Hi, road bike rider here, looking at doing a ride in May, of over 1000km through about 70% single track, lots of sand and elevation also. Current bike is a gravel bike with Shimano road gear. Suggested I look at a XC hartail instead, as this maybe a one off event, don’t really want to spend a fortune, so maybe an AL XC mtb, other option is a modification of my existing Ti gravel bike with going one by, getting a larger 10/51 and changing spline etc. The ride is called the Munda Biddi https://mundabiddi.org.au/. Have had a few people suggest mtb is the way to go, from people have done it. Will be about a 15 day adventure with camping etc, so loaded bike. I’m 64 years old, so speed is not the be all and end all, but need to get there over that time frame. Would appreciate opinions?
If the photos on the event website are true indication of surface, the MTB is overkill, and a gravel bike is ideal, but, what kind of gravel bike?
If you are wanting comfort, and therefore more pleasant overall ride, a gravel bike that can take MTB tyres would be sensible, and this also covers off the dealing with rougher sections should there be any. So, something that can take 2.1 or 2.2 MTB tyres, and then stick on ultra fast XC tyres, like Conti race kings.
My guess is a gravel bike with 700x45 Conti Terra Trail or Cinturato M, or similar, would also be ok, but you loose a little comfort and technicality headroom.
Your current bike might be ok, but you don’t state the tyre clearance. Given the mud on one of the photos, you probably don’t want to be maxing out the tyres beyond stated compatibility as you may need the spare space to avoid clogging etc.
You are familiar with drop bar, and presumably have you riding position sorted, so the other advantage of going for gravel bike is that you can just copy that across, rather than having to do lots of riding just to get used to the new position that you’d be riding on an MTB.
Thanks, max size is 45mm on current bike, Lynskey. Appreciate the comment regarding ride position etc, makes sense and was something I was a little apprehensive about with a mtb change.
For pea gravel you don’t need a hardtail, any gravel bike worth its salt should handle that. I second the recommendation for Conti Terras, I have Conti Terra Hardpacks and they are inexpensive, have low rolling resistance, are hard-wearing and work well on gravel and pavement alike.
The other thing is gearing, and it really depends on the terrain. Road gearing might not suffice, but that is a huge depends. Since you want to go bike packing, I’d err on replacing your current drivetrain with e. g. an XPLR drive train if it is flattish. I skimmed the website and the snippets of the route indeed suggest that the terrain is relatively flat.
A 38-tooth chainring coupled to a 10–44 cassette should be plenty, unless you want to ride something steeper afterwards, you may not need a mountain bike drivetrain.
Thank you, appreciate the response.
Just thinking of gearing, having read Max’s post. You might not need to change your groupset, at least not completely. What is the road groupset you have at the moment? You may find you can get away with changing the rear mech to GRX, cassette to 11-40, and chain. If you want to drop the whole range further, switch out the crank for a GRX crankset too. 2x GRX will work 11-40 cassetter (not stated, but I’ve seen it done), and that gives you a pretty low gear.
That said, switching to 1x gives you room to move the gear range about through chainring selection. For example, I have GRX 1x12, but with Easton crankset that means I can switch between 34t, 36t and 38t Raceface chainrings depending on route, whether I’m loaded up (bikepacking) or not, etc. That means I have an MTB range on a gravel bike for when loaded, and the option for a higher range for normal riding, all with road chainline.
Thank you ultegra di2 12 speed currently. Maybe a one by and lower gearing is the way to go
That’s the wireless group? If yes, you can stick with your existing levers and just switch out the mech for the new 1x GRX wireless mech, the cassette and the crankset. The cassette might prove a sticking point, as if I remember correctly the 12 speed road is still on HG freehubs, whereas the 12 speed off-road is on microspline. If you can source a microspline freehub for your wheels, fantastic, problem solved, otherwise you might have to go for a low end SRAM cassette (pretty sure they have an Eagle cassette that fits HG) or look for Sun-Race or other left field aftermarket cassette.
Thank you, really appreciate the help
To me, 1000k of mostly gravel or single track over 15 days, and camping, at age 64 is a big ride. You don’t say how much experience you have riding on such surfaces, or riding with bags, etc. You also don’t say what max width tires your current bike can fit. Without knowing more, I really wouldn’t know how to advise you, and so I’d be pretty cautious about the recommendations about just making minor changes to your current bike etc.
My intent here is not to be a downer! I’m envious about the trip. But from experience, day after day of gravel is much harder on the body than riding on the road. I’d err on side of comfort and control, which at least means decently wide tires (=more than 45mm)
Appreciate the feedback. Max tyre size is 45mm, done quite a bit of audax rides. Have done a few day to day rides to about 400km on gravel and pavement. The great adventure this brings are huts along the way approx every 80km or so to bed down on. The gravel I’ve ridden is not what this will be though. Intent is to do a couple of trials over a couple of days on the trail before making the end to end
Trials are a good idea!
Perth based roadie here, but I dabble in gravel from time to time. I haven’t ridden much of the Munda Biddi but I think the pea gravel is mainly contained to the Northern section and it turns into more forest trail south of Jarrahdale. Certainly the sections I’ve hopped on and off further South of there (near Nannup and Dwellingup) have been a bit harder packed and less of the pea gravel. My gravel bike is a Chapter 2 AO with Shimano GRX 2x drivetrain and 43mm tires. I’ve never found myself underbiked, so a MTB would be fine but I don’t think essential - at least based on the sections I’ve been on and the other gravel trails up in the Perth Hills.
You may well have seen this in your own searches but one of the first results I came up with trying to validate my recollection about where the pea gravel peters out was this blog which is quite useful as has photos of the surface (and a whole bunch of other details about the course) from each section: Pea gravel | Munda Biddi Ramble
Thanks mate, appreciate the sanity check! I’m in Bridgetown so a few sections are easy to get to and will do some trails after the next week or two, doing the maca200 first
I’m definitely keen to ride the full length one day. My kids are only young so I’m half thinking it would be nice to do with them when they are old enough.
Sounds like a great idea
Guys, in the fb group for Munda Biddi you will find a link to the survey results of literally a couple of hundred past riders who will tell you what tyres, gears, electrics, spares and everything else you might want to know. Use the wisdom of the crowds. Search for the string justlooking on the page. All the best.
Thanks, will check that out
I reckon you can ride it on whatever cx / gravel / mtb you have. I dare say the FB group will offer the full range of opinions. 
We rode Munda Bidi from Albany to Busselton in 2019 and took hardtails with panniers because we’d been told the gravel was too bad for our cx bikes.
Since we stopped at Busselton, the pea gravel was a non issue and everything we rode would have been ok on our cx bikes with 40mm tyres. There was a bit of sand but not a lot.
Our mate did it with us on his cx bike because he wasn’t gonna be told what to ride. He destroyed his Di2 rear mech with a stick on day 2 of 10 so he had to use my spare mechanical XT 9 speed rear mech as a chain tensioner and rode the other 6 days in 1st gear. So much for worrying about gear choice.