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PostPosted: Fri Sep 19, 2014 10:01 am 

Joined: Sun Aug 26, 2012 11:12 am
Posts: 9
Have been riding bikes for a while ;)
My past/current bikes include Kuota Kebel medium, Cannondale SuperSix EVo 54cm, BMC SLR01 2012 55cm, Parlee Z4 56cm, Colnago Master 54cm

Am looking at geometries of of Cervelo, Colnago, BMC, Parlee as am about to buy two new frames, one aero and one traditional

I am a bit amazed as to how makers approach differently STA, reach, stack and TT length
Colnago has almost the same reach number for frames with effective TT 519, 530, 540, 550, and 556 - the reach is always around 380-384mm. They adjust TT length with STA angle. Colnago are well known for making comfortable bikes and they do have plenty of experience in geometries gathered during the last 40-50 years.

How do we explain such a different approach by Colnago and say Cervelo (an other brands)??

Give you some examples for size c 530mm TT

Colnago C60 size 48s TT 530, stack 528, reach 384 STA, 74.58deg
Pinarello F8 TT 528, stack 525, reach 373, STA 74deg
Cervelo R5 2014 TT 531, stack 530, reach 369, STA 73deg
BMC SLR01 2015 TT 535, stack 530, reach 378, STA 73.5deg

PostPosted: Fri Sep 19, 2014 11:53 am 

Joined: Thu Sep 04, 2014 12:23 pm
Posts: 83
You are right. There is a divide in fit philosophy, especially when it comes to Cervelo with their patented 73 deg sta which keeps their chain stay length more consistent. Even though I don't ride a Colnago or even think that company who made some of the best vintage bicycles makes the best carbon bikes, I do side with the notion of changing sta with size. I believe Cervelo's philosophy is a compromise for rider fore/aft CG and or hip angle...but I personally ride a bike with a 73 deg sta so I could ride a Cervelo...and I am on the leggy side. And yes, sta does affect net reach as you know.

Most of the differences can be tuned out with careful frame selection either up or down and stem length and seatpost setback. But where the problem mostly occurs is with a proprietary seatpost like an aero bike. Now you can't change the seatpost to dial in setback and change effective seatpost angle...but some are available with different clamps or caps to accommodate this.

So if you have your heart set on a particular frame, you can probably make it fit with the right choices. I will say that many that can't and this does happen, many times are wrong about what should be their best fit anyway. I see this all the time in people I fit and riding position on the road....I would say more get it wrong than get it right in fact.

Posted: Fri Sep 19, 2014 11:53 am 

PostPosted: Fri Sep 19, 2014 2:53 pm 

Joined: Sun Aug 26, 2012 11:12 am
Posts: 9
Yep, I too often see people riding huge frames hoping that it would be more comfortable, heaving seat 2-3cm too high, people choosing bikes/frames based on weight/colour/stiffness tests. While all those do matter, people pay little attention to the frame geo ending up compensating some gross size mistakes with seatpost setback or stem length (usually going to 70-90 stems).

I like the fact that with C59 and now C60 Colnago varies for instance chain-stay length

PostPosted: Fri Sep 19, 2014 3:12 pm 

Joined: Wed Apr 09, 2014 2:54 pm
Posts: 7
What I think Cervelo (and others who use fixed STA/CS length over a broad size range) miss with their approach is maintaining weight distribution over the size range. When I look at bikes to get a feel for how they're going to handle, I'm going to be looking primarily at five things; wheelbase, front & rear centers, BB height and steering trail. You can throw a lot of quite different STA, HTA, Reach, Stack, etc combo's together that have the same results on my five parameters and they will handle extremely similarly after you fit yourself with saddle height, setback, and stem/bar setup. After all, your position really shouldn't change relative to the BB on whatever frame you ride, so all you're doing with the frame then is positioning the wheels underneath you to give proper weight distribution, while adjusting center of mass and steering geometry to tune the level of stability at speed.

On average, as riders go from short to tall, a greater percentage of overall height tends to be leg length, meaning a rearward shift of the torso and it's weight, with the opposite effect as you go from tall to short. So shorter riders will likely benefit from relatively shorter stays and steeper STA's, while keeping the front center from getting too short. This is what Colnago have always done; huge difference in front centers on say, a 54 Cervelo vs a Colnago. As for wheelbase, taller riders have a higher center of mass and need a longer wheelbase for proper tire loading, since body movements will have a greater effect.

I use reach as a tool primarily to let me know what length stem I'm going to need, but look a lot more closely at other things.

PostPosted: Fri Sep 19, 2014 4:02 pm 
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Joined: Sun Jun 18, 2006 10:29 am
Posts: 3374
Location: Athens, Greece
Colnago's experience (and view) on road bike frame geometry is indisputable...

My 6530gr Wilier Cento Uno
My 8618gr Colnago Master X-light
My 9745gr Pinarello Dyna

PostPosted: Fri Sep 19, 2014 4:31 pm 
User avatar

Joined: Sat Dec 06, 2008 10:14 am
Posts: 963
Location: Sweden
Kind of like claiming that Levi's experience on the fit of jeans is indisputable, instead of going for what actually fits your own rear end...

Also, on the subject of reach, remember that this is measured to the top of the HT, if the HT of one frame is 20mm taller than another frame with the claimed same reach, the actual reach will be offset by about ~5mm when measured at the same stack. Take that into account when going thru geometry charts.

Planet X Stealth w/ drop bars

Van Nicholas Zion Ti

PostPosted: Fri Sep 19, 2014 4:55 pm 

Joined: Sun Aug 26, 2012 11:12 am
Posts: 9
interesting comments THX!
would you mind casting your view as to differences in handling of three frames? would really appreciate

Colnago Master steel frame ( i do not have stack and reach numbers)
Colnago C59 s48
Parlee Z0 size M

Master C59 Z0
TT 540 530 545
stack ?? 528 545
reach ?? 384 383
STA 74 74.58 73.5
front centre 591 584 578
rear centre 405 402 410
Headtube 117 127 140

Wheelbase on Parlee is 9780 and on the Master 9800 (no data for C59)

I am riding Master now with a seatpost 25mm setback and stem 100 (saddle in the middle of rails)
for C59 i use c 15mm spacer

Thank you

PostPosted: Fri Sep 19, 2014 7:50 pm 

Joined: Wed Apr 09, 2014 2:54 pm
Posts: 7
No need to quote above

Well, there are some important missing bits there, such as BB height and head angle/fork offset/trail. Colnago no longer publishes their steering geometry numbers, but in general they tend to use much slacker head angles in small sizes, in the 71-72 degree range, which give higher trail numbers than what you'd see on say, the Parlee. Small Colnago's (I have a 55 Tecnos myself) usually run around 6cm of trail or greater, while most bikes, as do the Parlee run in the low-mid 5's. The two Colnagos will be a lot alike, with the Master being a bit more stable due to the longer wheelbase. The Parlee has longer chainstays and a much shorter front center with less steering trail. The wheelbase and trail differences should make it less stable at speed, as on a descent, but quicker to respond at lower speeds. It also has more weight on the front and less on the back, which in concert with the shorter wheelbase will result in more weight transfer to the front when you're standing or in the drops. You might notice that as rear wheel hop when sprinting hard in the drops, tendency to lock or skip the rear tire more often under hard braking, etc.

Given your stem length I'd say the Master might be a bit long in the front for you unless you're running a bar with a lot of reach/drop. A good way to know which is best for you is to get your loaded weight distribution, seated on the bike with hands in the drops like you'd be in a crit or the like. The position you use when you're going fast... Use a helper and a scale under one wheel with something under the other to keep the bike level, then swap the scale to the other end. Sum the weights to get a total and see what your front/rear balance is. The old CONI ideal number was 45F/55R; I tend to like it around 44/56 myself. If you're significantly different but are happy with your position in ergo/power terms, you need to think about perhaps trying a different frame. Longer front and/or shorter rear will move the weight balance back and vice versa.

PostPosted: Fri Sep 19, 2014 9:42 pm 

Joined: Sun Aug 26, 2012 11:12 am
Posts: 9
Very infomative! Many thx
For C59 I will be using stem of 120 and compact short reach bars

For Master am using traditional bars with a deep drop and non-compact reach

Parlee is an option to buy, which I am considering
Hence wondering how different it would be to the Colnagos
Parlee is a second hand and it is standrd M geo
If I was getting a brand new one I would probably take S

I have been riding 55-56cm frames and felt they stretching
me out bit too much and was trying to compensate with
some short stems

I love the way Master strears and handles high speeds

C59 is about to be build and will ride it from next week
So am very eager to see how it would ride.
I will be keeping C59 in Mallorca as my training and racing bike.

I need to buy two more bikes. Would like one for comfort and climbing and the other for aero.

Posted: Fri Sep 19, 2014 9:42 pm 

PostPosted: Sun Sep 28, 2014 3:01 pm 
User avatar

Joined: Tue Mar 04, 2014 4:44 pm
Posts: 16
Location: Phoenix, Arizona
Great info I'm going to try the scale and see,

Using Tapatalk

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