Frame Geometry

[ibis315]

I'm looking to buy a new frame, but I have some interesting geometry numbers I got from the manufacturer :

Size : 52.5 cm
Top Tube : 53.5 cm
Head Ang : 72 Degrees
Seat Ang : 74 Degrees
Chain Stay : 38 cm (really short)
Fork Rake : 4.3 cm
BB drop : 9 cm (wow!)
BB Height : 25 cm (wow!)
Wheelbase : 95.8 cm (short)

My question is, with such a low bottom bracket height combined with short wheelbase and shallow head tube angle, how would the bike handle? My current frame is :

Top Tube : 53 cm
Head Ang : 73 Degrees
Seat Ang : 73 Degrees
Chain Stay : 41 cm
Fork Rake : ?
BB drop : 6 cm
Wheelbase : about 98 cm

My main concern is the low bottom bracket and shallow head angle making the bike handle too slow. However, does the short chain stay/wheelbase compensate for BB and HA? Thanks for the information.

 

[Neo]

are you sure these figures are correct? these numbers seem very, well, outside the norm. BB drop is usually around 70mm giving a BB height of around 263 depending on tyres used, and the head angle of 72 would normally be matched with a 45mm offset.

Nevertheless, I'll draw it on a CAD program to see if the numbers you give will work.

Neil
www.billato.com

 

[dexmax]

the chainstay is too short, i guess??? shortest i've seen is 39.5cm.
good for 650c maybe....
wheelbase too short. i think.

bb height? is this some kind of sports car? hehe...

is this a triathlon bike?

I'll check the angles....

 

[steve]

Originally posted by dexmax

is this a triathlon bike?

Thats what I was thinking: 74 Degree seat angle, 38cm chain stay lenght, 25cm BB height sounds like a tri bike to me.

What sort of racing/riding are you doing idis?

cheers!

 

[Neo]

KACHUNK!!!!

of course, it's the numbers for a 650c wheel frame. Haven't had to build one for a while, that's why it wasn't immediately obvious
(to me anyway!)

On the other hand, if it's not......

Neil
www.billato.com