Chainring limits?

[fabs]

Hello Everyone.

 

I have just changed to a compact chainring setup.

I had a 52/39 and now have a 50/34

 

Is it possible to mix and match chainrings,

so I would have a 52/34 in future?

What are the considerations to evaluate?

 

I'm doing it to have more downhill speed and greater climbing ability.

Does it make sense?

 

Thank you.

[urbanroyal]

I think your chainrings BCD comes into play here...unless you have the new Shimano cranks that can take both compact as well as standard chainrings.

[Barend de Arend]

Limit is set by the FD (look for "capacity" of your FD) This will be something like "16 T"

 

I think the biggest spread will be 52x36. (52 - 36 = 16)

 

You can go beyond the limit, but the effectiveness depends a bit on:

- length of chainstays (how skew will the chain be?)

- shift ramps on the rings themselves. If these don't work shifting is possible, but will grind more.

- how much you can adjust your FD up/down, and if you can put a washer between the FD and hanger to move it further back.

 

If you've got the rings already, I say try it.

Edited September 16, 2013 by Barend de Arend

[JA-Q001]

For interest, what cluster ratio are you running?

[fabs]

A standard 23/11

[Tankman]

I think your chainrings BCD comes into play here...unless you have the new Shimano cranks that can take both compact as well as standard chainrings.

 

That is correct

 

Compact Crank = 110mm BCD with 50/34 chainrings normally

Standard Crank = 130mm BCD with 53/39 chainrings normally

 

Then new Ultegra cranks has a 110mm BCD with the option of either 50/34 or 53/39.

 

Fabs, if you want a 52/34 setup, it is possible on a compact crank.

Just buy a 52 chainring blade with 110mm BCD.

FSA makes them.

[gummibear]

With the new Shimano Ultegra you have 46/36, 50/34, 52/36, 53/39 to choose from and you can mix an match

[Pure Savage]

Why not use a 28-11 at the rear?

[Tankman]

Why not use a 28-11 at the rear?

 

He wants to go faster, thats why a bigger chainring 52

 

Do you have any idea how crazy you spin in 34 28 ... without actually going anywhere?

 

Plus on a compact crank, you want compact gearing. On a 11/28 the gaps between the gears are greater and you battle to find that comfortable cadence you are looking for

[Pure Savage]

 

He wants to go faster, thats why a bigger chainring 52

 

Do you have any idea how crazy you spin in 34 28 ... without actually going anywhere?

 

Plus on a compact crank, you want compact gearing. On a 11/28 the gaps between the gears are greater and you battle to find that comfortable cadence you are looking for

 

Sorry, meant to say instead of compact crank.

 

Guess the compact gearing makes more sense.

Different strokes for different folks.

 

But compact with 52 will give best of both, makes sense.

 

For interest sake, what does ratio does Froome run?

[Tankman]

Sorry, meant to say instead of compact crank.

 

Guess the compact gearing makes more sense.

Different strokes for different folks.

 

But compact with 52 will give best of both, makes sense.

 

For interest sake, what does ratio does Froome run?

 

Different stokes for different folks for sure.

I tried, I really did but compact just does not work for me.

 

Had 53/39 for as long as I remember.

Decides to try 50/34, that lasted a week, quickly went to 52/36 and that lasted about a month.

52/36 with 11/23 was much better than 50/34. I just could not get up to speed and it felt like I was never going to get into such a high spinning cadence in 34 - 23.

 

Moved over to rotor rings 54/40 with 11/25 and felt puuuuurfect ever since! Those have been on for about three years now. Only sad thing is that I need to replace them soon, their time has come.

 

Oh yea, Froome doesnt run!

Edited September 16, 2013 by Tankman

[Cippo]

Hi-jack. If you change from compact to standard do you need to increase chain length or is it negligible? Btw, a 34/23 is similiar to a 39/27.

[Tankman]

Btw, a 34/23 is similiar to a 39/27.

 

But a 34/28 (31) is nothing close to a 39/27 (37.9)

You do not need anything more than a 11/23 on a 50/34 compact crankset.

If you need a 11/27 or 11/28 on a standard crankset, then you most probably need a compact crankset!

 

50/11 (119.7) is also close to 53/12 (116.2)

[fabs]

Thanks for your help Tankman

[Cippo]

 

 

But a 34/28 (31) is nothing close to a 39/27 (37.9)

You do not need anything more than a 11/23 on a 50/34 compact crankset.

If you need a 11/27 or 11/28 on a standard crankset, then you most probably need a compact crankset!

 

50/11 (119.7) is also close to 53/12 (116.2)

 

Thanks for the advice. I had a standard on my previous bike with a 27 at the rear. I seldomly went pass the 25. I have a 11/23 with the compact but am changing to a standard with hopefully a 12/27 (11spd).

[8_Mad]

With the new Shimano Ultegra you have 46/36, 50/34, 52/36, 53/39 to choose from and you can mix an match

 

Is this also the case with Shimano 105 5700? I am currently using a standard crank and would like to know what are the implication of converting it to a 50-34 compact crank?