Choosing between 12-26 or 12-28 cassette

sully1001

Hi,

I am buying a new Ultegra compact groupset. I have a choice of a short derailleur and getting a 12-26 cassette or going for a long derailleur and getting a 12-28 cassette. The chainset is a 50-34T.

I want a low gear for those hard hills in wicklow etc but would the 12-26 cassette suffice. My knees are not great ( old football injuries) so do not want to be mashing on the steep hills.

Any advice would be appreciated. Is there any draw back on going for long rear mech?

Many thanks in advance.

Lumen

If your knees are crap then I'd go for a 28.

But then I'm a triple-chainring pansy so I would say that.

Chips Lovell

You won't be mashing at 34/26, it's a very easy gear for Wicklow. I'd say it's more than enough.

niceonetom

I've used a 12-27 cassette with a short cage derailleur. I don't think there's any need for a long cage unless you're using a triple.

Two teeth won't make a huge amount of difference, 26 is plenty to get you around wicklow, but if you want to be very very nice to your knees you can go 28. You'll be replacing the cassette after a few thousand km anyway so it's no big deal. Most of us experiment a bit before finding the ratios that suit best. I like 11-25.

rob1891

Specialized spec short cage derailleurs on their compact+27t/28t bikes. Between them and Tom, you can't go wrong :-)

scottreynolds

Lumen wrote: »

If your knees are crap then I'd go for a 28.

+1. I agree with everyone else that 12-25/7 is enough for wicklow but if your knees are really really crap 12-28 makes sense. TBH, 12-28 might be better anyway, I'm not sure you would miss it.

Lumen wrote: »

But then I'm a triple-chainring pansy so I would say that.

You could be the worlds only triple-chaino pansy with a power meter. Shame.

tunney

sully1001 wrote: »

Hi,

I am buying a new Ultegra compact groupset. I have a choice of a short derailleur and getting a 12-26 cassette or going for a long derailleur and getting a 12-28 cassette. The chainset is a 50-34T.

I want a low gear for those hard hills in wicklow etc but would the 12-26 cassette suffice. My knees are not great ( old football injuries) so do not want to be mashing on the steep hills.

Any advice would be appreciated. Is there any draw back on going for long rear mech?

Many thanks in advance.

34x28

Seriously, a 34x28 for anywhere outside the most brutal stages of the Giro is uncalled for. I think even Tiny, Lumen and the rest of the Pink Posse would think that it is excessive.

That being said you can always swap the 28 for something more sensible at a later stage. The gearing on a 28 will be a big on the flats, jumping all over the place.

Lumen

tunney wrote: »

Seriously, a 34x28 for anywhere outside the most brutal stages of the Giro is uncalled for. I think even Tiny, Lumen and the rest of the Pink Posse would think that it is excessive.

Sorry Tunney, I use a 30x27. Not a lot, but there are times.

Say, for instance you're doing a recovery spin over the Wicklow mountains and want to keep power at around 50% threshold.

If you're Tunney, that might be 180W. So you hit a 10% incline with a 20kph headwind. You might be 70kg with a 9kg bike. According to my calculator, that's 6.56kph on the hoods.

In a 34x28 gear that's about 45rpm, which annoys you (not to mention the speed).

Now being a hard mo-fo, you just power up that hill at 360W (threshold) doing 12.32kph at about 80rpm.

Congratulations, you've just turned a recovery spin into a hillclimb TT.

OK, so you don't do too much riding up 10% inclines with a 20kph headwind, but it's not hard to see why for us mortals with recreational power outputs, more and lower gears are good.

Gavin

Lumen wrote: »

Sorry Tunney, I use a 30x27. Not a lot, but there are times.

Say, for instance you're doing a recovery spin over the Wicklow mountains and want to keep power at around 50% threshold.

If you're Tunney, that might be 180W. So you hit a 10% incline with a 20kph headwind. You might be 70kg with a 9kg bike. According to my calculator, that's 6.56kph on the hoods.

In a 34x28 gear that's about 45rpm, which annoys you (not to mention the speed).

Now being a hard mo-fo, you just power up that hill at 360W (threshold) doing 12.32kph at about 80rpm.

Congratulations, you've just turned a recovery spin into a hillclimb TT.

OK, so you don't do too much riding up 10% inclines with a 20kph headwind, but it's not hard to see why for us mortals with recreational power outputs, more and lower gears are good.

Pansy.

uberwolf

Lumen wrote: »

Say, for instance you're doing a recovery spin over the Wicklow mountains and want to keep power at around 50% threshold.

Some would consider appropriate route selection better

OP, get the wider one, give yourself every opportunity, and you can replace it if you don't use it, rather than replacing it when you knees are even more knackered.

victorcarrera

12/13/14/15/16/17/19/21/23/25 - 262g
12/13/14/15/17/19/21/23/25/28 - 291g

If you were me you would go for the 12-28. See above they are practically identical except for the pain killer 28 which is always handy to have in case you bonk on a long spin or want to enjoy the scenery on the odd 20% gradient. Unless you intend to do Time Trials on flat courses or cycle predominantly on the flat you wont need the close ratio. Effectively its a choice between 16 or 28. There may be other combinations.

Raam

Lumen wrote: »

Say, for instance you're doing a recovery spin over the Wicklow mountains and want to keep power at around 50% threshold.

