New bike has quite a few changes from the old one.
I'm wondering which of these might be contributing to the front end feeling less stable, less planted, more twitchy than the previous bike.
Obvious order of attack is price but I fancy a discussion on what we think might be the biggest contributing factors as I'm sure it's more than one.
Front wheel is now 29. Previously 650B.
Front tyre is Assegai. Previously DHF
Casing is now Exo + previously Exo
Pressure is 18psi, previously 23psi
Fork travel is 170mm. Bike designed around 160, will take 170. Previous bike was 160
Stem length is 35mm, pervious was 45mm
Bars are now about an inch higher than the saddle, previously at, or just below saddle height.
30mm of spacers under the stem, previously none. More involved than that obviously due to head tube length.
Reach is 475mm, previously 435mm
Head angle 64° with 160mm fork. Previously 66.6° on 650B
Costs nothing to play about with tyre pressure and remove the stem spacers. I'm happy that body position is far enough forward as I've always ridden the front of the bike.
Anyone want to wade in with theories or experiences with similar?
Mostly riding rocky stuff around the Peak
I went from 26 to 29 so more of a jump, I struggled moving my centre of mass further forward on the longer bike. Once I realised how much grip the 29er Assegai ( Maxxgrip flavour) gave, I gained more confidence.
Slacker and taller front end, less supple tyre casing, bigger wheel creating more ‘trail’.
You need to get your weight over the front more to compensate. Hit the gym, get those push ups going and embrace it.
How do chainstay lengths and bb drop compare on the two bikes?
- Both 650B back ends new bike is 438 Vs 430
- Both 340 bottom bracket heights off the same rear wheel
As others have said, I'd assume you're not weighting the front wheel enough
I can see it's the popular option but I'm as confident as I can be that I am riding the front of the bike.
Likely it's you needing time to keep adjusting.
Also, whip those spacers from below to above the stem and slowly swap one at a time back down if you feel the need. IMO many new bikes seem way to high at the front. IANAER.
You need more air in your front tyre, that’s why it’s feeling so vague…
Due to the other changes to bike setup and geometry, you will need to adopt a more active riding style to weight the front wheel when descending. I assume you have let air out of the tyre to attempt to find the grip that your passive riding style (because your previous bike was much shorter and steeper) afforded you anyway…
Get that pressure up into the early-mid 20’s, and shift your body weight about more to get that weight over the front tyre as you need it…
An Assegai turns with quite different characteristics to a DHF. Especially while being leant over from the centre tread to the edge knobs. I'd also agree with the guy above regarding your tyre pressure. I wouldn't even consider going that low with a full DH casing. but you haven't mentioned your weight.
On paper your new bike is 40mm longer in reach but from geometry changes it will probably be closer to 80mm longer in wheelbase. with around 70mm of that bing from the front centre.
shorter stem and higher bars will both have contributed to reducing how much you are weighting your front wheel when riding and with a much longer bike you actually need to increase it to attain the same level of front tyre grip of your old bike.
Also. What do you mean by bars being an inch higher than the saddle? if that's with the saddle at climbing height. they sound far too high. You mention being more of an over the front rider bu that sounds pretty unlikely if your bars are as high as they sound from your description. it would have been helpful if you had mentioned your height TBF.
I’m going with the different opinion of don’t try getting over the front more but learn to trust the grip that the bike and tyres got. It’s going to take a while to adjust to the changes from old bike to new but there’s a reason bikes are much bigger than 10 years ago and that’s not so we have to ride with shoulders over grips to push the front down enough to go round a corner
I've just re-read.
18psi? Blimey, I can make that fold and squirm lots on corners....
That seems like a lot less pressure (assuming the tyres are the same width). I run almost the same pressure front and rear nowadays, 1-2psi more at the back. But if your weight is too far back then you’ll feel like you need the front softer, and that softer tyre won’t feel right if you get forwards and weight it properly.
A recent revelation of mine was slowing down the fork rebound a click or three and how that calmer feel at the front let me keep my weight further forwards on jumps and drops.
The rear tyre is double down at 20 psi and no matter what rocky mess I throw it down I don't ding rims. Both tyres feel surprisingly firm pushing a thumb into them given the low numbers in the gauge. The gauge is a Topeka D2 and agrees with others.
Agree that the Assegai is a very difficult tyre. I'm not convinced I get in with it. Tempted to try a high roller 3 but don't want to throw in too many chances at once while I'm trying to work out what's going on
I found the same - front can run wide - when I got my first Geometron in 2015
You’ll need to pressure the upper grip - best cue I heard is to be able feel the tricep of your “upper/outer” arm working as you lean the bike (not the body) into a corner.
here’s some armchair cornering fun -
Is Your Riding Posture from 2006?
Cure Your "2006 Posture" with Cone Training
Video from Finns feed
DIALED S2-EP8: Suspension vs Posture | Which is more important? (feat. Chris Kilmurray) | FOX
#FoxDialed: Prime Posture – Post Script – Point1 MTB Training
Barel
Bikejames
https://www.youtube.com/watch?v=Griqxy_7BOw
Have fun.
Sounds like a big change for you, so it's difficult to pick out one likely culprit in the geometry.
I'd certainly try raising the bar a little more, if that's possible. Or a higher-rise bar. I've found I've always needed to do that as I've moved to longer rear ends and slacker HAs.
And maybe just try riding a bit more centered rather than forwards and see how that feels?
Just guessing really though. One final thought - is the BB now objectively high?
From what you are describing it sounds like the new bike should be more stable. Therefore I'm wondering if what you are experiencing is the bike no longer responding to your inputs in the way you are used to (which would probably be more pronounced on low speed tech). It could result in you feeling like you're getting ridden by the bike rather than riding the bike.
You could try being more aggressive with your movements. A more stable bike probably needs larger inputs to have the same response as a less stable bike.
If more assertive technique doesn't improve things I'd start by looking at the following.
Is it low speed tech or high speed flow where the instability is worst (or just everywhere)?
Apart from quick stuff like trying reducing the fork rebound damping, I think the main things I'd look at/calculate is where your hands are in relation to the bottom bracket. So the Stack measurement plus any spacers/stem rise and the reach plus stem length. See what the difference in numbers are there.
Then I'd calculate what the front and rear mechanical trail. See here for explanation https://www.peterverdone.com/wiki/index.php?title=Mechanical_Trail
From that you should be able to see what the major changes in body position and the major changes in geometry are which might give you some clues as to what's happening.
For me, the issue of that setup also points to reach / stem length / stack and bar height changing the weighting of the front wheel compared to your old bike.
I personally feel that 35mm is too short for a stem, unless you have one of those Mondraker forward geometry bikes or similar. For me, 35mm feels like the front end is going to fold under itself, if that makes any sense. I'm still on 50mm and from experience and experimentation would certainly not go lower than 45mm. There's a great video on YouTube where a rider tests different lengths of short stems and came to the conclusion that 45mm was the best compromise, but like anything related to bike setup, it's all personal preference. 35mm might work for you with some technique changes.
Stack / bar height - there's definitely a current trend towards 40mm+ rise on trail bikes but going higher requires a change in technique and front end weighting, especially on flatter corners. I'm still running 35mm as a compromise for my ageing back but actually prefer 25mm to get a nice centered attack position.
Thanks all for the ideas. It's not even corners that feels unstable. It's loose rocky straight-line stuff. Think potato alley. Used to batter down that on the old bike. This one feels like the bars/front wheel just wants to wiggle about and break loose.
That sounds like it might be more of a suspension thing?
You to be seem quite into your suspension stuff though, so maybe you've already investigated that route?
Thanks all for the ideas. It's not even corners that feels unstable. It's loose rocky straight-line stuff. Think potato alley. Used to batter down that on the old bike. This one feels like the bars/front wheel just wants to wiggle about and break loose.
29 wheels do have a bit of a more pronounced deflection feel on rocky stuff if you have your weight back. Took me a couple of rides to get used to that. I'd certainly drop the stem a bit to get your weight more forward.
Throw that 35mm stem in the bin & run a 50mm on it.
I don't know how people ride 20psi or lower, it must feel awful unless you're a featherweight. My rims are on the floor at those pressures.
I'm on 25psi minimum with inserts and Continental enduro casing. I go up a bit for uplift days and bikeparks to avoid berm-squirm.*
I'm about 97kg kitted up.
* I just thought of that phrase. I'm going to use it all the time and see if it takes off.
Yeh try a longer stem. One of my bikes had a very long reach (495) with a 35mm stem, and it felt a bit weird (i just got over it / rode the damn thing). My bike now has slightly more conservative (475) reach and longer stem (45mm) and it feels more neutral / balanced to me. But i'm old and not particularly fast, and i'm sure my technique is dreadful etc.
I'm in the move your weight forward camp. It makes a huge difference on modern geometry bikes.
Also put some air in that front tyre to firm it up a bit and give you some confidence. Back off the air as you get used to the feel of the bike?
I don't know how people ride 20psi or lower, it must feel awful unless you're a featherweight. My rims are on the floor at those pressures.
I'm on 25psi minimum with inserts and Continental enduro casing. I go up a bit for uplift days and bikeparks to avoid berm-squirm.*
I'm about 97kg kitted up.
