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Geometry question - copy what works?

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Geometry question - copy what works?

Old 07-18-21, 07:35 PM
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basscadet
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Geometry question - copy what works?

I have a few bikes but the one that is my favorite is an OPEN UP in a size L - it just feels "right" to me. When shopping for an additional endurance bike to add to the stable, should I use the manufacturer's recommended sizing or find the geometry that is closest to the OPEN UP? Looking at the manufacturer's sizing, they're pointing me to a 58 but the 56 is the closest to what I have with my UP.

If it matters, I'm evaluating the Roubaix, Endurace, and Caledonia-5 and looking for a relaxed-geometry road bike that isn't a gravel bike and can easily fit 28-32mm.
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Old 07-19-21, 06:53 AM
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I would have thought you would want a slightly less upright position on the road bike. In other words a slightly lower stack and longer reach. Otherwise you might as well just get a second wheel set with road tyres for the UP. Having said that the Roubaix has a considerably higher stack than your UP and either a shorter or longer reach depending on size. The Endurace has a shorter reach even in size L. Stack is either lower or higher depending on size. A 56 Caledonia-5 is the best match to your UP, with identical stack and reach and very similar wheelbase. That would be the safe choice if you can't test ride. The position would be pretty much identical to your UP.

Have a play around on Geometry Geeks:-

https://geometrygeeks.bike/compare/o...nia-5-2021-58/
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Old 07-19-21, 07:11 AM
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What you want is to have the contact and control points---bars, seat, and pedals---to be in the same relationship as on the bike you like.

All the size numbers (or letters) are meaningless. Measure stack and reach, top center of the seat post (from top of seat) --- to the junction of the stem and bars, and to the top of the hoods on each side---how far back behind the BB is the spot on the seat where you sit.

I actually drew out a schematic of my body and my bike to get a good idea about what fit me and then I could transfer it to other bikes. Even so though, every bike is different. I got a Fuji Sportif in 56 and it fit perfectly right out of the box---I changed the saddle and seat post but otherwise it fit exactly as I had imagined. I didn't have to adjust anything.

But .... I did find that i have a tiny bit of toe overlap at very low speeds. Possibly if I had gotten the 58, I could have swapped the stem, remove some spacers, maybe put on narrower bars, and gotten the same fit but no toe overlap. Or maybe it would have been the same toe clearance, but everything else would have been bigger so I would have had to use a shorter stem, shorter seat post with less setback .....

So .... in summation, I have nothing helpful to add.
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Old 07-19-21, 09:24 AM
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Depends on so many things.

I bought my current bike knowing that I wanted a lower stack to get lower with the bars after riding comfortably in a more upright position for years. So if you want to keep the exact same position, what are you hoping to get out of that new bike?

I also came from large frames. Some that were way too large for me, but comfortable for the riding I was doing with them at the time. The specs for my current bike show me in a 56 or a 58 cm frame. Test riding showed that the 56 was the better option. And I very much like the fit. So don't get me wrong, but I'm wondering what a 54 cm would have felt like if I'd thought to try my Tarmac in a 54 cm frame. Oh well, I just won't know till I search for my next bike which probably won't be for a few more years.

So the gist of this if try them on. And if you are buying a mid to high priced bike, insist on a long test ride. Even if it's on the less expensive version of the same frame with lesser groupset. That's what I did for my current bike, then I felt good about ordering a more expensive version of the Tarmac. And the 10 mile ride on each had me choosing the other frame size of what I thought I was going to pick from the ride around the parking lot the previous day.
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Old 07-19-21, 09:25 AM
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Well, forgive me for being the fly in the ointment, but a bike that “just feels right” is not merely a function of the rider’s contact points, nor does copying contact point location ensure you’re going to get that feeling on another bike. In other words, fit (i.e. contact points) is a subset of that “just right feel,” and it takes overall geometry and design to get “the feel.”

Fundamental to this, I also don’t believe contact points are sacrosanct, and in fact, different geometry demands different contact points if you want to get the best out of the bike. Consider as an example, at the extreme end, the differences in fit between a standard road bike and a time trial specific road bike. Very different positions for the same rider there. In short, ideal fit is highly variable and dependent on how the rider interacts with the geometry.

Personally, I select bikes on their geometry and the handling attributes the overall design imbues. Size is just a matter of being within a workable range, and fit follows last, both because it’s highly adjustable and will be what it will be depending on how the bike feels when I ride it. I currently have 10 bikes, none of which share the same exact contact point location, at least not intentionally. Those 10 encompass a huge swath of frame designs, but even narrowing it down to, say, three roadies and the gravel bike, while they’re all comfortable, my position on them is dictated by the diverse charachteristics (of geometry and handling) and so fit on each bike is different.

So to answer the OP, yes, if you like the Open’s feel, copy the geometry for the next bike., paying particular attention to head- and seat tube angles, fork offset, chainstay length and wheelbase. If you in fact want and get an exact geometric copy, then you may not need to mess with fit, but ultimately, the frame will let you know. For example, different materials will probably have different attributes, and you might find something like a more flexible frame feels better when your weight is center balanced, or that a stiff frame allows you to get out front more and rewards driving the front wheel.
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Old 07-21-21, 03:13 AM
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Originally Posted by chaadster View Post
So to answer the OP, yes, if you like the Open’s feel, copy the geometry for the next bike., paying particular attention to head- and seat tube angles, fork offset, chainstay length and wheelbase. If you in fact want and get an exact geometric copy, then you may not need to mess with fit, but ultimately, the frame will let you know. For example, different materials will probably have different attributes, and you might find something like a more flexible frame feels better when your weight is center balanced, or that a stiff frame allows you to get out front more and rewards driving the front wheel.
Might be two different topics underone heading here.

