A newbie question about sizing for a cross bike.
I am looking at picking up a 59cm Cross Check. I am an experienced mtn biker but I have little knowledge on cross sizing. My inseam is 35in. Should I try this bike out or shoot for a smaller sz? Im mostly interested in this bike because of its versitility. I can commute on the road, switch it out for the trails, and switch it out as a fixed if Im feeling squirrelly. Any advice greatly appreciated.
This question has come up several times in the past few weeks - search this forum to see some of these posts. Most people seem to think that one should try a cross bike that is one size smaller than a rode bike that fits you. A rule of thumb is measure your inseam by standing against a wall in bike shorts and stocking feet and having a very good friend place a book, spine up, up to your crotch until it doesn't go anymore. The height from the floor to the spine of the book is your inseam for bike sizing purposes. Multiply that number (in centimeters) by 0.67 (or 0.65 according to Greg LeMond) and this reveals your frame size for a road bike. My inseam measured this way is about 31.5inches, which translates to about a 52cm frame. This is what I ride in a road bike. When I test rode a 52cm cross frame it was too big and I had to order a 49cm. Good luck!
I have a 34" inseam and ride a 56cm Cross-check. If I went any bigger the top tube would be too long for me. With a 35" inseam, you may want to try a 57cm.
The common wisdom to size a cross bike 0-2cm smaller than a road bike is because-
1) Higher BB on cross-specific design means shorter seat tube, so effective size is the same, although the BB to toptube measure is shorter than an equivalent road frame.
2) You MIGHT want to ride a little more upright than a racing position on a road bike
If you can straddle a few cross bikes in a shop before you buy, check out the standover height (floor to top tube) and top tube length. Different cross bike makers determine "frame size" differently so its a little less obvious what you need than it would be in selecting a road or MTB hardtail frame. Knowing your standover height and top tube length should get you pretty close to the right size, you can play with the stem length and saddle position from there.