This bike started out with a story. Back in 2010 I was looking for a used tandem for family adventures. After a bit of searching, I found a nice-looking candidate at a good price on Craigslist and made an appointment to see it up in Marin. I took the kids with me and they got to see one of the strangest deals ever. We arrived and took it for a quick test spin to check fit and function. We decided this would be a great bike and began the required gentle haggle because one must at least ask.
As we were doing it, we discovered that another buyer had an appointment scheduled also and he arrived. We both wanted the bike. You could see the seller getting excited about the bidding war to come. But no. Buyer #2 did want it, but was unwilling to raise the bid nor was I. Apparently, we both felt it was the right price and not one to bid up. So Buyer #2 and I agreed to flip a coin for it 🤷. The seller was clearly not thrilled but what can he say? We were both offering to pay the asking price. As you can probably guess, I won the coin toss. 😀
As purchased, it looked like this:
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| 1994 Frame Spec |
So we did all sorts of things with it. Sometimes my wife and I using it 'normally' with or without the kids. And sometimes turning it in to a full on bike train.
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| Early days with my eldest as stoker (barely) and youngest riding in the trailer |
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| And later with the youngest making up a flexible triple on a Trail-a-bike (Tour de Menlo) |
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| And eventually, the kids going out themselves |
Eventually usage went dormant as happens. It was collecting dust hanging in the garage. But eventually, as I started all of these rehab projects, I decided to tackle rehabbing it and upgrading a few things that hadn't been right before.
2023 Updates
Normal Stuff
- Standard cleanup to see whaat's going on
- Replace all the cables and housings to fix the sticky shifters and brakes
- New chains (the old ones had unfortunately rusted and figured that 30 years was enough) But this becomes kinda tricky. Tandems don't just have a drive chain, they also have a sync chain between the two riders' cranks. This is really long, particularly on such a big size. I had to use two chains and link them together to get the length. But tensioning it, led to the next interesting problem:
- The eccentric: Tandems do interesting things to adjust the distance between the two cranks to set tension. One method is for the forward bottom bracket to be massively oversized and use an eccentric fitting inside that rotates to move the crank spindle forward and back to adjust tension. All fine, if you can move it. But years of sitting in place made it quite a challenge. The way it works is that the cylinder of the eccentric is sliced at an angle with a bolt that pulls it tight to lock it in place. Over the years, that got stuck. But there's not really anything to get ahold of to apply force. The internet to the rescue once again. I found a reference to an elegant and effective solution. You remove the tightening bolt and reinstall another from the other side, threading into the wide end of the wedge. By placing a stack of washers under the bolt against the frame, the bolt can be turned until it applies enough force to pop the wedge free.
- Clean and service the rear derailleur. It was a bit of a mystery as the spec says it should be an LX but it was an XT. But the design didn't match the expected M735 7-speed of the era. So presumably it is an 8-speed (doesn't matter) RD-M737-SGS in great shape after cleanup.
- Shifters. Ugh. 90's trigger shifts. Care to guess what was wrong? Yeah, the mechanism was gummed up and missing shifts. The quick solution of shooting WD-40 in to flush didn't work well enough on the front one. Ended up having to disassemble and clean to get it working again. Very fiddly.
- 7-speed Cassette was in great shape after ultrasonic cleaning.
- Replaced damaged stoker bar tape and pilot seat. Fresh grips on the pilot bars along with some nice carbon fiber 90s bar ends for hand position options.
- New tires: Back to something resembling a mountain bike. Panaracer Gravelking SK+ 2.1" (53mm) since there is plenty of room (unlike road bikes of the era). The frame could have fit 2.2" and maybe even a touch more. But between the rim brakes (wheel installation challenges) and the fact that these are '90s rims which were sturdily built but only 16mm wide inside. 2.1" is already pushing it and can't be run at low pressures as the get to wobbly. But they work fine at 90s pressures.
Complicated part
The idea of these brakes was that in that large cylinder is a screw ramp. As you apply the brakes, the forward forces from the rim translate into increased torque to clamp the pads tighter. A form of power brakes on a bike converting kinetic energy of the bike and riders into braking power. Nice.
Well, kinda. They don't actually work all that well. Modulation is a bit tricky as part of it is automatic and not fully predictable, particularly as they age and move less smoothly. But the real dealbreaker is that they've been known to malfunction and fail to stop or not release. Neither of which is really a good thing.
I'd bought a pair of NOS Avid Shorty 4 cantilevers years ago which had been sitting on the shelf waiting to be installed. Now was the time. But as often is the case, the 'plug and play' part swap, isn't really. The problem in this case was that the old brakes used a conventional straddle cable where the geometry of that straddle and the cable housing coming to it can be quite flexible. The Avid Shortys use a through cable to one side and a fixed length bridge to the other side that have a pretty specific need for where the cable housing stops. And it was not compatible with what was on the bike.
After lots of internet browsing and a couple of failed experiments, I eventually found some housing hangers that solved the problem.
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| Front hanger bolts into fork crown bolt hole |
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| Rear hanger inserts through the seatpost quick release |
Finished the job with Jagwire compressionless housing in tandem length. Compressionless is a modern upgrade that is perfect for this application with such a long brake run. It reduces the 'squish' in the brake cable to make the brakes more easily modulated and powerful.
In the end, a big improvement in braking feel and performance with the Avid Shorty 4 and fresh cables.
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