Handling Problems

simonp123

I need some advice regarding sorting out the handling of my bike. I understand how to sort handling of cars, but mountain bikes are a bit more of a mystery to me on that score.

The problem I have is the front end, it seems to become very twitchy at speed, is hard to place where I want it, even at low speed, and can be very reluctant to turn.

The bike is a 2008 Kona Blast Deluxe with the front fork replaced with a 100mm Tora 318 Solo Air.
I have also just converted to tubeless (standard tyres) with a 2.1 Kenda Nevegal on the front and a Maxxis Ignitor on the rear.

My guess is there is a weight distribution issue which is probably compounded by the fact I am on the heavier side at 17 stone so probably weight in the wrong place will make a big difference. I have no idea whether the effects I am having would be too much or too little on the front though.

Of course it could be that I am just rubbish at riding :oops:

nicklouse

how much sag are you running?

simonp123

nicklouse wrote:

how much sag are you running?

A bit more than I was, around 25mm.

simonp123

Nobody got any ideas suggestions at all?

bomberesque

well, OK then ... I'll have a go but it'll only be half a one as there's not enough data

I assume the Blast came with a 100mm fork originally? In that case geometry should be largely unchanged. Sag at 25mm is in the zone so that should be OK

weight distribution is pretty much all down to you as you are the heaviest part of the bike so play round with your body position and watch how others place themselves on the bike.

different bikes handle differently and it's possible that you have a geometry that doesn't suit either your body shape (arm/leg/torso lengths) or your own handling preferences (which you may not be consciously aware of yet)

I'm a little confused that you describe the front end as both twitchy and reluctant to turn, which seem opposites to me.

Some guesses at reasons for different handling

twitchiness (quick handling, bike seems to turn itself)
steep head angle
short stem
short wheelbase
weight too far forward (short TT/ steep Seat angle)

Reluctance to turn (slow handling, bike difficult to turn)
Slack head angle / long trail
long stem
slack SA or long TT
Long wheelbase
stretched out rider position

I would get out riding with other people, find a club that suits you and/or book yourself into a group day at one of the trail centers. A good coach will be able to tell you within minutes what is up, no amount of internet pontification will get as close

simonp123

OK, maybe I have asked impossible questions then as I suppose there are so many variables.

I fully appreciate that a lot of it may be down to my riding & weight distribution, but I jsut need to understand what may be contributing so that I can make the changes required.

Yes the Blast nad a 100mm fork originally. It also has what are quoted as a relatively slack head angle at 68.5 deg.
I am also confused about the apparent twitchiness and also reluctance to turn, hence my confusion as to what to do. I suppose that both of these could be the result of too little weight over the front? i.e. it is not slow as such to turn, but there is no grip so it doesn't turn?

I am 6ft tall and have an 18" frame. Most of my height is in my body though, so I have ended up with my seat right back to get a comfortable riding position. Been wondering if a longer stem (original 90mm) might help?

Yes, perhaps I should try to get to some sort of training session, but I have fallen off and had injuries causing some time off riding tha last 2 times I have been on a trail, neither at much speed so need to sort out something or I'll really be in trouble!!

paul.skibum

If there is no grip you are probably riding the back wheel too much gte forward and weight the bars into turns, try feeling like you are leaning on the barsas you go to apex of corner, you can kind of move weight back as you exit.

You could try a different tyre but I doubt that's the problem particularly

bomberesque

simonp123 wrote:

it is not slow as such to turn, but there is no grip so it doesn't turn?!

ah, so when you're climbing, the front wheel lifts and so you can't turn?

OK, I'm going to guess the blast has a slack seat as well as head angle (68.5 being on the slack end for a trail bike, although there are plenty slacker) and this means your weight *whilst in the saddle* is too far back once the slope gets to a certain angle. This will lead to the front tyre wandering as it loses traction. 2 solutions; stay in the saddle and lean forward down towards the toptube, this will bring your CoG forward a little. Otherwise, climb out of the saddle into a more attacking position and bring your weight forward so you have enough on the front wheel to steer with. f course this means unweighting the rear wheel slightly so it's a balancing act.

experience with the bike will allow you to navigate with very little weight on the front at all (balance can steer the bike) but you may well have come up against a geometrical constraint of slack angled frames, they just don't climb so well.

