Access whole cassette in each ring?

[Dogtrousers]

It's part of the reason I've never updated my two vintage road bikes to STI, despite it being available just after I bought the bikes, and would still be 'period'. I like how fast you can change both the front and rear with one hand at the same time. On many a club ride, or especially a sportive, you've approached a hill in a big gear, a quick flip of the levers and I'm in the right gear with a click, click. All I can hear round me is crunch, crunch.

Although I love my new Spa Steel Audax bike, if I was building my dream bike now it would have down tube shifters: indexed for the rear and friction for the front (and stupidly wide ranges that you get with a compact like Apex). If/when these brifters ever fail they aren't getting replaced like-for-like.

 

[RecordAceFromNew]

The lack of fine control of my front mech is one thing I really miss since switching to brifters (Sram Apex). I mean what is the POINT of indexing something that has two positions? Down tube friction shifters for the front were already indexed (for a double).

What a brilliant post!

To answer the OP's original question, you will achieve the maximum of what is physically possible, short of performing surgery on front mech cage etc., by setting the H limit screw for minimum clearance* without rubbing between mech outer cage and chain when on large front small back, and setting the L limit screw for minimum clearance* without rubbing between mech inner cage and chain when on small front large back, assuming your cable tension is correctly adjusted.

* general guideline is 1mm, but there is nothing to stop you pushing for less..

 

[Lanzecki]

[QUOTE 2997829, member: 9609"]bike gears are crap, too many overlaps. you should work out and learn your ratios (may be you could skip the mid range).

For instance my bike pretends its a 14 speed (7 cogs on the back with two on the front) so basically it's a 7 speed box with a range change.
but in reality its a 9 speed. So to go through the gears correctly i would go
low range 1 - 2 - 3 - 4
then move up into high range and go 3 - 4 - 5 - 6 - 7

and I wish the range change was pre selectable so you didn't have to faf with two levers.[/QUOTE]

Truck driver by any chance?

 

[byegad]

Buy a recumbent! The longer chain run will allow this to happen*, but on a normal bike no way. Not only will you get rub but you're flexing the chain quite a bit over the 'normal' chain run and will wear it out faster.

*People will tell you that the dérailleur capacity wouldn't cope. They are wrong as one of my trikes will run 24 front to 11 back AND 55 front to 34 back with no issues!

 

[Lanzecki]

Buy a recumbent! The longer chain run will allow this to happen*, but on a normal bike no way. Not only will you get rub but you're flexing the chain quite a bit over the 'normal' chain run and will wear it out faster.

*People will tell you that the dérailleur capacity wouldn't cope. They are wrong as one of my trikes will run 24 front to 11 back AND 55 front to 34 back with no issues!

Noo, not the dark side!! It's quite and expensive option though

 

[byegad]

{best villain voice and twirl moustache}

Try it my dear, what harm can it do?

 

[Smurfy]

I don't think anyone has mentioned the efficiency penalty of severe chain angles.

 

[RecordAceFromNew]

I don't think anyone has mentioned the efficiency penalty of severe chain angles.

Because it is a myth?

The conclusion from this research was: "Experimental results indicated that the efficiency of the chain drive varied as a function of chain tension. It was found that the efficiency varied linearly with the reciprocal of the average chain tension with the highest efficiencies occurring at high chain tensions and lowest at low chain tensions. For example, the highest efficiency measured in the study, 98.6%, was measured at a chain tension of 305 N and the lowest, 80.9%, at 76.2 N. It was found that chain-line offset and chain lubrication have a negligible effect on efficiency under laboratory conditions. Calculations of frictional loss resulting from offset indicate that this loss should be small compared to those produced by other mechanisms. This was verified experimentally. Lubrication effects on chain efficiency were tested using three different chain lubricants under a variety of test configurations. No significant quantifiable effect of lubrication could be inferred from these tests."

 

[Smurfy]

Because it is a myth?

