about drum brakes on a tandem

ugo.santalucia

I just bought a vintage Reynolds 531 tandem frame for 40 quid, but it is meant to be fitted with drum brakes. I can drill the fork to take a front caliper, but the rear has to be a drum brake, I fear...
I did a bit of reading about drums... are they really that bad as Sheldon Brown says? I mean, this is not a bike to come down the Galibier and 1/4 a mile at 8% is probably as much downhill as it will ever see... we might use it to do a few vintage bike events on the flat/mildly rolling side, but nothing extreme.

Also, anyone has any experience with Shimano Nexus roller brakes? Are they better than normal drums? And are the basic 45 and 55 models just as good as the premium Nexus 80 ones?

Lots of questions...

woolwich

Sorry I can't help with the brake questions. Any reason why you couldn't find someone locally to retro fit a brake bridge or Canti/v mounts?

ugo.santalucia

All for nothing...

I picked it up today and the bridge is indeed drilled.

The problem is the rear bottom bracket shell... 73 x 36.2 mm... what kind of size is that? Standard british thread doesn't fit. Luckily there is a BB fitted, but it's not in pristine conditions, so to speak...

Edit: Chater Lea bottom bracket... better look after those cups... :roll:

andy_wrx

I know you've said the question doesn't apply any more, but we had a Suzue drag brake on the back of our tandem, about 6" diameter, weighed a ton and had no quick cable release meaning you had to do a fair amount of disassembly to get the wheel out, which wouldn't have been ideal in case of p*nct*re.

It was intended as a drag brake, operated by the stoker in addition to the front&rear cantis the captain had.
The idea being that you didn't get stiff hands braking all the way down a huge Alpine descent (instead the stoker did !) and you wouldn't heat up the rims.
The stoker had it on a very cheap MTB brake lever on their bars, but I've seen some where they're controlled by a MTB thumbie gearshifter, where you could click them on a notch or two and just leave them on for the whole descent.

Braking power was shite, basically. It may have worked to slow you on a long descent, but as a riding-about stop-quick brake it was hopeless.

Although the bloke who sold it to us told us to be careful as his teenage son and a mate had done Mcr-Blackpool on it the year before, and the mate on the back had panicked going round a roundabout, yanked it on, the tandem had crashed and he'd lost several of his front teeth...

ugo.santalucia

OK,

you have a point. I think I will go for long drop calipers, which should go on no problem, just need to enlarge the bore for a recessed nut, I've done it before, it's pretty straightforward.

Now the question is... gears? I'm thinking of getting a 105 rear hub (130 mm spacing) and for now fit spacers and a single sprocket and maybe in the future see if we need gears or not.

Stupid question: the gear ratio is dictated by the stoker chainring/ sprockets... the size of the captain chainring is irrelevant, yes?

ElectronShepherd

Usually the size of the captain's and stoker's timing chainrings are the same, so that actual number of teeth on both has no effect on gearing.

Not always though - see http://www.davincitandems.com/drivetrain-info/ for an alternative approach.

ugo.santalucia

I thought so.

Gear ratio... for the flat I would think something along the lines of 52 x 20 or 18 would be perfect, but on an incline it would be a bit on the hard side. 2 engines but more than twice the weight...

Maybe 48 x 20 is safe?

andy_wrx

You can often run a higher top gear on a tandem - twice the power, less than twice the drag.

They're usually quick on the flat or on long uphill slopes (and can be stupid-quick downhill !), where you lose-out is on the steeper uphills, particularly as novice tandem couple as you end-up putting lots of effort into keeping the thing balanced, fighting oneanother - this gets considerably better as you get better at it, smooth-off your power deliveries and become more in-tune together. Don't try honking out of the saddle together in week 1.

Think of it as a powerful diesel lorry - loads of power, accelleration not so great but speeds high when you get it going, manoeuvrability rather ponderous.

The captain has the steering, brakes & gears - weight-shift steering and balancing takes more effort than you'd think, thus captain should be the bigger, heavier stronger person.
The stoker does the signalling, looking over shoulder to see if it's clear behind, etc so captain keeps both hands on bars.
Stoker can also navigate, even using a map on the move !

Best way to start-off - without skinned shins and swearing at each other - is for captain to straddle bike and apply brakes, then stoker gets on and clips-in, when stoker says they're ready and it's clear behind then captain pushes-off, stoker soft-pedals initially whilst captain clips-in.
Stopping is reverse - stoker stays clipped-in, captain brakes to stop and straddles bike, stoker unclips and gets off.

Communication is really important - stoker can't see what's coming and doesn't appreciate being taken over a pothole without warning. A swerve to go round a parked car is alarming if sudden and unexpected. Retaliation is that stoker can jab captain in kidneys.
The captain should not fart - ever.

ugo.santalucia

good advice there, Andy

Here is how things are at the moment. Would like to build it up in time for the retro ride in Amersham in mid July, but that might not happen. At the moment I am sourcing shims and sleeves to make obsolete standards compatible with normal standards...