I run 15psi at the back and 13psi on the front. 35mm internal diameter rim on the back with a 2.35in tyre and CushCore Trail on the rear and a 40mm rim with 2.6in tyre and CushCore Plus on the front. Can't remember what the casing but not 'Enduro' level.
Probably around 90kg all kitted up.
A bit higher pressure if I'm going somewhere with hardpack and berms but still well under 20psi.
So yeah, since I started running rims which are generally considered 'too' wide with CushCore I've just been going nuts with dropping tyre pressure.
As an experiment try riding a long with no hands. I tend to find riding with no hands more tricky on the 29 as the front end is a bit less stable. Something to do with height and a longer front end but riding is fine as I'm weighting the front.
Experiment with body position, bars being rolled forward or back to hit the sweet spot
I don't know how people ride 20psi or lower, it must feel awful unless you're a featherweight. My rims are on the floor at those pressures.
I'm on 25psi minimum with inserts and Continental enduro casing. I go up a bit for uplift days and bikeparks to avoid berm-squirm.*
I'm about 97kg kitted up.
* I just thought of that phrase. I'm going to use it all the time and see if it takes off.
Same, even when I was a couple of stone lighter I've always hated the vague squirmy feeling of too-low pressures, wider rims and modern high volume tyres doesn't seem to have helped this either. Mine are about 25psi at the minute which feels ok but could probably still go harder.
Sounds like you might just be sitting a bit higher on the bike as a result of the various changes.
Higher COG and weight not quite in the same place is going to feel a bit squiffy until you make a change to actively improve it.
Might just be a case of a bit more elbow bend to bring your chin forward a little. Dropping the stem down the steerer and putting those spacers above it might have a similar effect.
I got a banging deal on a 650b bike last year to run as a fun option on the local trails... and the geo was far less of a change from your previous bike. It just felt completely alien coming from a modern-ish geometry trail bike. The front felt so much lower low and my brain could not reconcile how unstable it felt when going fast.
I was (am) very comfortable with my bike now, so might end up going through the same as you shortly as this week is new bike week!
Depending on your weight tyre pressue seems very low, Exo+ just not robust enough when your hitting stuff hard, especially if youre heavier,
bb drop is important too, but I wonder if the longer reach, shorter stem and higher front end has you too far back n descents, id try lowering the bars, moving spacers etc
Riding a hardtaail now and again helps remind you me to lean forward push into the forks
I run 15psi at the back and 13psi on the front.
Where do you ride, on the moon? I might be able to cruise down the street at that pressure but 15psi is a flat tyre for me.
Anything lower than 25 on man trails or an uplift day and you can literally rip the tyres off all too easily.
I long ago stopped wasting money on Exo and Exo+. Maybe I need to go on a diet.
Strange reading the the pressures - 25psi for me and it would feel horrible. I'm generally 18f/20r and never (rarely) seem to have any problems - I ride fairly hard. Mix of mostly tubes and tubeless/cushcore on one bike.
People say I have my forks too soft also when they bounce my bike around, but I get 25-30% sag and only bottom out occasionally. Theirs always feel way too stiff for me
I had to go for wider (and higher) bars when I made a similar switch. Sounds like you've played with bar height... but what width are they? As others have suggested, getting the weight right over the front is key... and bar width plays a part in this.
Isn’t it weird how people will type out all the details of tyre pressure and geometry but fail to say their height or weight? We can’t see you!
5'10" 100kg kitted up. Both bikes were "large" from there respective ranges.
Bars are 800 wide 35mm rise
I was going NG to ask about bar width.
It's not even corners that feels unstable. It's loose rocky straight-line stuff.
Bars too wide? Sure, they give great leverage when you want to turn the wheel but that same leverage is working against you when the wheel deflects off something. If you're used to narrower bars, it'll take a while to get used to wider ones.
I'm shorter than you at 5'7 but I found a huge amount more stability going down incrementally to 760 from 800. The 800s felt comfy and never felt like a problem but chopping a bit off made the bike feel more stable just about everywhere.
Not sure if I missed it above but what's the fork and what damper?
I've gone dine to 770 previously but felt too narrow. 800 has felt about right on a number of bikes.
Fork is Fix 38 with the Grip2 damper. Commonly regarded as the best ever damper until the Grip X2 was released 😉. It has the UK factory tune which softens the compression.
Still had these issues before the compression upgrade though.
I’m barely 1/2” taller and about 15kg lighter. I notice a significant difference in body position is required between my full-sus (~450mm reach and 455mm chainstays) and my hardtail (~470mm reach and ~435mm chainstays), with near identical stack heights (and the same 40mm rise 760mm bars). The full-sus I just get on and ride with zero thinking, but I’m on that almost every day commuting. The hardtail I have to mentally adjust at the start of a ride and then settle into that more attacking stance - and then I really like it.