Funny thing is; this *should* translate into more stable handling when pointing down. It's possible you just need some more practice to get used to the bike you have (I had a very steep angled rigid bike back in the 90s that took me over a year to get used to ... I've preferred steeper head angled bikes ever since)

To change the handling of what you have now, you could try a slightly longer stem (any idea of your current stem length? dn't go nuts as you'll be stretching yourself out at the same time) or a higher bar position (acheivable with a higher rise stem, a higher rise bar r, if you have spare steerer sticking out the top of your stem, just by moving the thing up)

simonp123

paul.skibum wrote:

You could try a different tyre but I doubt that's the problem particularly

I already replaced the front with a grippier one and I think it is worse now, but then it kept going flat on the lats ride as my tubeless conversion is not sealing well yet.

Whilst moving my weight may be the answer, presumably it is better to have your "natural" position giving the correct default weight distribution for rather than having to lean forward or back all of the time? To do this presumably means getting the stem length, and handlbar height/position right to do this?

nicklouse

Ok so other than getting a stiffer fork what else has changed, the sag is OK, were you running more or less before?

I would play around with where you are on the bike before spending anything.

also more detail of the problems would be good as reading it it seems it be happening in different situations where the "fixs" would be different..

is it a problem as speed on the flat or descending or both.

the lose front is it only when climbing.Or?

It could be that the frame might just be a little too short for you or you are not moving your body to the required positions for the riding.

forward for climbing and back for descents. Neutral for flats. You are rarely in the same place for much time.

simonp123

Shame I can't actually ride the bike at the moment and try some of these things as I buggered up my knee when falling off on a bridge over a ditch!

simonp123

The fork I had too stiff I think before as it was hard over roots etc and quite bouncy, sag was probably under 20mm as I found it was harder than I thought it was et to.

The fork feels right now, actually absorbs the bumps rathe than accentuating them.

It is the nuetral ridng that seems to be the issue. I get very forward when climbing and it seems OK, even if the front still likes to lift a touch. Decending is OK, though I am quite slow at the moment, when I try to go faster the front feels quite twitchy.
It is the flat or slight incline/decent that is the main issue. for example I turn into a fairly gentle sweeping bend on dirt and the front just feels reluctant to turn in, just feels like it will wash out at relativley slow pace. Then you get the slow twisty stuff where I jusy struggle to get the front end to go where I am pointing it. What I don't seem to get are these issues on more hardpack types of surfaces.
My knee bashing crash was at low speed, when after I lined up the bike to cross the narrow bridge it just changed course and went over the side, not sure what happened, it just seesm to not want to hold a line.

dave_hill

bomberesque wrote:

twitchiness (quick handling, bike seems to turn itself)
steep head angle
short stem

In theory yes, but I used to have a similar problem with my Giant which originally had a long stem and narrow bars.

First up I swapped the bars for a wider pair. Wider bars give you more leverage and you therfore don't have to make as large an input to change direction (even subconsciously - after all, riding a bike is all about constantly steering into falls to correct them).

If you don't have to make as much effort to steer, you're less likely to overdo it.

The next job was a shorter stem. This has gone from 110mm to 90mm and is now 70mm. The bike feels more planted and less twitchy than it ever did.

The Spiderman

Another suggestion for you to get your weight forward.Try pushing the saddle foward on its rails,or you could try an inline seatpost if your current one is a layback.

I`d also try moving the bars lower,by taking some of the spacers out from beneath the stem and putting them above.

The saddle and stem position will cost you nothing so try it.

