mdzukunft

192 cm cyclist. On 175 mm cranks.

Have a newish-to-me 2014 Cervelo S5 (61 cm, s/r 630/405). Having some fit issues and pro fitters in Bay Area are booked solid until late April/May. Obtained my measurements (thrice over) via CompetitiveCyclist and have been using the iOS BikeFastFit Elite to try to work on geometries. Everything is way off due to the stock, uncut Cervelo seatpost @ 350 mm (and I'm bouncing in the saddle with extreme toe-down position through the pedal stroke). Based upon my measurements (see below), it looks like I need to cut the seatpost by 60-70 mm. I figure that will help the other measurements fall into place; however, my question is whether cutting that much of the seatpost is an indication that the 61 cm is too big for me (previous bike was an 2007 Cdale Synapse (58 cm, no published s/r). In particular, CompetitiveCyclist spit out a top tube length of 547 - 551mm but the Cervelo is much longer at 596.

Below are the geometries of the S5, my measurements and the recommendations by CompetitiveCyclist (I know they are an approximation and not a replacement for a true bike fit).

Here is the link to video of me on the bike (showing the rocking motion in the saddle):
https://drive.google.com/drive/folde...et?usp=sharing

Do you all think the 61 cm is too big for me?

S5 Geometries
============
Reach: 405.0
Stack: 630.0
Top Tube: 596.0
Head Angle: 73.5
Seat Angle: 73.0
Head Tube: 205.0
Chainstay: 405.0
Front Centre: 618.0
Standover: 813.0
BB Drop: 68.0
Fork Rake: 43.0
Wheel Size: 700c
Tire Clearance: 23 mm


My measurements (cm)
===================
Inseam: 89
Trunk: 71
Forearm: 36
Arm:67
Thigh: 65
Lower Leg: 56
Sternal Notch: 159
Total Height: 192

The Competitive Fit (cm) → deep in drops
==================================
Top tube length: 54.7 - 55.1
Seat tube range c-c: 57.6 - 58.2
Seat tube range c-t: 59.4 - 59.9
Stem Length: 11.6 - 12.2
BB-Saddle Position: 76.3 - 78.3
Saddle-Handlebar: 55.1 - 55.7
Saddle Setback: 8.2 - 8.6


The Eddy Fit (cm) → less saddle to bar drop
====================================
Top tube length: 54.7 - 55.1
Seat tube range c-c: 58.8 - 59.4
Seat tube range c-t: 60.6 - 61.1
Stem Length: 10.5 - 11.1
BB-Saddle Position: 75.5 - 77.5
Saddle-Handlebar: 55.9 - 56.5



Crank @ 0



Crank @ 90



Crank @ 180

DaveSSS 

Are you so new to cycling that you don't know your proper saddle height, or the stack and reach of your previous bike? That's what stack and reach are for - to allow accurate comparisons of different frames. Reach can only be compared at the same stack height, so a larger frame with a taller stack is being compared, the reach should be reduced by 3mm for each 10mm of additional stack.

If the inseam posted is cycling inseam from floor to firm crotch contact in bare feet, the a typical saddle height might be around 79cm. My inseam is 83cm and my saddle height is 73cm. I use a stack that allows an 8-10cm saddle to bar drop, with a -6 or -17 stem. That requires a stack of about 525mm, plus the standard 15mm headset top cover and no spacers. My latest frames have about 15mm less stack height, so I use a 30mm tall headset to cover and no spacers.

If you really need to cut much off your post, you bought the wrong size frame.

mdzukunft

I am not new to cycling. But - again - Cannondale did not publish stack and reach data for my 2007 Synapse (or at least I am unable to find it for that vintage). Nor did the LBS who sold me that frame even talk about stack or reach, much less measure them for me. Moreover, that frame didn't exactly fit me like a glove which is why I sized up on the Cervelo.

And, yes, the inseam posted is a proper inseam measurement. All values measured 3x with a friend.

Unfortunately, there's a fairly good difference between a 58 and a 61. I'm in-between sizes it would seem.