Lumen wrote: »

Congratulations, you've just turned a recovery spin into a hillclimb TT.

Why would you do a recovery spin over the Wicklow Mountains?

Lumen

Raam wrote: »

Why would you do a recovery spin over the Wicklow Mountains?

Why wouldn't you? Quiet roads, nice scenery, fun descents.

tunney

Lumen wrote: »

Sorry Tunney, I use a 30x27. Not a lot, but there are times.

Say, for instance you're doing a recovery spin over the Wicklow mountains and want to keep power at around 50% threshold.

If you're Tunney, that might be 180W. So you hit a 10% incline with a 20kph headwind. You might be 70kg with a 9kg bike. According to my calculator, that's 6.56kph on the hoods.

In a 34x28 gear that's about 45rpm, which annoys you (not to mention the speed).

Now being a hard mo-fo, you just power up that hill at 360W (threshold) doing 12.32kph at about 80rpm.

Congratulations, you've just turned a recovery spin into a hillclimb TT.

OK, so you don't do too much riding up 10% inclines with a 20kph headwind, but it's not hard to see why for us mortals with recreational power outputs, more and lower gears are good.

I do see the advantages of a compact, and I definitely see the advantages of 27+ on the back. I ride a 27 when going very hilly (albeit not in Ireland).

(come on by this stage you know I am obliged to say something about triples, compacts and 27s, much as you are obliged to defend them)

On a more serious note - why do recovery rides over hills? I can't imagine, in any gearing, going up a reasonable hill at less than 50% threshold wattage. Assuming a reasonable power/weight of 4.5w/kg that would be 2.25w/kg - i'm not getting up anything at 2.25w/kg - I'm barely moving on the flats at that. There is no why 2.25w/kg would get you up a 10% climb even without a headwind.

Doesn't matter if you grind out the recovery at 40rpm in a 39x25 or spin it at 80rpm - its still going to be 6.56kph regardless. I think I'd fall off my bike at those speeds.

To summise: I don't think a 10% climb can be done at 50% threshold power unless your threshold power is greater than 6w/kg.

(yet another thread hijacked by this topic)

Can we leave this till the morning - I'm imagining tomorrow is going to be a slow day in work and would appreciate a good online argument. perhaps you could start a thread that is *going* to rise pople about 1045 tomorrow?

Raam

Lumen wrote: »

Why wouldn't you? Quiet roads, nice scenery, fun descents.

I think you answered that earlier yourself

Raam

tunney wrote: »

would appreciate a good online argument.

OK, here goes... you race like a girl. Oh no wait, you race WITH the girls!

uberwolf

folks, for the love of God. Somebody start a general chat thread, and leave these ones alone

Lumen

tunney wrote: »

To summise: I don't think a 10% climb can be done at 50% threshold power unless your threshold power is greater than 6w/kg

To summise: I agree with you, but a triple and 12-17 allows my paltry 3.something W/kg to wander around the hills with a reasonable choice of cadence and effort level.

Obviously I'm going to switch to a double at the next opportunity, because only girls and old men on delivery bikes need that many gears.

edit: sorry Uberwolf, I'll shut up now.

Home:Ballyhoura

tunney wrote: »

Doesn't matter if you grind out the recovery at 40rpm in a 39x25 or spin it at 80rpm

Are recovery rides supposed to be at a high/fast or low/slow cadence? Say I have an average cadence usually of 97-100RPM, could anyone reccomend a good cadence to spin at when on my recovery rides? Cheers

TinyExplosions

tunney wrote: »

34x28Seriously, a 34x28 for anywhere outside the most brutal stages of the Giro is uncalled for. I think even Tiny, Lumen and the rest of the Pink Posse would think that it is excessive.

Agreed, I have a 25 and a compact on atm and it's perfectly fine for all Wicklow has to offer (and Mount Leinster!), though I will stick a 27 on for the Marmotte, but that's cos I'm a fat bar steward. Even if you're starting out, I think a 12-27 and a compact is fine for everyone

Lumen wrote: »

Sorry Tunney, I use a 30x27. Not a lot, but there are times.

It's been said above, but I'll repeat. wimp

victorcarrera wrote: »

12/13/14/15/16/17/19/21/23/25 - 262g
12/13/14/15/17/19/21/23/25/28 - 291g

If you were me you would go for the 12-28. See above they are practically identical except for the pain killer 28 which is always handy to have in case you bonk on a long spin or want to enjoy the scenery on the odd 20% gradient. Unless you intend to do Time Trials on flat courses or cycle predominantly on the flat you wont need the close ratio. Effectively its a choice between 16 or 28. There may be other combinations.

Save the 29g and go for the 25 -that's a lot of weight, and every gramme saved means quicker up the hill

Raam wrote: »

OK, here goes... you race like a girl. Oh no wait, you race WITH the girls!

He only races girls, that's how he's so good. He also wears tiny outfits while doing it I bet

Lumen

Home:Ballyhoura wrote: »

Are recovery rides supposed to be at a high/fast or low/slow cadence? Say I have an average cadence usually of 97-100RPM, could anyone reccomend a good cadence to spin at when on my recovery rides? Cheers

Recovery just means low training stress. Spin at whatever is comfortable.

ISTR that you did a 100km recovery spin in the Wicklow mountains a week or so ago, which is obviously crazy