Swapping cassette from 12-25 to 11-28

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Swapping cassette from 12-25 to 11-28

Postby Le Velo » Tue Dec 04, 2012 4:52 pm

No doubt this would've been asked many time but if I was to swap wheelset with a 12-25 cassette to a 11-28 will I need a longer chain??
I have tried to swap the wheels only and it seems the rear derailleur is a very extended position and it could do with some slack in it which the extra links on the chain will no doubt provide however if I was to change to the other wheelset then the chain would have a lot more slap particularly on the 12.
Anyone use different sets of wheel with different size cassettes and have overcome any issues that may arise

The reason I want a 11-28 is that I now prefer to climb on the big chainring and find it comfortable on the 28 if it has some gradient in it rather than spin on the smaller chainring ( I have 39-53) however will still use the small chainring if needed when it gets nasty ...... and put the 12-25 wheels for crits and some racing
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by BNA » Tue Dec 04, 2012 6:15 pm

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Re: Swapping cassette from 12-25 to 11-28

Postby DoogleDave » Tue Dec 04, 2012 6:15 pm

From what I have read, it will depend on how long your current chain is and whether the person that fit the chain installed the minimum length or left a couple of extra links on. From the fact that your derailleur is extended already suggests it isn't long enough.
Otherwise, as long as you don't use your 53/28 combo then you should be fine with the chain you have using any other gear combos - HOWEVER, as you have indicated you want to use the 53/28 combo it will probably need a longer chain.

Also worth noting, using your 39/21 gear should give you a very similar climbing gear to the 53/28 - and would also mean you could keep a straighter chain line (and use the current chain).

I'm currently awaiting my new 11-28 to be delivered (to try instead of my 11-25), so I'll be interested in what everyone else has to say.

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Re: Swapping cassette from 12-25 to 11-28

Postby Le Velo » Tue Dec 04, 2012 6:20 pm

DoogleDave wrote:From what I have read, it will depend on how long your current chain is and whether the person that fit the chain installed the minimum length or left a couple of extra links on. From the fact that your derailleur is extended already suggests it isn't long enough.
Otherwise, as long as you don't use your 53/28 combo then you should be fine with the chain you have using any other gear combos - HOWEVER, as you have indicated you want to use the 53/28 combo it will probably need a longer chain.

Also worth noting, using your 39/21 gear should give you a very similar climbing gear to the 53/28 - and would also mean you could keep a straighter chain line (and use the current chain).

I'm currently awaiting my new 11-28 to be delivered (to try instead of my 11-25), so I'll be interested in what everyone else has to say.

Dave


Thanks Dave, I think the current chain is already at it's minimum from what I can see however good point about the gearing alternative might try that but I usually prefer to mash than spin :oops: and have recorded better climbing times on the 53 than 39 ..... maybe my climbing technique needs reviewing rather than a new cassette .... but that's another topic
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Re: Swapping cassette from 12-25 to 11-28

Postby toolonglegs » Tue Dec 04, 2012 6:29 pm

Unless your rear mech is really on a forward angle it should be fine. I run the same length chain for 11-23 as I do for 11-28 IIRC but I do run two seperate chains so they wear as pairs.
Heck I run the same length chain when I chuck the compact on ( 39 to 34 )...but the little chain ring and bottom 3 cogs are getting a bit sloppy :lol: ... does the job just fine though.

BTW cross chain I have no problems with... but 53/28 combo will certainly be robbing you off a fair few watts in chain drag... I prefer to keep my chain line a little bit straighter.
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Re: Swapping cassette from 12-25 to 11-28

Postby slian » Wed Dec 05, 2012 12:21 pm

Another newbie question as I'm in the same situation. If your chain is too short, is it a matter of adding link or do u need a new longer chain?
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Re: Swapping cassette from 12-25 to 11-28

Postby scirocco » Wed Dec 05, 2012 2:38 pm

You could insert extra links if you had them (plus the joining pins and a chain tool). But where are you going to get them from? You can only buy whole chains. Unless you have some left over from another chain or you can beg steal or borrow some from somewhere you are out of luck.
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Re: Swapping cassette from 12-25 to 11-28

Postby Le Velo » Mon Dec 10, 2012 2:55 pm

Well the new cycleops wheelset has arrived and decided to throw the 12-25 I had from the other training wheels.
Went up Mount Glorious yesterday and used the 39-23 most of the way but half way through glorious jumped on the 25 as the legs were starting to burn a bit.
Managed a descent 1h19min for the climb (29.9km total) from the Bus depot to the coffee shop of Glorious (Only 15min behind the KOM) and happy with that so based on this I won't even bother with a 28 (Unless I plan to ride the Alps)
Now to learn the fascinating side of training / riding with a powermeter and put the data to good use (On a note I did 3.4W/kg (AT) FTP - 60min) :)
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Re: Swapping cassette from 12-25 to 11-28

Postby hotshod » Tue Dec 18, 2012 5:57 pm

Before you get too involved you need to STUDY a gear inch chart.

From such a chart you'll soon discover that the gears you wish for ie 53:28 is replicated in other ratios that won't cause you to run an extreme chain cross...... I know bikes can do it , but in the good ol days you never ran extreme crossover to your 2 highest or 2 lowest gears ..... Absolutely no need unless you deliberately want to wear out your gear train unnecessarily...... and that was running 6 or 7 speed clusters .... Even less need with modern 10 & 11 speed cassettes.

I see it everyday done by cyclists who think they are experts and can't be told otherwise...... particularly Sm chainring running to 13:12:11..... they need lessons , ah forgot , they' re experts been riding for years.
Yes but refer to the Gear Inch chart ..... all will be revealed !!!!!

I appreciate you no longer need an answer to the 53:28 problem ...... But 53:25 is just as wrong .... No Need.
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Re: Swapping cassette from 12-25 to 11-28

Postby DoogleDave » Tue Dec 18, 2012 7:04 pm

Looking at Sheldon Brown's calculator, running a 50/34 chainring setup with a 11/28 cassette you'd have the following gear inches (in order of shortest to longest):

34/28 - 31.9"
34/24 - 37.2"
34/21 - 42.5"
50/28 - 46.9"
34/19 - 47.0"
34/17 - 52.6"
50/24 - 54.8"
34/15 - 59.6"
50/21 - 62.6"
34/14 - 63.8"
34/13 - 68.7"
50/19 - 69.2"
34/12 - 74.5"
50/17 - 77.3"
34/11 - 81.2"
50/15 - 87.6"
50/14 - 93.9"
50/13 - 101.1"
50/12 - 109.5"
50/11 - 119.5"

But in reality you wouldn't ride your bike and jump back and forth between large and small chain ring so you'd more than likely run this scenario:

34/28 - 31.9"
34/24 - 37.2"
34/21 - 42.5"
34/19 - 47.0"
34/17 - 52.6"
34/15 - 59.6"
(then change up to large chain ring and downshift two rear sprockets and continue...)
50/19 - 69.2"
50/17 - 77.3"
50/15 - 87.6"
50/14 - 93.9"
50/13 - 101.1"
50/12 - 109.5"
50/11 - 119.5"

These give slightly larger jumps between gears compared to the theoretical shortest to longest gear-inches list, but would be much easier shift-wise....and never crosses the chain too much or uses the extremes High-High or Low-Low.

I know when I'm riding I usually adjust my rear my two sprockets (up or down) and change the front chain ring accordingly to maintain a "similar" gear.

Also, as suggested by hotshod, if you need to ride at the extremes then you have other alternatives you can choose from which give similar gear-inches:
34/11 or 50/15 (or 17)
34/12 or 50/17
50/28 or 34/19
50/24 or 34/17

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Re: Swapping cassette from 12-25 to 11-28

Postby toolonglegs » Tue Dec 18, 2012 7:21 pm

I am running a 46 big ring at the moment... the jump between 11 & 12 is huge. I can now see why Tony Martin runs a 58 big ring in TT's... makes the jumps between gears tiny :lol: .
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