Optimal bike choice and setup for riding down actual mountains

I think what ought to dictate the amount of travel on your bike is what the rider decides they want.

Aye true but the OP wants advice on what type of bike and set-up for a specific type of riding. If you want to ride flat trails on a 180mm bike then cool, it just wont be very enjoyable. Similar if you’re riding steep techy trails on a 100mm travel XC bike.

@spooky211, exactly, it’s impossible to quantify.

If the bike industry or anyone had the right answers, there wouldn’t be any need for tuning camps for racers and we’d have “perfect” products.

It seems to me that geometry is the overriding design criteria for how steep you can comfortably ride, travel decides how fast you can achieve it. A true appraisement of when your nerve gives out should also come into the equation. It’s very easy to get in over your head if the bike gives you too much of a sense of security, and the consequences become increasingly serious.

I realise it isn’t as critical as it is for roadies, but don’t forget to consider how the bike fits with your morphology. At 5’7″ or so, with a 6′ wingspan i always felt cramped on most older MTBs that had acceptable seat tube/ stand over dimensions. Even now some brands still seem to run relatively tall seat tubes in the smaller sizes.

@uk-flatlander – agreed. I reckon a shorter travel (160ish fork, 140ish rear), but still long and slack with a steep seat angle would be great. High pivot would be nice, and if someone could do away with the rear mech so I don’t need to worry about where I put the rear wheel, that’d be even better!

It seems to me that geometry is the overriding design criteria for how steep you can comfortably ride, travel decides how fast you can achieve it. A true appraisement of when your nerve gives out should also come into the equation. It’s very easy to get in over your head if the bike gives you too much of a sense of security, and the consequences become increasingly serious.

For the most part I agree, geometry trumps all. We have just never been fortunate enough to have mainstream bike brands building bikes with geometry that would have been absolutely wild on a DH bike 10 years ago, let alone something that now weigh 25lbs & could be ridden in an XC race.

I’ve done some fairly simple testing of speed down a few local trails between the big bike & little bike & the results are generally the same. The only place the big bike wins out is on the nasty, rough stuff & it doesn’t make up enough time to cover its losses elsewhere. On the stupid steep stuff, there is little in it, as you are more limited on actual speed. My next game will be to see how much of a difference is wheels & tyres.

Perception however, can tell a different story.

I’m doing a mash up race in a few weeks & plan to ride both bikes again, properly against the clock & see which is fastest on a variety of trails.

It seems to me that geometry is the overriding design criteria for how steep you can comfortably ride, travel decides how fast you can achieve it.

Very much agree with this. There’s very little I can’t have a go at on my LLS-ish 140mm hardtail (mkV Soul), but you do need to manage it a bit more if its really rough. The big difference vs (more) travel at both ends is comfort. The Soul I can do a day, maybe 2, of absolutely nailing it; the Rocket I can go all week on.

agreed. I reckon a shorter travel (160ish fork, 140ish rear), but still long and slack with a steep seat angle would be great. High pivot would be nice

That makes me think Deviate Highlander, probably because I’ve watched too many McTrail rider videos. But the head angle is 66deg with a 150mm fork, and the reach on a medium is a pretty short 444mm.

I think a 150-160f/140-150r “all-mountain” bike is where it’s at. AM9, Ripmo, Stumpjumper EVO, Sentinel would probably be my shortlist.

That’s mostly because there wasn’t really any decent 120mm bikes 5 years ago. For me, they have only really become a really good thing in the last 18/24 months (where bike designers are seeing geometry > travel).

My 5 y/o Mk2 Cotic Flare Max says otherwise.

Of course everyone has their own ‘optimal’ bike for the stated purpose (optimal usually being the bike they own to justify the purchase), but if we look at those who ride down mountains (or at least big hills) in the context outlined by the OP (assuming that optimal = fastest) for a living (EWS riders) they are all riding Enduro/Super Enduro bikes which have been developed (and marketed) as optimal for the very purpose.

