flargle

Cantilevers (especially the old-school wide-profile ones) offer better mud clearance than V-brakes. Also, road brake levers have too much mechanical advantage with V-brakes, so you need to add a travel agent between the two.

Disc brakes are outlawed in UCI-sanctioned road and cross races. Even in races where they are allowed, they still have a weight penalty compared with cantis. Cross courses don't have the sort of sustained, technical descents that cross-country races have.

Cantilever brakes are simple, light, reliable, and have more than enough stopping power. Like all other kinds of brakes, they have their loveable and not-so-loveable quirks.

M_S

Well put.

pinkpowa

135mm spacing so you can build some robust wheels with MTB hubs. Especially for disc equipped bikes.

schnee

There seems to be some miscommunication with the whole 'top mounted cables' thing. It's important that the cables that run along the top tube are mounted on top of it. Otherwise cables dig into your shoulder, get caught in your glove, etc.

Many cross bikes run some cables along the down tube. That seems to be more of a matter of preference, because I wouldn't imagine an old-school company like Gunnar still doing it without good reason.

flargle

Wrong.

dirtyphotons

good eye schnee, i was talking about the former but looking back it seems others were talking about the latter.

due to preference and local course design i tend to shoulder a lot. when shouldering i prefer not to have any cables on the downtube because i almost inevitably pull them. sometimes it causes a skip in gears when i get back on, and i could easily see it causing me to dump my chain if i'm not careful.

the same could be said for suitcasing and cables along the top tube, of course, so i can see how that would be a matter of preference. sorry to MIN for misinterpreting.

mrtornadohead

I am wondering if there is an "ideal" size for the top tube. With tubing getting larger and shaped I have to think if there is a point of the top tube getting too large to handle easily, or it having a shape that hinders suitcasing.

Also, what about internal cable routing? Obviously, running the rear brake cable internally on the tt has been done on road bikes for a while but what about running the der cables thru the tt as well, or is that going to be too much of a mess to setup (yes, I have built up bikes with internal rear brake routing)? What about running the der. cables internally thru the down tube?

Just wondering out loud here.

cc700

internal cables make a lot of sense in adverse conditions, but they are marginally harder to engineer and manufacture, as well as the aforementioned issue of more cable decreasing performance of the brakes.

i don't CX (yet) but from a design perspective you're likely to be cleaning gunk out of an external cable more than an internal setup. the extra cost comes at a marginal added benefit.

the Repeater

Top tube routing for shifting stability and portaging, no braze ons whatsoever, 130mm spacing.

No exceptions.

carlfreddy

Why?

I'd have just the opposite; lower the BB.

My reasoning is two-fold; 1) the saddle height will be lower for re-mounts, and 2) the center of gravity will be lower making the bike easier to handle on technical courses.

schnee

On the flip side, too low of a BB and you'll get pedal strike on off-camber or super-rutty conditions.

Belgian Knee Warmers has a good write-up on this. Different CX manufacturers use different philosophies on this. All I could figure out was the BB drop varied, but was no lower than a road bike of the same size.

c_m_shooter

I would like to see some manufacturers off small and medium frames with 650B wheels, so I can ride trails without constantly worrying about toe overlap.

rankin116

Why not just run full housing? I'll be doing with my MB over the winter, seems like it would be beneficial to a CX bike as well.

arctic hawk

I have been running full housing on my Trek XO1 for the last 2 years.
I guess I don't fall into the true cyclocross frame as it is my full time commuter, summer & winter. The full housing does keep out the extra road crap & winter salt/ice/slush...

carlfreddy

I think it really depends on the region.

Here in St. Louis we don't run courses that would put you at a disadvantage with a road-height or lower BB. In fact, some of the short-track XC courses could even be tackled with a cross bike.

LWaB

The one point not mentioned yet seems to be light weight. A lot of current CX-labelled bikes have quite heavy frames. I recall when CX frames tried to be lighter than road frames.

flargle

Tire and wheel availability is an issue with smaller wheels. I know some makers (DeSalvo, for example) design their smaller frames for 26" wheels, which gives you decent tire availability, although for cross not nearly as good as 700c. OTOH there are some very light wheel and tire options for cross-country racing, especially tubeless, that would work well for cross.

sfcrossrider

I've ridden, and owned a lot of cx frames. None have ridden nearly as good as...https://www.steelmancycles.com/eurocross.html

dragonmg

... only in the pro mens and womens races that is. For all other categories they are legal at UCI events.

mrtornadohead

I thought that's what was normal with internal cable routing. At least on my old Trek's you ran cable + housing thru the top tube. I think it can be done with minimal amount of internal-crap buildup. Perhaps rubber grommets at entry/exits?

But back to what makes a true 'cross bike... I think Surly and Riv have it right with the 132.5 spacing. Run whatever wheels you want. As for braze-ons for racks, fenders. I think they are nice to have but would be out of place on a true, dedicated cross bike. I vote for the lower bottom bracket but I haven't run a lot of courses, let alone outside of the midwest. That said, I will probably be running the frames *with* the braze ons as I am certainly not to the point of being competitive enough to purchase such a dedicated race frame.

cs1

You're thinking more like a roadie. Remember, more than half the time a cross bike is used off road. The high BB also keeps you from from getting the crank stuck on ruts.

dirtyphotons

bb height's a tradeoff. lower bb makes for easier and quicker mounts.

flargle

You're thinking more like a mountain biker. Remember, the original reason for the high bottom bracket had nothing to do with clearing "ruts", but to prevent toeclips (i.e. "mudcatchers") from dragging on the ground during dismounts and remounts.

https://www.belgiumkneewarmers.com/2007/12/how-high.html

cs1

Touche!

the Repeater

Having tried both, the lower BB has worked far better for me, both for climbing and being able to quickly ride sharp turns by steering the bike, whereas a frame built higher requires more lean angle--a disadvantage in sharp turns as traction and control suffers.