Just wondering what size cogs would be needed to mimic a 30/42 bottom gear.
I must be tired and not reading it right. Does their website mean that it takes 3.3 crank revolutions to turn the drive ring once?
Or is it the other end, meaning that 1.82 turns of the crank turn the drive ring once?
does the calculator on their site not tell you?
[url= http://pinion.eu/en/p1-12-gearbox/ ]http://pinion.eu/en/p1-12-gearbox/[/url]
Sorry, I think I'm being an idiot. Thats probably what you are looking at. I don't know is the real answer.
Drop Olsen bikes a message, he's been running one a while and is selling them too plus he's a dead helpful chap.
Your second interpretation is correct. the crank turns 1.82 revs for each revolution of the ring.
So with the same size ring, a 30/1.82 ~ 16 or 17t sprocket will give you roughly the same gear.
Thanks, that's what I was trying to bottom out. The bike I'm looking at, has kinematics designed around a 30t chainring.
I'm wondering what size to run on the freehub to go slightly lower and a good bit higher than my existing 30-10/42 setup.
In that case, 12t on the back should give you roughly equivalent gearing with a 30t ring.
Must have buggered up my maths then. I thought it was closer to 24.
Oh... Hang on... We may be at cross purposes here.
I read that as 42t chainring, 30t sprocket. You're actually asking about the reverse, yes?
In which case, your maths is correct. The exact equivalent gearing would be 23.1t, so Pinion's standard 24t sprocket will give you exactly what you are looking for.
Cheers. Yes, I'm old and unfit and the hills are steep around here.
Now that's sorted time for the important question. What bike are you looking at?
Taniwha. But, they only come as complete bikes so are more expensive that I was originally planning. Also, not been a fan in the past of single pivot bikes in the past. However, the single chainline might put a new twist on that along with the improved sprung to unsprung ratio.
There aren't many gearbox bikes so I thought it may be. Did you not consider the Mojo Geometron/Nicolai Ion GPI? That is a four bar linkage.
I've looked at the geometron, both gpi and standard, but it's heavier and strikes me as a very single purpose bike that needs riding flat out. Our all day trail rides have flat out bits, but they're not flat out non stop.
