2 extra teeth how much difference?

nedmoran

I have a shimano 12-25 cassette on my giant defy3. I've been doing a 20 mile circular route with a 1.2 mile hill and 13% gradient which i've been trying to crack without stopping on the way up it(currently stopping twice for less than a minute). I'll probably spend a fair few weekends in Keswick throughout the year so will be doing hills like Honister and the Kirkstone pass also. Only been riding since september, but not much with the weather(north east). Will it make much of a difference if i get a 12-27 cassette or should i just keep trying?

Buckled_Rims

You never mentioned if it's a standard or compact. But at a guess, yes you'll notice the difference. For example, I have standard with 12-27. I go on a hard, steep hill I use for training that I can just make in the 23 or 25 cog. But, if I'm really tired and I almost dead pedal on the 25 cog, then I click into the last resort 27 and that makes a huge world of difference.

You might even be able to use a 28 toothed cassette. Not sure what the defy gearing is, but I think there's been a few on here fitting it.

nedmoran

It's a compact. I'm not sure the difference between standard and compact. When i bought the bike it was in the shop with a triple on it, but they didn't have my size frame. So when that came it was with a compact. Didn't realise until i took it out.

Gizmodo

See this thread: viewtopic.php?f=40013&t=12909507&p=18186394

To answer your original question I liked this answer in that other thread

southdownswolf wrote:

It will give you an extra 8% lower gear for the hills.

To answer your 2nd question, Compact = 50/34, Standard double = 53/39 front teeth, usually anyway.

diy

You need to check if your rear derailleur can provide the extra capacity. If its a short cage it may not be able take up the slack. see http://home.earthlink.net/~mike.sherman/shift.html for details on the difference in speed etc

ugo.santalucia

a lot according to my dad... 2 extra veneer have transformed his eating habits.

I still have 32, so don't think 34 would make much difference TBH

Bobbinogs

nedmoran wrote:

Only been riding since september, but not much with the weather(north east).

There's the easy answer, ride more!

On a more constructive note, try thinking about why you are having to stop, is it because you need more power or is it because you are exploding? If it is the latter then you can do quite a lot which will help yourself without getting a lower gear. It is not possible to climb a long hill whilst in the 'max zone' the whole way so learn where that max level is for you so that you can identify it and back off to get the pacing right. Good climbing is often a combination of good bike handling at slow speeds, the right cadence (very personal), knowing the right gearing at the right time, when to stand or sit and spin and when to work harder/when to work less.

As an aside, I struggle at inclines of more than 20% because I don't weigh shed loads so the low weight combined with low gearing (big leverage) and weight distribution means that I lose traction at the back. Hence, I often have to go up a gear (and slow cadence) rather than down.

A cassette with a lower gear will always come in handy but try and beat that b'stard hill on your terms :twisted:

simon_e

Bobbinogs wrote:

nedmoran wrote:

Only been riding since september, but not much with the weather(north east).

There's the easy answer, ride more!

This makes a far bigger difference than anything you can buy. However, for steep climbs you can't beat having lower gears and 2 or 3 extra teeth at the low end will never be a disadvantage elsewhere.

The Defy 3 is 9 speed, I don't know of a 12-27 9sp cassette. You could try a Shimano HG80 11-28. All current and recent road mechs can handle up to 28 teeth, though you may want to check the chain is long enough when in the combination of big chainring and largest sprocket (info).

If you intend to fit it yourself you will need a cassette tool and chain whip.

Mikey23

50/34 and 11/28 is pretty standard and should get you up most things

nedmoran

Thanks everyone for the advice. Going to get the extra gears and get out more.

simon_e

Simon E wrote:

The Defy 3 is 9 speed, I don't know of a 12-27 9sp cassette.

Update - I have since found 12-27t Tiagra 9 speed cassettes at Dotbike and on ebay. Ultegra 9sp is available in 12-27, but it's quite a bit more expensive.

However, I'd go for the 11-28, you never know when you might be glad of that extra tooth

zx6man

Sora (I think thats on the defy3) quotes max rear at 27T.

NITR8s

When i first started riding my first bike had a standard with a 12-25 cassette, stupidly i signed up to the billed as easy but stupidly hilly Exmoor Beauty. I done the whole thing without walking any of the hills and swore from that day I needed more gears. So i went out and bought a new bike with a compact and upto 28t cassette.

Now I am a stronger cyclist i would go as far as saying I harderly ever go over the 25 (aside from copplestone/elsworthy hill) and infact recently picked up an old 10 speed bike and I am enjoying riding that around with a standard chainset. In fact on the club ride on sunday I did the whole ride in a 52/18t or 42/18t, just to see if I could.

Bottem line, just keep cycling you will be amazed how much easier it suddenly becomes.

simon_e

zx6man wrote:

Sora (I think thats on the defy3) quotes max rear at 27T.

I think that's for 3400, the previous version, and Shimano are conservative with their capacity, so you could surely run 28t with it.

The current one, 3500, is for rear sprocket size range 11-32T - in which case you could fit the Deore cassette with 32 teeth on the back.

nedmoran

Got a 12-27 and used it today. Done 30mile along an old roman road(straight line over all the hills,albeit quite small ones). Needed the 27 twice, but i was amazed that i was getting to the top of some of these hills still doing 20mph. I usually drop it into an easy gear at the bottom of a climb but today i let the bike take me down the hills while just ticking over and going up the gears. Then at the bottom i was keeping the cadence high and once going up hill i was gradually knocking it down as the resistance was creeping up. Don't think i could of kept it up for more than 15mile though.

blackpoolkev

I don't live near big hills so when I visit them I need the help of low gears.I ride Campag Athena(Chorus cassette) 12-29 with a compact chainset.I will soon have to replace my cassette.

Ribble cycles offer the 12-27 for £84 and the 12-29 for £103.

I will pay the extra for the luxury of the smaller gear.