Bigger rings are more efficient?

I've searched through many threads but can't seem to find much discussion on this so thought I'd start a new thread. I've also Googled around and dug up one or two discussions which were pretty inconclusive and went off topic.

I want to change my gear ratio and realise that it's possible to achieve that ratio with a number of cog/ring combinations. I'm currently running a 74 gear (44:16) but want to take it down to 73. That could be achieved by 43:16, 46:17 and 49:18 amongst others. Is it all swings and roundabouts or is there a noticeable difference between them? Anyone have any experience? I remember that certain gears felt the same on a geared bike but haven't ridden geared in a very long time.

Thanks in advance.

i don't think there will be much difference,
shimano brought out a 10 pitch a while back, which gave the same gearing with smaller cog and rings, probably just to save weight.

basically the bigger the cog and rings, the lower the wear on the componants. the smaller ring/coog combos are lighter, but the load/torque isn't spread over as many cogs, plus the chain has to 'bend' more round the cog/chainring.

the bigger ring/cog combo is generally better for wear purposes, and if your into skidding then you need to factor that in too, as certain combos will add more skid patches

Cool. Well perhaps I'll just get a 43T chainring to replace my 44 to get my 73in gear rather than have to replace the cog as well. Heading down to Brighton on Wednesday to see a friend and I can make it up Ditchling on 70-71 gear.

I don't or can't skid and am happy to get new parts when they wear out quickly. Just want to remove as many niggles as possible from my riding experience.

can you tell the difference between 74" and 73"? just curious.

can you tell the difference between 74" and 73"? just curious.

it would be cheaper to just replace the cog, rather than a chainring with a 1 or 2 tooth difference.

I haven't done an A/B comparison but I think I can tell the difference between 73" and 74", sensitive soul that I am. I think perhaps because it's on the borderline between comfort and work.

I've got a 110 BCD crank so I can use one of those Sugino BMX chainrings which are about twenty quid on ebay. Not a huge expense. I can sell my existing one to recoup some of the cash. It's only had a few months use.

So really no difference between using big rings or small rings to get the same ratio?

I believe the common belief is that you should go larger to achieve said ratio. a larger setup will have less wear on the chainwheel, chain, and cog than the smaller setup.

smaller rings= lighter but wear out

bigger rings = last longer weigh more

I haven't done an A/B comparison but I think I can tell the difference between 73" and 74", sensitive soul that I am. I think perhaps because it's on the borderline between comfort and work.

I dunno... 1" doesn't seem so much? I recently dropped my chain ring down a couple of teeth from 48->46 (3gi) for the same reason. Feels much nicer - now I'm used to it I find myself spinning a little faster and lighter on flats but (more importantly) hills feel better - don't think I would have noticed this with only 1". I can now make it comfortably around the Dulwich Paragon Saturday morning ride (SS not fixed) - but there's one small hill that's still borderline - I reckon th extra 3gi would have me walking up it? Love your knees...

Bugger. Still can't decide. Almost bought that 43T ring but then hesitated. Think I'll be walking up Ditchling on Wednesday then. Thanks for the input guys.

smaller rings= lighter but wear out

bigger rings = last longer weigh more

Is the relationship between size and wear not linear?

If the load is dispersed over more teeth then wear to the chainring would be less; but would it not then increase as a smaller ring would be turning more, negating the marginal benefit of reduced wear of larger teethed cogs.

Does that make sense?

Good little article here http://www.gsportbmx.com/tech/super_small_gears.php

Rad that and enjoyed it. Cheers Tommy.

even with the same gearing the large chainring at the front seems harder to pedal than a small one

psychology prolly

Just bought a 43T ring on the bay. So don't need to worry about getting a new cog as well. Did London (Southall) to Brighton yesterday really noticed the overgearing. So let's see how it goes.

I heard goatse do some big rings

Not read the rest but in terms of track racing and that physic stuff. Smaller is good for sprinting. For instance if you are sprinting on 90, 47x14 is a good way to go rather than 50 x 15 as you have more torque to get you moving.

The differences are minute, but might gain you 1/100th of a second on a standing start 250. Plus you could save 20-30 grams, more if you can run less chain.

I was going to say that trackies tend to go smaller for events where you need to spin up to speed quickly and go bigger for the longer events with less speed changes. Allegedly the ratio of crank length to chainring diameter gives you more leverage with a smaller chainring, although I'm not sure if that's actually based on phsics!

smaller rings= lighter but wear out

bigger rings = last longer weigh more

Not necessarily, some large rings have scope for lightening holes that slightly smaller rings don't, so a "windowed" large ring might actually weigh less than a smaller ring with a fairly similar number of teeth.

This is my instinct, not tested. I don't have that many chainrings lying around!

I was going to say that trackies tend to go smaller for events where you need to spin up to speed quickly and go bigger for the longer events with less speed changes. Allegedly the ratio of crank length to chainring diameter gives you more leverage with a smaller chainring, although I'm not sure if that's actually based on phsics!

I thought it was B*llocks, so I spend a couple of hours working through the sums and it seems to be true.

So 49/18 would be better than 51/19? I'm trying to decide which to go for. Currently have a 51 and getting a 49 chainring and have 18 and 16 cogs. I want to be set up for Road and be able to flip for track. Plus the odd numbered chainrings for skid patches.

Initially this thread seemed to be in favour of large but got biased towards small later on. So I'm going to be 43:16 when my ring turns up. Which will apparently give me 16 skid patches - so I'm going to have to learn to skid. The late Sheldon says it's a must for fixed riders.