I’m sure this is covered in one of the articles written on fitting and thank you Dan for getting them all in one place. I’m hoping to get to sit down and read them all soon. In the meantime, I’m wondering how to use the Stack and Reach numbers I have. I did a fitting with John Cobb recently on my road bike with clip ons and got a stack of 550 and a reach of 390. In looking at the Stack & Reach database none of the bikes match up perfectly. So I’m wondering how to use my numbers to figure out which bikes are good for me geometrically. Is it better to be closer on the stack OR the reach? I’m guessing if a bike has a reach that is more than 390 that would be bad for me. Is that correct? How much over 390 can I go before it becomes a problem? Anything I’m missing here?
Anyone??? Anyone??? Bueller?
I’m waiting for the answer as well. Basically I’m looking for a new bike, and need to determine what numbers are relevant in my search (stack and reach? top tube? seat tube?) so I can figure out which bikes may work. And trying to figure out how to find out these numbers. (Do I get fitted on a trainer, then measure the resulting stack and reach?).
I can answer part of your question since I was just fit by John Cobb. I was having my road bike set up for tri with clip ons. I would say that you are better off if you are in the market for a tri bike to go to a FIST fitter with an Exit or Serotta bike. John Cobb is in the Dallas area if that is convienient. There is a retailer database on Slowtwitch. If you do the Advanced Search function you can find a retailer/fitter that matches your parameters. I don’t know how up to date it is. Colorado Multisports along with a few others offer fly-n-fit programs and usually apply the cost of the fit toward your bike purchase. My understanding is thatonce they have your fit coordinates they can build up your bike without you being there. The money you save on the taxes on your bike by purchasing out of state will likely pay for the trip. If you have sky miles like I do the trip becomes even more sound.
The #'s John Cobb told me were important for me (I assume this applies to others as well) are:
- Top Tube Length
- Head Tube height
- Effective Seat Angle
- Stack
- Reach
John recommended a few bikes at the fitting but those just didn’t appeal to me after looking into them. Now I want to do some additional research on other potential bikes. I’m confused about how to use the #'s I have. I can see why some bikes obviously are not right but don’t see how to weed out those that seem close but in reality are not right.
the trek seems to be the closest - 52.0 stack and 39.0 reach.
You have to remember that the stack and reach is for the stem and aerobar setup you used during the fitting. The good thing about the trek is the reach is right on, which should allow proper placement of the elbow pads closer to your elbows. To adjust the stack you can do a few things. You can get a taller aerobar, use a higher rise stem (or flip the stem if it was angled down before), use spacers, or maybe a taller headset.
What STA did he choose? You also have to make sure that the bike is able to be put to the same STA
This isn’t rocket science, just about getting the pads underneath the elbow. You can see the stack, reach, headset, spacers, stem, aerobar. By adjusting each one it moves the final placement of the elbow pad.
Yeah the Trek was one of the ones he recommended. I went in to check it out and I honestly just don’t like it. He also said to check out the Scott (my road bike is Scott tho and I want something different), Felt B-12 and the Slice. I looked at those bikes but they just don’t appeal to me.
He had my effective seat angle at 75.5 but remember that was on my road bike set up with clip ons. John said that I sould look for bikes with a top tube in the 51.5 to 52 range with a head tube length at least 110. There was also a note scribbled for an angle of 76.5 to 78 degrees but I’m not sure what that was for exactly but I’m guessing it is Seat Angle. I’ll have to get back to John on that one but was hoping to figure this out a bit more on my own first.
The bike I’m most interested in is the Look 596 and it seems to be a good match geometry wise from some of the #'s I have seen on it but because of the front end I’m not 100 percent that I’m right on the #'s. Jordan posted stack and reach #'s for it in another thread but said the #'s had to be adjusted. He gave the formula for adjusting the #'s but (I hate to admit this) I haven’t done that kind of math in 12+ years and have no idea how to recalculate the correct #'s. Shameful I know.
Did you get fit on your road bike? The problem is it doesn’t allow you to test steeper seat tube angles. If you change your STA to 78 degrees we don’t know what stack and reach you need so the numbers you have now don’t do you much good.
Really? I did the fit on my road bike WITH aerobars. Does that matter? I asked about that and my understanding was that the info I had was all I would need. I thought stack and reach would be the same no matter the seat angle. Either way are we not able to extrapolate based off the info I have? I’m primarily looking to get a ballpark idea about which bikes are an option in case I don’t go with the look 596. For the Look, I’m trying to figure out if I should be on the size S or XS. It looks like the small will be right though either will work.I just don’t want to get the wrong size.
What didn’t you like about the Trek? I love the black one, and they have great warranties on their bikes. Plus, they are tested in the tunnel. You mentioned the look, but that seems really pricey to me. IF you are worried about the trek look, have them custom paint it.
The Slice is a great bike too. I don’t like the new white paint, but the black one is sweet.
If I had to do it all over again, I would probably look seriously at both the trek and slice bikes, while also eyeing the p2c. I want the most bang for my buck, and all 3 bikes are great choices-plus you have money left over to live a little.
I guess it is like when your buddy thinks a girl is really hot and you just don’t see it. I tried really hard to like the Trek but just couldn’t. Nothing I can put my finger on though. I hate the slice. I would do the Plasma but I already have a Scott road bike and want something different. There are a few other bikes I’m interested in but none as much as the Look. I just love Look bikes in general and I think they did some really cool stuff with this one. I want a really stiff bike that handles well and is very comfortable. In Demerly’s review he said the Look is the best bike he has ever ridden at addressing each of these qualities simultaneously. That speaks volumes to me. Still I haven’t seen the bike in person yet and I’m afraid that in person I might not love the kinked top tube as much as I do from the photos.
If that ends up being the case then I want to have some back up options and might go with a used bike at that point. I look at my bikes as an investment. My road bike has been without a doubt the best investment I have ever made. Nothing I have ever purchased has made me that happy and when I average out the cost of the bike versus the time I have spent on it the upfront cost is relatively minor. I want good value but not at the expense of having a bike I love to ride and look forward to getting on every chance I get.
stack and reach is COMPLETELY dependent on STA
by sliding the saddle forward you are shortening the horizontal distance from the nose of your saddle to the armrest pad but the length of your torso does not change when you move your saddle therefore you need those armrest pads further in front of you IE a longer “reach”. And if you actually read any of the material you claim to have then you would know that this should allow you to have a much lower position and less “stack”. That is why your stack is so high is because you are using a road bike with a slack STA. Tri bikes should be designed for steeper STA and less “stack” and that is why your numbers don’t match theirs very well. If you want to get a tri bike then you should get tested on a fit bike or a bike that is approximately your size that would allow you to determine the specific size you need.
Hmmmm… I guess I’m confused a bir because: (a) this is a much more confusing subject than some of the “experts” like to think for those of us who do not live and breath bike fit and (b) I thought this is what John Cobb was giving me at our session.
My understanding was that the fit coordinates I was given were for any bike I wanted to be on but perhaps I misunderstood John. He did give me some guidelines for looking at tri bikes namely to look for a top tube 51.5-52 and a headtube length at least 110. He wrote some other stuff down but I need to get him to reinterpret what he wrote. Either way once I have identified the bike I will get fit on that specific model anyway, right? So really I’m just after whether the bike’s basic geometry will work for me and which size bike would work. Is there not a way to extrapolate this info from what I already have (roughly of course)? I know John said that Cervelo’s are not a good match for me because the head tube length is like 90 and I need at least 110.
#1) It is much EASIER than you are making it, it is very simple, you are complicating it
#2) your fit coordinates are for that STA, if you change the STA dramatically (IE 2-3 degrees like you are planning) it will also alter your stack and reach, your road bike does not allow enough adjustment of the STA to determine what your stack and reach would be at 78/79 degrees, if this is what you plan on using in the future then you need to be fit at this angle. you do not HAVE to have a 78/79 degree STA but the people on this site believe it makes you faster.
#3) If you use stack and reach then you do not need to look at top tube and headtube dimensions, only stack and reach. The headtube angle is affected by the angle of the seat tube. Imagine a bike where the bottom bracket and stem are fixed in place… now imagine the bike has a 72 degree STA and the length from the nose of the saddle to that stem is 55cm. If you move your saddle forward to say a 78/79 degree STA, that length is now 52cm yet the stem is in the same place. Therefore stack and reach are independent of the seat tube angle. That is why people like stack and reach because you are able to compare bikes regardless of their seat tube angle (which is different from manufacturer to manufacturer). Once you have your stack and reach you just have to make sure that your bike can achieve the desired STA. For example if you get fit on a “fit” bike at 78 degrees and find you need 55 and 32 stack and reach and you find a bike that has a 55 and 32 stack and reach you may think you have found the perfect bike, however, if the bike only allows STA’s of 70-74 you can not put the saddle in the position that allows for the 55 and 32 stack and reach.
Summary…
Is there any reason why you would want to stick with a 75 degree STA? If so then you should look for a bike with the stack and reach you found. If you plan on riding at 78/79degrees like most people on here do then you need to be refit in this position.
if you’re really riding at 75 or 76 degrees of seat angle then, yes, those stack and reach numbers sound about right. if i were you, i’d take a second look at the slice. that’s a fine bike. and, if you want to ride it steeper eventually, that bike will adjust to that nicely, and it’s long trail makes it a slower handler, which is what you’ll need if you do steepen up on a bike built shallow (as this bike is).
the trek equinox ttx is also a very nice bike.
since you used the girlfriend analogy, let me tell you mine. i was single, and i was divorced, and i sat myself down and asked myself not what sort of girl i am attracted to, but what sort of girl i should be attracted to, that is, what sort of girl is really good for me. danged if, after i went thru that exercise, i started being attracted to the sorts of girls who were best for me.
why don’t you try that exercise yourself.
Dan,
After that comment, all I can say is wow!
Enough said 
I’ll try to add a little more info for this discussion. I used this racer’s current bike because he was not sure at the time what he wanted to purchase or when. That leads to a problem that many bike fitters run into, customers with soon to change needs but having a need right now for a bike position that allows for better training. As rider’s loose more weight and get more in racing shape, the perimeters change a lot. I would encourage anyone in fatbastardtris situation to do what he is doing, take some time, continue to loose more weight and make the choice that works best. As a note, he has lost 100lbs so far and my hat is off to him for this effort. Because of some flexibility issues, I don’t feel that at this time he would be that well served on a steeper geometry frame, he needs the taller headtube length. I don’t think that moving him further forward at this time will help with the hill climbing, I based this on muscle firing points and the search for better seat comfort. He is an accomplished racer and has completed several long distance events so a broad power range was important. A couple of months from now, this will be all different, he needs to look for frames with the top tube and headtube length I recomended which I figured for a 77 - 78 degree frame. I like for bikes to handle well, having a bunch of weight directly over the bars is not always the best for fast downhills. Centering the rider in the cockpit will help with the bike stability and ultimately give a better ride.
Thanks John. I really appreciate all of your help with the fitting. I was saving up my questions for you until after I can get a few rides in with the new position. So far I’ve only been able to do two rides each a little over an hour. I will say that I did one ride pushing pretty hard and then got off and did my longest run ever (45 min which isn’t a lot but it is for me). My legs felt totally fresh on the run. It was a strange feeling after so many “brick” workouts where my legs were total mush at the beginning of the run.
Is it not easier to ride steeper when you are less flexible? I have a lot harder time riding in the drops on my road bike than riding steep on my tri bike. Your hip angle opens up the steeper you ride I thought. Unless you are talking about flexibility in a different area.
Riders with neck issues whether from spinal problems or a history of weight lifting where their Trap muscles are very large, have a very hard time of seeing down the road. In these cases, steep geometry makes it difficult for them to be comfortable when they have to try to lift their head to see. Taller headtube lengths generally make these problems easier to solve.
It looks like you should be considering an aero road bike like the Felt AR or Cervelo SLC (I also put the Noah in in case you would prefer Euro over Aero).
I’ve chosen a random bar position (overall stack and overall reach are to the centre of the bars) and matched it across the shown frames. I don’t know what spacer height JC was allowing for in his recommendation, or what aerobars you used. If you were sized with low stack bars then you could use a lower stack frame in conjunction with high stack bars.
I’ve put the 596 in using the higher slot on the medium (figures based on the measurements Jordan gave) and you can see that the stem would be up very steeply in order to match the position I’ve used which is probably not all that far off what you’re looking at. If you look at the weight dist % there is no real handling advantage to the 596 over the road oriented bikes.