Login required to started new threads

Login required to post replies

Caledonia geometry discussion (front center, wheel flop, etc.)
Quote | Reply
the question was asked, in the facebook comment utility just below this article on what is revolutionary about the geometry of the cervelo caledonia (because the caledonia is a ROAD bike):

"Doesn’t slacker head tube angles and increased fork offset also mean more wheel flop, even though trail stays the same? Won’t that negatively impact steering response, by creating positive feedback as you lean into turns?"

i don't find that those comment utilities are a helpful architecture for these discussions, so i'm answering this here.

if you turn the handlebars left or right, the front end of the bike dips a little in height. the amount it dips is called wheel flop. the more wheel flop, the more the bike tends to be easy to turn at very low speed. the more trail in the bike, the more the bike will tend to want to ride straight, self-center, resist turning, at higher speeds (normal riding speeds, or high speeds).

the issue has come up because, if you shallow the head angle of a bike, and you add fork offset, you can keep the trail of the bike the same. but that does not mean the front end steering metrics remain the same. if you move from, say, 43mm of fork offset and a 73° head angle to 50mm of fork offset and 72° head angle, you keep the trail the same, or, within a millimeter. but you increase wheel flop.

what has been said is that wheel flop counteracts trail. i don't think that's true. wheel flop is really not an issue at normal speed, only at exceedingly low speed. however, bikes do experience that, and a bike like the caledonia, with a 35 tooth chain ring and a 36 tooth rear cog (with an eTap AXS 2x groupset) is designed for difficult conditions, including steep hills, rideable dirt, and low speeds. so, low speed handling is an issue. however...

if you calc it out, the wheel flop on a 30mm tire mounted on a 700c wheel (what comes standard on the caledonia), using a 72° head angle and a 50mm offset fork (what comes on a caledonia) is 17mm. if you compare this with a more road standard front end on that bike (73° head angle and a 43mm fork), the wheel flop is... 17mm.

yes, technically you have more wheel flop, but not enough to even raise it to 18mm if you're rounding to the nearest mm. so, no, there is no practical increase in wheel flop in this bike. nothing you can feel. nothing that makes an appreciable difference.

Dan Empfield
aka Slowman
Quote Reply