eBay - trying to understand frame geometries
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eBay - trying to understand frame geometries
I have my fitting sheet, so how do I decipher other brand's frame geometries, especially when some frames are a few years old?
I've heard people say a 53cm can be like a 55cm, or vice versa. Sloping, compact, it gets all confusing. I'm looking around for a frame to build up over a year (or more), getting parts off eBay (or elsewhere) for deals, but I need to understand how to pick the right geometry for me.
Currently my sizing chart shows my ideal frame setup to be:
seat tube: 55 cm centre to centre (C-C)
top tube: 55 cm C-C
seat height from BB: 75.5 cm
saddle setback: 6.25 cm
top tube + stem: 66 cm
stem length: 11 cm
crank length: 172.5 cm
seat tube angle: 73 degrees
bar drop from saddle: 7.75 cm
reach (saddle-bar): 54.5 cm
The only changes the tech said may I may need is the stem length may go to 12, then 13 cm, and the crank length to 175 mm by next summer.
As for brands, my preference is for Italian like Tommasini, De Rosa, Fondriest, Cinelli, Coppi, Pinarello, Ciocc, and some others in that ilk. But I'm also looking at Look, Time, Cannondale, Merlin, Leader, Quattro Assi, etc. Basically anything that fits my price point, material, weight and purpose (racing).
Is there a main 'theme' for the Italian bikes vs US, or other Eurupean brands in frame geometry? Thx.
I've heard people say a 53cm can be like a 55cm, or vice versa. Sloping, compact, it gets all confusing. I'm looking around for a frame to build up over a year (or more), getting parts off eBay (or elsewhere) for deals, but I need to understand how to pick the right geometry for me.
Currently my sizing chart shows my ideal frame setup to be:
seat tube: 55 cm centre to centre (C-C)
top tube: 55 cm C-C
seat height from BB: 75.5 cm
saddle setback: 6.25 cm
top tube + stem: 66 cm
stem length: 11 cm
crank length: 172.5 cm
seat tube angle: 73 degrees
bar drop from saddle: 7.75 cm
reach (saddle-bar): 54.5 cm
The only changes the tech said may I may need is the stem length may go to 12, then 13 cm, and the crank length to 175 mm by next summer.
As for brands, my preference is for Italian like Tommasini, De Rosa, Fondriest, Cinelli, Coppi, Pinarello, Ciocc, and some others in that ilk. But I'm also looking at Look, Time, Cannondale, Merlin, Leader, Quattro Assi, etc. Basically anything that fits my price point, material, weight and purpose (racing).
Is there a main 'theme' for the Italian bikes vs US, or other Eurupean brands in frame geometry? Thx.
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In general, I think the true Italian frames tend to have shorter top tubes. I've seen a lot of 58 cm seat tubes with 56 cm top tubes. I've been casually scouting for a killer deal on one for a while now.
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Originally Posted by acape
In general, I think the true Italian frames tend to have shorter top tubes. I've seen a lot of 58 cm seat tubes with 56 cm top tubes. I've been casually scouting for a killer deal on one for a while now.
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Originally Posted by nostromo
Which frames are you leaning towards? I found some Fondriest I liked but some guys won't ship to Canada.
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It's hard to say exactly how a frame will fit without actually riding it. What fits you best is probably a combination of frame geometries, but I think most people would agree that the single most important measurement would be the top-tube length of the frame. You could get a frame with a slighly shorter top-tube and add a longer stube, or slightly longer top-tube and add a shorter stem. Just remember that it's always easier to make a smaller frame bigger than it is to make a larger frame smaller.
I believe that top-tube lengths are almost always measured from center-to-center, with the exception being frames with compact geometries. Those frames typically have a sloping top tube, so the actual measured length of the top-tube is shorter than the "virtual" top tube length, which is what your reach would really be, so on a compact frame, look for the virtual length, or "effective" top tube length.
As for "Frame Sizes" typically this refers to the length of the seat tube. Most manufacturers currently measure this from from the center of the bottom bracket to the top of the seat tube (Trek, Fuji, etc.) Some European and Italian companies will measure from the center of the bottom bracket to the center of the seat tube, so 50cm c-t-c might be comparable to 52cm c-t-t. To complicate things further, on a compact frame the measured size may be quite small, so a measured size of 46cm might correspond to being "equivalent" to 51cm c-t-t or something along those lines.
