I hope you will let a committed roadie beg for some guidance. I’m in the market for a new road frame and am working mainly from stack and reach measurements. The bike I’ve been riding is an older Cannondale Six 13, which is a little small for me. It’s a 60cm frame, but measures out like an old-style 58cm. I have measured the stack and reach as 59.3 and 41.5, respectively. This is from my eyeballing, but I’ve done it carefully and checked a couple of different times. I believe I am pretty close, if not dead on.
For the new bike, I’d like to have more stack and the same reach. It seems that the C’dale has a pretty long reach for a bike it’s size. Maybe some of that is due to the long drop – the saddle to bar differential is 13 cm. I am flexible and can handle that, but the handling of the bike would be better with the bars a little higher (sprinting out of the saddle, for instance). Most of the frames I’m looking at seem to have reaches in the 40 to 40.5 cm range.
So here’s my question. If I buy a frame with a shorter reach, am I committing to going with a longer stem? I think I’d need a 140mm or so. For instance, I really like the Cervelo R3, but the stack and reach in the 61cm size is 63 and 40.5, respectively. The stack would be about the same as my current bike (since I’m using a bunch of spacers), but the reach is a centimeter shorter. Am I correct in thinking that I’ll need a centimeter-longer stem to compensate?
Other bikes I’m looking at are the Focus Izalco Pro in the 62cm/XXXL size, the BMC SL01, and the Specialized Tarmac. Focus doesn’t publish stack and reach measurements. The BMC has a stack of 60.8 cm and a reach of 40.5 cm. The Specialized is 61.4 and 40.7 cm, respectively.
Any guidance would be greatly appreciated. Thanks in advance for the input.
Six13 geometry changed at one point so I’m not sure what you have but your measured reach is ~10mm longer than standard Cannondale race spec.
Original six13 geo basically the same as current CAAD10 and the 60 is 404,593
One thing you need to know when looking at bikes is that every 10mm added to the headtube (or spacers) reduces reach by ~3mm.
So if you have 30mm of spacers and want to reduce them with a longer headtube you need to look for a frame that has less reach than current.
So a 61cm Cervelo would require a 1cm shorter stem than you have.
Thanks, this is helpful. My Six 13 is of the first generation. I believe it’s a 2007. Head tube is 19.2 cm, tt is 59 cm c to c, head angle is 73.5, and the seat tube angle is 72.5. I’m working from the geo chart on p. 93 of the 2007 Cannondale catalog. I have 72mm of stack above the head tube (including the head set top cap, spacers, and the stem). Ideally, I’d like 1 or 1.5 cm more stack, but nothing more. The reach needs to stay about the same.
I’m not quite understanding why the Cervelo would need a shorter stem. The specified reach for the R3 is 40.5. I have what I read as a 41.5 cm reach on my bike. The taller Cervelo head tube will come to about the bottom of my stem clamp, as the bike is set up now. That is, I would not need any spacers. Given this, wouldn’t I need a 1 cm longer stem to make up the difference?
I’m not quite understanding why the Cervelo would need a shorter stem. The specified reach for the R3 is 40.5. I have what I read as a 41.5 cm reach on my bike. The taller Cervelo head tube will come to about the bottom of my stem clamp, as the bike is set up now. That is, I would not need any spacers. Given this, wouldn’t I need a 1 cm longer stem to make up the difference?
Six13 was same geo as CAAD7 in 2007 http://i40.tinypic.com/jigd4w.jpg
Stack and reach for the cannondale calculated from other geometry figures
Bar x,y is the reach,stack of the centre of the bar - once we match the height you can see that it takes a 1cm shorter stem on the 61 Cervelo to match the reach.
One of the clearest ways to see the true length of the frame is that the Cervelo has a 1cm longer front centre (and same HTA).
If we measured the x,y of your Six13 to the top of the spacers we would get ~390,~625 - so you can see that the Cervelo is longer when the height is normalised.
Put differently, if I measure the “desired stack” on my bike (i.e., to the top of the spacers/bottom of the stem clamp), I get 62.5 cm. That’s half a cm less than the Cervelo. I see what you’re saying about the reduction in reach. When I measure what would be the reach if the frame stack were actually 62.5, it looks like the reach would be about 40.5 (I’m having to eyeball it). That’s right at the published reach for the Cervelo. Doesn’t this mean that it would fit me about right? I think I’d just switch over my 130mm stem, and not have to change a thing.
Just double-checked my measurement of the reach my bike would have if the head tube were long enough to bring the frame stack up to 62.5. It’s definitely not 39.0 cm. 40ish is more like it. I’m guessing that different tire sizes are accounting for the difference, because the floor is level. Does this sound likely?
Tyres shouldn’t make a difference to reach measurement unless they’re different sizes front & rear
there is a few mm of fudge factor in the Cannondale figures for CAAD7/Six13 in my system as I don’t know the fork length precisely, but if you have a look at CAAD10 here you’ll note the similarity to your Six13 geo and they list the reach 1cm shorter than what you’re measuring.
I see. Thanks very much. So, based on what you’re saying, if I were to look for an “ideal” frame, I’d want something with a stack of about 63 (slightly higher than my current rig) and a reach of 39.5 or 40 cm. That would put me very close to where I am now, with the bars slightly higher and about the same reach, right?
I realize that. I like the vanity factor of the 130mm. Old habits die hard, I suppose.
Thanks for your help. This has been great. Honestly, I might like a little more reach. When I last had a fitting done, I was just getting back into shape and hadn’t been riding much. Now I’m about 15 lbs lighter and getting in about 300 a week. I’ve always had good flexibility, but it definitely improves with more time on the bike.
So now that I’ve been test riding and measuring some bikes, let me ask another question. (Maybe one with a really obvious answer.) As stack rises, is it common to feel the need for greater reach? That is, riding bikes with taller headtubes seems to necessitate greater forward extension to compensate for the loss of downward reach. I’m not speaking of huge differences, but it does seem to feel that way to me. Am I correct here, or am I letting my perception of how different bikes feel and fit mislead me?
If you’ve raised your bars it’s not uncommon to feel that you could handle more reach. But if you’ve kept the bars at the same height and the frame is filling up more of the space underneath them it shouldn’t make a difference to position.
Were the bikes you test rode properly set up to match your current position?
Sorta. We set each of them up pretty close, but didn’t change out stems or do anything like that. They felt pretty close without really being dialed in. Good enough for a fairly serious test ride (cleats, clothing . . . more than a parking-lot spin). Your explanation makes sense to me. I’m struck by the differences in handling and fit among similarly-sized bikes. Small variations can really matter.
As stack rises, is it common to feel the need for greater reach?
Not what you are referring to, but one thing I hate about the “reach” measurement is that it isn’t an independent frame dimension… ie it depends on “stack”. For instance, if two frames have the same reach measurement, the one with the greater stack will actually be longer.
In reference to your issue, there is no reason to let a bike’s frame geometry dictate your contact points. Get adjustable bars and stem and put them where you like. **You can only compare two bikes if you have your contact points in the the same xy coordinates relative to the bottom bracket. **