XC bike struggling with descents...?

neilus

Hiya
I'll tra and be brief. I've been riding a 2011 Scott Spark 60 for about 18 months now - http://www.evanscycles.com/products/sco ... e-ec025353
Climbing and fairly level terrain is great, but taking corners while descending is an absolute nightmare. The bike just seems to drift away from underneath me and just refuses to go where i want it to. Typically, as i approach a corner, ill try and pick a line...halfway through the turn, im already way off line and its not uncommon that by the end of the turn ive drifted so far off the trail that i have to break/stop, cursing myself as to why i seem to have forgotten how to ride a f'ing bike. Ive also given up trying to get any air off any small jumps, as it is just impossible to control.
I never experienced any of these issues (cornering/jumping) on my old bike, you probably wont be familiar with it, a Jamis Dakar Sport, unfortunately it was nicked so i cant really compare the two bikes. But I do know that a) the frame was bigger and b) the bars were wider.
Here's my list of possible reasons:
- Wrong size. I got a small which being only 5' 8 and around 70 kg I thought would be ok. Stupidly didnt really check if Scott have any frame size calculator (used the Canyon one last week; recommended a medium)
- Wrong bike. Seems the Spark is a straight xc bike and its struggling with descents. I could definitely use a bit more than the 120mm front travel but im also wondering if the geometry just isnt designed for essentially enduro riding.
- Ive lost my mojo. As mentioned, the bike is dreadfully unstable in the air; resulting in my first serious wipe out, getting airbirne off a wee kicker id done a 100 times on the old bike (and had been getting higher, and more confident every time). It shook me up a bit but ive ridden a lot since then and im nowhere near as nervous as i was immediately after the crash.
So...any thoughts chaps?
Thanks for reading!

rockmonkeysc

The bike is more than capable. I have seen riders on much more hardcore xc race bikes descending at a pretty rapid pace.
It sounds like you need to improve your technique and look at bike set up. Maybe your tyres aren't too good.
Cornering techniques are really easy to learn but a lot of people do it really badly. Maybe a day with a skills coach would do you some good, should sort your jumping as well.

cooldad

When I was a lad we had rigids with cantis.

rockmonkeysc

But no wheel, it hadn't been invented back then.

neilus

Cheers, yeah a skills session would be a good idea. You said something about the bike set up; tyres are 2.25 Rocket Rons which seem ok, Ive often wondered about the bars (15mm/640mm) which seem a tad tight and twitchy. Im just wondering if wider bars would give me more control...?

cooldad

RockmonkeySC wrote:

But no wheel, it hadn't been invented back then.

Not true. We carved them out of rocks.



Led to



Bringing us up to date with full sus

cooldad

neilus wrote:

Cheers, yeah a skills session would be a good idea. You said something about the bike set up; tyres are 2.25 Rocket Rons which seem ok, Ive often wondered about the bars (15mm/640mm) which seem a tad tight and twitchy. Im just wondering if wider bars would give me more control...?

Rocket Rons are rubbish on anything except dry hardpack.

rockmonkeysc

Especially if they are a cheap, ultra hard compound.

njee20

cooldad wrote:

neilus wrote:

Cheers, yeah a skills session would be a good idea. You said something about the bike set up; tyres are 2.25 Rocket Rons which seem ok, Ive often wondered about the bars (15mm/640mm) which seem a tad tight and twitchy. Im just wondering if wider bars would give me more control...?

Rocket Rons are rubbish on anything except dry hardpack.

I disagree, perfectly capable in all but sticky mud.

Sounds like your old bike probably flattered you more, the Spark isn't a particularly 'extreme' XC bike, quite well rounded. Skills course may not be a bad shout, but at the end of the day, if you've come from a more trail type bike it's unsurprising that the Spark doesn't excel at the same things.

cooldad

njee20 wrote:

cooldad wrote:

Rocket Rons are rubbish on anything except dry hardpack.

I disagree, perfectly capable in all but sticky mud.

Yeah but you have skillz and stuff. Some of us rely on our tools.
And something to blame.

Still wouldn't be my choice for gnarly stuff.

neilus

Thanks. I'll probably be investing in some Bontrager XR4 TIs as it looks like my local trails are gonna be a reet mess this winter, so it'll be interesting to see how they handle.
I dunno, I really, really hate the "bad workman etc..." arguament but it comes down to this; either a) my skills took an dramatic and inexplicable nosedive coincidentally at the exact time I changed bike, or b) its something to do with the bike. As mentioned, the previous bike felt big, noticeably bigger than the Spark...and looking back, it did feel somehow more stable...but as I say some scumbag nabbed that so I cant take it out for a spin as a comparison :evil:
Cheers

rockmonkeysc

It may just take a different riding style. I had a Giant XTC for a year after an On One 456SS. I hated it until someone gave me some tips on changing the way I rode, then I loved it right up until I snapped the frame (xc bikes are fine on 5 foot drops until you come up short) :-(

supersonic

I use Rocket Rons - fantastic tyre. Not very puncture proof granted, but grippy in a lot of conditions.

