Triple v Compact advice please

[alecstilleyedye]

there's nothing to be gained in moving from triple to compact, unless you think a triple is 'uncool'.

 

[GrasB]

Deciding what gears to install.

1/ Weigh yourself.
You can use your bodyweight to calculate the MAX torque that can possibly be applied to the B/B.
Take a safety factor. 75% is about right. ¾ of the MAX is what you can reasonably expect to generate with every successive pedalstoke when you are standing out of the saddle.

2/ Decide on your favourite cadence ( when you are standing out of the saddle).

3/ Use ‘Powercalc.xls’ off the CTC website to find out how much power is required to climb a hill at various speeds.

On a separate sheet, juggle the figures to get a speed, gear and cadence which will generate the required power to climb the hill.

Or, you can reciprocate the weight of the bike in lbs, multiply this by 1000 and subtract 6 ( 2 x 3" steps) for a 14% hill.

Or go for a 5 day break in the Alps with your bike to see how you really ride in the hills & find out what pisses you off while riding & what seems to work. Doing that proved that all the theory in the world is fine but sometimes you've simply got to get out there & try it.

there's nothing to be gained in moving from triple to compact...

For some people... for others they'll just get on better with a compact. It's a personal choice that one has to go out & try for them selves.

 

[TheDoctor]

When going up mountains I find a single ring would work perfectly well. For Mont Ventoux from Bedouin a 24T would have been perfect.
Actually, a singlespeed with about a 24" gear would have been perfect too.

 

[jimboalee]

GrasB. Your system sounds OK, if you've got money to burn and a lot of idle time on your hands. Most of the cyclists who I speak to haven't.

Most of the cyclist I speak to can get to use a pair of bathroom scales pretty cost efficient, and have at least access to an internet connected computer at their local library.

Then comes the tricky part. Getting a FREE session at a health club. It is possible if you blag your way in by pretending to 'want to join'. By doing this, you can get an estimation of your peak and sustained power.

Then its back to the library to look up some Mechanical Engineering to do the torque, power, ratios sums.

Final stop is the LBS for a cassette and an aftermarket chainring in a pretty pastel blue colour, because THAT is the most important.

 

[GrasB]

GrasB. Your system sounds OK, if you've got money to burn and a lot of idle time on your hands. Most of the cyclists who I speak to haven't.

I agree it does take more time but if you can find the time for a weeks cycling holiday or just a holiday where you do some riding it's a good way to find out what you going to want. Also you don't need to go to the Alps, it's just where I did my cimbing & found out a few things, some time in wales or the lake district should give you a feeling for the gearing too. Hiring a bike or taking your own shouldn't be to much of a problem & from there you can work it all out.

Most of the cyclist I speak to can get to use a pair of bathroom scales pretty cost efficient, and have at least access to an internet connected computer at their local library.

Then comes the tricky part. Getting a FREE session at a health club. It is possible if you blag your way in by pretending to 'want to join'. By doing this, you can get an estimation of your peak and sustained power.

Then its back to the library to look up some Mechanical Engineering to do the torque, power, ratios sums.

Funny thing is I did all the calculations etc. but what I found was that a 30/39/52 (iirc) triple & 13-26 cassette just didn't work for me & that a 36/52 with a 13-29 cassette was the better option.

 

[jimboalee]

When going up mountains I find a single ring would work perfectly well. For Mont Ventoux from Bedouin a 24T would have been perfect.
Actually, a singlespeed with about a 24" gear would have been perfect too.

Up a constant 8% in my present state of fitness, I find a 35" gear is about right. 30 x 23.

Years ago, I trained at just over 200 Watts all the way, which was simulated on the ergometer in 1997 ( Friday the 11th July to be precise. I set up the dyno to simulate Mt Ventoux because it was 30 years since Mr Simpson's tragedy ) on 45", 38 x 23.


40 Cadence for four frigging hours. Sometimes I have to slap myself for being so daft.

It was not all in vain though. The next year I waltzed up the Wicklow Gap.

 

[Eddigrae]

Once again thanks guys for all the input - definitely food for thought !

Eddigrae.

 

[jimboalee]

Folks are really quite lucky these days with triples and 34 ring/27 sprocket 'compacts' on light sports bikes.

In days gone by, there was 39 x 25 and not a lot else if it was a race type bike.


If a 'Compact' 34 ring to a 27 sprocket ratio is still not low enough, what is needed is a bit of weight loss and lot of strength building until it is.