1970s Sears Sportflite Tandem Restomod

Here's another one of those things that I thought I'd never have the reason to build: A tandem! 

My girlfriend, who has yet to successfully ride a bike on her own, thought it would be fun for us to get a tandem. I thought she was kidding, but when I came across this Sears Sportflite at the local bike co-op (Free Ride), she gave the green light.

Obviously, there are caveats against couples riding tandems especially if one of the riders hasn't ridden a bike before, but that was a risk we were willing to accept. There are also other words of advice based on real life such as "whatever direction your relationship is going, you'll get there faster on a tandem." Challenge accepted.

One of the first things I did to the bike after walking it 5 miles home was swap out the rear handlebar clamp for a 50mm 1-1/8" threadless handlebar stem. It was a perfect fit and better in every way.

To skip right to the chase, the bike needed a lot of work. I also ended up doing a lot more work than I needed to do, as always. For a period of six or seven months, I tinkered on and off and brainstormed along the way. The first hurdle was that my girlfriend lives in Pittsburgh's Hill District, which obviously meant that the single speed coaster brake drivetrain was not going to cut it. The coaster brake hub was also shot, giving me more encouragement (that I didn't need to begin with) to swap out the entire drivetrain.

Upgrading to a derailleur drivetrain meant using a narrower 3/32" chain, and therefore removing the 1/8" chainrings. I used the same one-piece to three-piece bottom bracket adapters that I had used before, as well as some generic cartridge bottom brackets. I chose two sets of the same cranks - early '90s Shimano Exage - so that I wouldn't have to worry about a mismatched chain line. I found one set in 170mm and one set in 165, which was perfect for us.

Chain tension was a headache (or not, depending how you look at it). The chain was almost tight enough to be perfect without a tensioner. I decided to retain the Biopace 42-tooth rings on the cranks, which actually wasn't the issue. The real issue was that the little idler pulley between the two cranksets was too far inboard to engage with the chain, and that distance was not adjustable. I thought about using a 53-tooth ghost ring which actually fit perfectly, but I was worried that one of us would accidentally kick it while riding. I ditched any sort of chain tensioner idea and it seems to be fine so far.

As a side note, I should swap the black chain ring for a narrow-wide because losing the rear chain while riding this bike would not be pleasant.

I had some special components that I had collected for no reason a while back, including a V-brake adapter which went over the rear wheel, and a Shimano roller brake cassette hub. I figured that having the extra brake couldn't hurt, despite the fact that the roller brake was no substitute for a real Arai drag brake. We don't plan to go super fast anyway, but I will keep a close eye on the brakes to see if they really are okay for us. The rear drivetrain is a 13-34 tooth 7-speed cassette with a Shimano Tourney derailleur and twist-grip shifter. 

Other previously-hoarded parts include 1970s Schwinn mattress saddles that were installed on bikes such as the Suburban and Twinn. They are far better than the colored saddles that came on their other upright bikes, and in my opinion, far underrated for casual riding and commuting. I had several that I pulled off bikes that were being junked and they were perfect for this bike. 

For rims, I opted for Sun Mach IV alloy rims with eyelets for strength and machined brake tracks. The front end got a new V-brake fork. 

I discovered after buying a new (old stock) fork and headset that the bike actually used what was closer to a 1-1/8" headset. Of course, being a Sears bike, the tandem had odd dimensions and poor fit and finish, so I had to use a Dremel to smooth out the inside of the head tube. I smashed a Ritchey Logic headset into the bike, surprising myself with the hardness of the cups. 

Because the original front fender was screwed directly into the fork crown and did not have a mounting bracket, I used the pivot from an old Weinmann drop bar brake lever as something to screw the fender into. I suspended it in the middle of the steerer tube with rubber washers to prevent it from banging around loosely. 

The bike was originally a single-speed, which meant that the rear spacing was 110 mm instead of the 135mm it had to be to fit the new hub. I used a cheap headset tool and flipped it inside out to spread the stays. The dropouts were re-aligned with an adjustable wrench. 

I chose to build a Shimano dynamo hub into the front wheel of the bike to power LED lights. I wasn't exactly sure if it was necessary but I figured that we did a lot of stuff at night and the dynohub was cheap, so if I was going to build a wheel anyway, I may as well use the dynohub. 

Also pictured above are the Blackburn front rack and Topeak Explorer rear rack. Both were acquired used for very little money - perfect. 

Every single one of the stickers I showed in the last post were applied to the seat tubes of this bike. There wasn't much of a reasoning for it, but it just felt appropriate. 

My current living arrangement is great for this bike as it allows me to store it under a motorcycle cover on the back porch, so that's where it stays. We have test-ridden the bike with success, but since it was already getting cold by the time I finished it, we will probably really start to ride it more next spring.