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What On Earth !


Danny Kearns

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Loads of different Geometry's on different websites for different frames:

GU ST 26" 08 (Stock)

Selectbikes:

Wheelbase: 1085mm

Chainstay Length: 380mm

BB Rise: 40mm

Head Angle: 72°

Tartybikes:

Wheelbase: 1085mm

Chainstay Length: 380mm

BB Rise: 45mm

Head Angle: 72 degrees

Centre of BB shell to top centre of head tube: 670mm (26.5")

TrialFutur:

Wheelbase: 1085mm

Chainstays 380mm

BB: +40mm

Head Angle: 72 degrees

GU Typhoon '08 (Stock)

SelectBikes:

Wheelbase: 1085mm

Chainstay Length: 375mm

BB Rise: 60mm

Head Angle: 71 degrees

Tartybikes:

Wheelbase: 1085mm

Chainstay Length: 375mm

BB Rise: 60mm

Head Angle: 71 degrees

Centre of BB shell to top centre of head tube: 660mm (26")

Trials-UK:

Wheelbase 1085mm

Chain stays Length: 380mm

BB Rise: + 60mm

Head tube length 115mm

Head Angle: 72 Degree

How come ?

Edited by Danny Kearns
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BB height varies depending on forks used. Tarty usually specify which one, but in that they 100% definitely measure the components they sell, I'm more inclined to believe them than what are effectively Ctrl C'd + Ctrl V'd details.

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tarty nearly always measure with echo urbans, where as the rest oif the websites probably get their info form deng himself who probably measures witht he relative forks ( e.g pitbull with pitbull forks, le with gu forks etc ) these can all be slightly different lengths and rake and so would affect the bb rise and wheelbase slightly

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tarty, why do you use echo urbans? i understand it sets a standard to compare all frames by but most of us are tarts and will buy matching brand forks, would it be too dificult to also give brand specific geo, espcially on the mbk? which comes with mbk forks. meh i know i already stated the main reason, but surely it would make sence to give the appropriate fork geo to.

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tarty, why do you use echo urbans? i understand it sets a standard to compare all frames by but most of us are tarts and will buy matching brand forks, would it be too dificult to also give brand specific geo, espcially on the mbk? which comes with mbk forks. meh i know i already stated the main reason, but surely it would make sence to give the appropriate fork geo to.

I'd imagine its so that it makes it easier to compare.

the GU has a high bb, but with short forks it doesn't. If it was measured with short forks then you'd buy it thinking, this is nice and low, and use your own forks and be completely surprised.

I think its urbans as well because they're the most popular forks.

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most of us are tarts and will buy matching brand forks

I doubt it's the majority, to be fair? If they've got one headset and one set of forks that are "The Measuring Forks", it's a lot better than having to potentially damage stock by pressing on a crown race, fitting it to the frame and measuring it, when you could just have one set of forks with a race permanently on that you could just bang in?

Plus having a standard is way better than just random sizes. I'm assuming the Urban was one of their more popular forks, so they just used what a lot of people use?

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I always go with tartys measurements as they always measure the frames up and give a proper full geo with the reach lenght which is an important measurement that riders neglect. But doesnt mean that other companies arnt measureing and it could be especially with deng frames that frame to frame the geo is slightly different and there not all made exactly the same. Ino my gu mod measure 15mm longer than stated on sites. But also different companies may measure them with different forks giving different geos.

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Plus having a standard is way better than just random sizes. I'm assuming the Urban was one of their more popular forks, so they just used what a lot of people use?

That was our thinking too, same forks and headset for all frames means you can compare the geo of each frame, rather than having more than one variable (Y)

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I noticed going from a short control to a Zenith.

5mm longer wheelbase

5mm shorter stays

5mm higher BB

When I looked into it, I thought "meh it's only 5mm here and there" but it made such a difference due to the factors adding up etc. It meant I was in a far more leany forward position, and it felt wank :P

Giving a measurement with a standardised setup is awesome - it lets you compare frames to each other, and if you want to know what it'll be like with your individual setup, you just have to factor that in to the standard, as opposed to looking through dozens of frames and forks to get everything on a level in your mind :)

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That was our thinking too, same forks and headset for all frames means you can compare the geo of each frame, rather than having more than one variable (Y)

Best way to do it and I guess Tarty/the others don't want to spend all day trying all the different combinations and then doing a table to go on the web.

Also you should be able to make a rought guess as to how different forks are going to affect the Geo as Tarty also provide the rake and length.

My '04 Control (long) has gone from 1085 with a +20bb with Urban forks to a 1080 with a +30bb (measurements are about right) but I was able to work out what was going to happen (roughly - shorter and higher bb) before I bought the forks thanks to the info off Tarty's site.

5mm can make enough difference as long as its the difference you want.

Although if they were really bored it would be possible to produce a table of how control forks would alter a bike compared to urbans (e.g. -5mm wheelbase, +10mm BB) but it would be a bit of a ball ache plus it would also depend on head angle.

Edited by Jamie_Neal
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As we've repeatedly gone over - to some people, yes. Some people just naturally are more observant when it comes to changing their bike setup than ever. I notice it when I'm riding my BMX if I've had to move my wheel back 'cos my chain's gone slack, but I know some people who ride whatever they happen to have at the time. Different strokes for different folks.

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