unravelling Gearing theory and formulae
- Thread starter peanut
- Start date
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ColinJ
Puzzle game procrastinator!
- Location
- Todmorden - Yorks/Lancs border
Won't we be able to do the calculation in reverse afterwards to work out your age?peanut said:blimey jimbo you'll be asking which primary school I went to next lol
I'll pm you my dob strictly in confidence ok
(I'm 53 by the way.)Here are the results.
Peanut’s fat % is somewhere between 30 and 31 % based solely on a Suprailiac fold of 28mm.
His wrist is large for his height. 21.5 cm indicates a large framed bloke at 180 cm height.
At his age, he should be aiming to be 17.75% bodyfat, so his ideal weight will be 14 stone exactly. His ‘Lean mass’ is above expectations for a chap his age, so my congrats to Peanut as being more than a ‘beginner’.
No way is he going to get to Royal College of Nursing recommended 12st 10lbs or the BMI on the Quack's chart.
Incidentally, Peanut’s basal metabolic rate is 1675 kCals /day if he wishes to reduce to 14 stones.
Now the nitty-gritty....
As said on an earlier thread, I reduce the ‘10% gear’ by 1” per 1 % bodyfat over and above 22% which the US Navy deem as OK for recruits into Basic Physical Training.
Peanut’s Winter bike is 23 lb. Add on 1lb for some water and another 2 lb for all his kit. This makes a 26 lb bike+kit weight.
1 / 26 = 0.038; 0.038 x 1000 = 38.
Subtract another 8” to compensate for Peanut’s bodyfat and the number comes to 30.
A 28” gear to make sure is accomplished by a 30T ring and a 28T sprocket.
Climbing speed will be 5 mph at a steady 59 cadence.
If a customer of Peanut’s age and stature came into the shop where I worked and chose a 23 lb bike to go up hills on a Brevet Populaire, I would recommend a Triple chainset of 50/39/30 coupled with a 11-32 cassette.
Lowest would be 25”.
It is a budget set-up using Tiagra and HG50. No really expensive kit. If the guy decides he likes cycling, he can come back and buy better later.
Tin hat on. Going round to girlfriend’s for supper and a Pimms.
Peanut’s fat % is somewhere between 30 and 31 % based solely on a Suprailiac fold of 28mm.
His wrist is large for his height. 21.5 cm indicates a large framed bloke at 180 cm height.
At his age, he should be aiming to be 17.75% bodyfat, so his ideal weight will be 14 stone exactly. His ‘Lean mass’ is above expectations for a chap his age, so my congrats to Peanut as being more than a ‘beginner’.
No way is he going to get to Royal College of Nursing recommended 12st 10lbs or the BMI on the Quack's chart.
Incidentally, Peanut’s basal metabolic rate is 1675 kCals /day if he wishes to reduce to 14 stones.
Now the nitty-gritty....
As said on an earlier thread, I reduce the ‘10% gear’ by 1” per 1 % bodyfat over and above 22% which the US Navy deem as OK for recruits into Basic Physical Training.
Peanut’s Winter bike is 23 lb. Add on 1lb for some water and another 2 lb for all his kit. This makes a 26 lb bike+kit weight.
1 / 26 = 0.038; 0.038 x 1000 = 38.
Subtract another 8” to compensate for Peanut’s bodyfat and the number comes to 30.
A 28” gear to make sure is accomplished by a 30T ring and a 28T sprocket.
Climbing speed will be 5 mph at a steady 59 cadence.
If a customer of Peanut’s age and stature came into the shop where I worked and chose a 23 lb bike to go up hills on a Brevet Populaire, I would recommend a Triple chainset of 50/39/30 coupled with a 11-32 cassette.
Lowest would be 25”.
It is a budget set-up using Tiagra and HG50. No really expensive kit. If the guy decides he likes cycling, he can come back and buy better later.
Tin hat on. Going round to girlfriend’s for supper and a Pimms.
MacB
Lover of things that come in 3's
- Location
- Farnborough, Hampshire
Jim, think I follow that, so the base calculation remains the same and the only real variance is for body fat? ie Peanuts gear requirement would be 38" if fully fit, maybe 36" to allow a bit of leeway?
Will1985
Über Member
- Location
- South Norfolk
No wonder riders must be able to pedal over the top without a recovery, they are hardly moving to warrant a rest!!
MacB
Lover of things that come in 3's
- Location
- Farnborough, Hampshire
Will1985 said:
now that's just the cruelty of youth speaking, I'll have you know that what you consider hardly moving may be bombing along for some of us!
Steve Austin
The Marmalade Kid
- Location
- Mlehworld
Absolutely amazing, after all the information supplied and all the equations, all we come down to is, 'Rider would need a triple 50-39-30 and a 11-32 cassette'
thats got lower gearing than my MTB!
