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pros/cons to having a 650cc vs 700cc tt bike???(9 posts)

pros/cons to having a 650cc vs 700cc tt bike???wheelsucker
Jul 18, 2002 11:05 AM
can someone explain the benefits of having a 650cc vs 700cc setup for a time trial bike??
Bigger engineChen2
Jul 18, 2002 11:19 AM
Sorry, couldn't resist. I think you mean mm, not cc.;
650 wheels might accellerate faster.
Bigger engineClydeTri
Jul 18, 2002 11:43 AM
he meant cm, not mm
Ok, butChen2
Jul 18, 2002 12:05 PM
700cm = 275 inches, that's pretty big for a bike wheel.
~Al
re: they're are small, frame sized specific and still debatableAkirasho
Jul 18, 2002 11:22 AM
http://www.bicyclesports.com/technical/davespage/index.html#072699
http://www.analyticcycling.com/WheelsConcept_Page.html

The prevailling opinions favor whatever works best for the individual... I've noted on overt advantage of one over the other...
re: pros/cons to having a 650cc vs 700cc tt bike???Andy
Jul 18, 2002 12:13 PM
Obviously the 650c wheels are lighter and are great for climbing but they are "squirrley" (sp?) on descents. A few years ago on the tour coverage I saw a few riders climbing with 650c wheels. As I recall one of the riders crashed on a descent. I like to ride my tt bike on a favorite canyon climb a few times a year. I hang on like he11 on the way down though.
re: pros/cons to having a 650cc vs 700cc tt bike???Steve Bailey
Jul 18, 2002 5:46 PM
"A few years ago on the tour coverage I saw a few riders climbing with 650c wheels. As I recall one of the riders crashed on a descent."

Which means nothing of course, could have any number of reasons the rider fell, none related to the wheel size. On a well designed frame, having a 650 instead of a 700 will not adversly affect handling.

The overwhelming reason they aren't used on the "Tour" is dissimilar wheel size. No team wants to carry both 700's and 650's when there's no advantage to 650 on a road machine in the peloton.

One of the major reasons they were used in TT bikes was to allow the frame designer some clearance when designing a steep seat tube angle, of say, 78-80 degrees. This steeper angle brings the rear wheel in closer on a machine with proper rider front/rear balance. It's somewhat more problematic using a 700 wheel with a steeper seat tube.

The jury still seems out as to whether a 650 TT bike is any faster then a 700. Pro triathletes seemingly do well on both designs. 650's can be well designed into a frame for a shorter person, but any weight advantage to the 650 on a larger frame is lost in building the frame larger. Same with aero advantage.

The biggest single reason to avoid 650's seems to be a very limited tire choice. They are generally only available in 20 and 23 mm width's and are generally much more expensive.

SB
re: pros/cons to having a 650cc vs 700cc tt bike???brider
Jul 19, 2002 9:30 AM
For shorter riders, the 650 front wheel allows a lower bar position, thus better aerodynamics. Beyond a 56cm frame size, however, there's little benefit to the 650s. The wheel itself may be more aerodynamic, but the frame tubes make up for it.
re: pros/cons to having a 650cc vs 700cc tt bike???DougSloan
Jul 19, 2002 9:46 AM
http://www.cervelo.com/text-art-cur-qa.html