BMX - 9-11t cog driver vs 12-18t cog driver

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i need to decide on this. does running smaller cogs and chain ring really wear chain out that much faster? also, is it nicer to have the broader range of 12-18...or would i never even use this range?
i like the small set up, but if the larger is more durable and a broader range it seems i should go that route
what do you think? from reading this site, it sounds like a 2.75 ratio is a good all purpose gearing. is this so?
so is a range of 3 to 2.5 ratio ideal to shoot for??
i need to figure this out now so i don't buy parts that are not suitable for a certain gearing should i want to change it.
CMcMahon
02-24-06, 09:38 PM
The chain might wear quicker (but if you're not grinding on it, it should last you several months anyway, unless you have it insanely tight), but the sprocket will be more durable due to it's smaller diameter.
The one-piece drivers are far better than cogged drivers in my opinion; they take about two seconds to install, are easy to maintain, and never come loose.
I've had 30-11, 28-10, and now 25-9, in addition to 45, 44, and 43-16 way back when. They all feel so similar, that it's barely noticeable once you get used to them.
The one-piece drivers are far better than cogged drivers in my opinion; they take about two seconds to install, are easy to maintain, and never come loose.
I've had 30-11, 28-10, and now 25-9, in addition to 45, 44, and 43-16 way back when. They all feel so similar, that it's barely noticeable once you get used to them.
so once people find a set-up the like, they don't necessarily keep changing cog teeth number to change the way it feels? you pretty much just leave it...or i guess in my case, i wouldn't need that kind of fine tuning.
when you say one-piece drivers, do you mean the ones that are sort of built into the "cog"? as opposed to the cogged drivers that are similar to that of a MTB...correct?
CMcMahon
02-24-06, 10:07 PM
1) Yes. If you want to change the feel and have a rear gear that small, you need to lower or raise the number of teeth in your sprocket.
2) Yes.
KinetikBiker
02-24-06, 10:32 PM
Dont small ratios put more stress on the sprockets and cogs/drivers(whatever you call them)?
And yes, you wont notice the difference as long as you left one of the standard "ratios" and switch to another standard ratio...
CMcMahon
02-24-06, 10:51 PM
They put more stress on the chain, causing it to stretch quicker than normal.
so, beerman...would a 25-9 ratio give you the same acceleration and speed as say a 16-44???
CMcMahon
02-25-06, 08:12 AM
Similar (the ratios aren't exactly the same), but you'd be torquing much harder with the smaller gearing.
KinetikBiker
02-25-06, 08:34 AM
They are very close, you probly wont even notice, except for the smaller chain wheel..
Similar (the ratios aren't exactly the same), but you'd be torquing much harder with the smaller gearing.
i thought as long as the gearing ratio is equal they would feel the same? why will you be torquing much harder?
less teeth to be grabbed right?
KinetikBiker
02-25-06, 04:45 PM
i thought as long as the gearing ratio is equal they would feel the same? why will you be torquing much harder?
i wonder why too....
hypersnazz
02-27-06, 12:04 PM
The torque on the chain doesn't change, since the gear ratios are the same. The forces applied to each individual tooth are greater, causing faster wear on *both* chain and gearing. However the advantages of micro gearing (increased impact durability and smaller drivetrain profile) far outweigh the wear issue, which is actually pretty minimal. Check your chain every couple months with a ruler, replace it on time and your drivetrain should last a good long time.
From Sheldon Brown's article on chain stretch: "Cyclists often speak of chain "stretch", as if the side plates of an old chain were pulled out of shape by the repeated stresses of pedaling. This is not actually how chains elongate. The major cause of chain "stretch" is wearing away of the metal where the rivet rotates inside of the bushing (or the "bushing" part of the inside plate) as the chain links flex and straighten as the chain goes onto and off of the sprockets."
The torque on the chain doesn't change, since the gear ratios are the same. The forces applied to each individual tooth are greater, causing faster wear on *both* chain and gearing. However the advantages of micro gearing (increased impact durability and smaller drivetrain profile) far outweigh the wear issue, which is actually pretty minimal. Check your chain every couple months with a ruler, replace it on time and your drivetrain should last a good long time.
Yes it does, the amount of force on a chain running a 25/9 is nearly twice the force on one running 44/16, it's simple leverage.
To that you have to add the fact that there're less teeth to carry the load and you get worn sprockets, ****ed driver bearings and broken chains.
hypersnazz
03-01-06, 02:34 PM
Yes it does, the amount of force on a chain running a 25/9 is nearly twice the force on one running 44/16, it's simple leverage.
To that you have to add the fact that there're less teeth to carry the load and you get worn sprockets, ****ed driver bearings and broken chains.
My bad, you're right about the leverage. However, the thing to understand is *still* that BMXers aren't roadies, they're not climbing Alpe D'Huez and the drivetrains don't suffer that much routine wear and tear from *pedaling* forces. They do however get smashed on things and thrashed around quite a bit, the kind of abuse that smaller gears handle better than bigger ones. So far nothing I own on my BMX bikes has actually *survived* long enough to wear out.
If people use their bikes for transport tooth wear will be an issue. But even if you don't chain snap is a real possibility, and 9t driver bearings get shagged as quick as you like, in fact odyssey won't sell then any more.
CMcMahon
03-01-06, 03:45 PM
Odyssey never did sell 9t drivers; they've been against it from day one. I can't say that I've had any issues with the 9t RNC driver I've got in my Odyssey, though.
All I know is a couple of people I know got rid of their 9t drivers, one because he wore out the sprocket and the other because he kept snapping chains. If it works for you then cool, but people should know the risks.
hypersnazz
03-02-06, 08:59 AM
No complaints here either, I been running tiny gears for years on the flatland bike and the street/park bike without hassle. I've got a much more appropriate bike for commuting.
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