The naysayers tell us that gravel bikes are ‘just 1990s mountain bikes’. However you feel about that sweeping statement, it got me thinking – why not take an old mountain bike and turn it into a full-supension gravel bike?
I've been all in on suspension coming to gravel and own a Cannondale Topstone with a suspension fork.
I’ve also recently been getting lots of miles in on the wild new Lee Cougan Innova Super Gravel and the just-launched Trek CheckOUT SL, with its 55mm of rear travel and all-new RockShox Rudy XL 60mm-travel fork.
We're also hearing more and more talk of MTB-sized tyres for gravel racers. Just look at this year's Leadville 100, the epic mountain bike race in Colorado, where Keegan Swenson won on a full-suspension Santa Cruz Blur with drop bars.
While I was tinkering with a few bikes in my garage, sitting rather unloved in the corner of my collection was an old Azonic Propulsion mountain bike. It’s an alloy full-suspension bike with a classic four-bar Horst-link back end.
Azonic was, back then, renowned for making great, tough bikes that didn’t cost the Earth.
So why not turn my Propulsion into a gravel bike? The goal is to build a full-suspension, fully equipped gravel bike for less than £1,000.
I can even test it head-to-head with the cutting-edge carbon Lee Cougan that’s been impressing me.
Out of date and much unloved
It’s a bike that’s considered hopelessly out of date in mountain biking circles, yet not quite retro enough for the rabid collectors out there.
Although it is still very retro, the frame originated in the 90s and it's built with a collection of parts of various ages.
Up front, it has a 160mm-travel Fox 36 Van R 26in fork. It rolls on a set of Mavic’s CrossMax XL wheels shod with gravel-racing appropriate 2.4in Continental Mountain King tyres in ‘Testrider’ spec.
The drivetrain combines the original mechanical SRAM X-9 rear derailleur with a Shimano Deore front, Race Face Turbine XC cranks, SRAM shifters and classic Hope Mono brakes.
The rear air shock is a Magura by Rond, complete with lockout.
Will 90s geometry work for a modern gravel bike?
What appeals to me from a gravel perspective is the geometry. While it’s both much too steep and far too short compared to a modern mountain bike, it’s not that far off what’s current in gravel.
Once the bike is cleaned and prepped in our workshop, I’m going to break out the protractor and my circa-2000 scientific calculator to work out what those angles are.
What I have at the moment is a mish-mash of bits, and a bike built up and changed multiple times over the years I rode it, thanks mostly to donations and expert fettling from MBUK tech legend Paul Smith.
If you want to have a go yourself, you can now pick up a once-desirable bike like this for a couple of hundred pounds. At the time of writing, I found one full-suspension Azonic on eBay (although that was the more freeride-aimed Saber model) with a starting price of £177.48 (and no bids).
Cost-effective off-road chops
Before I go any further, I plan to first enlist the help of our workshop wizard Will Soffe. He’s a mechanic par excellence and, more importantly, has serviced and maintained the bikes of world-class riders who would put far more abuse into the suspension than I. We’re talking Dan Atherton and Vero Sandler – not to mention working on his own bikes while riding to national podiums off-road.
If anyone can recommission suspension that hasn't seen active service in more than a decade, it's Will.
Then we’ll be adapting/updating the drivetrain to make it drop-bar compatible and the gearing a little more 2025 rather than the 3x9 SRAM/Shimano mash-up the bike has now.
I’ve got a little research to do and a few brand experts to talk to before I can settle on a course of action for the drivetrain and brakes. However, I’d like to retain as much of the drivetrain as I can. Keeping the spirit of this near-classic full-suspension bike is important to me.
So, my target is set – turn this unloved MTB into a full-suspension gravel bike for less than £1,000. I'll report back as soon as 'Project 2000 gravel' is complete.