If you're buying on eBay, I would ask the seller if the size is actually listed on the frame, then go to the manufacturer's website and take a look at the geometry and diagram on how they measure (Cannondale for example measures sizing from the center of the bottom bracket to the top of the top tube). I've also seen many bikes on eBay that are listed incorrectly either because the seller measured a ctt frame using ctc or vice versa. If you're not 100% sure of the size before buying, see if they'll measure some other part of the frame to be sure you're buying the size you think you're buying.
I believe that top-tube lengths are almost always measured from center-to-center, with the exception being frames with compact geometries. Those frames typically have a sloping top tube, so the actual measured length of the top-tube is shorter than the "virtual" top tube length, which is what your reach would really be, so on a compact frame, look for the virtual length, or "effective" top tube length.
As for "Frame Sizes" typically this refers to the length of the seat tube. Most manufacturers currently measure this from from the center of the bottom bracket to the top of the seat tube (Trek, Fuji, etc.) Some European and Italian companies will measure from the center of the bottom bracket to the center of the seat tube, so 50cm c-t-c might be comparable to 52cm c-t-t. To complicate things further, on a compact frame the measured size may be quite small, so a measured size of 46cm might correspond to being "equivalent" to 51cm c-t-t or something along those lines.
If you're buying on eBay, I would ask the seller if the size is actually listed on the frame, then go to the manufacturer's website and take a look at the geometry and diagram on how they measure (Cannondale for example measures sizing from the center of the bottom bracket to the top of the top tube). I've also seen many bikes on eBay that are listed incorrectly either because the seller measured a ctt frame using ctc or vice versa. If you're not 100% sure of the size before buying, see if they'll measure some other part of the frame to be sure you're buying the size you think you're buying.
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you need to go to the manufacturers' websites and look at geometry charts
anything else is just a guess
and fyi--most companies have a "bike archive" section where you can lookup geo for previous models
ignore the previous posts
anything else is just a guess
and fyi--most companies have a "bike archive" section where you can lookup geo for previous models
ignore the previous posts
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I agree that unless you are familiar with the bike you're buying or you can get a really accurate geometry chart, it will be very difficult to tell if a mail-order bike is going to fit you well. If you're in doubt, you should just pass instead of wasting your money. I know several people who wasted money on mail order bikes that were the wrong size.
Note, however, that older Italian bikes mostly have similar geometries. You should at least ask the seller for the seat tube and top tube lenghts and hope they give you an accurate response.
Note, however, that older Italian bikes mostly have similar geometries. You should at least ask the seller for the seat tube and top tube lenghts and hope they give you an accurate response.
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I'm not saying it's impossible. If you have one bike and it fits you relatively well, it's pretty easy to judge what else will fit. As for the "internet bikes" some of them have the same geometries as Fuji, I think it all boils down mainly to knowing what top-tube length you need, and then finding a bike that works for you. Just be sure to check the manufacturers website first to get all the sizing details from a particular year/model and then confirm that it's the same size that the eBay seller is selling.
Also, even if you find the right top-tube, and the seat tube is too short, you might have a lot of seat-post sticking out which you may or may not want. I haven't ridden them, but if you look at the entry level Treks (1000, 1200, 1500), I believe that the 50cm and 52cm have the same top tube length, so the main difference would be how much seat-post is showing.
Also, even if you find the right top-tube, and the seat tube is too short, you might have a lot of seat-post sticking out which you may or may not want. I haven't ridden them, but if you look at the entry level Treks (1000, 1200, 1500), I believe that the 50cm and 52cm have the same top tube length, so the main difference would be how much seat-post is showing.
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If you get the top tube length right, and the standover height gives you an inch or two of clearance most everything else can be adjusted by seatpost extension, set back of the seatpost, stem length and angle. May not be ideal, but you can get it to work.
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I've noticed on some geometry charts (Italian bikes so far) that the seat tube c-c will be 53, but the top tube c-c will be 57. Why the discrepancy? My Basso is 55 and 55, and I noticed De Rosa tend to be more even sized as well.