I have a 2011 Felt z85, size 56, that I had fitted at the LBS. I want to build a Cyclocross bike, I'm thinking that the Surly Cross-Check is a decent frame (open to other suggestions though).

My question is, if I'm a 56 on the Felt z85, which Cross-Check frame should I get for CX?

Here are the specs side by side of the frames I think are closest, with the z85 on the far left:

Anyone?

Match the effective TT length, your CX seat postion will be slightly forward of a road position so result in a slightly shorter saddle-to-handlebar measurements that is just right for cross. Dont go too small on the frame worrying about standover or else you will have too much drop from level of saddle to the bars, wont be able to use the bar drops wich is an important postion for good CX handeling. You might even look at the cross-check in next size up to ensure bar is high enough (so long as the TT is not excessivly longer than your road bike).

It depends on what your intended purpose is. If you like the fit of the Z85, the chart should tell you that you shouldn't get a Cross Check.

The problem with the Cross Check is that the relative proportions of the top tube and the head tube are such that it wants to direct you to an aggressive riding position. If that's what you want, then I'd say get the 54cm Cross Check, but don't overlook the 8cm difference in head tube size between that and your Z85. The fork on the Cross Check is about 2.5 cm longer, but that still leaves your bars more than two inches lower for the same spacer, headset and stem.

Check out this thread (https://www.bikeforums.net/showthread...Check-Lovefest) and notice all the rising stems and stacks of spacers. That's a result of the Cross Check's short head tube.

If you want something with a fit more like your Felt but with the utility of a Cross Check, check out the 55cm Handsome Devil. It will still have a bit shorter stack than your Felt, but it's closer.

If you want something for racing, you'll want to go in an entirely different direction.

What's your REAL inseam (turf to taint)? How tall are you? Do you like the fit of the felt? Can you get up a curb on it? Do you feel like you could maneuver the thing in the way you'd need to on a cross course?

have you ridden the size 56 felt cross bike? What'd you think of that? I'm asking because numerical size is pretty standardized over a brand line and may not necessarily reflect just the BB->TT seattube length, rather a common size for buyers to reference.

poke around here- https://www.google.com/search?source...locross+sizing
and here- https://www.bikeforums.net/showthread...oadbike-sizing

EDIT: looks like there isn't a 56 felt cross-

IF the 56 road fits you well, I'd try and match the 55cm cross' geometry in a surly frame.

https://www.bikeforums.net/showthread...clocross-Bikes

I'm 5'10" with a 33" inseam. I want to build a bike for racing, preferably with disc brakes. But I notice that most of the builder frames are multi-purpose, so they have disc and canti mounts, fender mounts etc. Are there any frames for cyclo-racing with disc tabs that are recommendable?

You can get a Specialized Crux with disc brakes. I'd definitely race that. There's also the Felt F65X or the Jamis Nova Race, both of which are at the low end of their manufacturers' offerings but are probably decent race bikes anyway. The biggest problem with disc brakes for racing is that they add a lot of weight to the bike. CX racers tend to be weight weenies.

I really like that Specialized Crux! But it looks a bit spendy, and I'd like to go with something a little cheaper especially for my first(ish) build.

I found a deal for a 2009 MOTOBECANE FANTOM CROSS OUTLAW frame and fork. I was thinking the 56cm, does that seem right?

https://motobecane.com/ftx_geometry.html

It's got rack braze-ons which I don't really want, but other than that it looks like it has everything I'm looking for.

You didn't read any of that did you? Because just skimming it I gleaned that a cross bike should be a size down.

I did read it. I read the whole thing. I even read the link at the bottom of that article:

https://velonews.competitor.com/2010/...ike-fit_136539

Which says you SHOULDN'T size down, but you should raise the handlebars. So there are multiple viewpoints expressed in the resources you linked to and I'm still trying to work through them.

"In shopping for a cyclocross bike, achieving your ideal position usually does not mean sizing down."