Which size chainring ?

smiggyontour

Hoping someone can give me some advice
Im about to buy a new bike which I hope to do some club league racing on.
But Im not sure which crank set /cassette combination to go for
I want to race it on a standard double 11-25 but I don’t think I will be able to get over the Dublin and Wicklow mountains without a compact and a 12-28 cassette which I have now
The bike comes with option of double with an 11/28 cassette.
Would this be killing two birds with the one stone or a waste of time ?
Is it possible to swap a double with a compact for hillier rides without changing chain length and derailleur position ?
Would I notice a big difference on hillier climbs between a compact and double using a 11-28 cassette on both

Thanks in advance
Mark

mistermatthew

smiggyontour wrote: »

Hoping someone can give me some advice
Im about to buy a new bike which I hope to do some club league racing on.
But Im not sure which crank set /cassette combination to go for
I want to race it on a standard double 11-25 but I don’t think I will be able to get over the Dublin and Wicklow mountains without a compact and a 12-28 cassette which I have now
The bike comes with option of double with an 11/28 cassette.
Would this be killing two birds with the one stone or a waste of time ?
Is it possible to swap a double with a compact for hillier rides without changing chain length and derailleur position ?
Would I notice a big difference on hillier climbs between a compact and double using a 11-28 cassette on both

Thanks in advance
Mark

If you fit a standard with a 11-25 ur lowest climbing gear is equivelant near enough to riding in ur 34-21 now, can you climb the hills in this gear?

A 11-28 will give a climbing gear equivalent to around a 34-24, could you climb on this? That cassete may be a bit gappy.

And as for club racing, I race on a 50-13 high gear i club racing. A 50-13 will give you 48.4kph at 100rpm and if you had a 50-11 you'd get 57.2kph at 100rpm, more than enough for club racing I believe

Slo_Rida

As someone who has now tried sportives, league races and open races, and someone who climbs like a stone, I can say I have used a compact crank set (50/34) and a girly 28/11 cassette in all 3 and it won't let you down in terms of top speed and bottom gear. A 50-11 or 50-12 combination is fine for racing (unless you're a monster descender) and 34-28 will get you up any hill.

The drawback will be the jump between sprockets. Again though, not an issue even in open races.

Slo

brasshead

smiggyontour wrote: »

Hoping someone can give me some advice
Im about to buy a new bike which I hope to do some club league racing on.
But Im not sure which crank set /cassette combination to go for
I want to race it on a standard double 11-25 but I don’t think I will be able to get over the Dublin and Wicklow mountains without a compact and a 12-28 cassette which I have now
The bike comes with option of double with an 11/28 cassette.
Would this be killing two birds with the one stone or a waste of time ?
Is it possible to swap a double with a compact for hillier rides without changing chain length and derailleur position ?
Would I notice a big difference on hillier climbs between a compact and double using a 11-28 cassette on both

Thanks in advance
Mark

I ran a double with 28/11 on the back and had no difficulty doing the Wicklow 200 last year and comfortably getting up the climbs. The crank went before Christmas on a training spin so I had to quickly replace it with a compact - I don't tend to go below the 21/24 on the cassette when in the small ring and because of this I find the gearing on hills similar to the double in terms of difficulty. You can swap the double for a compact depending on the terrain.

I think it's possible to manage Wicklow on a double with 11/25 but as ever it depends on fitness/climbing ability etc.

macnab

Your current set-up of a Compact double 50/34 and 12-28 in the easiest gear, ie 34 front and 28 rear, has a ratio of 1.21:1, so for every 1 rotation of the crank the wheel will turn 1.21 times.

Consider the following ratios for the lowest gearing,

Compact double 12-28: ratio of 1.21:1, current set-up.

Standard double 11-25: ratio of 39:25 which is 1.56:1, that is close to 34 front and 22 rear in your current set-up.

Standard double 11-28 cassette: ratio of 1.39:1, that is close to 34 front and 25 rear, though a little harder than 25.

I have a compact double on my bike and I know I would not like to tackle too many hills in a 22 ring (actually there is no 22, so its 21 or 23) I do actually have a Dura-ace 11-23 but I have only used it a couple of times as its too much work on the hills.

As for changing the crank-set for different races, its possible, the chain length should not be an issue but even then you could use a 2nd chain with power links. The front dérailleur might need to be lowered and raised to accommodate the 52 or 50 front chainring.

Slo_Rida

The question in the OP in a nutshell is can the OP manage The Wicklow 200 and a league race with the same setup and my answer is yes, once it's the 50/34 and 28/11. A 23/11 would ease any doubts for the racing if you had any. And it's very easy change cassette.

rab!dmonkey

My advice would be to take the compact crank with an 11-28 for your sportives and training. If you find that you are sensitive to the gaps in the cassette, you can easily swap the cassette out for an 11-23 as required. I wouldn't take a cassette with a 12t high end in combination with a compact chainset - a one tooth difference is quite a lot at that end of the cassette.

Try comparing the different set-ups on http://gear-calculator.com or http://home.earthlink.net/~mike.sherman/shift.html.

harringtonp

Definitely sounds like compact and 11-28 is what you need. Raced on this last year and never felt ran out of gears when the speed was high.

Guys talk about the jump in gears being bigger on a 11-28 than a 11-25. True but it is only the bottom 3 that usually differ: 21-24-28 instead of 21-23-25, others are the same 11-12-13-14-15-17-19. And when you get to the really low gears the hill is usually steep enough that your cadence is all over the place.

smiggyontour

Thanks for all the reply Lads thats helped me decide what to go for

dermabrasion

Compact with a range of cassettes is the most pragmatic solution for Ireland. I don't have one! I have a BBright and its too expensive for me to change, so I have a wiFli set up on the rear mech.
I also think this is personal determined by your max power at your cadence sweet spot. Like some in the A4 herd, I am a 85(+/-nkg). For me to keep up on long drags, I have to spin fast at a gear that does not make me blow up, relying on fitness and the top of the hill to show up. That is 80-85rpm for me. Then the gradient comes into play to determine which gear I can keep this cadence at FTP. If the skinnies are going faster, I am dropped.
So this is my set up.
I run a standard at the front: 53-39:
Flattish League races / North Dublin open races: 11-26T
Races with cat 3 4-8% 11-28T
Races with cat 3 and sharp (e.g 10%) climbs 11-32

smiggyontour

dermabrasion wrote: »

Compact with a range of cassettes is the most pragmatic solution for Ireland. I don't have one! I have a BBright and its too expensive for me to change, so I have a wiFli set up on the rear mech.
I also think this is personal determined by your max power at your cadence sweet spot. Like some in the A4 herd, I am a 85(+/-nkg). For me to keep up on long drags, I have to spin fast at a gear that does not make me blow up, relying on fitness and the top of the hill to show up. That is 80-85rpm for me. Then the gradient comes into play to determine which gear I can keep this cadence at FTP. If the skinnies are going faster, I am dropped.
So this is my set up.
I run a standard at the front: 53-39:
Flattish League races / North Dublin open races: 11-26T
Races with cat 3 4-8% 11-28T
Races with cat 3 and sharp (e.g 10%) climbs 11-32

Thanks for that dermabrasion
Is it as simple as swapping out the cassettes or do you have to change chain length and move derailleur position ?

cdaly_

It's pretty much just swapping over cassettes (assuming they're both 10sp or whatever). Set up your chain for the biggest sprocket and you'll be fine otherwise.

That said, chains wear into cassettes (and vice versa) so, unless you're swapping cassettes over frequently, you might be better keeping a chain/cassette pair together and swapping over both as desired. Re-useable power links are the thing here...

smiggyontour

cdaly_ wrote: »

It's pretty much just swapping over cassettes (assuming they're both 10sp or whatever). Set up your chain for the biggest sprocket and you'll be fine otherwise.

That said, chains wear into cassettes (and vice versa) so, unless you're swapping cassettes over frequently, you might be better keeping a chain/cassette pair together and swapping over both as desired. Re-useable power links are the thing here...

Sound thanks for that cdaly

Wishbone Ash

harringtonp wrote: »

Definitely sounds like compact and 11-28 is what you need. Raced on this last year and never felt ran out of gears when the speed was high.

Guys talk about the jump in gears being bigger on a 11-28 than a 11-25. True but it is only the bottom 3 that usually differ: 21-24-28 instead of 21-23-25, others are the same 11-12-13-14-15-17-19. And when you get to the really low gears the hill is usually steep enough that your cadence is all over the place.

It's normally 23/25/28 in any 28/11 cassette I've had.

quozl

To further confuse things, SRAM ten speed 11-28 are 22-25-28

Harringtonp's point stands though - it's probably just the last 3 gears that have differences between a 11-25 and a 11-28