Author Topic: Tandem drag brake  (Read 519 times)

DaT

Tandem drag brake
« on: July 17, 2020, 08:58:49 am »
I bought a tandem (Dawes horizon) for me and my wife a month ago and we’re loving it. It doesn’t quite fit her though and the brakes are poor for the hills in Cornwall. We still did 50 miles yesterday though which is double anything she has ever done before.

We have just purchased a Thorn Raven S&S Rohloff bike and it’s fitted with XTR brakes and CSS rims. The Rohloff hub can also take a disc as can the frame. What would people normally do, use a thumb shifter like on my previous ICE trikes?

Small side question. We don’t drive and want to use the S&S frame to take it on trains I presume we can just book it in as two bikes?

Tim Hall

  • I want to eat the fleeting shade of your lashes
Re: Tandem drag brake
« Reply #1 on: July 17, 2020, 09:12:23 am »
I've used a thumb shifter for drag brakes in the past, yes. 

Round these parts (Sussex) there's no booking required (or available)  to get a tandem onboard a train.

On services where booking has been required I had to book two spaces even though the tandem was in one piece. Services such as Great Western (or whatever they're called) to Cornwall have/had a guards' van which could easily accommodate a fully assembled tandem.
There are two ways you can get exercise out of a bicycle: you can
"overhaul" it, or you can ride it.  (Jerome K Jerome)

Re: Tandem drag brake
« Reply #2 on: July 17, 2020, 09:34:05 am »
Not got a drag brake on mine but I've seen a thumbshifter used. The other option is to fit a brake lever to the stoker's bars but that is fraught with communication issues.

Generally rail companies forbid tandems, but as they all have different rules you will have to check. If you are allowed on, in Cornwall you will have GWRs ICE abominations to deal with anyway. These have tiny bike compartments in which you are supposed to hang two bikes. It isn't impossible to do this, just inordinately difficult. Unless you are extremely lucky with the fold geometry it's not going to work with a folded tandem. If the folded machine is sherter and narrower than two solos you might be able to fit it in the space horizontally, but don't count on it.

Re: Tandem drag brake
« Reply #3 on: July 17, 2020, 09:35:45 am »
I have a Thorn Raven tandem with a similar specification to yours. 

Most train operators will expect you book it on as two bikes, I've seldom had to actually split it for train journeys as the most of the trains that run through Newcastle have decent bike stowage, (*new trains just introduced on the East Coast Line might change that).

I've been considering a second thumb operated rear disc brake myself but haven't bothered fitting one yet as I've never felt the bike lacking in stopping power. I guess if I were tackling long alpine decents it would be useful but round here, (Northumberland) it doesn't seem essential.

Re: Tandem drag brake
« Reply #4 on: July 17, 2020, 11:17:12 am »
I remember, years ago, we had a work ride to watch the rowing bumps near Cambridge. Two colleagues, (6 ft plus, ex-rowering and ex-rugby players) rode a tandem, and seemed to be making hard work of it. Eventually the tandem suffered a rear wheel puncture, and as I had tools, I fixed it.

It was when I burned my hand on the hub, they realised they had had the drag brake on all the time.  :facepalm:

That was a friction gear lever type.  ::-)

Hope this helps.  :demon:
If it ain't broke, fix it 'til it is...

Tim Hall

  • I want to eat the fleeting shade of your lashes
Re: Tandem drag brake
« Reply #5 on: July 17, 2020, 11:38:11 am »
I remember, years ago, we had a work ride to watch the rowing bumps near Cambridge. Two colleagues, (6 ft plus, ex-rowering and ex-rugby players) rode a tandem, and seemed to be making hard work of it. Eventually the tandem suffered a rear wheel puncture, and as I had tools, I fixed it.

It was when I burned my hand on the hub, they realised they had had the drag brake on all the time.  :facepalm:

That was a friction gear lever type.  ::-)

Hope this helps.  :demon:
I once struggled to get up Leith Hill under similar circumstances, although the drag brake was a thumb shifter type, operated by the stoker.  I think that we got as far as we did is a measure as to how efficient the drag brake (Arai drum) was on that bike.
There are two ways you can get exercise out of a bicycle: you can
"overhaul" it, or you can ride it.  (Jerome K Jerome)

DaT

Re: Tandem drag brake
« Reply #6 on: July 17, 2020, 03:19:07 pm »
I guess I’ll hold off on picking up the needed parts until I’ve given the brakes a go.

