Road bike cluster choice

[marshace]

Hi Hubbers

 

Need some advise, run a 9 speed Dura Ace system and as I am getting older and spending more time on mtb maybe, am looking for more cadence on the climbs.

 

Currently 53/39 std cranck up front and 11-25 at the back.

Rear derialeur S Dura Ace 7700 (9 spd)

 

Question:

Do I go for 12-27 road bike cluster or will 11-28 mtb cluster work and give me a bit extra on the climb without sacrificing the 11 at the bottom ?

 

Sure next option is to compact up front but thats costly.

 

Your comments please.

[LOOK695]

Try 12-27. Will make it easier on the climbs. Not sure whether mtb cluster will work?

[cwisking]

I ordered an 11-28 off crc and love it. lets me spin up some hills when i have wobbly legs.

[marshace]

Thanks for replies, much appreciated.

[marshace]

I ordered an 11-28 off crc and love it. lets me spin up some hills when i have wobbly legs.

Thanks, what rear de raileur are you running ?

I have oldish Dura Ace 7700 and an concerned whether it will take 28 ?

Have a shot mtb cluster with 28 ring and I was thinking I will take appart and slip the 28 ring on and check if de raileur has sufficient "reach" or what ever you would call it.

Do you think it will work ?

Cheers

Eric

[droo]

From Shimano's spec sheet (here), the capacity of a 7700 RD is 26t.

 

To work out the range of your setup:

 

front difference + rear difference

= (big blade - small blade) + (big sprocket - small sprocket)

 

So for your setup:

 

= (53 - 39) + (27 - 12)

= 14 + 15

= 29

 

So you're (technically) out of range. BUT if you promise to good and not cross chain (avoid the biggest 2 sprockets in the big blade, and smallest 2 in small blade) you'll get away with it no problem. Just make sure your chain's long enough to deal with the big/big combo in case of unintentional overshifting.

[marshace]

From Shimano's spec sheet (here), the capacity of a 7700 RD is 26t.

 

To work out the range of your setup:

 

front difference + rear difference

= (big blade - small blade) + (big sprocket - small sprocket)

 

So for your setup:

 

= (53 - 39) + (27 - 12)

= 14 + 15

= 29

 

So you're (technically) out of range. BUT if you promise to good and not cross chain (avoid the biggest 2 sprockets in the big blade, and smallest 2 in small blade) you'll get away with it no problem. Just make sure your chain's long enough to deal with the big/big combo in case of unintentional overshifting.

 

Thanks for great reply and explantion.

Much appreciated.

Eric

[EZRider]

I put a 11-28 ultegra cluster which works great with my standard derailleur, granted it's 10 speed. Just had to set the limits a bit and adjust the barrel away from the cluster.

I also run a compact on the front but I live in Tzaneen so every way I go is up!

[Eugene]

From Shimano's spec sheet (here), the capacity of a 7700 RD is 26t.

 

To work out the range of your setup:

 

front difference + rear difference

= (big blade - small blade) + (big sprocket - small sprocket)

 

So for your setup:

 

= (53 - 39) + (27 - 12)

= 14 + 15

= 29

 

 

I’m not a mathematician, but there is no way that formula can be right.

 

Consider my personal situation as an example. I bought a bike with a 25-12 cassette and 53-39 crank. This formula shows the largest sprocket I can run is a 27. I have fitted a 28-12 and it works fine. The 28 tooth sprocket is one tooth more than the range.

 

Now, lets do the same calculation with the 28-12 cassette. The formula now shows the maximum sprocket size to be 30. My 28 tooth sprocket is now 2 teeth within the range.

 

Also, one of the rear derailleur’s job is to take up the slack of the chain as it moves between the range of gears. There is more than just the largest sprocket to consider.

[Minion]

Consider my personal situation as an example. I bought a bike with a 25-12 cassette and 53-39 crank. This formula shows the largest sprocket I can run is a 27. I have fitted a 28-12 and it works fine. The 28 tooth sprocket is one tooth more than the range.

The formula doesn't directly tell you the largest sprocket you can run. It gives the size of your gear range. You need to compare this to your derailleur capacity to get the maximum sprocket you can use.

[droo]

I’m not a mathematician, but there is no way that formula can be right.

 

Consider my personal situation as an example. I bought a bike with a 25-12 cassette and 53-39 crank. This formula shows the largest sprocket I can run is a 27. I have fitted a 28-12 and it works fine. The 28 tooth sprocket is one tooth more than the range.

 

Now, lets do the same calculation with the 28-12 cassette. The formula now shows the maximum sprocket size to be 30. My 28 tooth sprocket is now 2 teeth within the range.

 

Also, one of the rear derailleur’s job is to take up the slack of the chain as it moves between the range of gears. There is more than just the largest sprocket to consider.

 

This formula doesn't determine the maximum sprocket size, but rather the range of your specific gearing combination. If it's within the range specified on your derailleur's spec sheet, you're ok.

 

Maximum sprocket size is a function of the centre-to-centre distance from the top idler pulley to the hub, and is also on the derailleur spec sheet.

[BLACKvoodoo]

Which cluster ?....... Always Peanut choc cluster, BTW never buy a road bike.