Double or Triple chain rings ?

[Steve B]

OK people, here it is.

It does involve weight, as everything in cycling does.

Weigh everything. Yeh, put everything on the bike that is going to be on the bike. Bottles, computer, saddlepack, etc.

For simplicity of calculation I will load two bottles on my Pug 531 and the entire weight of the bike will be 25lb.

Reciprocate 25. 1 divided by 25 = 0.04.

Multiply 0.04 by 1000 = 40.

That is the gear length that should be on the bike to get me up a 10% all afternoon. 40"

The Pug has a 52/38 chainset and if I'm going climbing, I fit a 13 to 25 six block.

38 and 25 = 40"


Those of you who have a triple with 30 and a 25 sprocket on a 23lb bike can carry another 8 lb of goodies to make 31lb total for that gear.


Choosing the longest gear involves a lot of honest self appraisal.

OK, some questions.

Why reciprocate by 25?
Why multiply by 1000?
Why should 40" be OK for all riders?
Where does a 10% gradient fit into this?
Why does the weight of the rider not make a difference?
Why does the fitness of the rider not make a difference?
If I lose 2 stone will I still need a 40" gear?

Your 'formula' is either a load of old twaddle or needs some careful explanation. I am quite happy to admit to being a novice in the cycling arena but I teach students all day long and have a fairly good eye for dodgy mathamatics - can you explain your workings for full marks please?

 

[MacB]

oh, this I have to see

 

[yello]

That may be an advantage

Ah, but it's not the detail's validity, or otherwise, that I admire. It's that sense of other worldliness, a kind of reference to a mystic bygone era with different beliefs and measures. I'll never know that. Whether I believe in it or not just isn't the question

 

[Crackle]

Ah, but it's not the detail's validity, or otherwise, that I admire. It's that sense of other worldliness, a kind of reference to a mystic bygone era with different beliefs and measures. I'll never know that. Whether I believe in it or not just isn't the question

Absolutely. I have never questioned how Jim arrives at this stuff it would destroy the magic. I have only ever questioned that it doesn't apply to me. It does not do to delve into the soul of something. I paricularly like his ice cream/hill analogies. We've been inducted to his cult Yello.

 

[Randochap]

Wait for Randochap to get on-line. Its 6 am in BC, so give him another couple of hours.

Well, Jimbo, it's 11am now and I'm still not sure I want to put my oar in another "double vs triple" thread. I have made my opinion known here and I have a whole page on "gearing for distance freaks" on my website.

And I'm not in the least bit inclined, so to speak, to examine my cadence from the perspective of a mathematical formula. Contrary to my technical rants, I'm a cycling poet, not a techno-geek.

I don't have a cadence function on my bicycle computer. I've been spinning these legs for so many years I know what RPM they want to do -- faster than most of my cycling partners -- about 80-90 rpm.

I'd say that indeed 40 inches (40X26) is a common gear for me to be riding on a long, steep incline, depending on how much weight I'm carrying and at what distance it arises. It's not uncommon for me to drop into the 36" on a long grade, on a long ride.

I'll also deliberately "save" my legs early into a brevet by using the 30T ring and a big cog (26 or 29T) for short steep (12% and up) grades. Long-distance is all about rationing.

If I'm on the Mainland, in the big mountains, the character of the climbs there is different -- the grades are generally slacker, but much longer and they wear you down over the long haul. On Vancouver Island, it's constant shorter but steeper rollers. In the end though, it all comes down to endurance and riding smart. False bravado gets you nowhere on this crumpled continent.

It's always amusing to read posts from the "I don't need no stinkin' granny" contingent, when you know their experience is restricted to weekend 50 milers on relatively flat ground.

Here's an interesting page that examines the minutiae of BC topography from a cyclist's perspective.

 

[Fab Foodie]

oh, this I have to see

Me too!
I've bet eating my Brooks saddle with a bottle of Peri-Peri on it!

 

[col]

With my leg power being pretty low at the moment, I find the middle ring very comfortable for most roads, but get a steep bit and its very nice to be able to drop onto the smallest at the front. The largest is used for flats and tailwinds, not so much down hill now as the novelty of trying to go as fast as I can downhill has worn off, and just freewheel it now. But the middle ring is a nice compromise at the moment, until I build my leg strength up again. Three rings is great for me, and the only difference I can see me using them is when I use the largest more as I get better.

 

[Tynan]

it's not about anything being a small ring ffs, surely? it's about it being a smaller ring of so many teeth, surely a double can have smaller small ring than a triple?

or a bigger cog on the back to give a higher gearing?

 

[MacB]

it's not about anything being a small ring ffs, surely? it's about it being a smaller ring of so many teeth, surely a double can have smaller small ring than a triple?

or a bigger cog on the back to give a higher gearing?

is the correct answer

 

[Tynan]

can bikes with doubles actually go up hills?

it's getting like the hi viz/helmet rows

 

[MacB]

can bikes with doubles actually go up hills?

it's getting like the hi viz/helmet rows

amazingly single rings were all the rage once, but obviously the hills puffed themselves up with the advent of doubles and triples

 

[col]

can bikes with doubles actually go up hills?

it's getting like the hi viz/helmet rows

I didnt think so the other day.

 

[Fab Foodie]

it's not about anything being a small ring ffs, surely? it's about it being a smaller ring of so many teeth, surely a double can have smaller small ring than a triple?

or a bigger cog on the back to give a higher gearing?

A double could have a smaller ring than a triple, but they generally don't.
You can have a bigger rear cog, I used to run a 10 speed 52/42 with a 12 to 34 rear, but that's a heavy cassette (Freewheel then) and a big old touring mech. Not the smartest way, but it was a cheap way to get low gears.

 

[Fab Foodie]

can bikes with doubles actually go up hills?

it's getting like the hi viz/helmet rows

Of course they can, it's not whether, it's how!

I ride a triple now but previously went everywhere by fixed. I don't recall pushing the bike up any hills... but it was gut-busting eyeball bursting stroke inducing stuff. I certainly couldn't do it now. I rode Ditchling on 42 x 15 and now struggle sometimes on 30 x 25.

 

[buggi]

haven't read all the replies but i'm sure it's been suggested.

Get a compact, it looks like a double but has different sized rings and basically sits in the range that would be in between a double and a triple. not getting too technical... you basically lose the smallest gear and the largest gear that would be on the triple, but you get the look of the double which is nicer and more sleek (and you don't notice the missing gears coz hardly anyone uses them anyway).

This means you get to climb hills as if you are on a triple but you look hard as if you were on a double

i'm sure someone has already pointed this out but i couldn't be arsed to sift through the replies

i started off on a double and had it changed to a compact when i wanted to ride to Paris, because it would have been harder for the shop to change it to a triple. i'm not good a climbing hills but it suits me. The hardest hill i've climbed on my Paris trips is a 14% (on record) and i was fine on a compact (well, i didn't feel fine but i made it up there lol) and if i can get from London to Paris on a compact then it should be fine for you