Raymondavalon

simonp123 wrote:

My knee bashing crash was at low speed, when after I lined up the bike to cross the narrow bridge it just changed course and went over the side, not sure what happened, it just seesm to not want to hold a line.

If a bike is straight, (as in no bent frame or suspension geometry) it will hold a line by default, this is demonstrated by riding a bike with "no hands"

No offence Simon, but always remember that you should look at the line you intend on following, if you look where you don't want to go, i.e. the ditch, rest assured you'll end up in the ditch. It's human nature, I've made this little mistake once or twice myself over the years, so I speak from experience.

paul.skibum

simonp123 wrote:

paul.skibum wrote:

You could try a different tyre but I doubt that's the problem particularly

I already replaced the front with a grippier one and I think it is worse now, but then it kept going flat on the lats ride as my tubeless conversion is not sealing well yet.

Whilst moving my weight may be the answer, presumably it is better to have your "natural" position giving the correct default weight distribution for rather than having to lean forward or back all of the time? To do this presumably means getting the stem length, and handlbar height/position right to do this?

This depends - riding off road is a not particularly static experience - you should be constantly moving your weight about on the bike. If you just perch on the saddle and pump away then you are inviting a whole world of issues - standing on the pedals and being active when riding are key to making the bike work best.

Some of the suggestions above will help but there is no substitute for a spot of technique improvement - try tackling some of the sections you have had issues with in the attack position, stand on pedals with pedals level (3 and 9 position), flex legs, let bike move under you rather than with you.

Sorry if this is an egg sucking lesson - In my experience many problems people have with factory built bikes stem from them rather than the bikes.

simonp123

bomberesque wrote:

simonp123 wrote:

it is not slow as such to turn, but there is no grip so it doesn't turn?!

ah, so when you're climbing, the front wheel lifts and so you can't turn?
)

No climbing is OK, it is flatish stuuf and quick stuff that is the main issue. Current stem length is 90mm

simonp123

paul.skibum wrote:

This depends - riding off road is a not particularly static experience - you should be constantly moving your weight about on the bike. If you just perch on the saddle and pump away then you are inviting a whole world of issues - standing on the pedals and being active when riding are key to making the bike work best.

Some of the suggestions above will help but there is no substitute for a spot of technique improvement - try tackling some of the sections you have had issues with in the attack position, stand on pedals with pedals level (3 and 9 position), flex legs, let bike move under you rather than with you.

Sorry if this is an egg sucking lesson - In my experience many problems people have with factory built bikes stem from them rather than the bikes.

I was meaning the weight distribution whilst in the attack position. Most of my problems (and craches!) have been whilst in the attack position. Whilst I agree that there is a constant moving of weght dist, we all have a natural attack position that is comfortable and presumably on the flat you would want this position to give the desired distribution of weight making it easy to move back and forth to the desired level. Obviosuly a lot of this is fixed in the bike geometry, but presumably where your hands end up has quite an effect on weight distribution.

Ironically my crash off of the bridge happened when I tried to be confident and take the line accross it with a little speed rather than the slow wobble previously. I am finding that I am looking at a line, but the bike doesn't seem to follow my eyes.

Perhaps the slack angles are in fact making it just slow to turn, which I am interpreting as twitchiness at speed.
I certainly don't find this issue on my local evening route which is farly quick (the downhill bits anyway!) hard packed gentle turns an dthe bike seems quite stable. Maybe if it is the tighter stuff causing the issue then it is slow response.

I need to get out and try the suggestions here, I just wish my knee would heal quicker. Bloodt chicken wire on teh wooden bridge sure makes a mess of your skin :evil:

simonp123

dave_hill wrote:

In theory yes, but I used to have a similar problem with my Giant which originally had a long stem and narrow bars.

First up I swapped the bars for a wider pair. Wider bars give you more leverage and you therfore don't have to make as large an input to change direction (even subconsciously - after all, riding a bike is all about constantly steering into falls to correct them).

If you don't have to make as much effort to steer, you're less likely to overdo it.

