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Yet another compact frame question(11 posts)

Yet another compact frame questionBulldozer
Aug 29, 2003 4:43 PM
Are compact frames similar across different bike lines? My measurements (34.5" inseam) say that I need a 59cm (c-t) or 57cm (c-c) tt. But, my LBS says that I should ride a size medium Giant (55.5cm tt). Meanwhile, I've found by looking at posted geometries that I would also fit a size XL (58cm tt) Cinelli. In looking at the Giant webpage, I guess I'm borderline between a medium and a large. Also, the Cinelli frame that I want is only an XL. I won't have a chance to ride the Cinelli prior to purchase so that's not an option. I suppose I'm just overanalyzing but I want to be sure the Cinelli will fit before I buy.

Also, the Giant webpage mentioned that to calculate fit, multiply your inseam by .65 while wrench science and colorado cyclist say to multiply by .67. The difference for me is almost 2cm (58.7 vs 56.9). What gives? The reason I keep going back to Giant is because I have a Giant mtb and it fits me very well (20.5" frame).
re: Yet another compact frame questionRusty Coggs
Aug 29, 2003 6:21 PM
If you don't know what you need, and TT length is most important,then without a testride,you are likely to get hosed. If a 55.5TT is right then a 58 isn't and the other way around.The multipliers are for c-c and c-t I think and don't tell you a thing about TT length. FWIW,my bike inseam is 35 and I ride a 57c-t or 58 c-t at the lagest,with a TT of 56.5 to 57cm. I'm betweeen sizes with giants and wouldn't mess with trying to make one fit.
not in between sizes..C-40
Aug 30, 2003 5:07 AM
You are not borderline between sizes. At your height and inseam, the large Giant is the only reasonable choice, and even it may be a bit small, since the head tube length on Giants runs on the short side. The XL size in a Cinelli would also be your only reasonable choice.

The best example of the dimensions you need is often provided by your existing road bike, if you have one.

Frame size for large inseams is better calculated by simply subtracting a fixed amount from your inseam. Subtracting 29cm from your 88cm inseam yields a c-t frame size of 59cm. An even better method for figuring frame size would use your saddle height, since folks often measure inseam on the low side. Carefully measure your saddle height from the center of the bottom bracket to the top of the saddle, along the seat tube. Subtracting 17-18cm from this length will give you a good range of frame size.

You also have to consider your height, which I believe was previously posted as 6'-3" (bare feet?). If this is correct, you have a fairly long torso, so the top tube length will need to remain fairly long, probably around 58-59cm. A 55-56cm TT would be much too short. While TT length is very important, so is the head tube length. Look for a head tube length in the 190-210mm range. With a compact frame, there are often large jumps in the head tube length also.

Take a look at Fondriest geometry at The 60 (XL) size might be just the thing.
use me as an exampleFrith
Aug 30, 2003 9:38 AM
your inseam is about .5 to 1 cm shorter than mine (depending on the accuracy of our measurements). You don't mention your height. I'm 6'.75" (185cm). I ride a large giant tcr comp and am completely confortable. Here's the setup...
First of all had to chuck the aero seatpost because it had too much setback (I guess I have shorter femurs). Once I swapped it for a straight post and adjusted my seat fore/aft I ended up with a 110mm stem (pretty average). I have 3cm of spacers and have the stem flipped up for max rise. This results in only about 3-4cm of drop from seat to bars (This is very little compared to alot of people). I'm about ready to flip the stem back and then possibly loose a bit of spacers. Overall though I find the reach right now very comfortable. In a more traditional frame I'm a 58-59(ct)ST with 57-58(cc)TT. The large giant is listed as 58.5 effective and I suspect it might even be slightly shorter. Of course seat tube angle plays a big role in fit also. So there's a long answer to a relatively short question :) ... how tall are you?
RE: use me as an exampletube_ee
Aug 30, 2003 7:07 PM
The other option, if you like where your tops and hoods are, but want the option of a more aero position, is to swap out your bars for ones with a deeper drop. Because saddle - handlebar relationships have gotten so radical, most bars now have quite shallow drops.

As I tell my customers, if you can't ride in the drops for extended periods, your bars are too low. My biggest beef with compact geometry is that it makes fitting much harder. Yes, you can get there with long seatposts, flip-flop stems and lots of spacers, but there are serious tradeoffs in handling and comfort. Only maing bikes in 4 sizes is great for the manufacturer, but bad for the rider, IMHO. Plus I think they look stupid.

--Shannon "traditional geometry for me" Menkveld
Aug 30, 2003 8:14 PM
I have a 3cm drop to the bars...Try getting that today with most standard geo bikes. I could easily lose half the spacers and flip the stem and still be closer to my bars than most people walking out of the store with todays so called traditional bikes (trek comes to mind). It's time to face the facts compact makes just as much sense as any other approach to frame design. So it comes down to asthetics...and if you think this looks ugly then I won't force you to ride it ;-)
not neccesarily bunk...tube_ee
Aug 30, 2003 8:34 PM
But it is more difficult to get the comfortable position that you have with compact geometry. Especially if you do what most people do, and go for the smallest bike that can be made to fit.

It looks like you were able to get an excellent fit with compact geometry. Many people can't. And compact's advantages still accrue much more to the manufacturer than to the rider.

Style is personal, of course, but the way you've got your bike set up makes it look more conventional than most of the compact bikes that we get in my shop.

Nice looking bike.

Peace and Grease,
--Shannon "not trying to insult anyone" Menkveld
Aug 31, 2003 3:29 AM
"if you can't ride in the drops for extended periods, your bars are too low"

I think that depends on your definition of extended periods. I spend most of my riding time in the hoods. It then naturally follows that I want to have the most optimal compromise between comfort and aero in this position. In my opinion the drops are there for all out efforts or for a temporary hand position change only. I have a 10cm drop from my seat to handlebars and can stay in the drops for an hour if I wish, but is this an extended period according to your definition?
re: Yet another compact frame questionBulldozer
Aug 30, 2003 7:40 PM
I'm just shy of 6'. I guess I'm all legs. My total reach is actually quite short, only 65 cm. This was one of the measurements that concerned me because it leaves a relatively short stem if I buy the frame with the longer tt. The recommended saddle height is 77cm. So, if I subtract 18, that too leaves me with a 59cm tt. I could take the time to measure my mountain bike (no road bike) one of these days. Like I mentioned it's a 20.5" frame with ample seatpost showing.

I should have mentioned before that my LBS recommended a size medium over the phone. One other point of reference is that I've test-ridden a 58cm Klein compact frame and it felt pretty good. 1cm won't make much difference. I'm sold on the Cinelli XL. Thanks!!!
not all legs...C-40
Aug 30, 2003 7:58 PM
You're 5.5 inches taller than I am with 2 inches or 5cm more inseam. That puts you on the shorter torso side, like me, but your dimensions should not keep you from getting a good fit on a stock frame.

I seriously doubt that your reach is only 65cm. I'm only 5'-6.5" tall and I ride a 54cm TT with a 11cm stem (65cm total reach). You've got about 9cm more torso length than I do. Unless you've got extremely short arms, your reach should be condsiderably more.
not all legs...Bulldozer
Sep 2, 2003 8:31 AM
My arm length is 24" so I don't think they're very short. I think I'll start with a 11cm stem and go from there. Thanks for the input.