Rock Shox Paris-Roubaix SL fork

P-R SL 01.jpg

Here’s an entry about 15 years late. The Rock Shox Paris-Roubaix SL fork, created to contest the legendary professional road race across the aged and treacherous country roads of cobbles in northern France. The fork was developed from the venerable Mag21 cross-country mtb fork; the main differences being modified internals and a taller bolt-on fork brace to accommodate a caliper road brake.

Did it work? Well, 2 consecutive Paris-Roubaix were won using that fork, so arguably it did. But the late-90s domination of the event by the Mapei team pushed road suspension out of the way, since Mapei’s bicycle supplier forbade the use of suspension forks. Rock Shox developed a ground-up road fork replacement, tritely named the Ruby, but that fork never caught on.

P-R SL 02.jpg

I have owned a Paris-Roubaix fork for more than 4 years. During the winter I use it because the fork gives better braking control on wet and bumpy descents on Seattle roads. I can also ride in the drops more comfortably at high speed, for longer periods of time. On cold, dreary training rides and commutes, I feel fresher and less stressed by the combination of cold muscles and punishing pavement. The fork doesn’t really help unless you are going faster than 18-20mph, though. Slower than that, and larger volume tires would likely be a better choice. And the P-R SL fork will not accommodate anything larger than a Michelin 25mm. Contrary to the elastomer and coil spring of the later (and from personal experience, inferior) Ruby fork, the Paris-Roubaix SL’s air-spring is easily tunable with air-pressure. The rider can also lock-out the travel by adjusting the dampers to maximum; the damper dials are on the op of each leg at the crown.

The fork also has two main drawbacks. The first is weight, and at about 2.6 lbs, the P-R SL is scintillatingly light for suspension forks but a gigantic boat anchor compared to an Easton or 3T carbon fork. The second is more annoying: the P-R SL, like its Mag21 forebear, is exceedingly flexible. Even under my weight, a trackstand puts the front rim against the brake pads. How I wish that Rock Shox would develop a road suspension fork with the features of the newest SID xc-fork. As it is, I cannot recommend my fork to any rider over 180 lbs.

P-R SL 04.jpg

I’ve customized my Paris-Roubaix SL fork. Since forks of the Mag21 family bolted together in many places that current suspension forks are either cast in one piece or are press-fit together, I have hot-rodded a 1-1/8” crown and steerer onto a fork that was only available stock with a 1” steerer. Also, back in the day before suspension forks standardized on 35-38mm of rake, Rock Shox made some forks with a 45mm rake. With the rake built into the crown and not the legs, this makes my fork probably unique with a the rake and steerer more suitable to my bike geometry. Well, not quite unique. I have a back-up P-R SL. They haven’t made these things in over a decade, so I’m planning ahead.

Thanks to HippieTech Suspension for doing the fork maintenance. Not a fast turn-around in my experience, but he does good work for these old forks.

P-R SL 03.jpg


I wondered what happened to all those PR forks. 
When I put the skinny tires on my hardtail and ride around town I really appreciate the comfort and control vs my road bike.  But like you say, the weight and the fork flex are the big drawbacks.

Any chance you’d like to sell one of these?  Been searching for years and can’t seem to find one.

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Nice piece.

I’m considering a similar hot-rodding of the PR SL and Mag21 crown. I’ve tracked down both.

Do you know what the axle to crown height of both forks is please?

How much space is there between the tread of your 25mm tire and the bridge?

Thanks, Jay.

I don’t know the axle-crown for a Mag21, but the P-R SL is right about 400mm (no sag).  25mm Michelin (large compared to other brands nominal 25mm)  fit no problem, but if you were riding in sticky mud conditions it would cake on the bridge.  There is approximately 2.5mm of clearance above the tread.  Most 28mm tires will not adequately fit.

I’m now looking at replacing the PR brace with one of the mag 21 mtb braces (I’ve been told they have an extra 5mm of clearance above the tire over the PR brace), and then adding canti studs and using a Paul Moto bmx brake to reach up to the 700c rim wall. Hopefully this will work and I can then use slightly larger tires, either a Paris Roubaix 27mm/28mm or a svelte cross tire in 28mm/ 30mm. I’m just looking for 10mm/ 15mm of compression to ease the burden on my hands and wrists. I think it will make all the difference to my riding comfort.

Does anyone know approximately how many PR forks Rock Shox made? They seem hard to find, and an NOS example almost impossible so far. People tease that they do have NOS but never suggest they are wanting to sell. A rare bird indeed. Jason.

I saw an NOS P-R SL on eBay about 3 months ago.  My best score is that I bought a lightly used P-R SL at the Seattle Bike Swap for $25.  I currently own two.

As far as swapping out the brake arch is concerned, my worry is that the bigger tire might actually strike the underside of the fork crown, as the travel isn’t the same as a Mag21.

I hadn’t thought about using a higher-reaching V(?)-brake to allow the Mag21 brace to work!
There were 700c canti braces available back in the day. RockShox and aftermarket both made them around 1995.
I ran a skinny, “28mm” cyclocross tubular on the front of my P-R/SL for a dry SacramentoCX series event, but clearance was nil so kinda dangerous imo.

The P-R fork raised my Windsor Profesional a good inch or so in front. That can increase comfort and slacken the head angle. It didn’t make a good CX bike because the top tube was shortish and the 120mm neck had me doing near-endo’s when braking for the barriers. I chose another bike to race instead of adapting to this.

I’ve also got the same fork on my Boulder Paris-Roubaix full-suspension(!) road bike. I weigh 158lb and run 51psi front and 175lb rear (in the Risse top-tube air shock). This bike has perhaps even less clearance in the back than in the front, so it’s no CX bike and I wouldn’t even try it on this rare, expensive bike.

I have no idea how strong the P-R forks are for actual off-roading, but can I assume they’re as strong as a Mag21 SL? Shorter is stronger if the upper tubes are the same thickness and of similar aluminum, but mine weighs only 2.25lb w/ti steerer.

Keep us posted on your Mag21 brace experimentation. 

Mark V wrote:
“I’m now looking at replacing the PR brace with one of the mag 21 mtb braces (I’ve been told they have an extra 5mm of clearance above the tire over the PR brace), and then adding canti studs and using a Paul Moto bmx brake to reach up to the 700c rim wall. Hopefully this will work and I can then use slightly larger tires, either a Paris Roubaix 27mm/28mm or a svelte cross tire in 28mm/ 30mm.”

Sorry, but I just quoted Mark V, above, for the comment (quote) actually made by Sparticus.
I stand corrected.

Sparticus, that sounds interesting and I have some of the same parts to play with if it works.

DaveS (who digs riding road bikes off-road).

I concur completely with the write up about the Paris Roubaix SL forks performance.

I used a pair for over three years until summer 2000 commuting 20 miles each way across London every day and it made a massive difference, every now and then i’d use my other bike with carbon rigid Time forks and the difference was apparent.

I upgraded to the Ruby SL and these worked well but the need to cycle commute ceased soon after so i’ve not used them much in ten years.

All together i’ve two pairs of Ruby SL - both 1” steerer 1x threaded 1x threadless. I still have the original Paris Roubaix SL fork also in 1” threaded which i’d intended to build into a period piece bicycle, Team Gan replica maybe a la Duclos-Lasalle…

Could be open to offers though.

Dave M.

Hi everybody from Italy. I’m looking for a Rock Shox Paris-Roubaix fork brace…. any suggestion?? It seems to be impossible to find!!!

Seeking for buy a fork Rock Shox Paris Roubaix SL if anyone knows who has for sale contact by e-mail .(JavaScript must be enabled to view this email address)

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