AM Ibis Ripmo - Take 2

beeb

Dr. Beebenson, PhD HA, ST, Offset (hons)
-2! You are a true bike tinkerer.
As long as it doesn't end in my face meeting with shattered carbon and a wayward steerer tube all is well! I don't do big jumps and these bikes survive EWS pros, so I really doubt any stresses I'm likely to put into the frame even with a -2 degree headset is going to do the frame any harm.

To be honest I'm using this as a bit of a geometry test mule at the moment as I'm planning on getting a longer/slacker N+1 in future and then backing this off to more of an all-around trail bike with a lighter build. But for now, sled mode - engage!
 

Paulie_AU

Likes Dirt
I like where you are going with this head angle stuff. 64HA is what the 29er I have ordered has. Current squisher is 66HA and Hardtail ~65.5 both due to overforking.
 

beeb

Dr. Beebenson, PhD HA, ST, Offset (hons)
Yeah, I'm interested to ride it this weekend and see how much difference (if any) it makes. Suspect weight placement on off-camber corners is going to need to be pretty precise, but otherwise everything else should be nice and extra-flowy.
 

beeb

Dr. Beebenson, PhD HA, ST, Offset (hons)
So I installed the -2 degree angle headset during the week (changing from the -1 degree I already had installed) taking the bike to a ~64 degree head angle. While it's not a great pic - it really doesn't look that slack surprisingly:
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I was expecting the slacker head angle to be better in rock gardens, but may make the bike/me more prone to losing the front end in flatter or loose corners.

Sorry for the mega-gush to follow - but damn I was wrong! Went for a ride yesterday arvo after work, and this thing absolutely hauls round corners now! I really wasn't expecting much difference to be honest and in fact thought it could likely have been a case of overcooking the head-angle change. But now it feels very, very different - and to my tastes - much improved. It's now much less "steer the bike" and just "lean the bike" and it'll follow the corner for you - which I friggen love. It just turns the way you lean it and you barely need to conciously steer with the bars unless riding through a switchback or something. Berms are mental especially - I normally feel somewhat rearward weight-biased when riding, and especially so in berms - but with this setup I could just lay the bike way over under me, completely trust the front, and while braking hard get the back so light I could flick it around a little with my feet. I have never been able to do this before and it just makes the bike feel so playful. Oversteer is defintely more fun than understeer!

Just to give a little context for how I like my bike setup - when I'm descending I basically never sit down. Just slam the dropper and stand for the whole descent (descents at the local trails are only a few minutes at best) - I see some people sit a lot while descending, and I think if you like seated cornering you'd likely struggle to weight the front tyre enough with this head angle and probably end up losing the front.

Fortunately this bike pedals so damn well, standing and pedalling really doesn't lose efficiency to pedal-bob so there's really no disadvantage there. It does still move slightly but just feels like a hovercraft, and still feels like you're still outputting all your energy into turning the wheel rather than loosing a percentage into having the suspension wallow around.

For general trail riding with a bit of seated cornering/attack position descents - probably half a degree steeper in the head angle would be better as you'd get a better all-around riding bike (better seated cornering grip, and would still charge descents), but this thing just feels so good on pure descents right now I don't know if I'll be able to bring myself to steepen it up again.

It did make the front feel a little more floppy on seated climbs, but unusually doesn't actually feel less efficient, it just wanders if the speed drops. Standing climbing is probably slightly improved, as you can lean on the front more easily, and the angle-of-attack of the fork makes it very willing to help absorb lumps and bumps. Track-standing is a little more fiddly though, as the shorter fork-offset (longer trail measurement) and slacker head-angle give the wheel more leverage over the bars.

To me this bike now just feels safe and comfortable, and the faster you go the more alive it becomes - It's a very addictive ride!
 

Chriso_29er

Likes Bikes and Dirt
You raise a very good point about the bike handling and how long low slack etc could be much affected by riding style.
Again reinforces that geometry numbers don't necessarily tell the whole story.

You're right about your photo, looks almost like a trail bike rather than a slacked out plow beast.
 

beeb

Dr. Beebenson, PhD HA, ST, Offset (hons)
Still been tinkering away little by little, getting the bike setup for Falls Creek.

I've dropped the headset back to a -1.5 degree trying to regain a little of the slow-speed manners and quick high-speed change of direction response, instead of just feeling like I'm riding an outright plough.

Wheel builder extraordinaire @The Duckmeister built a up new rear wheel for me. It has a Nextie Premium Enduro (30mm internal width) rim built onto a Project 321 "quiet" 216 POE hub, which I removed 4 out of the 6 pawls from (as 72 POE is still plenty), and bloody heck with only two pawls in there the thing has amazingly low rolling resistance.

I've installed a DHF 2.5" EXO up front to try (up from a 2.3") which I think will be better for the higher speeds and cornering forces at Falls Creek, and a DHR II 2.4" EXO rear (EXO because I love a light rear wheel, hopefully I won't pop it!).

Other than that, it's just been playing with lots of little tweaks tuning suspension, adjusting bar position, and even playing with pin configuration on the pedals (I actually removed some to allow the ones that are left to bite into the shoe a little better).

Suffice to say, I've run out of things to blame the bike for because it's a beaut. From here on in it's only my shitty skills and fear of stacking holding me back!