Re: Tandem drag brake
« Reply #7 on: July 17, 2020, 04:37:24 pm »
I have just acquired a similar Thorn.  It is my plan to add a mechanical disk such as an Avid BB7 and an extra brake lever for me, the stoker.

I haven't decided yet whether to make the disk the main brake with the XTR v brake the drag or just make the BB7 the drag.

DaT

Re: Tandem drag brake
« Reply #8 on: July 17, 2020, 04:54:57 pm »
Curiosity, how much was yours? I feel I paid the higher end of what is reasonable at £2100 but it will hopefully last.
https://tandem-club.org.uk/forSale?cmd=view&id=444

DaveJ

  • Happy days
Re: Tandem drag brake
« Reply #9 on: July 17, 2020, 05:45:58 pm »
We bought one second hand early last year.  We paid slightly less than that, but only slightly.

I too have been mulling over putting on a disk brake.  For us though, it means changing the end cap on the Rohloff first.  If we do, the disk will be the main brake, the V-Brake will get a thumbshifter, so it can be used as a parking brake, or an emergency brake.  The CSS rims do not appear to be much good in the wet with the V brake.

I don't think I'd want to use either the V brake or a disc as a drag brake.  Too much heat.  Our old tandem has an Arai, and that is a big lump of metal, and has the stubby little cooling fins.   

My daughter and her husband bought one last year too, for very much less, but they have had it resprayed to fix rust that was developing on the frame, and they had to have the Rohloff reshelled, by which time they have spent pretty much what we did.  Of course it does mean that they have the colours they wanted.

DaT

Re: Tandem drag brake
« Reply #10 on: July 17, 2020, 06:05:57 pm »
I should add that price is hand delivered to my door that is a 170mile round trip! This was important to us as we choose not to drive which means getting any large bike can be a PITA.

Re: Tandem drag brake
« Reply #11 on: July 17, 2020, 06:51:31 pm »
Curiosity, how much was yours? I feel I paid the higher end of what is reasonable at £2100 but it will hopefully last.
https://tandem-club.org.uk/forSale?cmd=view&id=444

It was a little cheaper than yours and it will be delivered on 9th August by a special courier known in these parts as The Velomancer.

Tandems are strange beasts because their spec makes them more difficult to shift.  Ours is a L/L, not generally a popular combination.

Re: Tandem drag brake
« Reply #12 on: July 18, 2020, 07:45:08 am »
A word of caution! A disc brake is NOT a proper drag brake like the old Arai drums used to be. You have to use the disc for short intervals and let it cool down in between. Otherwise the disc will warp from overheating and possibly lock the rear wheel. On our tandem, the disc is operated from an mtb brake lever on the (flat) stoker bar. S use it only for short runs when I ask her. You really need to talk to each other!

A

DaT

Re: Tandem drag brake
« Reply #13 on: July 18, 2020, 09:08:47 am »
Maybe the drag brake on the rim then?

Re: Tandem drag brake
« Reply #14 on: July 18, 2020, 09:45:26 am »
I really would not use a rim or a disc brake as a drag brake.

The old Arai drag brakes were terrific for moderating speed on long descents, they were designed to produce a low but constant braking force and were able to absorb and disperse the heat produced by continuous braking.
Using rim brake in that fashion could overheat the rim and cause a blow-out.  Using a disc in that fashion can warp the disc and boil the oil, (if not mechanical).
The best approach for a third tandem brake these days is to treat it as an alternative of redundant rear brake.

When used as an alternative brake descending big hills the idea is to moderate speed by alternating between all three brakes, thus ensuring that no one brake surface becomes too hot.

Used as a redundant brake means that its simply there in case of primary brake failure.       

Re: Tandem drag brake
« Reply #15 on: July 18, 2020, 09:52:32 am »
Interestingly, we once owned an ICE tandem trike which was fitted with two rim brakes on the rear wheel which were both ratchet operated.

An odd arrangement really as;
a. recumbent trike rear brakes are only ever used as parking brakes, all the stopping power is in the two front brakes.
b. even if one was intended as an alternative or redundant brake it’s still acting on the same surface as the primary.

