Gearing

CptKernow

Just ordered a CX bike with Sram Rival 1x11 groupset. The lowest gear is 42/42 which seems pretty low - I'm pretty light and ride a 36/27 on the road, which is plenty low enough.

I am planning on racing and just wondered if I'd need gearing this low or whether 42/36 would be good enough.

One reason I'm asking is the 11-42 cassette weighs an massive 538g compared to 366g for an 11-36.

imposter2.0

Stick with the 42 - you don't have to use it, and saving 170g is not going to make any difference at all.

keef66

Better to have it and not need it than the reverse. If after a few races you find you never trouble the biggest sprockets you can swap in a smaller cassette. Transmission components wear out quite quickly in CX anyway.

trek_dan

In CX racing you definitely won't need a gear that's lower than jogging pace, as above though 170g won't make any difference at all especially when your bikes caked in a few kilos of mud.

tgotb

trek_dan wrote:

In CX racing you definitely won't need a gear that's lower than jogging pace, as above though 170g won't make any difference at all especially when your bikes caked in a few kilos of mud.

Not sure I agree; sometimes there are places where you want to stay on the bike even though it's no quicker than running, just so that you're already on the bike for the next bit. There was a good example at the Cyclopark Nationals where there was a long-ish steep climb that was rideable by most in the prevailing dry conditions, but only just; if you did end up having to dismount you were then faced with an uphill remount at the top, on a steep camber that put non-drive-side dismounters (ie most of us) on the downhill side of the bike. If you couldn't remount there (most couldn't), you had to run quite a lot further, and probably lost a good 10 seconds. The MK Bowl often has less-extreme versions of the same thing, where you can lose disproportionately by running out of speed and having to do an extra dismount/remount.

This is particularly the case for less-experienced riders, who may not be able to carry as much speed into the start of the climb, for instance if the course designer has added an awkward turn at the bottom.

Also bear in mind that after 40 mins racing, many competitors aren't actually jogging up the hill that was too steep to ride, it's more of a trudge...

Edit: To answer the OP's question more specifically: You might aswell start with what you have, and revisit the question when you have a couple of months' racing under your belt, based on what gears you ended up using in practice.

CptKernow

Thanks all for the wise words. Will put my weight weeny-ism to one side and see how I get on first.

trek_dan

TGOTB wrote:

trek_dan wrote:

In CX racing you definitely won't need a gear that's lower than jogging pace, as above though 170g won't make any difference at all especially when your bikes caked in a few kilos of mud.

Not sure I agree; sometimes there are places where you want to stay on the bike even though it's no quicker than running, just so that you're already on the bike for the next bit. There was a good example at the Cyclopark Nationals where there was a long-ish steep climb that was rideable by most in the prevailing dry conditions, but only just; if you did end up having to dismount you were then faced with an uphill remount at the top, on a steep camber that put non-drive-side dismounters (ie most of us) on the downhill side of the bike. If you couldn't remount there (most couldn't), you had to run quite a lot further, and probably lost a good 10 seconds. The MK Bowl often has less-extreme versions of the same thing, where you can lose disproportionately by running out of speed and having to do an extra dismount/remount.

When I was a newbie and not very good at dismounting I was running a compact double and went down to using a 32 cassette on the back (so 34:32) to minimize dismounts and had people walking past me but I suppose it does depend on the course and your fitness.

CptKernow

After a quick pootle round the field and through the woods with the dog I'm quite liking the 42/42 gear...