Sensera

Hi!
Can anyone tell me if there is any problem with having a 36-60T chainring/crankset due to the big jump between the two sprockets? Also, when measuring the chain on one of those I would need to measure it at longest length, correct?

on the rear I wanted to have a 11-42T cassette.

Cheers!

Wilfred Laurier

I think there are two dimensions you need to work out - the jump between 36 and 60 (24 teeth) and the total capacity - (60-36)+(42-11) = 55. So to get this all to work properly you need a front derailleur that can handle a 24 tooth jump (24 tooth capacity), and a rear derailleur with a capacity of 55.

https://guides.wiggle.co.uk/rear-der...s-buying-guide
This link has a table of rear derailleur capacity - and it looks like the largest that Shimano MTB derailleurs can handle is 46. So with your proposed setup you will likely need to have a chain so long that the derailleur goes completely slack in the smaller cogs+small chainring combo. If you choose a chain length that maintains tension in those gears, you will likely not be able to reach the large chainring and larger cogs combo, and likely will damage the drivetrain if you accidentally shift into them.

As for the single jump from 36t to 60t, this might be a dealbreaker from the get-go - a 24tooth jump is more than the max that a triple front derailleur will generally accept (usually 20 teeth), and that is usually over three chainrings. The derailleurs for double rings only specify a 16 tooth max jump. I fear you will struggle to get a derailleur to move in the right direction to handle a 24 tooth jump over two chainrings. The derailleurs for double rings only specify a 16 tooth max jump. The derailleur is going to be rubbing on a big ring, or the chain is going to be rubbing on the derailleur.

HillRider

To cover that spread properly you will need a rear derailleur with a 55 tooth wrap capacity. I don't know of any that will do that. You will probably have to use two chains to get a total length needed to wrap big-big.

Also, do you really think you can make any practical use of a 147 gear-inch high gear (assuming 700c wheels) if you need a 19 gear-inch low?

Sensera

Thanks!
That helped quite a lot, specially with the gearing calculus....I'll see if I can get another setup then! Cheers!

Bill Kapaun

A 50x11 gear is extremely high unless you RACE downhill.
Personally, I save my energy for the uphill.

ThermionicScott 

$5 says the OP is trying to make an ebike go faster.

Kapusta

Yeah you will be hard pressed to find a front derailleur that will handle a single 24t jump.

Also, the 60t ring may start catching the chain when you are in the 36t ring and move to the smaller cogs on the cassette.

Sensera

I'll probably try and use a 38-53t chainring to a 42-11t. That'll probably work for what I want. It's a commuter road bike, but I have a lot of steep climbs, and usually it's not ideal to get very sweaty.

Bill Kapaun

Some details would be helpful. What's it on and the intended purpose.
There may be other issues such as chain stay clearance....

Then it may be a pipe dream thing--- higher gears make ME faster.

ThermionicScott 

My bad, OP just wants monster gearing to keep from getting sweaty. The gift keeps on giving.

Kapusta

You sure you want to fo down to a 53t? Your going to spin that out on the flats