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My I.R.O. Nexus 8-speed with 584 mm (650B) wheels

by Sheldon "Why Be Normal?" Brown

February 4, 2005

I own more fixed gear bikes than any reasonable person would, and one of them was an IRO Jamie Roy. I got it as a frame only, built it up with a Winwood plastic fork that I bought in a weak moment. The plastic fork was supposed to give a comfy ride, but I never found it to be so. There was only clearance for a narrow 28 mm tire in the fork (though the rear clearance of the IRO frame was lots better.)

For a while I had it set up with a suspension fork, as you may see below. This was an improvement, but I needed the fork for another bike so I put the Winwood back on and hung the bike on a hook.

Rivendell's Grant Petersen and a number of folks on the BOB email list have been touting the advantages of switching skinny-tire road bikes to 584 mm (650B) wheels, as used on classic French touring bikes. Since I wasn't riding the IRO much, it seemed like a good candidate for this.

I really do have a LOT of fixed gear bikes, and we had just received, at long last, a shipment of the new Shimano Nexus 8-speed internal gear hubs, so I decided to build the IRO up as an 8-speed.

It has only been together for two days, and the weather is slushy and icy so I've only got about 5 miles on it so far, but I thought folks might be interested in seeing it.

I must say I really do like the ride of the 584s. It's got Panaracer Col de la Vie tires, 38 mm width, running at about 50 psi, which makes a HUGE improvment in the ride of the bike. The smaller diameter compared to the original 622 mm (700C) tires turns niggardly clearance into fairly generous clearance, viz. the fact that I was even able to mount an SKS/ESGE P35 fender on the Winwood fork with the 38 mm tire, where previously a 28 mm tire all by itself was a tight squeeze.

The Nexus 8-speed hub seems quite nice so far, but I'm finding it a bit confusing because the twist shifter works in the opposite direction from the Rohloff shifter on my Thorn Raven. I think I'll need to reverse the cable connections on the Rohloff, fortunately a trivial job.

Spoke Divider

March 10, 2005

I put about 130 miles on this bike in February and early March and I'm just loving it! It turns out to be surprisingly fast. I've been surprised at how much of the time I'm spending in the top three gears.

Gearing:
Gain Ratio 9.07.96.85.64.74.23.62.9
Gear Inches1151018771.260.653.245.837.5
Meters9.28.17.05.74.84.33.73.0

Later Thoughts

I wound up riding this bike quite a lot after the section above was written, and it became one of my favorite bikes to ride, back when I was still able to ride bicycles.

I liked the Nexus 8-speed hub so much that I wound up buying a second one and putting it on my old Raleigh International.

07

Click on thumbnails for large images.
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Below is the previous version of this page, with the previous version of this bike:

My I.R.O. Fixie

iro-boing1
I got this I.R.O. Jamie Roy frame last summer. It came without a fork, needed a 1 1/8" size. I bought a plastic Winwood fork for it rode it a bit, but wasn't entirely happy with it, mainly because of the fork. The ride was pretty harsh, and the Winwood fork didn't have room for fenders or even for a medium width tire.

Recently, I came upon a closeout deal on some NOS Rock Shox Indy forks, not the latest technology but unusually light for suspension forks. I decided to try one on the I.R.O. The frame was built for 622 mm (700c) wheels, while the Rock Shox for was designed for 559 mm (26" mtb size) wheels. However, the frame was also designed for a tight clearance fork, while the Rock Shox has tons of clearance. Thus, the smaller wheel size and the taller fork pretty much cancel one another out. As a result, the geometry is pretty mainstream, even though the bike looks a bit funny. It handles just fine, and it's a lot more comfortable.

The whole bike weighs just a bit over 20 pounds, with no exotic lighweight parts aside from a recycled Merlin titanium handlebar.

iro-boing2 iro-boing3 iro-boing4 iro-boing5  
Components:
FrameI.R.O. Jamie Roy, Aluminum 58 cm
ForkRock Shox Indy
Front WheelShimano Ultegra hub, Bontrager rim, 28 radial spokes. Continental Grand Prix 25-559 tire.
Rear WheelMavic G40 rim, Miche Primato hub respaced for single speed use. 15 tooth Shimano Dura-Ace sprocket secured by Loctite
CranksetShimano 105 SC w/42 tooth Biopace chainring
PedalsShimano PD525 SPDs
HandlebarMerlin titanium, with Grab On road type foam grips.
HeadsetDia Compe Aheadset
BrakeShimano DX V-Brake, with Kool Stop BMX shoes. Cable run through fork steerer, permitting complete fork rotation

spoke

Copyright © 2005, 2008 Sheldon Brown

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