The conclusion from this research was: "Experimental results indicated that the efficiency of the chain drive varied as a function of chain tension. It was found that the efficiency varied linearly with the reciprocal of the average chain tension with the highest efficiencies occurring at high chain tensions and lowest at low chain tensions. For example, the highest efficiency measured in the study, 98.6%, was measured at a chain tension of 305 N and the lowest, 80.9%, at 76.2 N. It was found that chain-line offset and chain lubrication have a negligible effect on efficiency under laboratory conditions. Calculations of frictional loss resulting from offset indicate that this loss should be small compared to those produced by other mechanisms. This was verified experimentally. Lubrication effects on chain efficiency were tested using three different chain lubricants under a variety of test configurations. No significant quantifiable effect of lubrication could be inferred from these tests."

You are quite right, it's related to sprocket size rather than offset.

 

[snorri]

[QUOTE 3001307, member: 9609"]Can you go quickly from 14th to 1st (ie if you suddenly had to stop)[/QUOTE] Yes, just turn the gearshift before starting off again. .

 

[Lanzecki]

[QUOTE 3001307, member: 9609"]Didn't know you could get such things, very expensive, but presumably since as it's german it will be super reliable. Can you go quickly from 14th to 1st (ie if you suddenly had to stop)


I'm guess Low Range and High Range is not the correct terminology for bikes - so what is ?[/QUOTE]

It's ok I think. It was this line that got me :

"and I wish the range change was pre selectable so you didn't have to faf with two levers."

 

[kloeshuman]

I just use the trim on my front derailer, as others have said...you will get a little at the extreme. I hardly ever find a need to go that extreme though

 

[Trull]

The whole point of derailleur gears is to present a range of gears with consistent changes. It can be seen that modern compact styles fail this test unless you double shift front and rear, sometimes by as many as 4 or 5 gear changes!

On my 8sp triple, by way of comparison I can change just one at a time, and there is a slight overlap of gears so there is leeway built in. This makes a lot of sense on downtube shifters - but lots of people use their brake levers happily enough to double shift and it does not seem to slow them markedly.

I read the lab test report from the IHPV mag with interest, and would really like to see a repeat on a dirty mtb style setup comparing with a hub gear setup where you have set the front / rear cogs with efficiency in mind. I conjecture that in the real world, with oil/wax contaminated with aluminium oxide micro-flakes and a sludge of grit, chain angle will have an effect as well. On a microscopic level the lubrication long chain hydrocarbon molecules are compressed into a matrix like scaffold which supports the weight of the two mating parts, grit penetrates this and causes additional frictional losses. Surely the cross chain bush movement at extreme angles will add up? albeit as a much lessor effect than the effect of sprocket size? Or am I plain and simply havering?

 

[Lanzecki]

The whole point of derailleur gears is to present a range of gears with consistent changes. It can be seen that modern compact styles fail this test unless you double shift front and rear, sometimes by as many as 4 or 5 gear changes!

On my 8sp triple, by way of comparison I can change just one at a time, and there is a slight overlap of gears so there is leeway built in. This makes a lot of sense on downtube shifters - but lots of people use their brake levers happily enough to double shift and it does not seem to slow them markedly.

I read the lab test report from the IHPV mag with interest, and would really like to see a repeat on a dirty mtb style setup comparing with a hub gear setup where you have set the front / rear cogs with efficiency in mind. I conjecture that in the real world, with oil/wax contaminated with aluminium oxide micro-flakes and a sludge of grit, chain angle will have an effect as well. On a microscopic level the lubrication long chain hydrocarbon molecules are compressed into a matrix like scaffold which supports the weight of the two mating parts, grit penetrates this and causes additional frictional losses. Surely the cross chain bush movement at extreme angles will add up? albeit as a much lessor effect than the effect of sprocket size? Or am I plain and simply havering?

And that is why I change my after chain every ride. At least I think that's what you were touching on.

 

[raleighnut]

It's part of the reason I've never updated my two vintage road bikes to STI, despite it being available just after I bought the bikes, and would still be 'period'. I like how fast you can change both the front and rear with one hand at the same time. On many a club ride, or especially a sportive, you've approached a hill in a big gear, a quick flip of the levers and I'm in the right gear with a click, click. All I can hear round me is crunch, crunch.

I agree with you over the shifters but I will say that the crunch, crunch is more down to poor technique or hero-grinding as once you have lost cadence any shifting is going to be a messy affair.