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Compact frame verses standard(11 posts)

Compact frame verses standardJuanmoretime
Jun 1, 2002 5:58 PM
It appears many manufactures are building compact frames. Other than weight savings, what are the real benefits?
Current styleNessism
Jun 1, 2002 6:16 PM
I'm not knocking them it's just that they seem to have more to do with style than function. The only functional advantages I can think of are increased standover clearance for small riders and the ability to get the headtube higher which will help many people that use threadless stems.

Ed
re: Compact frame verses standardweiwentg
Jun 1, 2002 6:16 PM
one of the biggest benefits is that they increase the standover clearance. this makes it feasible to fit a large range of people with a few frame sizes. Giant's frames are cheap as they are made in 3 sizes - and the savings get passed to us.
the rear triangle is smaller, and therefore stiffer.
there is a slight weight reduction. it is argued that the weight reduction is offset by the increase in seatpost length.
it has been said that the CG of the bike is lowered. however, it isn't lowered very much, probably not enough to matter.
interestingly enough, I haven't rode a standard frame. very few standard frames fit me.
miniscule weight savings and NOTHING else.JohnG
Jun 1, 2002 6:26 PM
Might be an ounce or two difference once you take the longer seatpost into account. BFD.

The BIGGIST and only significant difference is the generally lower cost of a compact. I.e. you can get a TCR frame/fork/HS in the low $600 range. There are other similarly priced compacts.

BTW: I've got both compact and standard framed bikes and there is NO "performance" difference between them.

Bottom line: Get a frame that fits you and is appropriate for what you are planning on doing.

JohnG
What about comfort?hayaku
Jun 2, 2002 6:03 AM
Have you noticed a difference in comfort over long rides due to the longer seat post?

I have never ridden a compact frame but I think the aspects that are promoted are mainly the slightly lighter weight. (every little bit counts in my opinion and if you can get it without any pentalty in terms of flexability, gotta be good.)
The longer seat post should flex more than a standard fit, soaking up the bumps in the road. But that all depends on which post you get.
The lower center of gravity is said to be wonderful when standing on hills. I always hit my knees on my top tube so that aspect is interesting. However I think that the difference people mention may be due to the shorter seat stays-smaller rear triangle.
And then they also decrease stand over height, good if you have short legs.
I have put a lot of thought into the compact frame concept, I don't have any experience with them unfortunately... I hope this helps.
M.
What about comfort?gtx
Jun 2, 2002 10:45 AM
on a (compact) mtb frame the seat post (even an AL one) will flex quite bit and will soak up some bumps. I suspect that something like a Moots ti post would add quite a bit of comfort. This is in line with what Sheldon brown says here under verticle stiffness:

http://www.sheldonbrown.com/frame-materials.html#ride

Santa Cruz also hypes this idea with their Roadster

http://www.santacruzbicycles.com/bicycles/roadster/reviews.asp

Of course, it's impossible to do any kind of apples to apples comparison. I still say the biggest advantage of compact frames is that they are easier to clamp into the repair stand. The main reason you see them is that it allows the manufacturers to build fewer sizes, which in turn makes it easier for shops to stock all the sizes of a given model.
Lower center of gravity? Interesting...elviento
Jun 2, 2002 6:58 PM
The way I look at it, the sloping toptube probably lowers the center of gravity of the frame by maybe 1"-1.5", but since the frame is only 15% of the full bike weight, and since the rest of the bike is staying put, the overall center of gravity of the bike probably doesn't drop much. I just don't think it can have any practical effect while riding.

Any physics expert?
Lower center of gravity? Interesting...JohnG
Jun 2, 2002 7:06 PM
Not an expert but I agree with your general statement. I don't think any of this stuff is really of any import. In the real world your day to day performance variations will be MUCH more than any tiny weight or stiffness, or .... whatever.... will make.

I will say that I think my TCR frame is light, nimble, stiff, and fairly comfy by Al standards. It just plain flat out works good...... is that because of the slopping tt??? I doubt it, but it's an integrated package and we'll/I will never know. The bottom line here is that GIANT has delivered an excellent overall frame.

JohnG
Supposedly handling...PODIUMBOUNDdotCA
Jun 2, 2002 3:02 PM
From what I've heard from friends the handling on a compact bike is better in corners. This is probably just due to the fact they are stiffer so any new bike handles better than an old bike in my opinion. If you think of how much force you exert on a frame while cornering and even how a little flex could effect your trajectory I think that explains my point. I'm not an expert but I know a new bike handles better than an old one!

Cheers,
Nick Corcoran
PodiumBound.ca
Uh, noKerry
Jun 2, 2002 5:46 PM
Handling is defined by geometry, dimensions, and a little bit by frame stiffness. Compacts are only stiff if they are designed to be - any frame can be stiff or flexible. There is ABSOLUTELY nothing about compact design that makes them handle better.
ThanksPODIUMBOUNDdotCA
Jun 2, 2002 8:14 PM
Thanks for the clarification. I need a kick in the butt like that to learn.

I just know my friend got a new Opus a while ago and she said it handled amazingly different than her old specialized. Then a couple teammates got Colnagos and remarked about how good they handled. So it is mostly geometry I agree but frame stiffness does play into it in my opinion. I'm a 180 lbs at my heaviest and I have no problem leaning the bike completely into the turn so the bike has to be flexing at least a bit.

Cheers,
Nick Corcoran
PodiumBound.ca