Can anyone out there shed some light on the steering behaviour of my Orange hardtail? I have a 96 Orange P7 frame with 98 RC36 Evo forks (70mm travel) whose steering feels unstable, having a tendency to 'tuck under' past a particular point (ie. past a given point, the forks will want to fall to roughly 90deg angle). This is particularly noticeable on tight, twisty technical trails.
I've ridden a couple of 1999 Marins, which felt much more stable - they were easier to ride no handed for instance. I compared the frames with the Orange and the Marins seemed to have a steeper head angle - would a slack head angle cause this type of steering behaviour (I've measured the head angle of the P7 as 66-67deg when I am sat on the bike)?
I'd like to get a hardtail with more stable steering, as I'm trying to encourage my girlfriend to come out riding with me, but she doesn't feel safe with the current bike. Is a new frame the answer? If so, any recommendations (the obvious one would be a Marin, but I don't know if you can get them) - I have been looking at the Handsome Dog stuff, but wouldn't be able to try before buying.
Sounds a lot like symptoms of a slack head angle - this could make the steering do what you describe but should make things more stable in a straight line. If the frame isn't corrected for the higher crown height of suspension forks there's not a lot you can do about it. I'd have thought a '96 bike would be but maybe not...
66 degrees seems very slack - about 71 ish degrees is more normal. A wider bar will give you more leverage to counteract that tucking-under effect but won't really change the handling. Any modern frame should be suspension-corrected to avoid longer forks slackening the head angle so you have a very wide choice if you go down the new frame route.
I've got a 2 year old P7, now fitted with Z4 Flylights (about 70mm travel). I had the same problem with the front end tucking in/under, but it seems much better since I replaced the original 130mm(?) stem with a shorter one (about 110mm) and riser bars (yes, I know, fashion victim!). Changing from the soft original RST forks to the faster Z4's also helped.
The real problem lies with the point at which you stem beomes further forward than the axle of the hub, once this happens all your gyroscopic forces seem to fly out the window and your bike will handle like a barge with a very long tiller. Make sure that your forks dont move too far back when in compression (ie axle moves behind the bars) by fitting a short stem and you should be ok.
Thanks for the advice. I'm waiting for a 105mm stem to replace the 120mm one I'm currently using - if this doesn't sort the handling out, I can fit it to whatever frame I get to replace the P7 (my LBS reckons they can get me a 1998 Pine Mountain for £150).
I've done some digging into the way Orange set the geometry on their frames - unlike Marin and Kona (and most others I think) who quote for a complete bike - Orange quote for a frame alone at a given orientation. In the case of the P7, the head angle (70.5 deg) is measured relative to a line passing through the rear axle and a point 35mm above the bottom bracket centre.
However, measuring from my built up bike, the bottom bracket centre is only 18mm below the line between the wheel centres. Therefore, the frame is tilted back, slackening the head angle (to bring the head angle back to 70.5 deg, the forks would have to be shortened by about 70mm - the same as the available travel!). Strange how Orange don't seem to have done anything to allow for suspension fork use (I spoke to one of the guys at Orange's workshop and the geometry of the P7 hasn't been changed really since about 1993 according to him)!
My mate Derek has an original Clockwork frame and runs them with Pace EvoIII forks at 90mm, the bike handles very, very well and try as I might I cant sell him a replacement, all the Orange bikes have pretty much the same geometry and as they're one of the best handling singletrack bikes out there why should they change? Try a shorter stem and risers not for reasons of fashion but because they actually make a difference. What size is your bike ?
Gyroscopic forces do very little to steer a bike except at very high speeds. To prove this get your bike on a hill, and just let it roll down the hill without you on it. 99% of the time it just falls over, but if it does get to a reasonably high speed before it falls over then it'll zoom off down the hill for miles before it crashes into something. Have you seen those ski bikes with short skis instead of wheels - they steer just like bikes but nothing is rotating. Bike steering is just all to do with angles and changing angles and your unconcious correction of falling left or right (which is why you have to learn to ride a bike - I still learning!). The tuck phenomena is really hard to explain, my bike is now imune to it since it got longer forks, and other bikes of mine are prone, or imune to it for no apparent reason. Look at the contact patch where the tyre contacts the ground, as you steer it moves around, as you steer heavily to one side the contact patch goes to the side also. Once it is more than 90 deg past the axis of the bike then the resultant force doesn't steer the bike anymore, it twists your bars round. the force centralising your steering becomes a decentralising one. What to do about it? Without drawing loads of scale diagrams and performing trigonometry - not sure. Does anyone accurately know their head angle, rake and fork length measurements anyway?
Interesting your having handling problems with your P7. I've spent a lot of messing around with the front end of mine.
It came with a 130mm stem with I always felt was a bit long. I then got a 105mm stem and this was good for really steep technical descents. At first I thought it was great but after a while I descovered that the high speed corner of the bike was a nightmare. It tended to 'understeer' and there was always a danger of the front end washing out. I think the stem was to high and I didn't have enough weight on the front of the bike. I then changed back to the original 130mm stem and wondered why I'd changed.
Anyway, I recented decided that 130 was too steep (again) so I've got a 120mm. This seems to make a huge difference. It's amazing how such little changes can totaly change the feeling of the bike.
Anyway, I hope you get the problems sorted in the end and don't end up on your face after a fast corner.
My first bike (1988) had a really short high stem and wide bars. A bit like what's fashionable nowadays. My mate got a marin pine mountain in 1991 with a 135mm stem and narrower bars. When I rode this I immediately felt that it was stabler through fast corners, but not as much fun it the rough slow stuff. But god could it shift. Me and a mate then fitted 150mm monster stems, but this sent things a little too slow, with the bike handling like a pig, and just crashing through everything with little control. So I settled on the original 135mm and have stuck with it for 7 years. The way people talk about short stems nowadays it makes you think that it is some sort of miracle revolution that they've just invented. Of course a bike handles faster with a short high stem, but then it washes out on fast stuff and you can't keep the front end down on climbs. Perhaps it has something to do with suspension, but surely a modern full sus bike is better at crashing through stuff so has no problems with slower steering? Perhaps sus forks work better with less weight on them? Perhaps people are more into doing downhills because their suspension lets them? Whatever it is, it's hardly a secret. XC guy- longer stem narrower bars, DH guy -shorter stem, wider bars. Big deal. The way people talk thought you'd think it was a crime to use a 135mm stem anymore. Well I've ridden short high stems and I'd prefer to stay how I am. My mate's missus fits a high rise stem and she's forever losing control on steep climbs as the front wheel won't stay down. Make up you're own mind. When I look at my MTB position compared to my road bike position it is hardly 'stretched out' like many mags would claim.
You don't seem to be one for fasion, do you Kevin?
Anyway, I think like most things in life it comes down to being a compromise. And only you can decide whats good on the type of riding you prefer.
It does make me laugh, though, when you read in magazines about how riser bars and a short stem are the ONLY thing you should have on your bike. But then, I guess thats another thread..
Of course, on a bike with a reasonable amount of suspension, say 4 + inches a short stem provideds more neutral steering, which does not excaserbate the problems caused by the variable head angle of a full susser. A longer stem tends to exagerate all the different riding characteristics whic can be unnerving on a big travel bike.
