Geometry And Fit Comparison Question

[LesMiner]

It is winter and time on the trainer needs a distraction to fight off boredom. So I comparing my existing 2008 Scott CR1 to the 2015 Specialized Tarmac. They are different and there is 7 model years of technology between them. The Scott frame weight is 1006 grams and the Specialized is down to near 850 - 800 grams.

Here is the comparison. The seat tube measure is not exactly the same between the two. Scott provides 2 while Specialized has one. Scott does not have any fork dimensions in their spec. I added in Seat Post Diameter because that will effect the ride between the two. For the most part the dimensions are less than 10 mm apart, some nearly the same. Angles are different. The Specialized looks a little smaller and probably more sloped from head tube to seat post.

Would the fit difference be significant? The ride more plush or more harsh? Which of these dimensions would be more sensitive to fit?

http://i151.photobucket.com/albums/s126/LesMiner/GeoCompare1_zpsf0ad11a8.jpg (http://s151.photobucket.com/user/LesMiner/media/GeoCompare1_zpsf0ad11a8.jpg.html)

[seanile]

imo, you would hardly notice much if you were sit on the bike. a lot of those could be negated by wheel/tire selection and stem/seatpost/saddle positioning.
as far as riding and road feel.. tubing dimensions and type will make a bigger difference.

[sandyrs]

The only difference that seems at all significant is the head angle. It wouldn't be different enough to be a problem for handling, but it would be different.

[kgreene10]

The ST angles are hugely different. I'm guessing you are tall and so the 0.8* slacker angle on the Tarmac means you will have to push the saddle quite a bit forward compared to the Scott. How much depends on saddle height, but it's an easy calculation using the Pythagorean Theorem. My guess is that it will be more than 1cm.

[sandyrs]

The ST angles are hugely different. I'm guessing you are tall and so the 0.8* slacker angle on the Tarmac means you will have to push the saddle quite a bit forward compared to the Scott. How much depends on saddle height, but it's an easy calculation using the Pythagorean Theorem. My guess is that it will be more than 1cm.

Tru. That won't have a serious effect on handling assuming he can get his saddle in the same spot, but that might be easier said than done if his saddle is forward on the rails.

[LesMiner]

Tru. That won't have a serious effect on handling assuming he can get his saddle in the same spot, but that might be easier said than done if his saddle is forward on the rails.

I am not so tall as I am longer legs and shorter torso. My current saddle position is about in the middle of the saddle rail range. I included the seat post diameter because the Tarmac would have a greater seat post exposure. The smaller diameter means greater potential flex of the seat post.

[John H.]

Hard to say if the Tarmac will work better/same without knowing your actual fit coordinates.
Stack is less on the Tarmac- Do you have much in the way of spacers on your Scott?

[LesMiner]

Hard to say if the Tarmac will work better/same without knowing your actual fit coordinates.
Stack is less on the Tarmac- Do you have much in the way of spacers on your Scott?

I have one spacer that might be a cm, maybe less. I do have the stem flipped and its a 7 or 8 degree slope. When the bike was delivered it was nearly completely assembled by Scott. The stem was mounted and the handle bar was loose with bar tape and shifters mounted.

[John H.]

Flipped up or flipped down?

[LesMiner]

Flipped up or flipped down?

Up

[John H.]

Then it might not make sense for you to purchase a frame with less stack than the Scott has.

[LesMiner]

The 8 mm could make a fit problem particularly on longer rides. Before the Scott I had a Litespeed. It had a 7 cm drop from the saddle to the handlebar. Since the frame was a compact type with a long sloping top tube, the seat post had to be extended to accommodate my longer legs. So the ride would feel a bit wimpy at times because the seat post could flex quite a bit. I liked riding that bike, I felt fast. Over time the Litespeed became uncomfortable. I got to the point where I could not get down into the drops and keep my head up to see. Aging has its downside, loss of flexibility is one of them. Currently the Scott is not a problem.

This Tarmac is the newest road bike that also has hydro disk brakes and Shimano Dura Ace Di2. This Summer I rode around Southwestern Wisconsin for a couple of weeks on a new endurance type road bike with mechanical disk brakes. The fit was not much different than my Scott. I rode over 800 miles and a few days were over 100 miles. Its is hilly and the climbs are short and steep, a couple of miles or less. Riding the flats and climbing were a disappointment. The downhill however was great. Very stable and the disc brakes are so much better going downhill into turns. The longer wheelbase and chain stays make a difference. So the Tarmac could be the best of both. That is what makes this daydream what if interesting. Actually purchasing is a whole other thing.

[kramnnim]

Something like this might work to compare the two geometries? http://www.os2.dhs.org/~john/Bicycle_Geometry/index.html

...I had a simpler version, but can't seem to find it.

Oh, here it is- http://gearinches.com/blog/misc/bike-geometry-comparator

[lhuerta]

stack and reach are all that matter

[rnhood]

Seat tube angle of 73.3 on a 61cm frame just doesn't sound right to me. 72.5 does.

[LesMiner]

Seat tube angle of 73.3 on a 61cm frame just doesn't sound right to me. 72.5 does.
I rechecked the seat tube angle here is the CR1 Geometry (http://dfp2hfrf3mn0u.cloudfront.net/188/18863_original_1.jpg) and it is 73.3 degrees.

[LesMiner]

Something like this might work to compare the two geometries? http://www.os2.dhs.org/~john/Bicycle_Geometry/index.html

...I had a simpler version, but can't seem to find it.

Oh, here it is- http://gearinches.com/blog/misc/bike-geometry-comparator

Thanks for sharing, this is very helpful.

[Tommasini53]

Thanks for sharing, this is very helpful.

+1 intestesting tool for comparison....I am also shopping for a new frame and this will help evaluate the difference in geometry across brands. very confusing for some of us. thanks for the link!