[Wumpus]

I don't understand how a road bike is faster than a cyclocross bike if they are similarly equipped. The HT angles are only a degree or so slacker on modern crossbikes and steeper than early 90's road bikes. The BB might be a tad higher on a crossbike, but what does that effect? If you aren't doing crit racing, I just don't see it.

Please help me out.



Some of these sizes are only different by .5*.

Cannondale Cyclocross Geo

Cannondale CAAD8 and Six13 geo

 

[LordOpie]

It looks like the other significant difference (besides BB height) is chainstay length.

I suppose the difference is like the difference between a roadie with areo bars and a TT bike... in the end, it's the engine, as you already know.

Frankly, I think cx bikes are probably better for more people than the market tries to go after.

 

[indieboy]

if you've got stock gearing then that's the limiting factor. i was hit by a car last year and all i had was my cx bike for my training. i kept the 42t as my only ring. i got great leg speed out of doing local weekly crits on it but lost a lot of top end from not really developing any true power.
if you've got a 53 on there then you'd be good to go.

 

[JRB]

Interesting. I may throw a 53 on my cross bike and put some smoothies on and see what happens.

 

[sanjuro]

There are some significant differences. Comparing two sizes I might ride:

Six13-and-CAAD8-Geometry-------------------Cyclocross
Frame-Size-----------------52------54------52------54
Seat-Tube-Angle-(degrees)--74------73.5----74------73.5
Head-Tube-Angle-(degrees)--73------73------71.5----72
Hrznt-Top-Tube-Length-(cm)-53.5----54.5----54------55
Chainstay-Length-(cm)------40.5----40.5----43.2----43.2
Fork-Rake-(cm)-------------4.5-----4.5-----4.5-----4.5
Bottom-Bracket-Height-(cm)-26.5----26.8----29------29
Wheelbase-(cm)-------------96.8----97.5----102-----102.1
Trail-(cm)-----------------5.6-----5.6-----6.9-----6.6
Standover-Height-(cm)------76------78.2----81.3----82.3
Bottom-Bracket-Drop-(cm)---7.2-----6.9-----5.8-----5.8
Front-Center-Distance-(cm)-57.4----58.0----59.5----59.6

One degree of head tube angle is significant.. Chainstay length is almost 3 cm, a huge difference. And the a 4 cm wheelbase difference is also significant.

There is a lot of differences, although I was surprised to see the standover was higher on the cyclocross, given the dismounting...

 

[Wumpus]

There are some significant differences. Comparing two sizes I might ride:

One degree of head tube angle is significant.. Chainstay length is almost 3 cm, a huge difference. And the a 4 cm wheelbase difference is also significant.

There is a lot of differences, although I was surprised to see the standover was higher on the cyclocross, given the dismounting...

What difference does that make in straight line speed?

 

[JRogers]

What difference does that make in straight line speed?

Not much. CX frames are generally heavier than road frames, though. I think that as long as parts selection is comparable, a CX bike is close to a road bike in speed in many situations. I took all the parts of my road bike and put them on a CX frame. Might be a little slower in some instances, but not by much. I ride with buddies who have road bikes and keep up fine.

 

[sanjuro]

What difference does that make in straight line speed?

Well, chainstay length will affect frame stiffness. A true roadie might complain about the pokey handling of a CX bike, and the higher BB (the offset is from the rear axle to the center of the BB, extended) means a higher center-of-balance.

If you are going to ride 100% road, get a road bike. You might get a CX bike if you commuting or touring, but anything besides CX you should ride a road.

 

[LordOpie]

I think Wumpus' point is, the difference isn't that great, yet they're marketed for two completely different sports and the implication is that they aren't interchangeable.

 

[sanjuro]

I think Wumpus' point is, the difference isn't that great, yet they're marketed for two completely different sports and the implication is that they aren't interchangeable.

Could a beginner tell the difference between a 3 inch travel and a 5 inch travel full suspension bike? Could they tell the difference between the Scapel and the Rush? Or the Rush and Prophet?

You certainly can ride a CX bike without a drop in speed. But the difference would be noticable to an experienced road rider, which he would be over a few months.

Put it this way, what is the advantage of getting a CX bike? Riding it off road?

 

[LordOpie]

I ride my road bike off road sometimes.

 

[JRogers]

Could a beginner tell the difference between a 3 inch travel and a 5 inch travel full suspension bike? Could they tell the difference between the Scapel and the Rush? Or the Rush and Prophet?

You certainly can ride a CX bike without a drop in speed. But the difference would be noticable to an experienced road rider, which he would be over a few months.

Put it this way, what is the advantage of getting a CX bike? Riding it off road?

The advantage of a CX bike is versatility. I ride mine off road sometimes on the same trails that I ride my XC bike on. It's also better on dirt roads, which there are a lot of here in VT. And because tire clearance is better, those in winter climates who might throw on 28s or CX tires for winter training will be better served. Those who might want a more stable ride on the road could also be better served with a CX frame.

I've been riding for quite a while and the only places I see a CX bike having disadvantages are in some climbs (because the frames can weigh a little more) and some sprints (a steeper headangle feels better in a sprint to me; allows the bike to tick over a little faster when out of the saddle). But, for versatility, a CX wins no contest.

 

[sanjuro]

I should point out that road riding is not point and shoot. You might not be scraping pedals, but you will corner frequently, even around potholes and broken glass.

The gain in stability does come at a price of the handling, and most roadies choose the faster handling bike.

Put it this way: I just finished a short ride, and it was a curvy, up-and-down, low traffic road. My 38 inch wheelbase bike ate it up...

 

[sanjuro]

Question: What kinds of roads do you plan on riding? A lot of dirt?

 

[LordOpie]

wait, Wumpus isn't looking for advice, he's an experienced roadie as well as other cycling styles. He was exploring the topic, that's all.

 

[sanjuro]

f*cking newb...

 

[JRB]

I'm gonna put discs on my CX bike and kick everyone's ass stopping.