Try and weight the front a bit more in turns. Is easy to try and hang too far off the back with xc bikes. You loose grip and steering becomes vague.

heavy_rat

cooldad wrote:

neilus wrote:

Cheers, yeah a skills session would be a good idea. You said something about the bike set up; tyres are 2.25 Rocket Rons which seem ok, Ive often wondered about the bars (15mm/640mm) which seem a tad tight and twitchy. Im just wondering if wider bars would give me more control...?

Rocket Rons are rubbish on anything except dry hardpack.

Surely you're confusing Rocket Rons for Racing Ralphs?

neilus

cyd190468 wrote:

Get a friend that knows stuff to set up your fork. If you're running wide on fast turns and losing control in the air it could be an overly hard and under damped fork. Check the sag and dial in some rebound damping.

The fork is a total mysery...RS Recon Silver RL. The Silver TK seems well established but Ive found nothing about the RL...Havent been particularly impressed to be honest. Setting up this bike has been tricky...Im only about 70kg, and 20% sag on the frame shock (DT Swiss M210) gives me a very bumpy ride indeed as there isnt much weight on it. Its probably around 40% at the moment, but thats only possible with fairly low tyre psi to try and smooth out descents. But thats not really ideal for climbing (normally do 800m +/-), its a much lower psi than id like. But if I up the psi - even to 25 - then the sag id need on the frame shock to avoid bone rattling descents would be like 70% or something daft.
So its been tricky trying to juggle sag and psi with my pretty low body weight...but i cant be the only MTBer who isnt 16 stone?
Might be worth giving the tyres a good pump and see how it handles? I cant image low psi makes for good cornering. So yeah I should perhaps take it to someone who knows what theyre doing...!

rockmonkeysc

40% sag is far too much. Suspension is designed around 10-12 stone riders.
It will feel just as harsh for a heavier rider when set for the same sag.
Running your fork at 40% sag will also sharpen the head angle and make it feel unstable.

neilus

RockmonkeySC wrote:

40% sag is far too much...

Cheers, yeah I know it is! But if I have it at say 20%, the ride is so rough I think "screw this, i might as well ride a HT" As I say, dropping the tyre psi is an option, until im climbing and i feel like im pulling a caravan and its just far more exhausting than it should be...
Its a spring fork. There is a rebound adjust which I have on the slowest setting, and on the left stanchion a "preload" dial, though to be honest neither seem to make a noticeable difference...

The Rookie

Having then preload on its slowest setting means it will jack down on bumps, even more so with the 40% sag.

the preload sets the sag, you say you've set the sag yet the adjuster does nothing, so how did you set it?

Its not the bike, possibly not the rider, its' the daft burger setting the suspension up!

neilus

The Rookie wrote:

Having then preload on its slowest setting means it will jack down on bumps, even more so with the 40% sag.

the preload sets the sag, you say you've set the sag yet the adjuster does nothing, so how did you set it?

Its not the bike, possibly not the rider, its' the daft burger setting the suspension up!

Nope, the 40% sag is on the DT Swis M210.
2 options on the fork, rebound (set to slow) and preload (on minimum, gives 25% sag)

paul.skibum

neilus wrote:

The Rookie wrote:

Having then preload on its slowest setting means it will jack down on bumps, even more so with the 40% sag.

the preload sets the sag, you say you've set the sag yet the adjuster does nothing, so how did you set it?

Its not the bike, possibly not the rider, its' the daft burger setting the suspension up!

Nope, the 40% sag is on the DT Swis M210.
2 options on the fork, rebound (set to slow) and preload (on minimum, gives 25% sag)

You have put air in it right? Pressure in the air can should set the sag not the preload. https://www.dtswiss.com/Resources/Support/SHOCKS/DT-Swiss-Shocks-M210-User-Manual-en

Unless I am missing something I havent read all of the thread.

The Rookie

No air, he says it's a coil fork!

You still need to speed up the rebound, it's going to almost certainly be too slow.

rockmonkeysc

It's starting to sound like most of the bike probably could be caused by weird suspension set up but to end up with that sort of set up would suggest that there's some poor riding technique as well. If you ride properly you could very quickly tell what the bike isn't doing right.
Skills coaching could fix everything. A good instructor will start the day with bike set up to make sure the bike is working right for you to ride well.

neilus

Ok just had a proper look; frame shock is bang on 25%, or 10mm which is within the 8 - 13mm range suggested in the user manual...so not 40%, dunno why i said that, its been a while since i set it up and more often than not I look at the position of the ring during a ride (shut up!) when its been pushed further down.

cooldad

To make life simple - the shock is at the back, the forks are at the front.

rockmonkeysc

Having the bike the right way around is also recommended for best results when riding.

