Gearing on a triple

[stevevw]

Hi all I am going to build up an Audax/Winter bike using an as new Ribble frame. I have settled on a triple and would welcome any suggestions on what ratios to use I have a 30/39/50 chainset so it is the 9 speed cassette that I am interested in, had thought a 11-25 might work?
I realise that it depends how fit I am and how big the hills are but any general rules of thumb would be good.

Thanks Steve

 

[Crackle]

Waht do you use most? Personally I use gears around 60" so my triple setup reflects this. Then when it gets steeper I need gears that I can turn at 50rpm on long hills. Again my setup reflects this. We need a bit more to go on to answer the question.

 

[ColinJ]

Hi Steve.

I have a Campagnolo triple on my Basso which is the bike that I use for audax rides. I'm big and heavy and the events I ride are hilly to extremely hilly.

I have 30/39/52 chainrings. I started off with a 12-23 cassette. I found that I hardly ever used the '12' and often wished for a lower gear than the '23'. I therefore switched to a 13-26 cassette. I sometimes used the '13' but not often and the '26' was usually enough, but 25% climbs were still a bit tough. Eventually I swapped again for a 14-28. I find 52/14 gear is high enough to get me up to about 35 mph and I'm happy to freewheel downhill if I'm going faster than that. The 30/28 gear is a real luxury when tired on very steep hills into a headwind.

So, my comments on your gear selection... I really can't see why you'd need a 50/11 top gear on an audax. I think that you'd be better going for a cassette starting with a '13' sprocket. If you need the '25' go for a 13-25, if a '23' would be okay, go for 13-23. You'll probably appreciate the closer gear ratios and never miss the '11' and '12'.

 

[Greenbank]

Campag do a 13-29 rear cassette which is very useful.

My geared Audax bike has: 30/40/53 and 13-29

And I still walked up the Devil's Staircase.

 

[stevevw]

Thats the problem I do not know what I want or need I have never done an Audax before, first one will be local to me at the end of March 210km I have only come back to cycling since August 08 and have tried to average 100 miles a week gradually increasing the weekend ride up to about 55miles as of last week + the 70 miles a week commute. I have lost approx 2 stone in that time but more impressive is the 4" off the waist

I have two bikes that I use and thats all I have to judge against.

Bike 1 is my commuter a Marin San Rafael which has 48/38/28 and 11-32 (8 speed) on this I find that I can maintain a good speed on the flat when in 48-11 and have never had to use the 28 ring on the hills we have round here.

Bike 2 is a what I use at the weekends a Marin Fairfax which has 50/36 and 12-26 on this 50-12 is for down hill only and on some could do with being a bit higher. I have used all the lower gears but never had to get off and push. But as I say the hills round here are not that big or long.

My power to weight ratio is getting better all the time but I am still a fatboy.

 

[Greenbank]

Audax is about miles in the legs. If you regularly do 100 miles during a week you should be fine on 200km Audax. Just remember that it's not racing. It's long plodding distance riding which is all about stamina not speed or power. Improved power to weight ratio will certainly help on the hills though.

 

[Crackle]

Sounds like the 50-39-30 would be good then with the 11-25 or a 12-26 or thereabouts. Why not a 10 speed? Not much more money and it just keeps it all a bit tighter and closer which helps keep the cadence the same over lumps and bumps.

 

[stevevw]

Why not a 10 speed? Not much more money and it just keeps it all a bit tighter and closer which helps keep the cadence the same over lumps and bumps.

Only because I have a new pair of Tiagra 9 speed levers and do not want the expense of yet more new parts. I am now thinking that I will go for the 12-25 cassette as I know I can handle the 50-12 and hopefully 30-25 will be low enough for now.

 

[De Sisti]

Bike 1: 46/34/24.......... 11 13 15 17 19 21 24 28 32

Bike 2: 48/36/26...........13 14 15 17 19 21 23 25 28

Bike 3: 50/39/26...........13 14 15 17 19 21 23 25 28

Perfect.

 

[Randochap]

Front rings seem good. I'd agree that 10-sp would tighten things up a bit. Your options on Shimano road are up to 27, if you have the right derailleur.

In combination w/ the 30-T ring that gives you a 29.3" low. The rest looks like this:

12 66.0 85.7 109.9
8.3 %
13 60.9 79.1 101.5
7.7 %
14 56.5 73.5 94.2
7.1 %
15 52.8 68.6 87.9
13.3 %
17 46.6 60.5 77.6
11.8 %
19 41.7 54.1 69.4
10.5 %
21 37.7 49.0 62.8
14.3 %
24 33.0 42.9 55.0
12.5 %
27 29.3 38.1 48.9

I like something a bit lower and closer spaced, myself. Depending on hills and fitness the former would do for a 200. I personally need lower for longer, esp. hilly brevets.

