What size small ring can I use with a 53 big ring?

Jackle

As per subject really.
I'm currently on a 39/53 chainset with a 12/27 cassette, most of the time this is absolutely fine. But occasionally I really struggle getting my 15st self up some of the more steep climbs.
I can't really afford to go for a complete compact chainset, so was thinking about just changing out the small ring for a slightly smaller one, question is how small can I get away with?

morxy

What's your front derailleur? Let's assume it's a Shimano Tiagra 4500. See the capacity measurement? It says 16T. That means it can tolerate a difference of 16 teeth between your smallest and largest chainrings. E.g. it can work with a compact 34/50 or, in your case, a 53/37. (Can you get a 37T chainring?).

Also be mindful of your rear derailleur's total capacity. Mine is 29T.

The capacity you need is the difference between your chainrings plus the difference between the extreme sprockets of your cassette. E.g. I run 39/53 and 12/25 so my "capacity" is (53 - 39) + (25 - 12) = 27T. This falls within the tolerance of my rear derailleur's 29 tooth total capacity. I could in theory run a 12-27 cassette (or 11-26) and it would still be ok.

Shimano's newer groupset versions (e.g. 105/5700 compared to the older 105/5600) generally have larger capacities these days to tolerate a larger range of gears.

SRAM make 11-28 cassettes. Give them a thought. One extra tooth can make a difference.

nmcgann

The smallest inner ring that will fit on a Shimano standard chainset (130mm BCD) is 38T. This probably won't make a worthwhile difference over a standard 39T ring.

You can find a 34/50 compact chainset for £60-ish if you shop around (e.g. Tiagra 4550 at Parkers) and if you already have a modern-spec bike with a Hollowtech 2 chainset it's a very easy swap with no need to change the BB.

newburb_1968

Just to jump on board on this question.
If I was running a Double where it is quite flat, and I am going to switch terrain full of hills for a weekend or few days away.
How easy is it to switch over the chainrings to a 50/34? Easy/med/hard?
Also I may has well ask if I had 105's double chainring would it be able to fit a compact rings on this?

Sorry for hijacking your question, but I am also thinking along the same length. Thinking I could just change a inner ring from 39 to a 34 and it would make no difference, however it does by what has been said?
Thanks

micken

Newburb_1968 wrote:

Just to jump on board on this question.
If I was running a Double where it is quite flat, and I am going to switch terrain full of hills for a weekend or few days away.
How easy is it to switch over the chainrings to a 50/34? Easy/med/hard?
Also I may has well ask if I had 105's double chainring would it be able to fit a compact rings on this?

Sorry for hijacking your question, but I am also thinking along the same length. Thinking I could just change a inner ring from 39 to a 34 and it would make no difference, however it does by what has been said?
Thanks

You need to change the chainset from double to compact because of the differences in fit of the chainring bolts between double and compact cranks. Compacts have a smaller bolt circle diameter of 110 BCD compared with doubles at 130 BCD.

That is the point that nmcgann was making.

Rule74Please

Not that long ago 39/27 was as low as you could go without fitting a girly triple.

Just ride more and you will get more POWERFUL. All you need for a day in the alps climbing cat 1 or HC hills is a 39/25. Those fitting 34/28 or lower are just going too slow. On a ride i regularly do I give guys 300m start on a 3k climb and not only catch but put another 300m into them. they are ALL on compacts with 25 or 28 sprockets whereas myself and the others that can climb are on 39/21 for the same gradient.

Just push harder on the pedals and you will go faster

newburb_1968

Did not realise that there was a difference there and yes when I was looking on CRC & Wiggle both had the 130 and the 110 did not know what it meant untill you have mentioned it!!! THANKS!!

I thinks I will have to push the peddles harder and get used to it!! :oops:
So thanks again!!

John.T

Rule74Please wrote:

Not that long ago 39/27 was as low as you could go without fitting a girly triple.
Just ride more and you will get more POWERFUL. All you need for a day in the alps climbing cat 1 or HC hills is a 39/25. Those fitting 34/28 or lower are just going too slow. On a ride i regularly do I give guys 300m start on a 3k climb and not only catch but put another 300m into them. they are ALL on compacts with 25 or 28 sprockets whereas myself and the others that can climb are on 39/21 for the same gradient.
Just push harder on the pedals and you will go faster

Not very helpful. When I were a lad the lowest you could get on race kit was 42/24 and we managed quite well with that. I am now 68 and find a 34/27 very useful in the Pyrenees and on 25%+ Yorkshire hills. Yes I have slowed down a bit and so will you.

Pokerface

Newburb_1968 wrote:

Did not realise that there was a difference there and yes when I was looking on CRC & Wiggle both had the 130 and the 110 did not know what it meant untill you have mentioned it!!! THANKS!!

I thinks I will have to push the peddles harder and get used to it!! :oops:
So thanks again!!

It's possible to get smaller chainrings for a double (130BCD) chainset. You can get a 50T ring for instance, but you'll struggle to find a smaller INNER ring than a 38T - and that's really where you would want to go smaller to get help on hills, etc.

skyblue337

I managed to pick up a Tiagra compact from Ribble a couple of months ago for less than £40 so it can be done quite cheaply if you already have the Shimano Hollowtech BB

maddog 2

two rings!

girls blouses!

In my day we 'ad just one 55t ring and a fixed gear at the back with a 11 tooth sprocket on.

I could ride up Hardknott and still wave at the crowds

newburb_1968

So I can opt for a cheaper version, like Tiagra which will fit on the hollowtech bottom bracket?
I cannot just get a Inner & outer ring with of 50/34 in different hole positions that match a double 105?

Sorry for being such a numpty??!! :?

John.T

No. The bolt holes on a standard double crank would be right in the middle of the teeth on a 34. The bolt circle is too big.

newburb_1968

Therefore I need to buy a whole chainset in order to drop to a compact, when I change the terrain.
How long would that take me?
What sort of tool would I need to change the chainset?
How experianced or how easy is it to change?

I have removed chains and done some minor upgrades or repairs to my bike, so I am not a total spare part? [Well that's my opion :oops: ]

sungod

Newburb_1968 wrote:

Therefore I need to buy a whole chainset in order to drop to a compact, when I change the terrain.
How long would that take me?
What sort of tool would I need to change the chainset?
How experianced or how easy is it to change?

I have removed chains and done some minor upgrades or repairs to my bike, so I am not a total spare part? [Well that's my opion :oops: ]

swapping chainsets is quite straightforward, you may need to reposition the front mech (move it down a bit for the compact) but perhaps you can get away without doing it (i haven't tried that)

tools etc. depends on which model 105 you have, instructions are here... http://techdocs.shimano.com

if it is the hollowtech ii type then some hex keys and one of these... http://www.wiggle.co.uk/shimano-crank-i ... owtech-ii/

for the older octalink type you need a crank extractor and a hex key

P_Tucker

Rule74Please wrote:

Not that long ago 39/27 was as low as you could go without fitting a girly triple.

Just ride more and you will get more POWERFUL. All you need for a day in the alps climbing cat 1 or HC hills is a 39/25. Those fitting 34/28 or lower are just going too slow. On a ride i regularly do I give guys 300m start on a 3k climb and not only catch but put another 300m into them. they are ALL on compacts with 25 or 28 sprockets whereas myself and the others that can climb are on 39/21 for the same gradient.

Just push harder on the pedals and you will go faster

You are AWESOME. However, Alberto Contador would put more than 600m into you on a 3k climb, thus is even more AWESOME, and he's recently been using 34x32 for some of the Giro climbs:

http://velonews.competitor.com/2011/04/ ... %99_170127

Put that in your pipe and smoke it.

rolf_f

Rule74Please wrote:

Not that long ago 39/27 was as low as you could go without fitting a girly triple.

Just ride more and you will get more POWERFUL. All you need for a day in the alps climbing cat 1 or HC hills is a 39/25. Those fitting 34/28 or lower are just going too slow. On a ride i regularly do I give guys 300m start on a 3k climb and not only catch but put another 300m into them. they are ALL on compacts with 25 or 28 sprockets whereas myself and the others that can climb are on 39/21 for the same gradient.

Just push harder on the pedals and you will go faster

Lol - you're silly!

Basically, once you are in bottom gear in a standard, you are dropping below optimum cadence. The rider on the compact can still climb on an equivalent to 39/25 if they like but they also have the option to change down to maintain cadence and thereby improve efficiency. I usually find that as I change down on a climb, my speed increases (generally because I change down too late). Using the correct gears isn't being girly - it's being efficient.

Of course, you could be genuinely awesome but most of us aren't cycling gods.

schweiz

Rule74Please wrote:

Not that long ago 39/27 was as low as you could go without fitting a girly triple.

Just ride more and you will get more POWERFUL. All you need for a day in the alps climbing cat 1 or HC hills is a 39/25. Those fitting 34/28 or lower are just going too slow. On a ride i regularly do I give guys 300m start on a 3k climb and not only catch but put another 300m into them. they are ALL on compacts with 25 or 28 sprockets whereas myself and the others that can climb are on 39/21 for the same gradient.

Just push harder on the pedals and you will go faster

You're my hero!

p.s. I ride in the Alps almost every weekend from the start of spring till the end of autumn and most of the mountain goats in our club are opting for compact chainsets for days in the mounatins. I'm slow...they ain't! It doesn't make you slower, you push as hard as you want to.

In fact I reckon the only two people still on normal chainsets are this guy http://www.cyclingarchives.com/coureurf ... urid=28979 and this guy www.martinfanger.ch/ but we can't all be (ex-) professionals

Garz

Rule74Please wrote:

On a ride i regularly do I give guys 300m start on a 3k climb and not only catch but put another 300m into them.

He is definitely a hero!

CumbrianMan

P_Tucker wrote:

Rule74Please wrote:

Not that long ago 39/27 was as low as you could go without fitting a girly triple.

Just ride more and you will get more POWERFUL. All you need for a day in the alps climbing cat 1 or HC hills is a 39/25. Those fitting 34/28 or lower are just going too slow. On a ride i regularly do I give guys 300m start on a 3k climb and not only catch but put another 300m into them. they are ALL on compacts with 25 or 28 sprockets whereas myself and the others that can climb are on 39/21 for the same gradient.

Just push harder on the pedals and you will go faster

You are AWESOME. However, Alberto Contador would put more than 600m into you on a 3k climb, thus is even more AWESOME, and he's recently been using 34x32 for some of the Giro climbs:

http://velonews.competitor.com/2011/04/ ... %99_170127

Put that in your pipe and smoke it.

Great link to Contador's climbing. Cheers for that.

Rule74 - that must've been you in the video that Contador shot past then whilst on your 39/21. Very impressive mate. See AC didn't have the balls to match you the same gearing then :!: