Sunday, January 13, 2013

Surly Pacer 650B conversion

At Auburn State Recreational Area

Surly Pacer with 650B wheels.

650B wheels are a size between 26 inch and 700c. They used to be popular in France many years ago with cyclotourists and utility bikes. More recently, Grant Petersen of Rivendell revived interest in this size and has produced several 650B bikes. Jan Heine of Compass Bike has also helped drive interest in this tire size.

One popular result of this interest has been the conversion of 700C bikes to the 650B wheel. This allows the rider to mount larger width tires, resulting in a bike that is a bit more comfortable and versatile and can be used on rougher dirt roads.

It turns out that the Surly Pacer, already one of my favorite bikes, is a very good candidate for 650B conversions. The clearances are just about perfect for a relatively easy conversion. Basically, all that you need are the wheels and associated tires, tubes and rim strips, and a very long reach brakeset. Fortunately, all of this is now readily available and pretty affordable.

For brakes, you will need something with a reach in the range of 70mm. Tektro now makes several models, including the 556 and 559. These are both very nice looking and well made. I chose the 559's, making sure I got the recessed allen nut type. I found some on eBay for $45 shipped! 

Tektro 559's installed; lots of room!

As you can see from the picture, these brakes have ample reach, and there's lots of room for adding fenders, (which I hope to do eventually). Installation was straightforward, the only change I had to make was to shorten the cable housing about 1cm, the Tektro's needed a little bit more cable than the Campy Centaurs.

Next, of course, you'll need some 650B wheels. I wanted this experiment to be very cheap, so I searched on the web and found a wheelset for $65 on Amazon. Tires, tubes and rim strips were all ordered. The tires I chose were the Panaracer Col de la Vie, about $21 each. 

The wheels are certainly nothing special, Weinman rims (ZAC19?), with a bottom of the line Shimano freehub and some unknown up front, but this is more or less a trial, so I don't really care if they last forever. Everything went together, but the Col de la Vie's do not want to seat evenly, they have a slight hop from a couple of low spots. It's not really very noticeable when riding though, so I'll let that slide for now.

Update-I found a solution to the tire seating problem. Something I learned from mounting a motorcycle tire; I sprayed "Endust" furniture cleaner/polish between the tire sidewall and the inside wall of the rim. Then I pumped the tires up to about 80 lb's. pressure. That did the trick, now the Col de la Vie's seat well on these rims!

 Rear brake install. Note that there's still some reach left on these 73mm reach brakes!

A look at the front brake, again, plenty of reach left over!

A head-on shot of the front fork install. Note the clearance of the 38C tires.

The photo above shows the one limiting factor of the stock Pacer in fitting a wide range of 650B tires. The 38C Col de la Vies fit fine, but you would be hard pressed to fit anything much bigger. I have seen conversions which have replaced the front forks with some of additional clearance. Personally, I think 38C is wide enough for my uses of this bike. I'd be shopping for a Mountain Bike if I wanted anything bigger, anyway.

 Plenty of room in the back though!

Finally, with the work completed, it was time to ride! I took it over the hill to Lincoln and was pleasantly surprised by the feel. With 75 lbs in the tires, they felt responsive and fast! The bike tracked and cornered well. It almost seemed like I was riding at one gear lower than usual. I wonder if this was a result of the smaller diameter tires?

 After it's maiden flight!

All in all, I found this a worthwhile project. Total cost was about $170. I think it really expands the possibilities of the Surly Pacer. I anticipate adding some nice metal fenders and probably upgrading the entire wheel set. Adding a dynamo hub and lighting, this would make a very nice and economical randonneuring bike.