I feel pretty bad about shit-canning my prior Ripmo now, because they're a pretty bloody amazing bike once setup properly to be honest. Only thing they 'stuffed up' from factory IMO was the "steep" 65.9 degree head angle. Mine's now at 64.4 degrees and it still feels like a light and flickable trail bike and doesn't really have any weird handling traits - if anything it's a lot more predictable than the stock HA which (IMO) I found felt pretty easily overwhelmed in rock gardens, and sometimes felt difficult to weight the front correctly for slow or flat corners. It was only once I tipped the fork slacker than 64 degrees that things made a marked shift towards getting too sleddy.

As far as derailluer bikes go, this is pretty close to a quiver killer. I could be tempted by an even longer bike for alpine days, or a slightly steeper/shorter rear-centre bike for goofing around on trails rides but this does a bit of everything quite well. I do find it's more travel than I generally need though, but the geo is so damn dialled.

Regarding the geo - recently I had wondered if I would buy the Ripmo again in hindsight, or a (similarly slacked out) Ripley? Truthfully - I don't know. A slack Ripley would be a bit more fun when JRA at low and mid-speeds and just looking to play around and pump and jump trail features - but knowing the geo of this bike (and the Ripleys being damn-near identical) I know it would also very easy to go fast enough to massively overwhelm the available travel and get yourself in too deep. You'd have to have the discipline to not get too greedy and know when to get on the brakes early. The trade-off being you'd get more playfulness on the bits of trail the Ripmo barely notices in return. Either would be awesome - just subtly different - flavours of fun.

PS: It's pretty. :)
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wkkie

It's Not Easy Being Green
Premium Enduro (30mm internal width) rim built onto a Project 321 "quiet" 216 POE hub, which I removed 4 out of the 6 pawls from (as 72 POE is still plenty), and bloody heck with only two pawls in there the thing has amazingly low rolling resistance.
What's the theory behind taking the pawls out? Purely for reducing the rolling resistance?
 

beeb

Dr. Beebenson, PhD HA, ST, Offset (hons)
What's the theory behind taking the pawls out? Purely for reducing the rolling resistance?
Yep, mostly for reduced rolling resistance. Having had the Pro-4 (44 POE) hub on this for a while though, I've never felt I needed quicker freehub engagement. If anything the full 216 POE would just create more pedal kickback on trail chatter.

And doesn't it increase the stress on the remaining pawls?
I wondered about that, and it is a risk technically - but I pulled the hub apart because it had been skipping teeth after a pawl magnet disintegrated and the debris was fouling the mechanism. I was expecting the drive ring to be stuffed (I ignored it a little longer than I should've...), but it was totally unmarked inside. I figured if it survived that, it'll survive only having one phase in use. It'll mean more wear on the pawl pivots in that one phase, but there's spare phases and pawls for the longer term.

Aren't they asymmetrically placed so there's only two in engagement at any point anyway?

EDIT: answered my own question. Project 321 hubs use a 2x6 or 3x6 pawl setup in order to achieve the high engagement. They're spaced asymmetrically so that only ever two pawls are in full engagement (or three if you get that hub drive ring/pawl setup recommended for e-bikes and touring). Because you have three (or two) sets of pawls trying to engage at different times, you can get your PoE cut in three (or two).
Exactly this. The 216 POE hubs like mine are 3 phases of 2 pawls being engaged, I've just taken out two of the phases.
 

wkkie

It's Not Easy Being Green
Can't say I've noticed any extra drag with all mine in, but I'm no racer, so it doesn't really bother me.

I did notice it was super smooth after the clean and new oil. Virtually silent too. Riding on the trail you can't hear them at all even in the back pedal. It just highlights the rest of the noise on the bike though...

Great hubs, but I suppose they'd want to be at that price!

The quiet pawls are also meant to have less drag than the loud, would be interesting to see the difference.
 

beeb

Dr. Beebenson, PhD HA, ST, Offset (hons)
Can't say I've noticed any extra drag with all mine in, but I'm no racer, so it doesn't really bother me.
Oh there's hardly any drag as is in stock form, but I figured even less is even better!
 

clockworked

Like an orange
How could pawl drag even be noticable? Surely tread on the tyres, or the roughness of the ground would make more of a difference
 

beeb

Dr. Beebenson, PhD HA, ST, Offset (hons)
How could pawl drag even be noticable? Surely tread on the tyres, or the roughness of the ground would make more of a difference
Flip you bike over and sit it on the bars and saddle, make sure the rear brakes aren't dragging and spin the wheel. The difference between hubs can be surprising. The Pro4 would spin down well before the P321 (despite being laced to an alloy rim with heavier rotating mass). If you watch when the wheel speed gets to slow speeds with a heavily sprung freehub like on a Pro4 you can see the wheel drop speed with each click of the ratchet (ie: it's not just tighter seals or bearings slowing it faster).

The wheel with the P321 takes longer to spin down (like, a few rotations of the wheel longer from a similar input). Still loses speed "notchily" with each click of the ratchet, but much less. So even less pawls = even less losses.

Is it a huge difference, no. But it's sort of like fixing a slightly dragging brake. It might only make 1% difference in overall rolling resistance but it costs me nothing and has no negatives.

Back when I was riding my 5010 I never thought there would be much rolling resistance difference between hubs, until I swapped from my bike (with Pro4's on at the time) to a mate's bike with Chris King hubs on it. Same wheel size, same tyres, near identical weight rims, pretty much same tyre pressures even! The thing just rolled so effortlessly. I knew why he was quicker along the trails - he's a better rider than me - but I could never figure out how he'd roll away from me on the flats when we were just rolling along. One brief spin on his bike made the difference clear.
 
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