Frame size, new bike fitting, questions

Discuss light weight issues concerning road bikes & parts.
efeballi
Posts: 471
Joined: Tue Dec 17, 2013 2:50 pm
Location: Body in Milano, mind in Istanbul

by efeballi

Boralb wrote:Hi,

I ride a 56 cannondale ss evo but plan to downsize my frame to a 54.
I'm 181cm tall with a 83cm inseam. bb to saddle is 73.5cm.
My current 56 frame has a 15.5cm headtube, where the 54 size has 14cm.
I only use the 25mm supersix conical spacer under my -12deg/110mm stem(115mm actual)
To be able to simulate the drop of a 54 frame by using the same conical spacer again, i lowered the stem 1.5cm and took some pictures.
What do you think about my downsize choice?
Note:Drop will be about same, and reach will be 1.5cm closer with a 54 frame, different from the pictured 56 frameset
When looking at the pictures, i also find out that, i have to lower my seatpost about 0.5cm(last picture) :mrgreen:

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Bora abi hello, it's Efe from Tuesday-Thursday group :)
I remember you were using a Scott CR1 size 54 and loved the fit, before moving to the Evo. I'd suggest looking at the CR1 charts and see how close you can get with a 54 Evo.


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SHUT UP LEGS
2015 Giant Propel Advanced
2013 KTM Strada mod. GOT IT BACK!
2011 Pinarello Dogma 60.1(loaner)
2011 Scott SUB 45(sold)

Politecnico di Milano Ingegneria Meccanica

by Weenie


MNX1024
Posts: 286
Joined: Thu Apr 28, 2011 1:21 am

by MNX1024

Planning to get a Giant TCR Advanced, possibly an SL, and I'm having a very hard time deciding between the XS and S since they're very close to each other. Anyway, making a decision based on my current ride, which is a Jamis Xenith Comp, and how I'm fitted on it based on a Retul fit session.

Anyway, here's a little geometry chart I made for the two Giants and my Jamis:
Image
The second numbers on the stack and reach of the two Giants are measurements pulled from the Retul Database, first are from Giant.

Now.... Here's why I'm having such a problem deciding between the two. My current ride is smacked right in between the two sizes in terms of stack and reach. Currently riding with no spacer, just the headset, with a 83-85mm handlebar drop.

If I go with XS, I have the ability of lowering my stem by 28mm. Though I'm not so sure I really want to or even need to go that low because I actually dropped 1cm last year during my fit. Though I ride fast and hard, I do enjoy doing 100-125mile rides every weekend(with a lot of climbs involved). My worries for the XS is, the seat tube angle, currently riding my Jamis with a zero setback post with my saddle almost all the way forward. Of course, as a weightweenie, the XS is lighter!!!!!!!!!!!!!!

Now, with the S, I have more leeway in terms of saddle position. The extra reach is good, because I may use a 110mm stem instead of my current 120mm since I do prefer a little bit more stiffness to it. Going back to the stack, The most I can drop my stem/handlebar is 1-1.5cm. Though I did express that I'm not sure I would be interested in going any lower, wouldn't that amount be too limited in terms of adjust-ability?

So yeah, very tough choice. Both sizes do have its own merits. What do you guys think, what size should I get and why?

Valbrona
Posts: 1482
Joined: Fri Oct 28, 2011 3:25 am
Location: United Kingdom of Great Britain and Northern Ireland

by Valbrona

MNX1024 wrote:... currently riding my Jamis with a zero setback post with my saddle almost all the way forward.


How are you deciding on your fore/aft position? But yes, both of the Giants have steeper seat angles.

MNX1024
Posts: 286
Joined: Thu Apr 28, 2011 1:21 am

by MNX1024

Valbrona wrote:
MNX1024 wrote:... currently riding my Jamis with a zero setback post with my saddle almost all the way forward.


How are you deciding on your fore/aft position? But yes, both of the Giants have steeper seat angles.



The fitter took care of it for me.

Though I am worried about the steeper seat angles, ultimately I need to decide if 10mm meter is enough for lowering my stem(S) or I would need the XS which would give me about 28mm of space.

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canbakay
Posts: 455
Joined: Sun Oct 31, 2010 10:54 pm
Location: London

by canbakay

Hi guys,

Just a little background - In May last year I had an accident where I cut 2 tendons in my hand with plenty of nerve damage. After having surgery and a lot of physiotherapy I'm finally back on the bike - perhaps better than before with a more focused/organised structure.

Somehow over that time my seat post went down by 3cm (I was fiddling around with the clamp, must have happened then).

When I got back after such a long time off, I was oblivious to the seatpost being lower and I've been riding like that for about 3 weeks now.

