Is it too Highly Geared ?

[Illaveago]

This may seem like a bit of a how long is a piece of string question?
I'm new to being a tandem owner and rider . My bike is an old Coventry Eagle Triple Ace Convertible Tandem . It has a Sturmey Archer 3 speed which at the moment is being operated by a Shimano friction shifter. The proper one has the cable stuck inside it at the moment .
I have done a couple of test rides of about 5 miles on it in tandem form riding solo. My pace seems to be similar to that of my steel racing bikes around 10 -12mph average speed .
The other day I think I found the lowest gear, as I say it is a bit hit and miss. My cadence was slower than on my road bikes on the flat but on any gradient it slowed even more . The bike is fitted with a 46 tooth chainring . I don't know what the rear sprocket is.
My questions are. Would the input of another rider change things or would it remain the same as you would be carrying extra weight ? The second question is . Should the lower gear on the Sturmey Archer have given me a much higher cadence ?
To me it seems as though the chainring may be suited to the single rider set up .

 

[Tigerbiten]

You've 3 factors to take into account on a tandem.
You've around 2x the leg power, about 2x the weight but only 1.??x the wind resistance vs a standard bike.
So on the ........
Flat:-
With ~2x the power and only 1.??x the wind resistance you'll probably go an mph or two faster for the same power input from each rider.
Downhill:-
Which ~2x the weight and again only 1.??x the wind resistance you'll probably pick up speed faster and hit a higher top speed.
Uphill:-
With ~2x the power and ~2x the weight you'll climb around the same speed.
Until you run out of gears down.
Then you may well find it's very hard/impossible to pedal while out of the saddle for any extra power.

So with the limited range on a 3 speed hub it's a question of ....
Do you gear it up slightly to take advantage of the higher flat speed, but hill climbing will be harder.
Do you gear it down to make it easier to climb hills, but you'll spinout at a lower speed.
Or do you split the difference and keep the gearing balanced.

Luck ...........

 

[Illaveago]

You've 3 factors to take into account on a tandem.
You've around 2x the leg power, about 2x the weight but only 1.??x the wind resistance vs a standard bike.
So on the ........
Flat:-
With ~2x the power and only 1.??x the wind resistance you'll probably go an mph or two faster for the same power input from each rider.
Downhill:-
Which ~2x the weight and again only 1.??x the wind resistance you'll probably pick up speed faster and hit a higher top speed.
Uphill:-
With ~2x the power and ~2x the weight you'll climb around the same speed.
Until you run out of gears down.
Then you may well find it's very hard/impossible to pedal while out of the saddle for any extra power.

So with the limited range on a 3 speed hub it's a question of ....
Do you gear it up slightly to take advantage of the higher flat speed, but hill climbing will be harder.
Do you gear it down to make it easier to climb hills, but you'll spinout at a lower speed.
Or do you split the difference and keep the gearing balanced.

Luck ...........

Thanks .
As I say I'm new to this type of bike and I haven't yet tried it 2 up . My wife was the intended pillion and isn't that used to bikes. The new one she bought hasn't been ridden much .
Going from my test rides I'm wondering If the bike was geared for single use being the main setup and as in their advert was converted into a tandem for the weekend . I was wondering if I changed the rear chainring for a 44 instead of a 46 it would lower the ratio just enough to make it a bit more rideable. It would make it easier for my wife to pedal . That is if she ever climbed aboard!
As I say it will be a new experience for the both of us . I'm wondering if it would be better to try it out with a more experienced rider on the back at first ?
There isn't any rush at the moment as there is still some work I need to do on the bike but I would like to try it at some time .

 

[davidphilips]

Bit of how long is a bit of string as you say, what may be a reasonable idea is wait until you get the gear shifter sorted and then try the tandem with your wife? theres the chance if you do change the gearing now and dont get it right then may have to change it perhaps back to the present gearing.
Know the old sayings dont fix some thing thats not broken. or dont look for problems? Good luck with the tandem and can you let us know how you get on.

 

[Illaveago]

I think one of my problems is trying to figure out in which way the gearing works . I haven't used a Sturmey Archer 3 speed before. I know that you stop pedalling when changing gear but as to how the gearing works is another matter . Does it gear up or down ? I've never contemplated it before. Just going by my couple of rides it seems as though first gear is about bearable one up without a headwind. 2nd or 3rd seem to be like overdrive . It is a puzzle as to how many years I have at the moment as it is a bit of a lottery. It's a "Ah that feels better" technique.
As for having too high a cadence when it comes to going down hill I'm very good at freewheeling .
Swapping over a chainring either way wouldn't be too much of a problem , cotter pin out and either add or remove a few links .

 

[figbat]

The Sturmey Archer 3-speed gears up and down. The middle gear is direct drive, with the top gear overdriving and the bottom gear underdriving. The AW hub (the most common one) goes + 33% and -25%. For all you’ll ever need to know about them, look here.

 

[mickle]

Sturmey Archer 3 speed hubs aren't ideal for tandem use, unless you're just cruising up and down a boardwalk. If you change the sprockets to give better hill climbing ability the torque generated by two riders will kill it. I know for sure that SA hubs are not rated for mountain bike use, so it's very unlikely that they are tandem rated.

 

[figbat]

Sturmey Archer 3 speed hubs aren't ideal for tandem use, unless you're just cruising up and down a boardwalk. If you change the sprockets to give better hill climbing ability the torque generated by two riders will kill it. I know for sure that SA hubs are not rated for mountain bike use, so it's very unlikely that they are tandem rated.

Yes - I’ve also seen it written that one shouldn’t even stand-up-pedal with a SA hub.

 

[Chris S]

I swapped the 19T sprocket on my Sturmey Archer 3-speed for a 21T one. It reduced the top gear from 84 inches to 76 inches and actually made it usable.
I know that on conventional SA bikes the chainring must have at least twice as many teeth as the sprocket to prevent torque damage. It must also be at least this on a tandem with two people pedaling.

 

[Chris S]

Yes - I’ve also seen it written that one shouldn’t even stand-up-pedal with a SA hub.

That's because they can slip into neutral and topple you over.

 

[CXRAndy]

Sheldon brown has internal hub gear calculator. This will help you understand ratios, speed, cadence etc.

Knowing what cadence you're capable of maintaining will also help the calculations to which gearing is best.

Do you have a cadence sensor?

 

[figbat]

That's because they can slip into neutral and topple you over.

My understanding, and experience, is that under load the gears will stay firmly engaged. If you try to shift whilst loaded the gear will stay engaged until you unload the hub, at which point it’ll shift as commanded. I thought the stand up advice was for the same reasons as mentioned above - the pawls in the hub won’t like the torque.

 

[Tigerbiten]

The risk is not all the pawls engage evenly and/or fully.
The more stress you put on the hub, the more likely this is to happen.
Eventually one of the pawls doesn't even engage.
The off centre forces are then enough the kill the hub.
But Brucey over on the CUK forum is the person to ask about all things IHG.

Some more useless info ..........
With the right gearing the two 33% up steps of the hub will give you 3 optimal speeds, something like 9mph-12mph-16mph.
A old standard 53-40-30 road triple has the same 33% steps between the chainrings.
The old standard 14-16-18-21-24 5 block again has roughly the same 33% step between the 14-18-24 sprockets.
That is assuming you do have a 33% step between the gears.
SA did/do make other hubs with narrower/wider steps between their gears.

Luck .......

 

[davidphilips]

Just looking in my parts bin, have a new unused 13 teeth sa sprocket if any one can make use of it, will send free?

 

[Chris S]

My understanding, and experience, is that under load the gears will stay firmly engaged. If you try to shift whilst loaded the gear will stay engaged until you unload the hub, at which point it’ll shift as commanded. I thought the stand up advice was for the same reasons as mentioned above - the pawls in the hub won’t like the torque.

That's what's supposed to happen in theory. In practice they slip even if the cable is only slightly out of adjustment.