Check out my page on gearing for long-distance.

 

[Jonathan M]

I've used anything between a 23 max rear cog and a 28 on my bikes, a lot depends on how fit I've been in the run up to a ride etc.

My Ribble isn't the lightest bike in the world -low end campag kit, pannier rack & dynamo light see to that, so it has the 28 fitted all the time.

 

[MacB]

Been trying to understand this gearing ratio thing and input my current stats into Sheldon Browns calculator. My inputs were 30/42/52 chainrings, 175mm cranks and an SRAM 9 speed 12-26 cassette. This gave me my range, in inches, running from 31.4 to 117.7. Being a novice, and quite unfit, I haven't found any need to use the 52 ring yet, except to check it worked. I currently seem to use an inch range from 31.8 to 81.5. I'm spending most of my time on the 42ring between 54 and 82 inches, with cruisng at approx 60inches. The 30 ring gets used about 10% of my route for the steep bits, or on a long uphill drag at the end.

Am I right to stay in the middle ring a lot? As I'm cruising around the 60inch mark should I vary useage, between 42/19, 52/23 & 30/13, to even out wear? Or is it easier to stay in the 42 and expect to replace that individual ring more than the others?

Is it correct to avoid the extremes, ie 30 to 12/13 and 52 to 23/26? If so why do they put them on there as an option?

Any other gearing related info you think would be useful for me to know. I'm sure the 52 will get more use once I'm fit enough to pedal down the other side of the hills

 

[Gary D]

Am I right to stay in the middle ring a lot? As I'm cruising around the 60inch mark should I vary useage, between 42/19, 52/23 & 30/13, to even out wear? Or is it easier to stay in the 42 and expect to replace that individual ring more than the others?

Is it correct to avoid the extremes, ie 30 to 12/13 and 52 to 23/26? If so why do they put them on there as an option?

What you are doing is pretty much spot-on!

The general idea is to keep the chain as straight as possible. So. When on the middle ring, the "ideal" gear at the back is the one in the middle of the cassette (about 18 or 19T) However, you can use the whole of the cassette when on the middle ring if necessary (well I do anyway ) but I wouldn't leave it at the extremes for long periods.
When on the large or small ring it is advised that you don't use the 2 or 3 gears on the opposite end of the cassette from the front ring i.e not 12 or 13 when using the small ring or 24 and 26 when on the large.

If the drivetrain is set up correctly you should be able to actually change in to these extreme gears and ride using them - but the chain will be bent at such an angle it will cause accelerated wear on the chain, chainrings and cassette. Try it with the bike stationary and you will see. So in actual fact, using a 30/13 combination instead of 42/19, will cause more wear not less . Never seen it mentioned, but I am sure there is also more risk of the chain coming off as well?

In spite of all this, don't ride along getting all anal about chain line and being in the "correct gear" all the time - just enjoy it

Hope this helps,
Gary.

 

[vernon]

As my bikes also have to earn their keep as fully laden tourers and I carry excess lard; my rear cassettes are 11-32 or 11-34 combined with 50/42/30 and 48/36/28 chain sets respectively.

The first pairing is on a newly built 27 speed Dave Yates Randonneur and the latter pairing is on a 21 speed Dawes Galaxy.

Until I built up the Dave Yates bike I did all of my audaxing up to 200km on the Dawes Galaxy with no problems.

The taller gearing on the Yates has seen me get round 100km faster in terms of pedalling time.

When I drop below 20 stones I might have a go at a 300km on the Yates.

 

[Randochap]

Any other gearing related info you think would be useful for me to know. I'm sure the 52 will get more use once I'm fit enough to pedal down the other side of the hills

GaryD has given you a very good primer on chainline. But, as he said, don't get overly concerned. As you aren't spending much time on the 52, you aren't going to run into the issue much ... running up to the big cassette cog by mistake. If you notice -- and the chain will start feeling rough when you do cross chain -- just drop it down one or two in back and shift to the middle ring (double shift).

As for the 52; I'd have no use for one on my long distance bikes. In fact, I haven't run anything bigger than a 50 in 25 years. My 50X13 gives me a 103" gear. That gives me enough speed for anything I'm doing. Now low gears, you can't have anything too low after a long day on a hilly route!

BTW, downhills is where you tuck and rest, after pushing hard on the uphill! Who pedals?

Gearing for long distance.