"Geometry" properly includes all the things you mention, which affect handling , stability, responsiveness ... whichever words you choose to use to describe it. But is that what the OP really wants?

My initial take is that the OP feels comfortable riding the Up not because of its handling characteristics but because of its riding position---hence the focus on my response. OP talks about size, but not head-tube angles, rake, trail, wheelbase, etc. which are the geometry issues which affect ride characteristic. This gives me the impression that h wants it to feel the same when he sits on it.

The UP seems to have pretty standard road-bike geometry. A Giant Defy seems to be comparable, or any number of other "rqacy but relaxed" "endurance" frames. I wanted to compare to the Domane and Roubaix .... and came across these two articles which the OP might find interesting. https://cyclingtips.com/2018/11/the-...-the-steering/ and https://cyclingtips.com/2017/10/spec...e-bike-titans/

Personally, if I had the UP, I'd buy more wheelsets and keep the frame.

Exactly what are you looking for in the new ride, OP?
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Old 07-21-21, 05:29 AM
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Realize that geometry of frame and fit to bike are NOT the same thing. There is some overlap. For fit to bike if your fit is spot on use stack/reach to compare frames. Geometry really relates more to handling/stability etc., while fit relates more to comfort and efficient position on the bike.

I hope that helps but it might muddy the waters.
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Old 07-21-21, 08:53 AM
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Originally Posted by basscadet View Post
I have a few bikes but the one that is my favorite is an OPEN UP in a size L - it just feels "right" to me.
RAD.

Using the stack and reach measurements figure out the length of the hypotenuse on that bike. Bikes that have the same hypotenuse (or within a few mm) as the bike that "just feels right" will always be comfortable for you.

While this article is specific to MTBs it can be applied to all bike types.

https://www.pinkbike.com/news/lee-mc...ke-set-up.html
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Old 07-21-21, 09:29 PM
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Hi all - so lots of great input and questions.

As to what I'm looking for and why not just buy a second set of wheels for the UP: I want to be sure to have a second bike as a backup bike but also a dedicated trainer bike for the winter months.

I'm enamored with the UP but I don't want to just buy another UP, I'd like to find something that is similarly relaxed in terms of riding position. My current "second bike" is a Canyon Ultimate CF SLX 9.0 which I find too twitchy, unreliable on imperfect surfaces, and frankly I'm only able to extract the additional performance ceiling of that bike in perfect, ideal conditions (no crosswind, good pavement, etc) which is a rarity where I live. My average speeds in Strava between the two bikes is incredibly close which I also find very confusing as I'd expect the Canyon to smoke my UP.

I originally went with the Ultimate as I thought endurance bikes had too much overlap with the UP but the reality is that I just simply don't like the Ultimate and would prefer the looks, feel, comfort, and approachability of the UP to the Canyon, 9 times out of 10.
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Old 07-22-21, 09:37 AM
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Originally Posted by basscadet View Post
Hi all - so lots of great input and questions.

As to what I'm looking for and why not just buy a second set of wheels for the UP: I want to be sure to have a second bike as a backup bike but also a dedicated trainer bike for the winter months.

I'm enamored with the UP but I don't want to just buy another UP, I'd like to find something that is similarly relaxed in terms of riding position. My current "second bike" is a Canyon Ultimate CF SLX 9.0 which I find too twitchy, unreliable on imperfect surfaces, and frankly I'm only able to extract the additional performance ceiling of that bike in perfect, ideal conditions (no crosswind, good pavement, etc) which is a rarity where I live. My average speeds in Strava between the two bikes is incredibly close which I also find very confusing as I'd expect the Canyon to smoke my UP.

I originally went with the Ultimate as I thought endurance bikes had too much overlap with the UP but the reality is that I just simply don't like the Ultimate and would prefer the looks, feel, comfort, and approachability of the UP to the Canyon, 9 times out of 10.
On that basis the Caledonia-5 seems like a good option. Fit should be very close to your UP and its geometry should give you the stability you want. A Giant Defy should work well too. Mine is super stable. The Endurace is still quite a racey geometry by comparison to these. The Roubaix too, despite the compliance and high stack, is very much a race bike geometry.
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Old 07-22-21, 11:43 AM
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A link to the bike's geometry would be helpful. https://opencycle.com/UP

The large frame has a 580 stack and 387 reach. The stack is about 15-20mm more than a more race oriented frame.
The seat tube angle is less, just so it works with a zero setback post. No big deal there. LOOK used put a 72.5 STA on all frame sizes many years ago.
The steering trail is on the quick side, just like a racing bike might have. To get an exact value, the tire size must be known.

Bicycle Trail Calculator | yojimg.net

I'll disagree with others. All you need to do is compare the stack, reach and steering trail to figure out if a prospective new frame is similar. In most cases there are two sizes that I can make work, but I prefer one that requires few or no steering tube spacers. I prefer more steering trail, like Colnago or Cinelli use. It makes the bike more stable on high speed descents. My latest Cinelli superstar frames are one my all time favorites.
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