Gearing question for recumbents.

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PDQ Mobile
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Re: Gearing question for recumbents.

Postby PDQ Mobile » 17 Feb 2018, 11:35am

[XAP]Bob wrote:It might be bad technique - but it’s less bad for the longer chainline of a bent.

I add an IGH to spread the gears - a csrk3 SA hub gives a virtual ‘extra chainring’ at bithnends


Bad technique with significant advantages not to do it!!
But no plusses.IMV

Yes IHG is a great solution. I had a Sram 3/7 coupled with a double upfront. Fantastic wide range solution especially on a 20".
Stationary shifting etc.

Brucey
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Re: Gearing question for recumbents.

Postby Brucey » 17 Feb 2018, 2:36pm

PDQ Mobile wrote: ....And any tendency to approach those gears would be betrayed by stiffer rear mech lever and more transmission noise anyway...


Not so. Most modern derailleur systems will quite happily select the big-big combination and on a recumbent it will probably run OK anyway.

I don't plan to use big-big on a conventional bike but I always make sure that it is possible because it is easy enough to lose track and select it in error. I've seen plenty enough folk who thought they were smart enough not to ever do it....... prove themselves disastrously wrong.... :wink: :roll:

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

PDQ Mobile
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Re: Gearing question for recumbents.

Postby PDQ Mobile » 17 Feb 2018, 2:53pm

Brucey wrote:
PDQ Mobile wrote: ....And any tendency to approach those gears would be betrayed by stiffer rear mech lever and more transmission noise anyway...


Not so. Most modern derailleur systems will quite happily select the big-big combination and on a recumbent it will probably run OK anyway.

I don't plan to use big-big on a conventional bike but I always make sure that it is possible because it is easy enough to lose track and select it in error. I've seen plenty enough folk who thought they were smart enough not to ever do it....... prove themselves disastrously wrong.... :wink: :roll:

cheers


I guess I've just got a light sensitive touch! Because mine goes tighter as I get up there and the rear mech starts to straighten right out.
I never use more than smallest 3 or 4 perhaps 5 cogs anyway. I will always then go back to middle ring because that's where the flexibility lies.

It's a honed technique!
I never lose track. Always stay sharply focussed. :wink:

You have not discussed the significant advantages?
The wider and lower available range.

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[XAP]Bob
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Re: Gearing question for recumbents.

Postby [XAP]Bob » 17 Feb 2018, 3:05pm

I tend toneun in the big ring all the time, which inevitable means that I run big-big at times, but since ICE sell this system with a single ring... how bad can it be?
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.

PDQ Mobile
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Re: Gearing question for recumbents.

Postby PDQ Mobile » 17 Feb 2018, 3:22pm

[XAP]Bob wrote:I tend toneun in the big ring all the time, which inevitable means that I run big-big at times, but since ICE sell this system with a single ring... how bad can it be?


Clearly not an issue with single front.
Or probably with most doubles.

Run on big ring all the time round here and you would simply have to push a great deal.
It's the chasing after a big range (with a focus on climbing and load lugging ability) with a triple that causes issues I guess.

I simply never have a problem.
And I climb hills! Slowly!

I would never run big to big on any bike.

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[XAP]Bob
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Re: Gearing question for recumbents.

Postby [XAP]Bob » 17 Feb 2018, 3:30pm

But *why* is it bad? I understand in a cross chained environment, but the trike has snnidler, so the cgsinline doesn’t appreciably change anyway.
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.

PDQ Mobile
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Re: Gearing question for recumbents.

Postby PDQ Mobile » 17 Feb 2018, 3:49pm

If it is crossed chained with high tension on any triple equiped bike, everthing is under more strain.
And the crossed chainline is undesirable both in high/ high and low/low combinations.
Chain (and transmission) wears best, runs best, straightish.

On a trike you can use those higher gears to start slowly I guess. Less useful on a two wheeler where a good fast push off is helpful.

Running a slighter tighter chain one can use a real granny gear up front. Climb those hills, tour in hilly country, etc.
Only compromise is that the two or three large cogs at the back overtighten things- they need a lot of chain comparatively. But why use them anyway?
The middle ring does it all better.

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[XAP]Bob
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Re: Gearing question for recumbents.

Postby [XAP]Bob » 17 Feb 2018, 3:56pm

But the chain isn’t crossed significantly on the trike
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.

PDQ Mobile
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Re: Gearing question for recumbents.

Postby PDQ Mobile » 17 Feb 2018, 4:00pm

I agree it is less of an issue with a long chain.

OldBloke
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Re: Gearing question for recumbents.

Postby OldBloke » 17 Feb 2018, 11:14pm

I ran 22/36/48 chain rings and 11-36 cassette on my trike. I inadvertently cut the chain a little short so that 48 on the front and 32 or 36 on the cassette would jam the derailleur into the cassette. At a minimum it would require getting off the trike and unjaming, at worst it could damage the cassette or the derailleur.

Cross chaining is never a problem on a recumbent, unless you ride a Cruzbike.

OB

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Cunobelin
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Re: Gearing question for recumbents.

Postby Cunobelin » 18 Feb 2018, 10:13am

[XAP]Bob wrote:Except that the large large combination is no longer counter indicated by chain crossing..



Setting up is no different

Each screw, tensioner, kinks in cable runs and everything else remains as it is for an upright

PDQ Mobile
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Re: Gearing question for recumbents.

Postby PDQ Mobile » 18 Feb 2018, 11:30am

Though presumably the tension through the drive train will be very high. Pretty much at the limit of rear mech capability?
It it always my impression that higher tensions reduce efficiency, the bike feels less "willing".
More wear on chain tubes rollers etc.

I personally can't see any reason whatsoever to use large/large (on a triple)?
The only step down then available is the big jump to middle ring which may well be too much and require the double shift anyway to maintain smooth cadence.

Though perhaps on a trike it's a bit different?

I understand the drive train danger concerns but as I already said personally I never ever approach large/large on the road.

Whereas I use small front to the largest five or six or rears all the time. I want them to change seamlessly.
Plus I want the big 50 ring up front.

My requirements are unusual perhaps, being faced with such steepness here. Up and down. Hey ho!!

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Tigerbiten
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Re: Gearing question for recumbents.

Postby Tigerbiten » 18 Feb 2018, 2:22pm

What's your total range ??
I agree that you want the maximum gear range that's easily possible.
I found that a long cage rear derailleur pushed to its limit will just cope with 49 teeth.
I split it 26 front and 23 back.
This gave me a 48-36-22 triple with a 9-32 cassette for around a 7.8x gear range.
I found no easy way of increasing the gear range without adding hub gears.
Hence I ended up with a HSD-Rohloff combo for an 18.7x gear range.

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[XAP]Bob
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Re: Gearing question for recumbents.

Postby [XAP]Bob » 3 Mar 2018, 12:39pm

I no longer have the capreo on the rear, so my rear range is slightly reduced there. But I have 22?4?/36/48 up front (IIRC) and that runs quite happily with the full rear range on the big ring. I am not often in ‘commuting bottom’ gear, but I do use it occasionally.
I can’t tell by feel/noise when I select it, I just can’t go down any further ;) the visual indicators are on the *outside* of my bars, since I found them annoying on the inside.

If I was loaded, or doing more serious hills etc then I’d undoubtedly be shifting down at the front, but on the commute it’s not necessary (especially not with the rear wheel motor to help out as well).
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.

nigelnightmare
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Re: Gearing question for recumbents.

Postby nigelnightmare » 3 Mar 2018, 2:11pm

PDQ Mobile wrote:I understand the concerns about large to large.
Yet in practice it is a combination that I personally would never use.
Not on any bike.
It's a poor technique. (ducks!)
I don't select 1st gear in my car at 70mph.


But you would select HIGH and 1st in a landrover or a large rig in certain circumstances, and also TOP gear LOW ratio.( NOT at 70 MPH though).

+ it is always better safe than sorry, A "loose" chain is ride-able "Broken" is NOT. :roll: And I know which one I prefer. :wink: