Fly2High

Recently I had a Retul bike fitting and in it they defined the stack and reach for the bike I had tuned. For me it returned the following parameters:
Frame Stack: 623 mm
Frame Reach: 390 mm

Handlebar stack: 706 mm
Handlebar Reach: 470 mm

BB to Grip Reach: 594 mm

Grip Reach (tip of saddle to front of grip): 674 mm

Handlebar Reach (saddle tip to center of bar): 560 mm

Saddle height: 791 mm

If a bike does not match the frame's stack and reach, what are the next steps? What do you hoold fixed and what can be varied to determine the right frame?

redfooj

reach for the model you crave the most and stack your cash to pay for it

WalksOn2Wheels

Stack: Add/remove spacers.

Reach: Change to a shorter/longer stem.

Fly2High

But according to the Retul, this is the stack and reach without spacers.

So if I understand, you are saying that if the bike is too short, add spacers to jack up the effective height and add a longer stem if the reach is too short.

OK. So as long as I do not go over, I could accommodate, theoretically.

Let's look at a Cervelo R5.
I am a size 58 on my current bike. The 58 R5 has a stack of 605 and a reach of 396. Now these are not to the handlebars but to the top of the head tube.
A 56cm R5 would be stack: 580 and a reach : 387

My Frame stack and reach are 625 and 383. If it matters, a Specialized Roubaix.

Since the reach on the 58cm R5 is 396, either I would need to be much more flexible or grow. Not sure it would work for me but it would only need 2cm of spacers to get the stack. I would need one hell of a lot of spacers to get the 56 R5 to work (4.5cm) and a little shorter stem.

What I find interesting is that at 6' 1", I was really sized at a size 59 based on the computer measurements. How is it possible the 56 could be the right fit for me? I am not doubting you but only questioning this because when I got onto a 58cm R5, it was a nice fit.

for that matter, it doesn't look like any bike in Cervelo will fit since they appear rather similar in stack and reach ranges.

Sorry, I am new and rather ignorant to much in the bike world and really appreciate the understanding.

Thanks

WalksOn2Wheels

You already have the Handlebar Reach number, which is really the most useful number. Stack and reach are going to be more of a ballpark figure because manufacturers are going to vary a lot for a given frame size. You pick a frame close to that, get the height and fore/aft of the saddle dialed, correct stack with spacers, then determine stem length using the Handlebar Reach.

That's just one way. There are various methods of arriving to this number as long as the frame is not too long or too tall. But this is why they sell spacers and different stem lengths. Fit is going to vary enough that it would be impossible to produce 4 or 5 frame sizes with a static bar height and reach and expect everyone to find a bike that fits.

EDIT: To be more specific, that 396 number is frame reach. That does not include stem length.

Maelochs

Pretty simply, there is a difference between Endurance geometry (Specialized Roubaix) and Race geometry (Cervelo R5.) The Roubaix has a longer head tube per top-tube length, to create a more upright seating position.

You apparently want your Roubaix slammed and stretched as if it were race geometry. It is going to be hard to find a race-geometry frame which fits exactly the same—basically, you have made a race bike out of an endurance bike and now want to convert a race bike into an endurance bike.

As I read it: Roubaix 58 Frame: stack 625, reach 383
Cervelo R5 56 Frame: stack 580, reach 387 = 25 mm spacers and a 17-degree up-angled stem, reach already good.
Cervelo R5 58 Frame: stack 605, reach 396 = 25 mm spacers, flat stem, 10-mm shorter stem

So the same approximate dimensions can be achieved—but it is sort of a backwards way of going about it. Why buy a bike designed to be ridden long and low, and try to make it short and tall, or vice versa?

Not saying that is wrong, by the way ... there can be good answers. For instance, I bought a Workswell Cervelo copy that I am setting up with spacers and a shorter, up-angled stem—because the frame was affordable, really light, and I wanted the option of going longer and lower as I ride it more, assuming I stop getting hurt and can actually log some miles.

I wanted a more racy ride because my others are more relaxed—less seat-bar drop, shorter cockpits; I wanted one bike in the stable which was a little more demanding and hopefully would also reward me with a little more performance.

But for me, I wanted a very similar but slightly different riding experience, a slightly longer, lower cockpit. (By the way, my R5 copy is 56 cm, and I am about the same height as you, though I have an abnormally short torso, so the reach ought not to be an issue for you.)