MidTNBrad

I have a 61 cm Cervelo R3 manufactured in 2015. I'm 190.5 cm tall and am quite comfortable on my bike although it looks like your S5 is longer and lower (MUCH lower it seems) than the R3. Stack and reach for my bake are 630 and 405 respectively and I have a 110mm stem. I don't know my exact measurements but I do know my torso is taller than average.

Iride01 

Set your saddle height first. Most everything else builds off of that.

Be careful about that pointing toes down thing. I know some like it, but I don't. My feet are pretty much in the same position (give or take a little) through out the entire crank revolution while normally seated. It's only when accelerating or standing that my foot angle changes.

mdzukunft

The pointed toes isn't preference. It's due to the saddle height. I experimented on the trainer last night. If I pedal with a slightly toe down or flat position, my rocking in the saddle is more pronounced as I have to shift my pelvis to finish the down stroke. On motion capture analysis, I'm also "flicking" the back of my knee on the upstroke. So the pedal stroke is not smooth.

I guess I'm torn between the 58 and the 61. Since neither one fit super well, the most appropriate action is to get fitted for stack and reach on an adjustable bike with a fitter. If only I didn't have to wait 2 months.

Iride01 

Smaller bike will be more fun and sporty. Larger will be more like a four door luxury sedan on the open road. Don't forget to look at things like crank length, stem length and handlebar width that sometimes change between sizes.

DaveSSS 

There's not that much difference between a 58 and a 61. The stack difference is 23mm. That's easy to handle with a -17 stem instead of a -6. The reach is about 15mm longer, but if you've got a long torso, that shouldn't be an issue. The frame may be on the tall side, but then you can probably ride it slammed.

I assume that the seat post is hitting the water bottle cage mounting bolt. Most posts need a 10cm minimum engagement. Take 1cm off at a time, if that is the case. I'm guessing 79cm saddle height.

Dean V

The competitive fit you listed is fairly close to what I have except I have a bit more reach.
But I am only 180cm tall.
I usually ride a 56cm frame.
I can't imagine it being right for someone 15cm taller.

Cervelo

First of all let me preface this with I am not a fit expert but I own and have owned many bikes over the years and as you might have guessed several Cervelo's . I also owned a 2009 Cannondale Synapse. I am 178 cm tall so it does not directly translate to your experience but speaking from experience the numbers you are quoting from the sites you have plugged into do not appear correct to me. All the Cervelo's I have owned except my time trial bikes have been 56 cm and they fit me perfectly. You are 17 cm taller than me so my first thought would be that a 61 would be the proper size for you.

As I said I am not a fit expert and as others have recommended I would recommend getting someone who is to fit you. I just wanted to let you know I do not feel the online calculators are serving you very well.

The last thing , actually really the biggest reason I responded to this thread, is a warning. Make certain that when you or someone else cuts your seatpost if you keep the bike be absolutely certain that the when the seatposft is cut to make sure it is chamfered on the side toward the seat tube. Many S5's were ruined by the seatpost hitting the wheel cut out and permanently damaging the frame. Let me know if you need any more description of this.

big john

Get on any other bike and figure out your seat height as best as you can. Use a plumb bob to get the fore-aft the same as the Cervelo. I'm a little bit shorter than you and I could ride that 61 provided I could get the bar high enough.

mdzukunft

I tried embedding or linking the photo of this but it won't let me until I hit 10 posts. Anyway, already done. Saddle setback positioned at 9 cm.



Saddle setback from BB

big john

What I meant was use the bike with a standard seatpost to figure your saddle height then transfer that measurement to the Cervelo. Figure out the bar height and stem length after.

Iride01 

Just write the URL to the pic in plain text in your next message. Remove the https:// and then put a space on each side of any . (dot)

Of course you might have just reached your maximum number of post within a certain time. Not quite sure what that is.

tomato coupe

If you're riding on the uncut seat post, I wouldn't worry too much about the frame being too big. I'm guessing the supplied seat post is long enough for a really tall rider.

For a given seat post length, how much can you adjust the saddle height on this bike?

mdzukunft

The amount of adjustable post length above the seat post collar is 180 with 170 recessed within the top tube. That is as low as it goes due to the asymmetrical rear wheel cutout. In order to go lower, it has to be cut. The question is how MUCH to cut. (DaveSSS is probably right by suggesting 10 mm at a time but I need a bike shop to do this for me and the only one who will is 20 min away. Annoying.) I don't really trust CompetitiveCyclist's calculator at this point. Wrench Science's calculator suggested 790 mm which sounds more accurate (a delta of 35 mm) and also what DaveSSS suggested.