Going from 435mm to 475mm reach would be a big change for me, and would definitely require a significant change in body position. I’ve gone up in ~20mm increments over the years, no big jumps like that.
I run 50mm stems on both bikes because I prefer the calmer steering feel and the ease of weighting the front in flat loose turns.
On the hardtail I run 19/20psi front rear, with an insert in the back on tyres similar to Exo+, but our trails aren’t rocky - I’d go 10-20% harder on spiky trails based on past experience.
On the e-full-sus I run 22/25psi F/R with inserts at both ends. I’ve not run dual ply tyres but I assume you can go maybe 10% lower on the pressure, similar to adding inserts. After two punctures in two weeks the rear of the ebike is getting a dual ply!
Anyway, based on all that, I’d be running almost the same pressure front and rear on your bike, probably around 25 psi at your weight on rocky trails. And I’d experiment with bar height and consider a longer stem.
Some years back I recall riding a bike that felt too long at the time and weirdly switching from a 35 to 50mm stem made the bike feel less long, I think because the extra stability from the longer stem encouraged me to shift my whole position forwards and weight the bars more.
TLDR - more pressure in the front tyre, maybe a longer stem.
I’ve got the exact same fork running roughly the recommended damper settings for my weight with the rebound sped up a bit, and 100psi with no token. Feels very damped and calm vs the 160mm Lyrik RC2 I had before but uses more travel.
I really really think your set-up and body position is too rearward biased. Get some weight into the front and let that big 29” wheel and fork track properly!
Where do you ride, on the moon? I might be able to cruise down the street at that pressure but 15psi is a flat tyre for me.
I don't know. It works for me. After I started running CushCore front and rear I was still running 23psi/25psi and was worried about going any lower. Then I saw this video:
and on a particularly wet day with lots of wet roots and slick rocks I just started dropping pressure until I started feeling some grip. When I got home I checked the pressures and I'd ended up at 11psi/12psi.
That was getting a bit squirrely in the dry so I eventually settled on 13psi/15psi.
I like the way lower pressure tyres lose grip (when they eventually do lose grip) because it feels like I get a lot more notice before it lets go. At 25psi if the front was losing grip half the time I was on the deck before I even noticed.
I also ended up running my suspension much stiffer as the tyres were doing a lot more of the small bump stuff that the suspension used to do so now the bike feels a lot more stable in corners.
Dunno, I can't imagine going back to high pressures for mountain biking. And honestly, I'm not sure I can see myself riding without inserts if I had any kind of choice.
Thanks all for the ideas. It's not even corners that feels unstable. It's loose rocky straight-line stuff. Think potato alley. Used to batter down that on the old bike. This one feels like the bars/front wheel just wants to wiggle about and break loose
Before you get too micro with everything, I'd start by changing the easy stuff like steerer spacers, tyre pressure, bar rotation, fork settings and see if that settles things. It might, at least, give you some pointers - eg: if lowering the bars improves things, then that''ll presumably be weighting the front end more etc.
I think a fair few suggestions centre on cornering, but there are no corners in the Peak District, just rocks... I wonder if there's a confidence thing going on too as you adapt to a new bike. Some people seem able to swap bikes and recalibrate really fast, others take hours of riding time to feel really at home. You'll have a lot of baked-in automatic micro-adjustments going on and they'll be eliciting different responses on the new bike to the old.
If I go back to riding my old Ragley Ti now, it feels - initially at least - horrendously short and twitchy. Some of that is because in relative terms it is, but some of it will be that the sort of inputs I need to use on a 29er or 650b+ are 'too much' for a 26" hardtail, even a very good one. I guess I'm saying that you may need to adjust yourself at least as much as the bike, some of which may simply just be about riding it more and recalibrating rather than trying to tweak your new bike to respond to your entrenched riding style?
All of which could be absolute cobblers, but in your position I think I'd ride the new bike lots and do some simple tweaking to start with - the free stuff - and see where you are in a few weeks time. In the past I've found even small adjustments to, say, bar rotation, can make a significant difference. With Potato Alley type stuff, I think I'd start with fork set-up and tyre pressures and session the same section of rocky stuff repeatedly and see what - if anything - helps.
Sound advice from BWD there, and I'd just add that maybe you should swap bikes with a pal on a similar modern enduro weapon and see how that feels/see if they experience similar issues to you.
I think you need to rule out whether it's something unique to your bike.
Finally got a shuttle driver and did a few repeated runs.
Played with increasing pressure and that made things a bit better. Got up to 25psi both ends before I decided to try something else.
Dropped the stem down 20mm and that made a big difference.
Might have a look at increasing spring rate on the rear next. Sag is currently 33% so I think the bike might be sitting back a bit which isn't going to help.
Already feeling a lot better though