Quick question on stack & reach between two bikes

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grnrcr
Posts: 105
Joined: Sat Nov 05, 2011 12:23 am

by grnrcr

Take a look at the two bikes below. Why do they have almost identical stacks when bike A has a taller HT by 15mm?

Bike A
HT: 17.5
HTA: 73*
TT: 56.5
STA: 73*
BB drop: 6.6
Stack: 57.5
Reach: 39


Bike B
HT: 16
HTA: 73*
TT: 56
STA: 73*
BB drop: 7.0
Stack: 57.4
Reach: 38.5

Tenlegs
Posts: 289
Joined: Wed Jul 16, 2008 10:37 am

by Tenlegs

The fork length (axle to crown) would probably account for most of it

by Weenie


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hornedfrog
Posts: 235
Joined: Tue Feb 28, 2012 9:13 pm

by hornedfrog

BB drop homie...

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fa63
Posts: 2533
Joined: Mon Feb 19, 2007 7:26 am
Location: Atlanta, GA, US

by fa63

Probably the combination of the two factors mentioned above.

cyclenutnz
Posts: 854
Joined: Tue Jul 18, 2006 5:18 am
Location: Cambridge, New Zealand
Contact:

by cyclenutnz

Aside from the valid points already made. Some manufacturers are not very good at calculating reach and stack.
There are a lot of brands where I have to check their calcs before importing into my database (including some of the big brands)

Tenlegs
Posts: 289
Joined: Wed Jul 16, 2008 10:37 am

by Tenlegs

BB only 4mm diff, what frames are they?

grnrcr
Posts: 105
Joined: Sat Nov 05, 2011 12:23 am

by grnrcr

Bike A is Helium SL. Bike B is Bura SL.


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Tenlegs
Posts: 289
Joined: Wed Jul 16, 2008 10:37 am

by Tenlegs

Neil pryde Bura size L Vs Ridley Helium SL in M = very similar geometry, medium NP bura has a much lower stack

wingguy
Posts: 4318
Joined: Thu Mar 08, 2012 11:43 pm

by wingguy

look at the side on shots of the bike, the fork crown on the Ridley is almost down to the brake bolt, on the Bura it's a lot further above. So while the HT on the Bura is significantly shorter it has a lower BB and a taller fork. Which is why stack is a better measurement for comparisons.

Also cyclenutz - who's bad at calculating stack and reach - and what do you actually mean by calculating? It should be a pretty basic physical measurement, but a difficult to impossible calculation from a traditional geo chart.

grnrcr
Posts: 105
Joined: Sat Nov 05, 2011 12:23 am

by grnrcr

I see it now. Thanks a lot.

by Weenie


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