Double or Triple chain rings ?
- Thread starter Banjo
- Start date
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I had a howling gale up my jacksee last night and spent all of my commute on the 52 ring.
Lowest length used was 94" on the 15 sprocket. Even through Warwick, I stood up and heaved my way through the traffic.
In the calm, my usual gear is 76", 42 x 15.
This is the bike I use for Audax and believe you me, I use the 30 ring on some hills.
Lowest gear is 35", which allows me to load it up to 28lb ( 23.5 + 4.5lb ).
Lowest length used was 94" on the 15 sprocket. Even through Warwick, I stood up and heaved my way through the traffic.
In the calm, my usual gear is 76", 42 x 15.
This is the bike I use for Audax and believe you me, I use the 30 ring on some hills.
Lowest gear is 35", which allows me to load it up to 28lb ( 23.5 + 4.5lb ).
Fab Foodie
hanging-on in quiet desperation ...
- Location
- Kirton, Devon.
Jimbo
I'll hazard that you're still talking Bollock and that my Brooks is safe for tonights training run.
I'll hazard that you're still talking Bollock and that my Brooks is safe for tonights training run.
MacB
Lover of things that come in 3's
- Location
- Farnborough, Hampshire
Jim, how do you account for weight of rider? i started with a goal of losing 70lbs and have amanged 21lbs so far. When looking at these sorts of poundage doesn't a couple of pounds here and there on a bike pale into insignificance?
Over The Hill
Guru
- Location
- Ridden off into the sunset
The difference in ratio between each ring on the front of my triple is about equal to two rings on the back. So approaching a hill I can drop down a ring on the front and it is a smooth change.
Drop down the front cog on a double and you are dropping a huge amout equal to about five rings on the back, so to get the same sort of step down you have to go down one on the front but UP two on the back. That seems to be complicating things too much and making for lots more gear changes.
Also with the overlap on a triple if you are caught out in the wrong gear you will not be too far out but in a double the two sets of gears having very little overlap have less room to move.
Drop down the front cog on a double and you are dropping a huge amout equal to about five rings on the back, so to get the same sort of step down you have to go down one on the front but UP two on the back. That seems to be complicating things too much and making for lots more gear changes.
Also with the overlap on a triple if you are caught out in the wrong gear you will not be too far out but in a double the two sets of gears having very little overlap have less room to move.
Chris James said:
I love jimbo's calculations and theories! I'll have nothing said against them!
Whilst I rarely understand the detail, those theories and calculations speak to me of old-school, nuts-and-blots understanding of a subject. It's an understanding gained from a wealth of experience - I can only admire that.
Crankarm
Guru
- Location
- Nr Cambridge
Hi, I am new. I printed out my bikes’ gear inches using Sheldon Brown's calculator. On my main commute bike I have a triple chainset 52-42-30 with 12-23 cassette. I looked at which ring and sprockets I use most frequently. I use the middle chain ring 42 most frequently between 21T (52") and 12T (92"). The 52 and 30 chain rings get used when spinning out or needing granny gears. If loaded the front 30 chain ring will be needed more often as obviously more weight to carry. If riding light the 30 front chain ring is not needed at all.
I also printed out gear inches for other chainset combos including double chainsets as I have a road bike as well looking at the spread of gear inches taking into account tyre size, crank arm lengths and cadence. It’s very helpful identifying cog combos you don't use, don't need or cause excessive strain and wear to the chain or rings or do your legs no favours.
I also printed out gear inches for other chainset combos including double chainsets as I have a road bike as well looking at the spread of gear inches taking into account tyre size, crank arm lengths and cadence. It’s very helpful identifying cog combos you don't use, don't need or cause excessive strain and wear to the chain or rings or do your legs no favours.
Chris James
Über Member
- Location
- Huddersfield
yello said:I love jimbo's calculations and theories! I'll have nothing said against them!
Whilst I rarely understand the detail, those theories and calculations speak to me of old-school, nuts-and-blots understanding of a subject. It's an understanding gained from a wealth of experience - I can only admire that.
That may be an advantage
You should be able to climb a 10% on 40" gear at 9 mph spinning at 78 cadence.
If you're like me - a 190 lb heavyweight on a 23 lb bike, this will be 35 Watts for the horizontal speed + 120 Watts for the vertical lift.
155 Watts for an hour or three should not be beyond most cyclists.
If you're like me - a 190 lb heavyweight on a 23 lb bike, this will be 35 Watts for the horizontal speed + 120 Watts for the vertical lift.
155 Watts for an hour or three should not be beyond most cyclists.
MacB
Lover of things that come in 3's
- Location
- Farnborough, Hampshire
I think Jim left us mere mortals behind a while ago, and as for 190lbs being a heavyweight........I don't think so
There's a hill I do coming out of town that goes upto 8%. It's a continuous climb for 2 miles. The average gradient is close to 4%. I can do that on a 42" gear that isn't insanely painful it is actually the gear I use, I don't know about all day though and on better days that'd average close to 9mph for sections I reckon. I think the formula is about bang on if you halve it. I'm not the slowest climber in history either.
One of the other hills back from town is nearer your 10%, the mid section averages 8.2% for 0.8 miles and kicks up above 10%. There's no way I can do that at 9mph. It's pure pain after about half a mile at whatever speed.
It's a bit like this anybody should be able to do 15mph thing. It's true for higher end cyclists and nonsense for normal people.
One of the other hills back from town is nearer your 10%, the mid section averages 8.2% for 0.8 miles and kicks up above 10%. There's no way I can do that at 9mph. It's pure pain after about half a mile at whatever speed.
It's a bit like this anybody should be able to do 15mph thing. It's true for higher end cyclists and nonsense for normal people.