Re: Tandem drag brake
« Reply #16 on: July 18, 2020, 09:56:13 am »
When I had my Moulton ATB converted to a tandem with a central insert into the separable frame, a Rohloff hub with disc brake was also installed. The original rear rim brake was retained with the lever on the stoker's bars, as an emergency extra brake. This has never been used as we don't do major ascents and descents, but it provides reassurance.

LittleWheelsandBig

  • Whimsy Rider
Re: Tandem drag brake
« Reply #17 on: July 18, 2020, 09:59:15 am »
Deep section aluminium rims (non-ceramic) have enough mass and surface area to avoid overheating when used on tandems doing long descents. Ditto disc brakes with a 200+mm rotor.
Wheel meet again, don't know where, don't know when...

Re: Tandem drag brake
« Reply #18 on: July 18, 2020, 10:00:25 am »

My daughter and her husband bought one last year too, for very much less, but they have had it resprayed to fix rust that was developing on the frame, and they had to have the Rohloff reshelled, by which time they have spent pretty much what we did.  Of course it does mean that they have the colours they wanted.

We did the same a few years ago. Best bargain to ever come my way, Rohloff tandem with S&S couplings and many other extras for less than the price of a new Rohloff.
The paint was in a shocking state but once Bob Jackson had done their thing it was like new.   

Re: Tandem drag brake
« Reply #19 on: July 18, 2020, 10:04:36 am »
Deep section aluminium rims (non-ceramic) have enough mass and surface area to avoid overheating when used on tandems doing long descents. Ditto disc brakes with a 200+mm rotor.

I have noticed that many tandems now seem to have rather large rear discs and wondered about their heat shifting abilities.  I've only ever seen them set up with hydraulics though, anyone using a big disc with a BB7 or similar?

LittleWheelsandBig

  • Whimsy Rider
Re: Tandem drag brake
« Reply #20 on: July 18, 2020, 10:08:27 am »
Avoid tandem disc brakes with plastic components, both cable and hydraulic. They melt in severe terrain, killing the brake surprisingly quickly. BB7s use plastic adjusters, though the main mechanism is metal.

Last century, I had to walk out a disc MTB tandem several times after various brake and disc failures. It was a painful learning experience... Brake technology has improved but there are still many disc brakes with inherent weaknesses.
Wheel meet again, don't know where, don't know when...

Re: Tandem drag brake
« Reply #21 on: July 18, 2020, 10:09:41 am »
OK, let's be more pedantic.  Having read the jdtandems view on brakes as well as many others, I would prefer to swap my rear v-brake for a rear cable disk.  The rear v brake will be left in situ as a backup brake and for any cheek-clenching extra duties.

I don't think that we will have the need for a traditional drag brake to be honest.

Re: Tandem drag brake
« Reply #22 on: July 18, 2020, 07:41:46 pm »
We are just back tonight from a week in the Pyrenees, and I can now say two things for sure:

1)A third brake is an absolutely necessary item.
2) For a heavy team with heavily loaded panniers, two rim brakes plus one disc may even not be enough.

Let me explain. On all long descents, we use the three brakes in turns to let them cool down in turns. On one long descent, where we lost 300m of altitude in 5 km, S told me that the disc smelled like it was toasted, but everything went fine anyway. Then, the next day, on a very steep and twisty secondary road, I had to keep braking all the time, until we blew out the front tube. Fortunately, only the tube was damaged, the tyre was fine, so we changed the tube and continued the ride.

What we didn't realize at the moment was that the overheating probably weakened the rim tape enough, so the next day, another puncture due to the rim tape collapsing through a spoke hole. I saved the day by putting a piece of old tyre between the tube and the punctured rim tape, and we kept riding while praying for no other spoke hole decides to swallow a tube before we reach the next bicycle shop. Then we bought new rim tapes, and nothing bad happened until the end of the tour!

A

LittleWheelsandBig

  • Whimsy Rider
Re: Tandem drag brake
« Reply #23 on: July 18, 2020, 07:45:34 pm »
Velox rim tapes, rather than plastic, are the best option for tandems. They seem to be mostly immune to high temperatures.
Wheel meet again, don't know where, don't know when...

Re: Tandem drag brake
« Reply #24 on: July 18, 2020, 07:54:22 pm »
Yes, we had plastic rim tapes, and I think we will change for cotton tape as soon as we are back home.

A