Moving from compact to normal crank

[Slowbee]

Count the number of teeth on the smallest and largest cocks on the cassette.

 

If you're spinning all the time, that's to do with the gear ratio, not the crank length.

 

You will probably find that the actual crank length will be the same with your setup and a non compact one. The compact part refers to the spider not the length of the crank.

 

Right so I did some counting, and it was not pretty!

 

The crank part is stamped with 53/39, and it is a 170mm crank length.

 

The casette is 50/12, whatever that means.

 

Help.

[Captain Fastbastard Mayhem]

Right so I did some counting, and it was not pretty!

 

The crank part is stamped with 53/39, and it is a 170mm crank length.

 

The casette is 50/12, whatever that means.

 

Help.

 

Cassette can't be 50/12! Maybe 25/12?

 

And 53/39 means you don't have a compact crank - you have a normal sized crank. You do, however, have a short Crank ARM at 170mm. That would probably be why you're feeling like a washing machine on spin cycle...

Edited August 16, 2012 by cptmayhem

[SwissVan]

Right so I did some counting, and it was not pretty!

 

The crank part is stamped with 53/39, and it is a 170mm crank length.

 

The casette is 50/12, whatever that means.

 

Help.

 

So you have not got compact cranks, just short crank arms (170)

 

But where the hell did u learn to count get a 50/12 cassette?

 

IF thats true then no wonder you spinning on the road bike, normaly road cassettes are in the 23, 25 tooth range

[Escapee..]

I think I need some pictures to understand this

[Captain Fastbastard Mayhem]

I think I need some pictures to understand this

 

He has a normal sized crankset (chainrings) at 53/39 t

 

He was asking if the crank arm (spider) being shorter than his MTB's crank arm (spider) at 170mm vs 175mm could cause him to spin faster than a bottle at a co-ed dorm room party. (or at least make it feel as if he is) - the answer to this is Yes, by the way. You will be spinning smaller circles with your feet, and your feet will travel a shorter distance per pedal stroke than if the arm was 5mm longer.

 

He can't count...

Edited August 16, 2012 by cptmayhem

[Mr SingleTrack]

well knock me sideways with a broomstick ! I just learnt something here. I thought compact meant shorter, as in compact.

 

So a longer crank will make a difference. And from Thastig's post, will be easy to get used to. Now what websites can I use to buy a crankset .

 

Just avoid those cape based merchants…

[JA-Q001]

He has a normal sized crankset (chainrings) at 53/39 t

 

He was asking if the crank arm (spider) being shorter than his MTB's crank arm (spider) at 170mm vs 175mm could cause him to spin faster than a bottle at a co-ed dorm room party. (or at least make it feel as if he is) - the answer to this is Yes, by the way. You will be spinning smaller circles with your feet, and your feet will travel a shorter distance per pedal stroke than if the arm was 5mm longer.

 

He can't count...

 

That would actually mean his leg speed is slower, so for the same RPM his legs would turn slower, because its a shorter distance being coverd in the same time. Speed = distance X time. But, he will not be able to push the same amount of torque for the same speed to get the same wattage, so you will tend to spin more, using a lighter gear.

 

A longer crankarm will give him more leverage to push a harder gear and so his leg speed will drop.

Edited August 16, 2012 by JA-Q001

[JA-Q001]

Thats why crank length has less to do with your leg length and more with your ride style. If you like spinning, go shorter, if you like grinding, go longer, if you can do both, go middle. If you look at marco pantani, he was a smallish dude, but climbed with 180mm cranks, where Armstrong used 172.5mm because he could grind and spin.

[Slowbee]

 

So I counted the teeth on the large thingymabob (cog?), and it is 50, and then I counted the small cog and it is 12.

 

Doing something wrong ?

[Slowbee]

So you have not got compact cranks, just short crank arms (170)

 

But where the hell did u learn to count get a 50/12 cassette?

 

IF thats true then no wonder you spinning on the road bike, normaly road cassettes are in the 23, 25 tooth range

 

I counted again, just to make sure, and yep it is 50. But it is funny that you ask, because round about the 3rd or 4th cog from the large one on the casette, the chain does seem to "jump" when changing. It is never really smooth as with the others. Your thoughts?

[Grebel]

 

So I counted the teeth on the large thingymabob (cog?), and it is 50, and then I counted the small cog and it is 12.

 

Doing something wrong ?

 

I think they mean the big and small cock cogs in the casette. There is no way that the big cog has 50 teeth...

[JA-Q001]

thats a 12 - 25, learn to count.

 

Or remember to stop when you get to the start again.

Edited August 16, 2012 by JA-Q001

[dracs]

Srry slowbee - my thoughts are you definately have a counting problem... that and your chain needs a clean....

[Slowbee]

Srry slowbee - my thoughts are you definately have a counting problem... that and your chain needs a clean....

 

leave my chain alone .... I need to go count AGAIN ...

[SwissVan]

I counted again, just to make sure, and yep it is 50. But it is funny that you ask, because round about the 3rd or 4th cog from the large one on the casette, the chain does seem to "jump" when changing. It is never really smooth as with the others. Your thoughts?

 

Dude, your big chain ring on the front is a 53.... right?

 

You say your big"cog" at the back is a 50...right?

 

Now look closely at both, do they look almost the same size as each other?

 

50 tooth cassette....Pfffft...

[SwissVan]

leave my chain alone .... I need to go count AGAIN ...

 

Ooo bliksem...just wait until hairynut see's this....