I'm really not sure all the sums are worth tbh. Its pretty widely accepted you need a certain gear ratio to be able to comfortably ride up stuff. a 30/32 is stupid low, and not worth pedalling on the road.
and thistheory opinion does not follow for all riders. As we are different. we all have different physiology, different muscle structures, different power outputs. Paper sums don't prove a thing, although they could be a very rough guess at what might be right.
thats got lower gearing than my MTB!
I'm really not sure all the sums are worth tbh. Its pretty widely accepted you need a certain gear ratio to be able to comfortably ride up stuff. a 30/32 is stupid low, and not worth pedalling on the road.
and this
MacB
Lover of things that come in 3's
- Location
- Farnborough, Hampshire
rich p said:
nope, and he's mentioned, in several posts, that the manufacturers have done the calculations for us already. I think it only falls down when you factor in ignorance, either sales person or, more frequently, customer. I wonder how many go into a shop fancying a certain type of bike and buy it regardless of suitability advice to the contrary?
RESULTS
Well I am kind of pleasantly surprised actually.
Jimbo has asked a clever question actually by which he has arrived at my body structure which is mesomorph.
Jimbo has suggested that my ideal weight should be 14 stone and I would probably agree with that assessment. Most Dr's and medical professionals suggest a totally unrealistic 12st 7lbs
Jimbo is spot on with my calorie intake too. I have kept a food diary and when i added all the little snacks the hidden calories brought my daily intake up to 2000 .I know that unless I get under 1500 cals per day i don't lose weight . I have remained at 16st 10lbs for a month now.
Jimbo has added an extra 3lbs for water and tools but the tools wereincluded in bike weight so 2 lbs could be deducted . 1/24 =0.0417 X 1000 = 41.67" -8" = 33.67"
Jimbo has suggested allowing a further 2" leeway so 31.67 call it 32"
To achieve this the formula would I think suggest
34t chainring and a 28t sprocket which could be accomplished by a compact double with a 12-28 cassette
Ok now to the conclusion.
On the basis of Jimbos original calculation and proposed gearing my idea gearing would require a triple chainset and MTB 12-32 cassette.
Now that i have corrected the bike weight and recalculated a compact double chainset with a 12-28 cassette would achieve the required 32" low gear for climbing.
Over the past 6 months I have played around with several cassettes and dozens of sprockets and lots of fast flats, fast descents and loads of hill climbing. Ive drawn up loads of gear tables and finally settled on .....
compact 50x34 with 9spd 12-27 cassette
So Jimbo was only 2" out
well done Jimbo I can't fault the result .
I'm going to try sticking to 1675 cals a day for a couple of weeks and see how my weight goes .
Well I am kind of pleasantly surprised actually.
Jimbo has asked a clever question actually by which he has arrived at my body structure which is mesomorph.
Jimbo has suggested that my ideal weight should be 14 stone and I would probably agree with that assessment. Most Dr's and medical professionals suggest a totally unrealistic 12st 7lbs
Jimbo is spot on with my calorie intake too. I have kept a food diary and when i added all the little snacks the hidden calories brought my daily intake up to 2000 .I know that unless I get under 1500 cals per day i don't lose weight . I have remained at 16st 10lbs for a month now.
Jimbo has added an extra 3lbs for water and tools but the tools wereincluded in bike weight so 2 lbs could be deducted . 1/24 =0.0417 X 1000 = 41.67" -8" = 33.67"
Jimbo has suggested allowing a further 2" leeway so 31.67 call it 32"
To achieve this the formula would I think suggest
34t chainring and a 28t sprocket which could be accomplished by a compact double with a 12-28 cassette
Ok now to the conclusion.
On the basis of Jimbos original calculation and proposed gearing my idea gearing would require a triple chainset and MTB 12-32 cassette.
Now that i have corrected the bike weight and recalculated a compact double chainset with a 12-28 cassette would achieve the required 32" low gear for climbing.
Over the past 6 months I have played around with several cassettes and dozens of sprockets and lots of fast flats, fast descents and loads of hill climbing. Ive drawn up loads of gear tables and finally settled on .....
compact 50x34 with 9spd 12-27 cassette
So Jimbo was only 2" out
well done Jimbo I can't fault the result .
I'm going to try sticking to 1675 cals a day for a couple of weeks and see how my weight goes .
rich p said:So Jim suggests 50/39/30 with 11-32 and you've got 50/34with 12-27 - near enough
blimey Rich read the whole of my post mate
Jimbo suggested a triple because a compact wouldn't get the gear inch needed for 28"
Once I had adjusted the bike weight correctly the gear inch required went up to 32" which now meant that it could be achieved by a compact double or a triple.
I happen to have a compact double but the gear inch is what it is all about and he got that right
dunno why I bother sometimes groan
