Help deciphering stack and reach for frames?

Discuss light weight issues concerning road bikes & parts.
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SolidSnake03
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by SolidSnake03

Hey everyone!

So I'm looking to buy a Cervelo Soloist, S1 or possible an S2 as my next bike but I'm having a bit of trouble trying to figure out if I should buy a 51 or a 54. I was wondering if I could get a bit of help deciphering the stack and reach info compared to my current bike to see what the difference between the two would be.

Brief not, I like a long stem and more post showing vs. less. Saddle height is 71.5cm, I'm 5'8ish Currently ride a Cannondale SuperSix 52cm with a 120mm stem -6 slammed, Thomson Elite setback post post 53.4cm from saddle nose to middle of handlebar clamp.

Image
From the look of it the 54 would be close in reach to the 52 but with a lot more stack. How would this translate to the stem and amount of seatpost showing? The 51 has a good bit less reach but about equal stack, where does that put me?

I have edited the chart to show the adjusted numbers. The stack and reach are now correct showing that the 54 is actually pretty close to what I have now albiet with a bit more stack
Again I prefer longer stem+more post but it isn't like I "need" a certain look or something
Last edited by SolidSnake03 on Wed Oct 09, 2013 12:10 pm, edited 1 time in total.
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shimmeD
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by shimmeD

It looks pretty simple to me:
If you can't get down low enough the Cervelo 54 doesn't fit you, end of story.
You'll need to increase your stem to 130 from your 120, on the 51. Is that too long?
Less is more.

by Weenie


JN2Wheels
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by JN2Wheels

Why is the 54cm headset stack figure 20mm more than the 51cm? Shouldn't they have the same headset cone? That is a good bit of your stack difference if that's wrong. Assuming its wrong, you can go for the 54 with a 120 -17 stem slammed and get lower than your cannondale, with the same reach.

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SolidSnake03
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by SolidSnake03

The headtube on the Cervelo 54 is 140mm while on the 51 it is 120mm same as the Cannondale 52 *120mm* The added 20mm headset stack is taking into account the different in headtube height/length.
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davidalone
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by davidalone

assuming the seat tube angles on both bikes are similar or about the same, and you're going to set them up with equal BB setback and saddles, I'm guessing you wont see much different in post height between the dale 52 and the cervelo 51. you may see a pretty big difference in the 54 though.

have you considered -17 stems?

I did the math. on the 54 cervelo you could go with a slammed -17 degree 120 stem. that would put you 8mm higher than the 52 dale and with 5mm less reach, which is pretty close.

shimmed is right about the 51, you'd need to go up a stem length to 130mm for that with a -6 stem.

davidalone
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by davidalone


NGMN
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by NGMN

No, you don't need to add 20mm to the headset/spacer numbers, that is already accounted for in the STACK number itself.

Your current bike has a stack and reach of 529, 382

Cervelo's are 522, 370; and 541, 380

You could either run a 5ish mm spacer and a 1cm longer stem on the 51; or a -17 stem on the 54.

I'd probably go with the 54 if it was me, but it forecloses going lower in the future.

GT56
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by GT56

fwiw, i run a 71.8 cm saddle height and got a 6,5 cm saddle to bar drop on a 54 soloist, with a 7,5 mm spacer and a 13 cm - 6 deg stem

stay away from a -17 deg stem on a bike with a sloping top tube as is looks awful

also, too large a frame feel like a block of wood

my vote goes to the 51

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SolidSnake03
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by SolidSnake03

I have edited the chart now with the correct stack/reach numbers. Basically I made the mistake of adding in the +20mm of headtube to the headset+stem stack section when this was actually already accounted for in the stack number.

The newly updated chart shows the numbers more clearly and it looks like the 54 Soloist is actually pretty close aside from the +12mm higher stack. It actually still has less reach than the 52 Cannondale! The stack I think could easily be accounted for by a greater stem angle or even bar choice, currently running some Easton EA70's but like a more classic shape.

Tough choice, looks like the 51 Soloist would require 130mm stem at least.

GT56, regarding your set up, I would have a similar saddle height but no spacer meaning my drop would be closer to 7+cm.

I'll be honest I'm a bit torn on this one, I could see either working I think but could use some more opinions? 1 thing is I do prefer the stem slammed which would happen without a doubt on the 54.
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cyclenutnz
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by cyclenutnz

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Definitely go with the 54 - the 51 has a really short front centre
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SolidSnake03
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by SolidSnake03

What does short front center mean exactly? Sorry noy familiar with it....
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WMW
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by WMW

It means you will have toe overlap... but that is the price you pay for quick handling and good weight distribution.

Most manufacturers kick out the head angle and increase the fork rake on small frames to prevent this.

Getting back to frame sizing and setup, you need to determine the xy positions relative to the bottom bracket where you want your saddle and bars to be positioned... then calculate what is necessary to connect the dots... stem, spacers, seatpost, etc. Pick the one you like the best.
formerly rruff...

by Weenie


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