Triple on a road bike - yay or nay

[wafflycat]

Interesting. unplanned maintenance, sometimes with a birmingham spanner or similar, is not entirely unheard of with derailer equiped mtb's.....

Indeed this is true, but as the entire purpose of MB going for a Rohloff was the supposed utter reliability of it, it let him down an awful lot over the trip. He always seemed to be needing to fiddle with it.

 

[adscrim]

Indeed this is true, but as the entire purpose of MB going for a Rohloff was the supposed utter reliability of it, it let him down an awful lot over the trip. He always seemed to be needing to fiddle with it.

Indeed, but the need to fiddle with ones equipment is not always due to faults with said equipment!

Didn't James Bowwhatshisface use a Rohloff belt drive? I was under the impression they were supposed to be more reliable in general but maybe more importantly, more difficult to break (vs it being very easy to bend a rear mech).

 

[GrumpyGregry]

time to start a new thread I think......

 

[Fab Foodie]

steve52, can you tell me why?
I am just about to buy a new road bike and had pretty well decided on a specialized roubaix with a compact 34/54 chainring and 12/27 cassette. that gives me way more gears than my current 42/52 and 12/24 set-up.
I don't really understand this gearing in inches thing - in laymans terms, roughly how many more "easier" gears would I get on an average triple than a compact (as above)?

have a go with Sheldons gear calculator.

select 'Gear Inches' then plug-in your chainring sizes and select your rear cassette options.

The calculator will give you a ratio which demonstrates the differences between gears and the range between highest and lowest gears for a given set-up.

Thus compare 52/42 & 12-24, with 50/34 & 12-27 and also a triple of 52/42/30 &12-25 or 12-27 Cassettes to see the range and spacing between the gears.

Sheldon also explains gear inches elsewhere on his site. The calculators fun and useful, it also shows gear overlaps or where you have the same gears duplicated which might not be a good thing!

 

[HJ]

Move along now, move along, it is time this thread was moved to Room 101

 

[jimboalee]

Move along now, move along, it is time this thread was moved to Room 101

Why?

Jimbo might butt in and say something like "try looking for a website calculator that tells you what gears you need on your bike for a hill of x% gradient".



Carry on lads, He's not.

 

[P.H]

He had to resort to unplanned maintenance of said hub on several occasions IIRC from the TV progs.

I think you're mistaken.
He did have several problems with wheels, which made him question the choice of hub as he couldn't just swap wheels.

 

[lukesdad]

I use a triple on my Race Bike. I hear you say ! Its got sweet F.A to do with looks. I don t drive and sometimes find it hard to cadge a lift, which means I ride to alot of my local events,which sometimes can be upto 1 1/2 hours away. The triple allows me to do this. Add to this the fact there are some rather large hills around here.

Years ago (in the south -east anyway) my father tells me all "men" did it that way. There s no "rules" only fashion.

I use a double on my training bike for other reasons 53/42 with a 12/25 cassette. The triple is a 53/39/30 with either 12/23 or a 12/25 depending on event.

Who on earth in their right mind would want to use a gearboxes with wide ratios when they could have three with close ones.

The reason a lot of roadies frown on them is it comes from the world of mtb " and that would never do! wouldn t be seen dead and all that".

If your that much of a style Icon that you hate the look of rear mechs ride asingle speed.

Oh and by the way as some of you know the race bikes got S60s as well so put that in your pipe and smoke it.

 

[GrasB]

Who on earth in their right mind would want to use a gearboxes with wide ratios when they could have three with close ones.

Cause navigating a triple quickly is slow & requires thinking where a Rohloff gives you access to 14 gears instantly & if it's not quite right you can use the front chainring to give you 6.5-7% gearing steps? Since I'm now logging cadence & road speed I can see how I shift & it seems like I tend to do 2t jumps when going through the gears most of the time & it's only when I'm on a staticish cruise speed that I'll change in 1t steps. In short it looks like a Rohloff with a 38/46 chainring setup really makes sense for me.

 

[lukesdad]

What about when your climbing ?

 

[GrasB]

What about when your climbing ?

When you ride an 79" gear up a 5-15% gradient suddenly exact gear becomes rather less than relevant... certainly not the quickest way to climb for me but I can do it though I will zig-zag a little on the steepest parts.

 

[lukesdad]

Using a triple can be tricky if you go about it the wrong way. Forget about gear inches and similar ratios. What you need to focus on is the chainwheel. Its simple after that.

 

[Tollers]

Serious now.

Let’s take the favourite 10% gradient.

For example, a cyclist rides along at 18.5 mph and is putting 200 Watts into it.

Climbing up the 10%, his speed will reduce to one third ( 6.2 mph ) and the power required will approximately increase by 50% to 300 Watts.

What gear is required to ride at 6.2 mph at 80 cadence? It happens to be 27” or a 28 chainring to 28 sprocket 1:1 ratio.

How many ROAD bikes have this gear? Only very recent ones where the manufacturers have identified their customers haven’t much cycling experience.

The normal situation is that a 10% hill will be climbed in something like a 40” gear, 30 ring to 20 sprocket, or 39 ring to 27 sprocket, or other combinations with 34, 36 and 38 tooth chainrings.

So does it matter what size chainring the bike has?

Let’s go mental and try a 20 % hill.

Speed will be something like 3 mph at 300 Watts into the cranks. The bike will need a gear down at 21”, or 28 ring and 36 sprocket for the rider to turn the cranks at 50 rpm.

Only Touring and MTBs have these kind of gears.
Roadies are seen struggling at 35 rpm on a 30 ring and 27 sprocket.

Climbing up hills steeper that 8% at 80 cadence is really ‘out of the question’ on a road bike, even one with a 30 ring and 27 sprocket.

And the way to have a 30 tooth chainring, is to fit a triple.

Sure. Your calculations are sound (i've just built my own model to check). However, you have made 3 huge assumptions in your modelling:

1) The rider max mean power output over the long hill is 300w. The riders real mean climbing power and weight are critical inputs to this calculation.
2) The rider slows to 6.2mph (a conveniently nice round 10kph )
3) You chose the " fit rider in cycling clothes on a good touring bike" assumption. Which is probably reasonable generalisation, but not for all of us. My cycling weight (including bits is less than 80kg)

When i think about my riding as a reasonably athletic sort of guy going up a 10% hill with my compact 34x25 gearing, i can maintain an 76 cadence at 8 mph burning a heavy 340 watts. Not easy, and i'd prefer to go slower with a 34x27 but it's definitely not "out of the question for me to climbing up hills steeper that 8% at 80 cadence even one with a 30 ring and 27 sprocket".

 

[GrasB]

Using a triple can be tricky if you go about it the wrong way. Forget about gear inches and similar ratios. What you need to focus on is the chainwheel. Its simple after that.

See that's the problem with triples, because they have a fair amount of overlap working out what chainring to be on is a pita. With a compact setup it's high or low simple.

 

[lukesdad]

Exactly the same with a triple with an extra low gearbox can t see the problem. Look at the terrain select the ring use the cassette simple.