Why do some CX bikes run a single ring in front?

[610]

inquiring mind want to know!

[Merckx Rider]

Many cx courses don't require the use of a large chainring, using a sinlge ring (with guards) saves a little weight and is one less part of the drivetrain to get fouled up with mud. Most riders use a mid size ring like a 42 this way they can get both some speed and climb.

[greybeard87]

Simplicity = improved reliability.... hopefully

[lunacycle]

Also, since you have only one ring, you can shorten your chain. This reduces the likelihood of dropping your chain, assuming you're using some form of a chainguard / chainkeeper up front. I've been running a 38t x 12-28 combination for years, in conjunction with a DA short-cage rear derailleur, and I have never dropped a chain.

[ronbridal]

I ran a 42 tooth chainring with a 12-27 cassette in the back. This gave me all the gears I needed for the courses I raced on. In addition, I didn't drop a chain in any race because I used a chain guard on each side of the chain. I am changing bikes for next year though, and may run a double up front, I am undecided. Ron

[Lectron]

Single 42 with a ten speed 11-28. Saves weight, gives me all the gears I need.
If anything should demand lighter gears than 42-28, I would probably be shouldering the bike anyway.

[jaqb]

Lectorn has right, in my winter bike cyclocros EMPELLA i've 42 and 11-28, those gears are best for me too training and competiton.

Simply and lightnes quick shift and no problems.

[Ronsonic]

Simpler, lighter, cheaper, sturdier - how often do you get all that at once.

Why carry more parts around than you need. Most cross courses don't have long enough paved sections to do a lot with the big ring and if you need a granny gear you'd go faster running so why have the extra stuff on your bike.

Ron