The next job was a shorter stem. This has gone from 110mm to 90mm and is now 70mm. The bike feels more planted and less twitchy than it ever did.

My brother and nephew (both have Giant XTCs) had trouble getting through a gap between 2 trees on 1 trail as their bars were wider than the gap. Mine went through OK, so my bars are obviously narrower. It is them who I have been slowing down with my lack of speed and grip. I might see if I can pick up some cheap used wider bars and a shorter and longer stem on ebay and see what effect it has.

paul.skibum

Simon - no idea then mate - I still think that somewhere along the line its more likely to be handler error rather than the bike! Sorry!

I just checked out the Blast on kona's website and its not a particularly slack bike - 71 degree seat and 68 degree head which puts it bang on where my Cove Handjob is which I run on 100mm forks also. Now I have a 70mm stem, 660mm wide bars and a 1/2 inch layback seat post with the saddle mounted mid rail. Obviously as a short guy (5'6 weighing 70kg clothed) and riding a 15" bike this means nothing vs you but realistically whilst a shorter stem and wider bars do make a difference its not going to make the difference between crossing a bridge and going of the side of it! There has to be forces bigger than that at issue here!

supersonic

I would try a 100mm stem.

simonp123

paul.skibum wrote:

Simon - no idea then mate - I still think that somewhere along the line its more likely to be handler error rather than the bike! Sorry!

Yeah, fair point, and I'm not saying you are wrong. However, in my defence if something is happening that reduces my confidence in the bike that is going to increase my mistakes. I know from cars that a small suspension change can totally alter how a car feels and your confidence level accordingly.

When I follow my brother round a corner at the same speed and he goes round no problem and my front tyre washes out whatever I try is that all me? Maybe I suppose. I'm not saying the bike caused my crashes, they were probably down to me, but should I not get some predictability in the bike handling?

Interesting about the angles though as everyone always goes on about how slack the Kona bikes are, looks like it is not strictky true.

Plenty of ideas from people here though. I will try shifting my weight more forward, and back when I ride to see the effect and then see if it generally needs to go in one direction. Only then i guess will I know if a small setup change will be of benefit. I know that lowering may saddle a bit over bumpy stuff made a hige difference before as my ttack position was way too high previously due to clearing the high saddle.

supersonic

68 degrees is quite slack for a 100mm bike. And if your weight is quite far back, it will have a tendancy to wash out. Exactly the problem I have with slacker angles - vague front end.

simonp123

I have found recently that after a climb, I have tended to stay sat forward on the saddle till it gets uncomfortable and I slide back.

I guess the only way here is to keep going round the same section trying different rider positions. Ironically this was sort of my intention when I last rode as there is a nice woodland loop for trying this. Shame I crashed before I reached it, and whilst I carried on it was more a matter "getting back on the horse" and tryinmg different things was low on my agenda!
Might be worth trying my brother's bike too to see how that feels by comparison, might shut me up if it is the same/worse, then I'd have no excuses

papasmurf.

what pressure you running you front tyre on, out of interest?

simonp123

papasmurf. wrote:

what pressure you running you front tyre on, out of interest?

Tricky one, previously it has been around 45-50 psi, but withe the tubless one on tha last ride, it SHOULD have been a little below 40psi, but as it kept going down who konws? When i pumped it back up it was certainly better. I wonder if my weight means I need to be on the upper end of what tubless can be.
Need to lose weight to ride better & crash less, need to crash less & ride more to lose weight :roll:

simonp123

OK, been mulling this topic over whilst I am still waiting for my knee to be ready to start riding again. By the way I don't have to go back to be checked up again, so hopefully now it is scabbing up and drying out I might get out for a small, gentle ride later in the week now I have my knee pads too

Anyway, it seesm everything drifted off the subject really and became a discussion as to whether my problems were the bike or me which wasn't really the original point of the post. Maybe my wording wasn't quite right either, so...

