Efficiency of Road vs. Cyclocross w/road tires

I have been riding a MTB with slicks on pavement and packed dirt/gravel for a year and a half and figure it is time to get a more efficient bike. I have been considering a cyclocross bike (example Bianchi Axis) just because in my area it is easy to encounter dirt roads or packed trails within miles. However, I have long rides as goals, like the MS 150. I know a cyclocross bike can have road tires put on it, but I wonder wether I will ultimately be dissapointed with road performance (although I have nothing to guage it against). Are there any reasons other than weight that should be considered when using a cylcocross bike on the road with road tires? Any ride qualities, etc?

Given that you already own an MTB, I'd recommend a road bike if you have high mileage goals. I own both road and cross bikes (actually sold my old MTB to fund the cross bike) and can't imagine doing long road rides on the latter. In addition to higher weight as a drawback, cross bikes generally use slacker geometry (somewhere b/t road and MTB), making them less efficient. And I personally can't stand the feel of the cantilever brakes on the pavement when compared to the modulation I get from a nice set of calipers. Also (tho not necessarily), the gearing tends to be lower, potentially limiting your on-road speed.

My own opinion is that owning both an MTB and a cross bike is far more redundant than owning road and cross bikes. Since I was never into serious technical MTBing, dirt jumping, huge drops, etc, I find my cross bike to be at least 90% of an MTB. I ride it on singletrack, fire roads, in crappy weather, etc. And it is far more efficient than the MTB ever was for mixed use (e.g., loops through the park that have some paved sections). And it was a great urban/suburban commuter (still would be if I hadn't moved to the sticks) - cutting through alleys & parks, over really roughed up pavement, through road repairs, up & down curbs, etc.

OTOH, even with road tires on it, my cross bike isn't half the bike my road ride is. It just can't compare to the efficiency, comfort, and speed of my road bike. I live on a stretch of dirt road, so every road ride I take involves 1/4 mile of dirt. And I occasionally ride longer stretches if I am visiting some friends/family on rides. I don't consider this a problem on my road bike - I just take them nice and slow. I'd say, if there is a chance you'll be on decent dirt roads for up to a mile or so (I'm sure others would say far longer is just fine!), a road bike will be OK.

The above blather, er, I mean, analysis, is based on having two bikes since I assume you're planning to keep your MTB. But if you're looking to replace your MTB with either a road or cross bike, then cross prolly makes more sense - it is certainly the best happy medium if you're sticking with only one bicycle.

Bottom line: if you're keeping an off-roader, I'd suggest going for a road bike. If it's a one-bike-only decision, cross splits the difference nicely. I find far more overlap b/t cross and MTB than b/t cross and road for my habits.

This is all of course one man's opinion and your mileage will vary. I'll be interested to see how other folks feel on this one.

Steve

Before I knew any better I did 5 hour Century rides with my old Miyata cross bicycle. It was comfortable and versatile. I did reset the brakes when switching narrower wheels/tires for road to wider wheels/tires for dirt. I later used it for touring and found it to be good with fenders and racks for that too.
I got some strange looks when joining pacelines. However, I found the ride to be great and very suitable for all the riding I did.
How fast do you intend to ride?
How flexible is your body? (usually can't get low flat back)
How much do you weigh? (wider tires can cushion ride of heavier riders and still comfortably fit in frame/fork/brakes)
You won't see cross bicycles in competitive road races.

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David Ornee, Western Springs, IL USA

Thanks for your post Steve, I have had the same question before, and always thought the Cross bike would be 98% as good as a road bike with the same tires...Never really thought about the effects of geometry though. I hope to hear other opinions on this as well.

Maybe not at an Elite level, but I can remember racing against guys on cross bikes with road wheels and tires in Cat 4 and 5 races in PA and NY... That is kinda why I figured they were 98% as fast, maybe those guys were just really strong.

A CX bike is a great compromise when you know you're going to be doing a fair amount of dirt road/off-road riding, and is much better handling on-road than a MTB. Usually lighter and faster overall too.

You can get a set of wheels and mount 28/30/32/34c CX tires on it with a lower geared cassette, and have another set for your road-only tires/cassette. Or have a set of CX and road tires and change them on a single wheelset.

If you can only have one "do everything" bike, wheelset, and tires, a CX bike with 28c or 30c CX tires is usually the best way to go. Most CX tires have low-profile knobs, but the better ones are also made to consider hard pavement riding and roll pretty well even with the short knobs, while still getting good grip on dirt.

When I had my CX bike used this way, the best tire I found for it was the Vredestein Campo 28c. They would pump up to 100+ PSI with no problem and were good on pavement, then I could ride trails and dirt roads with the PSI lowered to 45-55 PSI with excellent grip and never had a pinch flat.

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"Bush is the first President to admit to an impeachable offense."

- John Dean, former Counsel to the President (Nixon)

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But what about the efficiency vs. a pure road bike? Could you get a kick-ass cyclocross frame/fork and be almost as fast as a comparible road frame while using a set of road tires on the CX?

no - cx bikes are, IMHO, the most versatile bike around. I use mine for commuting, training, road riding and racing. Other people use them as touring bikes as well. I feel cx bike performance, speed and weight are just as good as any road bike assuming both are well maintained and have equal horse power in the engines. I love the sharp handling, strong wheels and frame, decent braking, high BB and large frame clearance. My recommendation would be get a CX bike for general use and light trail use and keep the MTB for those gnarly technical/long xc rides. I would strongly recommend buying a CX bike with either disc brakes or disc brake compatability. This will mean better braking in all conditions, less fade, better modulation and longer rim life.

http://gallery.roadbikereview.com/sh...&ppuser=246067

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shameless POWERCRANK plug
Don't run red lights, wear a helmet, use hand signals, get some cycle lights(front and rear) and, FFS, don't run red lights!

Absolutely.

Let's remember, CX started with roadies using their regular bikes to keep in shape in the off-season. A modern CX frame is not much different than a 'standard' road frame other than a bit different geom and a stouter fork that will accomodate wider tires and canti brakes.

__________________
"Bush is the first President to admit to an impeachable offense."

- John Dean, former Counsel to the President (Nixon)

The aim of big corporations is to separate fools from their money all of the time and ordinary folks from their money most of the time. The rest of us must fend for ourselves.