1995 Specialized RockHopper Gravel Conversion

Early mountain bike were relatively a limited evolution of touring and cyclo-cross bikes of the same era with few modifications mainly:

• 26” wheels with bigger knobby tires

• Cantilever brakes adopted from cyclo-cross and touring bikes

• Triple cranksets with granny gear imported from touring bikes

• The frames were an evolution from touring frames with relaxed angles and significantly longer wheel base

Only in the late 1990’s the MTB geometry evolved with significantly increasing front fork travel, then rear suspensions and disk brakes, and during the 2000’s the bigger wheels (650B – renamed 27.5 and 700C renamed 29”) were introduced. When mountain bikes, especially enduro and downhill models started more and more to look like motorcycles without an engine to address more and more extreme terrain, a gap was created for people that enjoy riding off road but whose focus is more on covering large distances on non-paved roads and wide trails.

That gap was filled by gravel bikes, but when looking at it closer and ignoring for a second the high tech of carbon frames and hydraulic disk brakes, aren’t gravel bike more or less a re-incarnation of the early Mountain Bikes?

Based on that question, and upon a request from a client, I embarked on turning a 1995 Specialized RockHopper into a gravel bike.

Original 1995 Specialized RockHopper (Google Images)

RockHopper frame brought by Guy (my customer), those 1990 cromoly frames (or complete bikes) without suspensions can be bought for close to nothing)… 3300 grams for frame, fork and steel headset, not light for a cromoly frame and heavy compared to a modern carbon gravel bike, but not that heavy when compared to many modern suspended MTB frames.

In addition, if you ever crash on a rock the cromoly frame may get dented, but the carbon frame will end up in the garbage…

Looking for a limited budget build which should serve as a part-time gravel ride and part-time bomb proof commuter (with some slick tires), I went for a collection of quality parts, who used to be expensive but can now be sourced for a very reasonable price (if you have the patience to look for them), because they will be considered obsolete by anyone looking at a reasonably modern MTB or gravel bike.

• 1998 era 26” wheels with top notch Shimano M950 XTR hubs and Mavic 217 rims (No one wants to be seen with 26” wheels these days)

• Rim brakes (first I installed short V-brakes, then changed to Tektro CR720 cantilevers to increase the rim clearance with the SRAM road shifters)

• Square tapper BB and a recycled polished Shimano 105 from the 80’s with a single 38T ring (polished silver: Looks cool? yes, Modern: hell no)

• SRAM Red 1x10 Shifters: I know unlike Rival 1 and Force 1, SRAM never made a Red 1, but who said you cannot make your own and what’s wrong with a pair of brake levers/shifters that weigh in at 260 grams?

• On that generation of Shimano freehub, 10 speed 11-36 is the way to go and I had a super light all alloy CNC’ed Recon cassette available, so why not…

• The beauty of 10 speed at SRAM is that road and MTB were compatible, so a shiny and light SRAM XX at 180 grams nicely completed the drivetrain

• The Flite Titanium Selle Italia is the most iconic saddle of the 90's, my client intends to change it for a Brooks B17 later

• Ritchey Adventure Max alloy bars providing the right look to play the gravel part

• 1.75” WTB Wolverine with small knobs, perfect for gravel (let’s call them 47mm that sounds much cooler…). Those are not tubeless ready, neither are the Mavic 217 SUP, so inner tubes have to go in there...

Geometry:

The geometry is actually quite good for excellent stability and tracking on fast gravel roads. The rear is a comfortable 43cm actually close to what is used on modern gravel bikes designs to clear good size 650B or 700C tires, and the overall wheel base a very significant 108cm. So if you are looking for the responsiveness of a cyclocross bike, that is not the right ride, but if you are looking for something that will track nicely even at high speed on loose terrain, it is it…

The main geometry difference with modern gravel bikes is the frame length. In a size where the ctc height of the frame is 48cm (which is good for having a comfortable stand over), the frame comes with a whopping 59cm ctc effective length and that results in a big 43cm reach. Those numbers (108cm wheel base, 59cm frame ctc length and 43cm reach) are about 40mm longer that what we are used to on dropbars bikes. This means that to get back to a normal position the following adjustments are required:

• A no-setback seat post (brings you 25mm forward, without even feeling it since the seat tube is slacker than a road bike)

• Short reach handlebars (The Ritchey Adventure Max have about 70mm of reach that’s 10 to 20mm less than most road bars even the modern compact ones).

• A short stem is still required, we tested with a 70mm and 60mm. I have found that the concerns about twitchy behaviors are way exaggerated when talking about a bike with a 108 wheel base, and actually I think the short stem bring back a good amount of liveliness to a bike which would feel like its running on rails with a 100mm or more stem…

Also the frame good very easily accommodate 650B wheels with good size tires, one would just need to find cantilever or V-brakes with a reach of about 40mm above the studs or use brake stud extenders…

On the scale:

I was quite surprised to see the build coming out to 10.4kg (including Look pedals). That’s not bad at all. Hey, that’s actually less than many top of the pack $10,000 fully suspended XC bikes these days despite the carbon frame and wheels, simplicity has its advantages…

That is about 2Kg more than a modern gravel bike pretty much all of it is accounted for by the hefty cromoly frame 3.3Kg compared to a modern carbon gravel frame. The rest of the build is actually pretty light (drive train, rim brakes and on par with what you would find on a modern bike where the crank set and tubeless would weigh less, but the disk brakes and rest of the drivetrain would actually weigh more…

Test ride:

The first test ride was with the 25mm setback seat post, 70mm stem, and 80mm reach handlebars it pretty much matches my road bike setup (my customer and I are both 1.76m tall but with saddle height at 75cm I have relatively long legs for my height).

The front is just about 1cm longer and 2cm higher than my normal road position, well within normal potential bike to bike variations for slightly different riding styles.

I used my quick standard one hour test ride out of home to test the bike. It consist of 11km out Zur Hadassa where I live to the Salactite Cave National Park which includes about 700 meters of vertical drop and back home. I have done it so many times that Strava will give me a good sense of how fast a bike is. Result: 1h02. That it is about 5 minutes slower than a similar effort using my road bike with its 50mm deep carbon wheels. I think half of the extra time can be accounted for by the knobby 47mm tires compared to 25mm tubeless or tubulars which is what I tend to ride on my road bike. That could be cut down with a pair of slick tires. Most of the other half probably comes from bringing close to 3Kg extra weight back up 700m in altitude.

Altogether not bad for a 25 year old cromoly MTB frame converted into a budget gravel rider…. Bottom line: if you have the engine, this thing will move...

This is the second time I have played the vintage MTB to gravel conversions game, the first one was the Litespeed Tellico below and I think there is some potential here and there will be more such projects…

1998 Litespeed Tellico Ti6/4 conversion

Next on my list is a 1997 Aluminum Marin that has been gathering too much dust in the garage…

About the author: Julien Meissonnier stared riding seriously just a bit over 40 years ago as a 13 year old in the late 70’s when 10 and 12 speed included both front and rear not just cassette... After long distance cyclotouring, pass hunting, cyclo-camping across much of Europe and the US, and some triathlon racing, gently slipped into a lower bike gear going into the 1990’s and making a reasonable comeback in the 2010’s... After a high tech and entrepreneurial career decided that I would focus on doing interesting bike stuff, anything that does not feel like work. Enjoying developing a line of carbon wheels and all sorts of custom projects with a more pronounced interest for “mature” bikes and non–standard projects and materials.

www.roi-cycles.com