JayKay3000

I'm going to preach to the choir.

I rode my 80mm specialized carve hard tail on the mbr at coed y brenin. My fs is faster there, but mountain biking ain't all about the ride. When I had it I'd not ridden mtb for 10 years. I started on easy trail centres e.g. Nant-yr-arian here in Wales where I knew that every obstacle could be rolled without the need for much body english. I made it down fine and for the next few months hammered around these trails over and over. I then moved on to coed y brenin and did the dragons back a bunch of times. Eventually I felt confident enough to try the black graded mbr and did it a few times. As a bit of fun I took the bike up the mountain called Cadair idris. After that I upgraded to a full suss where I had to start from scratch.

There is youtube video floating around of one of the pro riders on a road bike sliding down steep descents and crashing through rock gardens (so he got a lot of flats from the out takes), but point still stands.

To be fair the suspension setup can make a huge difference even if it's only small tweaks. I had mine set too low on my current fs and didn't notice in the dry on hardpack trail centres.

Winter comes along and suddenly i'm riding more in the mud and goop where the lack of support combined with the squishy conditions made me a far wimpier rider till I put some more air in the setup and they became stiffer.

Take into consideration tyre pressures too as this can affect the feel. I have nobby nics on my trail bike, but a mountain king would do the job just as well. Although when I'm going mud bogging I stick the hans dampfs on. Equally I've tried race kings in the dry and the tyres on the carve were great. I always like to have a grippier front with 5psi less pressure than the rear. Talking of mud. It's a fantastic surface to learn bike control - woodlands. Even slippery concrete will help you work out what happens when you shift your weight.

Oh and erm. Don't forget to put your seat down going downhill, put your heels down and remember to push into drops. If you're riding trail centres then most people put their runes on the internet. It can be worth watching them.

I can't claim to know if the frame is too small, but I can tell you it takes a while to get used to a bike. I can look back to steep stuff I'd never touch when I first picked up my new bike. Now I might be on the road on a fitness ride not intending to go offroad and happen to see a stupidly steep, rocky, sketchy descent that I can work into the route and know that one way or another I have the skill to do it. But start off on small stuff as another major part of trail riding is having the mental speed to read the trail and sub consciously plan ahead. Riding only gives you this.

A good tip is also to practice riding slowly over difficult terrain because you'll get your bike skillz honed. Anyone can ride fast downhill and make it down through sheer luck and cohornes. My friends have often tortured me by making me re-do sections of trail or obstacles that I'm scared of. Session sections especially with friends who are good and ask them to comment on body position, etc, but even on your own allows you to try the right and wrong lines and different speeds. Set your phone up somewhere and see what you look like riding by.

I can only say to ride, ride and ride. Skill comes over time. You will go through months where you think you are never getting better.

Have fun though. Don't make it a chore to become as good as your friends. They were rubbish once too.

supersonic

Slowest rebound usually handles awfully.

neilus

supersonic wrote:

Slowest rebound usually handles awfully.

Cheers, thats good to know. I'll change it to fast and see how it handles. And cheers for some good advice JK.
Dunno how the fork/shock/front/back confusion arose, I didnt mention anything about setting the fork sag! All i did was - to use one of my favourite GWBisms - "mis-underestimate" shock sag at 40% when its really 25%. On the DT Swiss 210. Not forks :P
Yeah starting to like the idea of a skills day. But living in Austria as i do, I guess all the mtb trainers will be swapping bikes for skis soon, woohoo!! Not long now :P

paul.skibum

You dont want it set to fastest either. there are many increments of rebound speed between slowest and fastest - usually one of them is best rather than the extremes.

The Rookie wrote:

No air, he says it's a coil fork!

You still need to speed up the rebound, it's going to almost certainly be too slow.

DT Swiss M210 came up as a rear shock on Google where I live....

defride

what tyre pressure are you running?

supersonic

neilus wrote:

supersonic wrote:

Slowest rebound usually handles awfully.

Cheers, thats good to know. I'll change it to fast and see how it handles. And cheers for some good advice JK.
Dunno how the fork/shock/front/back confusion arose, I didnt mention anything about setting the fork sag! All i did was - to use one of my favourite GWBisms - "mis-underestimate" shock sag at 40% when its really 25%. On the DT Swiss 210. Not forks :P
Yeah starting to like the idea of a skills day. But living in Austria as i do, I guess all the mtb trainers will be swapping bikes for skis soon, woohoo!! Not long now :P

Start with it bang in the middle. See how it feels.