Of course there will always be those who disagree and / or push the boundaries (eg. Paul Aston) and bikes adn ‘optimal’ will continue to evolve.

agreed, since 27.5 and long/low/slack became a thing all enduro bikes have been excellent.
Your optimal bike now is personal preference, but most of the big brands follow the same format for a descent oriented bike.
look across the range of all major brands, Pick the one with the best colour, ride more, think about all this stuff less.
(Fit is the other thing, if you are very short or very tall, this becomes an issue, for most people it isn’t)

I been giving this some more thought and have been considering what parameters folk are trying to optimise when judging the performance of a bike. For me the actual speed of the descent is less important than the feeling of fun I have when doing so, and how that fits into the whole day out. Sure if I was doing lift assisted stuff then the coils go on front and rear for that magic carpet ride, and a bit more speed and control on the descents . But personally I try to avoid both lifts and crowds. I relish a good long day out – climbs, rolling trails and the descents. For me weight starts to become a real issue. The gains from longer travel and coils on the down hill are such a small percentage of the day. For me at least they make the climbs a major chore and dull the rolling stuff. Taking the day as a whole they negatively impact the my average speed, and due to the increase fatigue sap some of the fun from the rolling and descending sections. I guess you have to decide what is important to you and run with that.

The description in the first post has basically pretty-much described an Ibis Ripmo, which, having owned one for the past couple of years, I can say is a wonderful bike for riding both up and down mountains.

There’s certainly slacker-forked bikes out here, but head angle doesn’t mean a whole lot without other geometry factored-in, and the overall length and balance of the bike makes it both reactive and stable at speed in the rough stuff. It’s not a complete downhill sled, and despite it’s renowned plushness it’s certainly more fun and poppy than ‘plough’. But (aside from the fact that she’s a damned fine rider) there’s a good reason Bex Barona had the EWS success she did aboard her Ripmo, before moving to Yeti.

On the setup front, I fully agree on the front end – I like a compliant bar with a high-ish position, so upgraded to a USE Flow Wide Carbon bar with 40mm rise, mated to a matching 31.8mm USE Vyce stem.

I’ve not bothered to fit a bashguard to mine, but have suffered a couple of chainring knocks, so maybe I should. I have been dabbling with flat pedals, but after 27 years on clipless I’m really a committed SPDer, so will likely go back to my Nukeproof Horizon CS pedals.

On the bounce front, I’m air at both ends, with the stock Fox 36 up front and X2 in the rear. The Ibis setup guides are great, and I’ve not deviated too much from the stock pressures and damping settings. I have wondered how the bike would ride with a 38 up front (38 is now specc’ed as stock), but I’ve not found the 36 limiting at all, and it’d be an expensive upgrade.

Tyres-wise, I have an Assegai/Dissector combo, with an insert in the rear. I also have a second lighter duty wheelset with Specialized Eliminator/Purgatory combo, also with a rear insert, which get ridden most of the time on tamer home trails.

That makes me think Deviate Highlander, probably because I’ve watched too many McTrail rider videos. But the head angle is 66deg with a 150mm fork, and the reach on a medium is a pretty short 444mm.

I’m running 160 on the front of mine (140 rear), 65 deg HA doesn’t have any negative effects. 475mm reach in a large, seat tube isn’t super tall either

My 5 y/o Mk2 Cotic Flare Max says otherwise.

The one you said you put an angleset in?

I was riding my Smuggler with an angleset and offset bushing in the mountains five years ago too, but it wasn’t right for the job in stock form.

if we look at those who ride down mountains (or at least big hills) in the context outlined by the OP (assuming that optimal = fastest)

Not actually what I had in mind. Average person riding down a mountain wanting to enjoy it, not die, and not be too beaten up by it.

assuming that optimal = fastest

Blimey what a daft assumption!

assuming that optimal = least dabs/ portages

FTFY 🙂

If you’re not in a hurry, is a long slack 29” hardtail with a big fork and tough sticky tyres a terrible idea? I’ve yet to take mine up or down any actual mountains…