The bottom line is that I perceive that there is an issue with the handling of the bike that makes me lack confidence and I feel is hindering my ability to progress my skills.
Whether the problem is actually me is perhaps a different matter, but we all know that confidence has a lot to do with how you ride, and if I don't feel confident with my bike it is going to affect how I ride and learn.

My feeling is that the front end doesn't grip well, and I also do not feel that I am able to place it as I would like, so my original question really should have been, is there anything that I could change that would assist in recovering some front end confidence?

Another thing I should mention is that I have been riding this bike for about a year, though a lot of it has been on relatively non-technical bridleways etc. I have done the MTB trail at Ashton Court in Bristol a couple of times, and several rides round a trail near me called Spirthill. So, whilst I am a relative newbie I am not a complete beginner, so have developed at least some level of skill, hence my feeling that the bike is holding me back a little, though I accept that at least some (if not all) of my issues are down to me.

I also presume that the reason there are so many different stem types, handlebar widths, rises etc etc is so that you can tune where and how your weight is dstributed on the bike to help with your riding otherwise what are they for?

For the record I have bought a 10mm longer stem (used) on ebay to see if moving my weight slightly forward helps me get some traction at the front. Not got it to fit yet though.

I also found that my front (tubeless converted) tyre would drop 20psi within an hour, so would have been down below 20psi by the time I started my last ride, and with me at 17 stone that would not have helped :shock:

CycloRos

It sounds like you've just not found a setup you're happy with.

At less than a years riding on the bike and not very technical by your own admission, I'm not surprised that its taking some time for you to feel confident on it on technical terrain.

All these different stem lengths, bars, seatposts are on the market to make a difference, whether any of them will make a difference to you though only really you can answer.

If I were in your position I'd try the following all on a familiar section of trail :
- tweaking the tyre pressure (start at 30psi and adjust as neccessary)
- saddle position
- longer stem
- shorter stem
- wider bars

simonp123

CycloRos wrote:

It sounds like you've just not found a setup you're happy with.

Quite, at the moment it feels like I am fighting the bike rather than the terrain. It has actually been a bit over a year rather than under, but you get the point.

What is odd is the previously I didn't notice this issue until I went out with people who are much quicker than me, so it does seem to be in some way related to speed. All is fine up to a certain speed then it all feels very nervous and washes out, but still way slower than the other 2 are going. They are not expets either I would add, but are more experienced.

Would the switch to tubeless give a different front end feel to the tubed setup I had before. Also gone from a Maxxis Ignitor to a Kenda Nevega.

With regard to stem length, longer will be slower, but more weight over the front, and shorter give faster but "twitchier" front end?

paul.skibum

I have no experience with tubeless but if its giving you issues at present I'd consider chucking a tube in to at least get a consistent feel from the front end over the course of a ride - a flat front is pretty much the worst way to ride a bike.

As for stems and what not - sure they are there to fine tune your ride and soem fiddling may help. I know I have attacked your skills previously and I have to say after a years riding I was pretty lacking in bike handling skills - I know I braked more and in the wrong place than others. If going faster is making you worried dont go so fast! Allow the speed to develop rather than throwing yourself down the trail and ultimately off it!

I'm no skills instructor (well I am a ski instructor but thats different) but I have done some basic MTB skills tuition with beginner family groups in alps and I always taught everyone stand up on pedals, weight the front into corners, brake in a straight line and lean the bike with the weight on the outside pedal. If they got that in a day riding with me I was stunned!

simonp123

paul.skibum wrote:

I know I braked more and in the wrong place than others. If going faster is making you worried dont go so fast! Allow the speed to develop rather than throwing yourself down the trail and ultimately off it!

Yeah still brake a lot in the wrong place or too hard esp steep bits.
Tricky balance pushing yourself a bit but not too fast for your skills, also I don't like to hold up the others too much :roll: I would consider my speed at teh moment pretty slow, which is why I am surprised to get things like washing out front end.