[Salami]

I have been doing research about what new frame I am going to buy and came up with some questions.

How is geomety measured? Specifcally under what condititions are the bikes measured?

A friend of mine told me some companies measure the bike at a certain level of sag and others with no sag.

I am curious to compare my current ride to the ones I am looking at to get a rough idea what to expect since I have no way of test riding them. How should I measure my bike to get numbers that will be fair to compare?

I am specifically looking to compare geometry of my 03 Bullit & Super T to the geometry of the Ironhorse Sunday Factory and Turner DHR . The 03 Super T will transfer over to the new frame until money allows for new one.

Please no generalizations, I know the angles will be more slack and the BB lower. I would like to try and figure how much if anything for just curiousity.

 

[zedro]

A friend of mine told me some companies measure the bike at a certain level of sag and others with no sag.

does this friend also hang out at Pinkbike?

 

[Salami]

does this friend also hang out at Pinkbike?

Ummmmm, no. :mumble:

Zedro, you have all kinds of knowledge about this ****. Can you point me in the right direction (someplace I can read up) or share some useful insight, please?

 

[zedro]

oops, forgot the advice part :redX: :

the geometry listed is without sag, although you'll have to pay attention to the particular fork used in the calculation (it will make a difference between a tall 888 and anything else).

never heard of anyone using sag in the calcs (thats just silly), however it may be usefull to compare certain geometry relative to what sag will be used. For example a BB height of 14" vs. 14.5" wont be any different if the latter bike typically runs 0.5" more sag (like a V10 or comparatively longer travel bike would).

 

[Salami]

never heard of anyone using sag in the calcs (thats just silly),

Okay, now I understand the Pinkbike comment. Usually my friend gives me very sound advice as he a very sound bicycle mechanic. Guess not so sound this time.

Is measuring goemetry without also the same as what I have refered to as measuring static?

If I take measurements from my bike than I shoud be able to get a somewhat fair comparison of the numbers, correct?

 

[Weaver]

my best advice is to find these actual frames and make your own measurements....

it can get very tricky and a little here and there adds up to a lot...

 

[zedro]

Is measuring goemetry without also the same as what I have refered to as measuring static?

If I take measurements from my bike than I shoud be able to get a somewhat fair comparison of the numbers, correct?

yeah, static should refer to the bike just sitting there with no rider.

i wouldnt try to take measurements physically off your bike since its hard to get anything accurate. Also note that toptube measurements dont equate really well between frames since they are measured differently.

 

[Weaver]

i wouldnt try to take measurements physically off your bike since its hard to get anything accurate. Also note that toptube measurements dont equate really well between frames since they are measured differently.

ill take my personal measurements over the stuff that is listed any day...

i measure from the middle of the bb to the middle of the top tube if its frame only... thats my main measurement... then its chainstay and then looking up angles

 

[Salami]

i wouldnt try to take measurements physically off your bike since its hard to get anything accurate. Also note that toptube measurements dont equate really well between frames since they are measured differently.

I mostly concerned about the head angle and BB height. There isn't an easy way to get within a degree or so? I would think the BB should be fairly easy, am I wrong?

 

[zedro]

I mostly concerned about the head angle and BB height. There isn't an easy way to get within a degree or so? I would think the BB should be fairly easy, am I wrong?

heh, i got BB measurements drastically wrong. You need to make sure the bike is perfectly vertical and the ground flat. Its very easy to be an half-inch off, especially if you have wide cranks. Headangle is even harder to get accurate to the degree.

 

[Salami]

You need to make sure the bike is perfectly vertical and the ground flat. Its very easy to be an half-inch off, especially if you have wide cranks.

The first part shouldn't be too hard but I lost you on the wide crank part.

Do you mean if the bike has a long spindle length and the bike isn't perfecly straight up and down it will affect the measurement more?

 

[zedro]

Do you mean if the bike has a long spindle length and the bike isn't perfecly straight up and down it will affect the measurement more?

yeah a bit more. Put a 'T' at an angle; you'll notice the tip of the T is lower than the center. Longer the T, the lower it'll be.