Frame Geometry

Jimbeam3678

Anyone fancy trying to simply frame geometry for me please my head is hurting to work this out:p

Geometry of the bike I smashed up http://technobike.com/hot_promo/detail/ ... K%20YELLOW


Geometry of my winter bike
http://www.sigmasport.co.uk/item/Specia ... -2013/1D82

I'm after a new bike based on the geometry of the Orbea and not anything like the Allez geometry.

For example I'm looking at cannondales based on the above should I be looking at the Super Six or Synapse? Also my preferred LBS stock Trek bikes which Trek frames offer a similar geometry to the Orbea.

As I can't get out to try them at the moment I'm slowly trying to discount certain bike based on the geometry.

Cheers in advance

drlodge

I can't see the first link (its blocked by work). My simple method

1. Work out the "reach" i.e. effective top tube length considering seat tube angle. 1 degree difference in seat tube angle = 1cm difference in effective top tube required. 73.5 deg STA + 54.5 cm eTT (my Rourke) is the same as 74 deg STA + 54cm eTT (my Condor)

2. Head tube length. You want it to be about the same as your current frame, but the frame will come with whatever headtube length a frame of the right size (considering [1] above) comes with.

Once you get an idea of (1) and (2) you can quite quickly and easily compare difference frames. Its not perfect, but its very quick and easy to do.

If I was picking the Allez Sport for example, I would need the 54 size with an eTT of 548, seat tube angle is the same as my Rourke (73.5) so I end up with 3mm extra reach and would use the same 110mm stem. The headtube at 145 is quite short so would need lots of spacers and might end up with the bars a bit low. The 56 would give a longer head tube but too much reach, so always a compromise.

drlodge

What size and year is your ORCA frame? I need to see the geometry specification for it

Jimbeam3678

55cm and it was 2013.

Allez was a 56 2012.

Drlodge I'll have a look through your comments.

gloomyandy

Stack and reach are really the two key measures (the nice thing about reach is that it in effect means that you can ignore the issues of different seat tube angles, sloping top tubes etc.). This is a nice article about them:
http://www.cervelo.com/en/engineering/t ... d-fit.html
Not all geometry data provides them though.

holiver

There's also a stack and reach calculating spreadsheet that I have found useful.

http://bb2stem.blogspot.co.uk/2011/10/s ... -v100.html

drlodge

I think this is the chart then

A 55 size has a 555mm eTT with a 73.2 STA, headtube is 165mm

Supersix EVO 54 has eTT 545 with STA 73.5 (quite a bit shorter) headtube is 140 (shorter)
Supersix EVO 56 has eTT 560 with STA 73.5 (a little longer) headtube is 155 (still shorter)

Synapse 56 is the same geo as the Superize EVO except the headtube is longer at 180

All these have a similar STA around the 73.5 mark

So really boils down to whether you want a longer or shorter headtube at the 56 size.

Jimbeam3678

Wow thanks for the reading material I'll have a read through it and come back to you.

Thanks again

letap73

Be careful here!

The geo chart for the Orca has a relatively high value of stack versus the reach value - tends towards a relaxed geo circa Defy, Synapse or Secteur/Roubaix.

The supersix evo geo has a relative high value of reach versus stack -the other way around - a more aggressive geometry ( much like the Allez geometry).

With regards to the Treks - the Domane is the least aggressive in Geo and the Madone more aggressive (less so than the evo). I would go to your LBS to fit yourself up.

Jimbeam3678

Thanks I do plan on going to various LBS and I have a trek pro bike fit so I have measurements. However I am still recovering from a broken leg so can't really hop on a bike to try out yet. I was just trying to rule put various bike models like the Allez and grab a sort of shortish list to research.

Thanks for the helpful advice.

letap73

If you are happy to post the trek pro fit data, I can see if I can replicate those measurements - I own a 54 himod supersix evo as well as other bikes.

Jimbeam3678

Can you read the measurements ok from that?

letap73

Yes I can, I'll have a look on my bikes - first impression is the evo is not right for you but I will confirm!

Jimbeam3678

letap73 wrote:

Yes I can, I'll have a look on my bikes - first impression is the evo is not right for you but I will confirm!

Thank you very much for taking the time out.

letap73

On the supersix evo (54)

With saddle height of 78.5cm (setback 8.5cm), the saddle tip to centre of bars is 57cm.

The drop however is circa 10cm and you have 5cm of spacers underneath the stem (stem at -ive angle).

For comparison Giant advanced defy (ML)
With saddle height of 78.5 (setback 8.5cm), the saddle tip to centre of bars is 57.5cm.

The drop is circa 10 cm, however the stem is slammed and you can reduce the drop and the saddle to centre of bars measurement by putting spacers under the stem.

Conclusion:

The evo is probably too aggressive (as a 54 certainly), you may fit a 56, however, in my honest opinion you would probably achieve a better fit with a synapse (56) or a Trek domane (guessing 56) or the less aggressive Trek Modane (two fits H1 and H2). If I was you I would go back to the LBS and see if the shop will allow you to replicate those measurements.