HER c1989 TREK 1100
A 650B Conversion

Last Updated: 04/22/2010

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We got this bike for my wife right around 1990, or maybe a bit before. The hope had been to find her a sport touring bike and this was what Trek had to offer. It came with short reach brakes, a tight geometry the biggest tires that could be stuffed under the brakes were 700x25s.

She rode this bike for a few years but never really took to it. About 5 years ago, she took a nasty spill on it, dropping the front wheel out from under herself at low speed on a slick surface. She hurt her hip pretty badly and since that time, has really only ridden her steel mountain bike which we converted to a flat barred touring type of bike.

My hope in converting the bike to 650B was that wider tires would make the bike more comfortable and that has a more stable, secure handling. Gratification was immediate. She took the bike out for a quick 10 minute ride around the block and came back an hour later with a big smile on her face. That was priceless.

I'm not a 650B afficionado by any stretch of the imagination. I've received several question about the conversion process and will share what I can here.

The Trek 1100 was one of many bikes that Trek sold through the 90s as a sort-of replacement for a sport-tourer. But they were more sport than touring. Generally speaking, these bikes had the same geometries as all of the Trek mid to low end racing bikes. This may bode well for people wanting to convert other 90s vintage Trek aluminum road bikes. The only concession to touring was that they shipped with triple cranks and had eyelets on the drop outs.

One important thing to note about this 1100 is that it was old enough to have a traditional lugged fork crown. By 1995 (and maybe earlier), Trek was using unicrown cr-mo forks, which may limit clearance compared to this 1100.

The wheels were purchased from Rivendell as built up wheels. They use Velocity Twin Hollow rims and lower end Shimano hubs. The rims were pretty much true out of the box, requiring only minor tweaking. They were definitely ridable out of the box.

The tires on the bike are Panaracer Col De La Vies, which are labeled as being 38mm. The limiting point in terms of clearance is definitely between the chainstays, just behind the bottom bracket. These tires fit but I wouldn't want to try anything any bigger.

The hubs came spaced for 130mm OLN spacing, which is slightly problematic since the frame is spaced for 126mm. By 1995, the Trek aluminum frames were spaced at 128mm so they could accept either 126mm or 130mm wheels (I know this since I used to own one). But, this 1100 was old enough to be set at 126mm and it didn't make sense to push the issue, so I down converted the hubs to 126mm spacing. In a nutshell, I reversed the process described by Sheldon Brown here. Luckily I had a spare 7spd freehub kicking around in the parts bin.

The one issue not mentioned on Sheldon's page is that the freehub has a dust cap inside the outer mouth of the cup section that must match the cone precisely to make a good seal. The dust cap on my 7spd freehub didn't match the cones on the new hubs, so I needed to swap the dustcaps too. With both freehubs off, I put a large screwdriver in through the back of the freehub and gently tapped out the dust caps in order to exchange them. If you attempt to do this, note that they dent easily, so be careful. I reset them by tapping with a block of wood. Once things were reassembled, the hubs fit perfectly with no additional fiddling with new spacers. Of course, the rear wheel needed to be redished after this.

There was also an issue with the brakes. I had a set of long reach Dia-Compe centerpulls that I had been saving for this project but this frame, like most of this era, uses an internally run rear brake cable that exits from the top tube just ahead of the seat post. Another complication is that this bike uses a fast back seat binder bolt assembly with a recessed bolt. This meant that the only type of rear brake hanger that would would work would need to be the type that hangs off the binder bolt. But, a short hanger would cause too radical of a bend between the exit from the top tube and around the seat post while a long hanger (like the Surly) was so long that it interfered with the straddle cable of the centerpull. So, I just went with the Tektro long reach calipers and it was a super easy matter of unbolting the old calipers and putting the new ones on. I didn't even need to recable.

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