The question remains: why did you buy the Roubaix, and endurance-geometry bike, and why are you looking at the Cervelo R5, a race-geometry bike, and moreover, why do you want the same riding position on two bikes designed to do two different things?

Maybe the R5 is the perfect next bike for you, or maybe you would be better off looking at a less racy frame, if you don’t want to go with spacers and an up-angled stem. Or maybe don’t worry too much and assume your body will function through a wide range of positions, and maybe you will be fine with two bikes with slightly different cockpit dimensions and riding positions.

When I was riding a little more, I tuned in each of my bikes to a similar but slightly different riding position: one for touring, one, for quickness but reasonable comfort, one for daily driving—the Cervelo will be for more quickness (more aero) and less comfort, while still fitting me comfortably.

No reason you cannot have two very comfortable bikes that fit you really well and also have different riding positions.

softreset

The only way you're going to find a bike that matches your numbers is to work with a custom builder. You'll get close but you wouldn't check all the boxes.

The three stats that you'll be able to most easily compare with big brand manufacturers are:

Frame Stack: 623 mm
Frame Reach: 390 mm
Saddle height: 791 mm

2lo8

You simply need a stem and spacer combination that is within reason that converts your frame stack and reach to your bar stack and reach, for a given bar.

WalksOn2Wheels

This is the best sentence in the whole thread.

Garfield Cat

Perhaps this comparison chart will give you more information based on your height

On Bicycles, and.... what else is there?: stack-reach comparison: Specialized, Colnago, Felt, Parlee, Cervelo

Fly2High

Love the advice. seriously.

When I read all these threads on bike selection I have come to what can only be the wrong conclusion in that for each person there is only one reach and stack. Clearly there must be many. I came to this conclusion because in fitting a bike, there appeared to me to be a finite range the spine should be at, a defined reach a person has and since one's legs are not plastic, a fixed seat height and stack related. Clearly I am incorrect in this thinking. It also seemed to me that some just do not fit certain types of frames no matter the amount of gymnastics attempted.

So if I wanted another endurance geometry, I could use the determined reach and stack for a bike that fit but clearly, it will do no good if I wanted a racier geometry. Over the last year and a half, I have been becoming more flexible and might like to try something racier since I wasn't when I purchased my current bike.

Am I relegated to trial and error or can anything be salvaged from the current numbers to get a direction to a suitable less endurance minded frame?

2lo8

Or you could get another fit. Fits are about balancing comfort, aerodynamics and power generation. Some riders will give up one for another. Others have physical limitations. You could also just ride in the drops more.

If you don't tell a fitter what you want out of a fit, it's fair for them to guess someone with an endurance bike prioritizes comfort, and someone on a racier bike prioritizes performance.

Fly2High

Actually, on this fit, we raised my seat and flipped (pointed downward - OK, less upward since the head tube is not vertical) and lowered the stem to get a better riding position. I actually indicated a goal was do do longer rides (70-100+ mile). No, I do not think he wasn't listening but also heard through our conversation that I wanted a better aero position since I found myself trying to lay down on the top tube when needed to 'cheat' the wind. I also indicated I was having some pain at times and wanted to address these items.

2lo8

You did get a somewhat better aero position. Fitters will tend to be conservative when trying to give you a more aggressive position because it takes time to adapt and decreases comfort, and people will follow up with a complaint about discomfort. Fitters tend to be quite liberal in reducing aero to increase comfort and power generation, because these will almost always make the rider feel better even if it doesn't make them faster. It also might make them faster, and going too aero might make someone slower.

The best way to get an aggressive fit is to come in with all your spacers on top of a slammed -17 stem, it basically tells the fitter you want to be as low as you can go. They might think you're a fredly poseur and they're enlightening with a proper fit with bars at the right height though.

Fly2High

So if I would like to look into racier bike, will I just have to go on trial and error or pray the salesman isn't trying to SWAT (Sell What's Available Today)?
Is there anything useful from the fitting that could help? Would the seat height or something be reusable?

rpenmanparker 

This is it. It is the handlebar stack and reach that you are shooting for. I call it the finished bike stack and reach. If you know what stem and spacers the fitter was using to convert the frame stack and reach to the required finished bike bar stack and reach, then you just adjust those to accommodate differences you may encounter in the frame that you are looking at. Because of the angles, the changes aren't so simple, but you use an online calculator to help you adjust for the frame differences. Here is a popular one: Stem Comparison Tool | yojimg.net

rm -rf

Just to recap, here's stack and reach measurements:



It measures from the crank axle to the top headset, center-to-center.