I took some motion capture video and sent it to one of the prospective bike fitters. He thinks the 61 cm is appropriate (or that I could probably do a 58 cm with longer post/stem) but the saddle is too high. So I'll work with what I have for now.

Also, I spoke to a representative from CompetitiveCyclist. Admitted the calculator needs an overhaul and there have been complaints re: recommendations being way off. He advised me not to trust it. It is planned for an overhaul this year.

Dean V

You said you are not new to cycling, but it sounds like you don't know what your seat height should be??

DaveSSS 

I found the geometry chart for the 2014 S5. Page 46. It shows a head tube length of 225 and a stack of 630. If your inseam and saddle height are only 60mm more than mine, then the frame is much too large.

https://issuu.com/grahames/docs/2014-catalogue

tomato coupe

You're 5' 6" and ride the smallest frame offered by (?). Telling the OP, who is 6' 5", that his frame is "much too large" based on your body dimensions and your bike fit is silly.

DaveSSS 

If a longer inseam (and hence saddle height) are accurately known, then the stack height should be proportional to that saddle height, to produce a given saddle to bar drop. The OP claims to have a cycling inseam that's only 6cm longer than mine, so the other 21cm must be torso length. A large frame size, might fit his torso reasonably well, but it sure wouldn't go with those short legs.

The geometry chart that I found also listed a much taller stack than the OP listed, so a comparison of the head tube length should be made to see it the OP's bike is really a 61. A stack of 630mm shouldn't be needed. That's over 10cm more than I need.

tomato coupe

Again, you're almost a foot shorter and have very different body proportions than the OP. Using your inseam and bike fit parameters to determine the OP's correct frame size is misguided. MidTNBrad makes for a much better comparison, as he's only 1.75" shorter than the OP, also has a long torso, and is currently riding a Cervelo with the same geometry as the OP's frame.

DaveSSS 

I'm sorry, but you are wrong. A given saddle height can be correlated to a specific saddle to bar drop. There's so much information missing here that all others can do is post some information, so the OP can determine what frame size he really has and what the stack and reach might really be. One rider might think that a 4cm saddle to bar drop is plenty, but even as a small rider, I use 10cm. Large riders might use 15cm or more. Large riders may also use extremely long stem and a lot of handlebar reach. I've read of one extremely tall pro rider using at least a 170mm custom made stem. I'm assuming that a person buying an S5 doesn't want to make an endurance bike out of it, but who knows.

The OP really needs to see a fitter for some advice. Buying a frame when you don't know your saddle height or stack and reach is risky. When I buy a new frame, I know exactly what stem length, stem angle and spacers I will need to make it fit. My latest purchase is the smallest frame I've ever owned, but instead of using 15mm of spacer and the stock 15mm headset top, I use an omni-racer 30mm conical headset top, with a -17 x 110mm stem. I could also use a 10mm headset top and a -6 stem. That might look more slammed, but it would also limit the number of resell customers, with an overly short steering tube.

mdzukunft

This is getting to be a little silly guys... I CAN read. There's a sticker on the frame that says 61 cm and S/R 630/405 mm.

Gear Science calculator recommends BB-saddle of 790 mm, which is a delta of 35 mm. Probably going to cut have the LBS cut to 770 mm so there is play. And, yes, already confirmed about the 45 degree posterior cut. Don't want the post slamming through my seat tube!

P.S. And 35" is a short inseam? Since when?!



Seeing is believing

tomato coupe

I think there's only one person on this thread that thinks you don't know what size the frame is, and it's definitely not me.

P.S. Another random data point: my recently retired Colnago had a S/R of 627/397 and it fit me perfectly, yet I'm 4" (10cm) shorter than you. I think there's no chance your 630/405 frame is "much too big" for someone of your height.

Iride01 

So where do you want to go from here with the discussion? If you didn't form some sort of idea from the replies whether bickering or not, then we have not done our jobs.

New questions on the same topic? Refinement or more info about something that sounded interesting?