[golgiaparatus]

Drivetrain wear issues aside... Finally someone gave me what seemed to be a valid reason why (without changing the actual gear ratio) they would actually improve acceleration/torque.

He said, "it's like running longer crankarms"

Basically he explained that the place where the torque is applied to the chain is closer to the center of the BB/Axle therefore making the effective crank length longer.

I'm no engineer so I'm not 100% convinced.

 

[norbar]

Nay. I have it on my dirt jump bike and I don't feel it yet it feels crappy.

 

[golgiaparatus]

Thinking of running a little trial. I run a 32/20, there's a giant climb that I can never power up the steep section at the end... I can almost get there with 32/20, but with 32/21 I can get it every time.

I'm going to go out with a 24/15 (same ratio as 32/20) and try to hit the same climb. If I make it, success. Then I'm going to go down a flat section of trail where I know my top speed at max spin. If I can maintain that same speed... double success.

 

[4130biker]

Basically, the concept of a longer lever arm providing more leverage is correct, but the lever in this case is not longer, it simply appears longer because of the sprocket its sitting next to. The gear ratio remains the same, and the lever, your crank arm remains the same length despite the difference in its size relative to the sprocket. So no, it doesn't change anything accept it may feel mushier and rougher because of the smaller sprockets.

 

[4130biker]

This is part of the reason I'm still running a 36-13 on my bmx bike, even though 25-9 has been all the rage for some time now. The smaller the combinations get, the worse they feel. But I'd say I'm mostly being cheap in the case of my bmx bike...
I say do it if you're up for the trade off of a positive feeling drivetrain to save some weight and look cool (which I personally think micro drive looks cooler). I really want to try a micro gear cassette to simplify my trail bike, once they become available.

PS-did your hbc sprocket show yet?

 

[Westy]

If it is the same gear ration nothing has changed unless you actually put on longer crank arms. It would be wise to ignore everything this person has to say to you.

 

[norbar]

This is part of the reason I'm still running a 36-13 on my bmx bike, even though 25-9 has been all the rage for some time now. The smaller the combinations get, the worse they feel. But I'd say I'm mostly being cheap in the case of my bmx bike...
I say do it if you're up for the trade off of a positive feeling drivetrain to save some weight and look cool (which I personally think micro drive looks cooler). I really want to try a micro gear cassette to simplify my trail bike, once they become available.

PS-did your hbc sprocket show yet?

I really regret going 25:10 on my dirt jumper. Going back to 32omething as soon as possible.

 

[golgiaparatus]

This is part of the reason I'm still running a 36-13 on my bmx bike, even though 25-9 has been all the rage for some time now. The smaller the combinations get, the worse they feel. But I'd say I'm mostly being cheap in the case of my bmx bike...
I say do it if you're up for the trade off of a positive feeling drivetrain to save some weight and look cool (which I personally think micro drive looks cooler). I really want to try a micro gear cassette to simplify my trail bike, once they become available.

PS-did your hbc sprocket show yet?

Nope, not yet. The building of my frame starts on December 1.
It will be a hell of a laugh if the frame is built and shipped before those Chainrings show up.

 

[golgiaparatus]

If it is the same gear ration nothing has changed unless you actually put on longer crank arms. It would be wise to ignore everything this person has to say to you.

So moving the load bearing element closer to the fulcrum does NOT improve leverage?

 

[4130biker]

So moving the load bearing element closer to the fulcrum does NOT improve leverage?

It would, accept you are moving the load bearing element closer to the fulcrum on the rear hub as well (by going to a smaller rear sprocket), thus canceling any gains in leverage.

Same as if you go to granny gear in the front, then 2-3 rings smaller in the rear when riding- you can get a very similiar gear ratio by using two different sized front chainrings.

 

[Rip]

I run a 25x13 gearing on the dirt jumper and the feel is about the same when I was running 32/15.

 

[ioscope]

Micro drive is lighter, less likely to catch your pant leg, and clears lips and ledges more easily.

 

[jonKranked]

Micro drive is lighter, less likely to catch your pant leg, and clears lips and ledges more easily.

only matters when riding freestyle. not so much for actual MTB.


and golgi, whoever told you that BS in the first post is an fvcking idiot.

 

[TheMontashu]

So moving the load bearing element closer to the fulcrum does NOT improve leverage?

Think about it this way, you have 2 set's of levers. Everything is correct that you have this far said yes, but you have to remember, you can also look at the cog/ wheel as a lever as well. When you make your front cog smaller, yes it effectively gives more torque on the chain-ring, but the now smaller cog in back has to push harder to spin the lever that is now the wheel. Because there are 2 geers/ levers as such what is important to power transfer is not necessarily the size of the gearing but the ratio.

Think about it like this, you have a 32-16 (2/1 ratio), for every crank revolution your wheel moves around exactly twice. Now you have a 18-9 (2/1 ratio) your wheel still turns twice per revolution of the cranks

 

[ioscope]

Micro Drive: Faster wear, high chain tension, lighter, more expensive, less efficient, stays out of the way

Conventional: Slower wear, low chain tension, heavier, less expensive, more efficient, hits logs and stuff more often.

For something that you dirt jump or freestyle, micro drive is the clear choice. For a road bike or xc bike I would go conventional.

 

[ioscope]

On my roadie I have a 53-22. On my 24" I have a 25-10.