It's for comparing frames. You have your current bike's stack and reach, and also have the stem and bars stack and reach. And you can count the spacers under the stem (10mm is the standard height, and there are 5mm, 2mm, etc, short spacers) to add onto the stack number. And you know your stem's length and angle.

EDIT--this bike stem calculator compares two stem setups and shows the change in height and reach between them. Very useful.

When I was shopping for a new bike, it's stack was 8 mm higher, and the reach 5mm shorter than my current bike. So i knew I could go from a 90mm stem to a 100mm on the new bike (adding a net 5mm more reach), and drop one 10mm spacer to get close to my current fit. And this new bike was a 55cm, the old one was 54cm, so I could ignore that sizing difference, since stack & reach compares them way better.

So, if you want a lower, more stretched out, "racing" bike, you can compare the differences on stack and reach to see how much the frame affects your riding position. And then different stems (using the calculator linked in the previous post) and bars, determine if you can get your hand positions where where you want them.

Or, for riders whose current bike is too low, they can see if the new bike frame will allow for a high enough position without adding too many spacers. (usually 30mm or 40mm is the maximum spacers on carbon fork steerers.)

Range of fittings
Sure, riders can use a range, but a wrong size frame means adapting by more spacers, short stems, and other non-optimal means. Then if the rider wants a minor adjustment later on, it might be difficult to do, since it's already at the edge of a reasonable size range.

And a rider can use a wrong size bike, but they may not be fully comfortable on the hoods and drops.


Racing setup
First, have you contacted your fitter? Advice on a racier frame might be free, included in your original fitting.

It's hard to say how much lower and farther forward you need. You can roughly estimate it by kind of half-holding the hoods or drops, and sliding your hands farther ahead. Is is a minor change or a very large difference?

Lowering the bars
Is your stem angled up now? Flip it, and even get a cheap longer stem with more angle (or even an adjustable stem for this test) and try it out. Performance has a 120mm adjustable. You could see if the longer stem, angled way down, gives you a good position. You'd be able to ride it for a while, instead of at just a single fitting session. Any spacers under the stem? Try moving them above the stem (you don't want to cut the stem down.)

Compact bars
A lot of bikes come with compact style bars. These have a shorter reach distance to the shifters, and the drops aren't as far down. This style works great for a lot of riders. Compact bars let me ride in the drops comfortably. Typical measurements are 80mm reach and 120 mm drop.

You may want more traditional bars with a longer reach and a bigger drop.

Fly2High

Thanks Robert and RM-RF. I think I better understand now. Much appreciated.

2lo8

I have a webapp on my blog that will tell you what stem/spacers you need to get the same handlebar position on two frames if that's all you want.

There's little risk in playing with your spacers to see if you can have more saddle to bar drop, just keep track of what you do with the spacers.

Maelochs

I don't know how to do it right ... but I know how I do it.

Seat position is invariable. My leg is only going to work with power and without injury at one length, and while I can slide the seat forward or back some, there isn't much range fore-and-aft before i start compromising power or comfort.

Once I get my seat set, it will be about the same on every similar bike (obviously a road bike, TT bike, or MTB will not be similar.)

The same vertical rising from the BB that is used to figure reach, is also used to figure seatpost setback and saddle position. Drop a plumb bob (ties a string around the top tube with a weight on the end) to get a sure vertical to the BB center.

Once the saddle position is determined, to can sit on the bike and reach out and down and see how different positions feel. Get into the drops and bend your arms to see if your body is comfortable and you can spin your legs. When yo know where your torso can fit, well, your arms are connected to your torso.

All of rm-rf's ideas are great. Take out all the spacers, flip the stem if it points up---try holding the brake levers for a couple inches further forward reach, to see if it is puts your torso in a comfortable place. All these can help you figure how long and low you can ride while still both breathing and making power.

Of course ... if you happen to know someone about the same size as you who rides a racier posture ......

NVR2L8

Sorry for digging up graves!
Just wanted to say this really should be a sticky I'm the Newbie section.