My initial observations were:

- The slight knee pain & neck aches I got after long rides went away.
- I was able to ride in the drops for longer and comfortably.
- My legs got tired much later than before despite taking such a time off the bike.
- My time/speed averages haven't changed (after building my fitness back up I was able to compare them)

Before the accident I was chatting to one of the fitters down at Sigma Sport in London (ones that I would trust) and he was surprised at my saddle height, I coincidentally had my Retul fit results handy on my phone, when he looked through it he said yeah it all seems correct (based to angles etc & measurements were all correct).

So, when I noticed the difference in the saddle height, I brought it back up and it was an agonising ride. I got that feeling of [hard to explain] when you fully extend your legs and flex them hard after a ride feeling while on the bike. In other words, tired, crampy, lactic acidy feeling very early into my ride (as well as over stretched). Another thing I noticed was, I had much better control over the bike with a lower saddle height.

My questions are,

Can anyone help make sense of all this?

Can a bike fit method such a Retul get it wrong?

Thanks!

John


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Screen Shot 2014-03-07 at 00.48.03 by canbakay, on Flickr

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Screen Shot 2014-03-07 at 00.47.46 by canbakay, on Flickr
Last edited by canbakay on Fri Mar 07, 2014 2:19 am, edited 4 times in total.

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fa63
Posts: 2251
Joined: Mon Feb 19, 2007 7:26 am
Location: Atlanta, GA, US

by fa63

I have my saddle about 1.5 cm lower than where my fitter wanted it. I tried to make it work for a long time but in the end decided that I should listen to my body instead of the fitter so I left it where I liked it the best.

That said, 3 cm is a lot. How tall are you?

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canbakay
Posts: 455
Joined: Sun Oct 31, 2010 10:54 pm
Location: London

by canbakay

fa63 wrote:That said, 3 cm is a lot. How tall are you?


Yeah I think the 3cm lower was a bit too low, I'm going to experimenting a bit but definately not the original retul result.

I'm 185.5 (6 1)
Long legs short torso

Note: 120 stem was also recommended, I felt a lot better 110 which I stuck to.

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fa63
Posts: 2251
Joined: Mon Feb 19, 2007 7:26 am
Location: Atlanta, GA, US

by fa63

Not that this means much, but my personal database of bike fits of professional riders show saddle heights ranging between 77.5 (Michael Rogers) and 82 cm (Mikel Astarloza) for riders between 185 and 186 cm (sample size is 11). But those values are somewhat outside the norm, with the average saddle height at about 79 cm. So your saddle height would be at the upper end of that range, but you mentioned you have long legs.

I would ride it at 79 cm and raise the saddle slowly, until you feel like it is not working anymore. Of course if it feels best at 79 cm, then just leave it there.

GT56
Posts: 571
Joined: Fri Jun 05, 2009 9:40 am
Location: Switzerland

by GT56

canbakay wrote:
fa63 wrote:That said, 3 cm is a lot. How tall are you?


Yeah I think the 3cm lower was a bit too low, I'm going to experimenting a bit but definately not the original retul result.

I'm 185.5 (6 1)
Long legs short torso

Note: 120 stem was also recommended, I felt a lot better 110 which I stuck to.



what is your inseam ?

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canbakay
Posts: 455
Joined: Sun Oct 31, 2010 10:54 pm
Location: London

by canbakay

fa63 wrote:
I would ride it at 79 cm and raise the saddle slowly, until you feel like it is not working anymore. Of course if it feels best at 79 cm, then just leave it there.


Thank you

79 feels great so far, still experimenting. To be honest, coming down from the original height, my ride has changed dramatically, much better, makes me wonder why I was fitted at tht height or rather why it felt "correct"...

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canbakay
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Joined: Sun Oct 31, 2010 10:54 pm
Location: London

by canbakay

GT56 wrote:
what is your inseam ?


Thanks,

It's 87 cm

GT56
Posts: 571
Joined: Fri Jun 05, 2009 9:40 am
Location: Switzerland

by GT56

canbakay wrote:
GT56 wrote:
what is your inseam ?


Thanks,

It's 87 cm


in the old days (before retul and all that), that would have meant a saddle height of 87 * 0.885 = 77 cm

no wonder things felt better when you lowered the saddle by 3 cm from 82

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fa63
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Location: Atlanta, GA, US

by fa63

82 cm saddle height for 87 cm inseam indeed sounds high. I have a 85 cm inseam, and have my saddle at 77 cm with about 10 cm setback.

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BRM
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Joined: Sun Mar 16, 2014 3:43 pm

by BRM

< edit> no longer relevant
Last edited by BRM on Sat Apr 26, 2014 11:47 pm, edited 1 time in total.

by Weenie


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BRM
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by BRM

< edit> no longer relevant
Last edited by BRM on Sat Apr 26, 2014 11:47 pm, edited 1 time in total.

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