current steel bike, and want to pick the one with the smoothest ride, but I'm tired of waiting for the Cervelo to ship.

Get the bike that fits and get a decent wheel set that fits your riding style and needs.

IF you were told by a seller of a bike that the 58 might be better because this frrame feels better, go to another shop.

Wheels roll on the road, not your frame. Wheels are the point where all road vibration is transmitted. I cant ride a 58, my 56 feels swell. But I am 6'1.5" tall, short femured and have alot of knee and shoulder injusries which make it very hard from me to be more laid out on the bike.

I'm with cyclust on this one. If you can trulyfit on either, the determining factor isn't so much comfort, but overall positioning, fit which includes headtube length. The only way you can know which is better for you is if you ride both. :idea:

I (like others) doubt the 2cm difference will have a noticeable impact on smoothness but they may have a big impact on other parts of your body, like your back. I rode my first real bike for 3 years before my back complained to the point that I had the bike fitted. Irritations to the body can be cumulative, so if you start out with the best pure fit for your body, you will be in the best position to make future adjustments if needed. Your tire choice will have a bigger impact than a little bit of seat post difference.

I just got fitted and had a custom bike built. I ended up going from a size 56 to a 58. I don't think the frame will make so much a difference as the fit to overall comfort. The weight distribution on the frame makes a huge difference in handling and comfort. I would suggest you get the frame that fits best as is often said (and often ignored)

one of the two sizes will fit better than the other, thats the size i would go with everything else would be a distant second place, fit comes first then the details