Help with modern road bike sizing
- Thread starter Peachy!
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Knowing the virtual top-tube of 58.2cm for their size recommendations, you can now compare with your other bikes to see if you are in the ball-park for being more stretched out or more upright along with a better idea of what size stem, etc. would be needed.
Splatter Paint
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Head over to the geometry geeks website, they have loads of info.
At 5’11” I also ride a 56
At 5’11” I also ride a 56
Splatter Paint
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Stack and reach comparisons are very useful, as well as head tube length. Road bike geometry is very diverse now.
Bar drop / width / reach also makes a massive difference.
Bar drop / width / reach also makes a massive difference.
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Another look at the geometry table with it's 73.5 degree parallel, it will feel very very racey compared with your
"My 60's Tourer - 23" (58cm) Probably my most comfortable with a tall seat post and normal stem."
You most likely will need at least a 120 cm stem to slow the steering down; for sure that frame is not built for comfort but speed.
"My 60's Tourer - 23" (58cm) Probably my most comfortable with a tall seat post and normal stem."
You most likely will need at least a 120 cm stem to slow the steering down; for sure that frame is not built for comfort but speed.
Fatal Swan
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There'll be others here who know this stuff much better than me, but having worked my way through the same kind of issues from moving from old MTBs to modern/modernish road bikes in the last few years, my thoughts would be:
Manufacturers nowadays use the numbers they use to designate frame sizes (55, 58 etc) to refer different things, and they won't tell you what - you have to determine that from the geometry chart so finding that is crucial. Traditionally the frame size number would refer to the seat tube length, but with the variation in modern road frame designs the top tube length is sometimes taken to be the single most significant dimension, in general. So some manufacturers might still use the size number to refer to the actual seat tube measurement, but others to top tube measurement - and usually the 'effective top tube', since many frame designs now have sloping top tubes. More confusingly still is when the manufacturer's frame size number refers to neither of these, but to the corresponding bike size in 'old money' (seat tube): so if you've always ridden old 58cm frames, say, then you'd still be suited to that manufacturer's size 58, even though there might not be any relevant dimension on the frame that is actually 58cm!
What it boils down to is that the sizing and geometry of each frame is very specific to that model. The only way to be fairly confident about what size is best is to look at the manufacturer's geometry chart for the specific model you're interested in. That said, my own experience is that modern road bike sizing is pretty forgiving if you're willing to switch seatposts (setback/inline) and stems, and then if you buy a frame with an uncut fork or one with an inch or two of stem spacers already present (failing that replace with a stem with a different angle, or even flip it) then you should have enough scope for adjustment along all the main dimensions to make it fit well. In any case, everyone likes their bike to fit a slightly different way so to a certain extent you need to do that tweaking anyway. For many manufacturers there's an overlap where two sizes of frame can be made to work well: I know I can fit both medium and large Canyon road frames well for example. I'm a fraction under 6'0 and over the past few years I've made frames with top tubes between 53.5cm and 56.8cm work absolutely happily as far as comfort and handling are concerned. It doesn't sound much but it's quite a big range in terms of sizing - a smallish medium to a fairly large 'large'!
Though if you're looking for an exact/professional-type fit with a specific length of stem to produce a particular feel to the steering etc, then that would be a different matter of course. I'm not enough of a purist for that and am happy to buy close enough to the right size and tweak it until perfect!
Manufacturers nowadays use the numbers they use to designate frame sizes (55, 58 etc) to refer different things, and they won't tell you what - you have to determine that from the geometry chart so finding that is crucial. Traditionally the frame size number would refer to the seat tube length, but with the variation in modern road frame designs the top tube length is sometimes taken to be the single most significant dimension, in general. So some manufacturers might still use the size number to refer to the actual seat tube measurement, but others to top tube measurement - and usually the 'effective top tube', since many frame designs now have sloping top tubes. More confusingly still is when the manufacturer's frame size number refers to neither of these, but to the corresponding bike size in 'old money' (seat tube): so if you've always ridden old 58cm frames, say, then you'd still be suited to that manufacturer's size 58, even though there might not be any relevant dimension on the frame that is actually 58cm!
What it boils down to is that the sizing and geometry of each frame is very specific to that model. The only way to be fairly confident about what size is best is to look at the manufacturer's geometry chart for the specific model you're interested in. That said, my own experience is that modern road bike sizing is pretty forgiving if you're willing to switch seatposts (setback/inline) and stems, and then if you buy a frame with an uncut fork or one with an inch or two of stem spacers already present (failing that replace with a stem with a different angle, or even flip it) then you should have enough scope for adjustment along all the main dimensions to make it fit well. In any case, everyone likes their bike to fit a slightly different way so to a certain extent you need to do that tweaking anyway. For many manufacturers there's an overlap where two sizes of frame can be made to work well: I know I can fit both medium and large Canyon road frames well for example. I'm a fraction under 6'0 and over the past few years I've made frames with top tubes between 53.5cm and 56.8cm work absolutely happily as far as comfort and handling are concerned. It doesn't sound much but it's quite a big range in terms of sizing - a smallish medium to a fairly large 'large'!
Though if you're looking for an exact/professional-type fit with a specific length of stem to produce a particular feel to the steering etc, then that would be a different matter of course. I'm not enough of a purist for that and am happy to buy close enough to the right size and tweak it until perfect!
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Peachy!
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Thanks for all the info gents.
If it wasn’t for the fact that I like a short reach I wouldn’t bother going to look at this “medium” frame, but as the seller is happy for me to try before I buy I might as well go have a look. I’ll take some measurements from my steel road bikes to see if anything lines up (pedal to seat height, seat to bars etc)
If it wasn’t for the fact that I like a short reach I wouldn’t bother going to look at this “medium” frame, but as the seller is happy for me to try before I buy I might as well go have a look. I’ll take some measurements from my steel road bikes to see if anything lines up (pedal to seat height, seat to bars etc)
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Fatal Swan
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I guess this would be one of the ones I mentioned in my post just before yours (#17) where the manufacturer's designated size number doesn't refer to any actual dimension of the frame, but to the corresponding size in 'old money' = a traditional 56cm frame? Like I said in that post, the problem is that the manufacturers don't actually tell you which of the several possible measurements or correspondences their frame size number refers to!
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