Converting a 2009 Helius AM into a Helius AC
I thought I would share this project with you as some of you may be interested in replicating it and as far as I can tell, itís not been done before. At least that is what Stephan at Nicolai has told me.
The basic premise of the exercise is too lose weight off the AM by running a lighter 32mm fork, rather than a 35mm or 36mm fork. This switch saves at least 1lb/450grams, which is significant in the scheme of building a light trail bike.
When I bought the AM, I had originally mused that the ideal bike would be an AC built with an AM tube set, on the basis that I was (at the time) 110kg and quite hard on bikes as a result. In the end I didnít think it made enough of a difference to warrant the extra cost involved, so I just went with a more or less stock AM, but had the shorter ST with a 30.9mm internal diameter.
The first build of the bike came in at 33lbs. Nothing really wrong with that and it never really bothered me too much until I started riding with a couple of guys who are pretty quick along and up and since then the quest to drop weight has gathered pace. That project saw me lose 10kg and the bike lose 4lbs. I still run a CCDB but I also have an RP23 and I switch between the two depending on my mood and the trails Iím riding. But with the RP23 and otherwise the exact build shown here, the bike weighs 29lb dead. With the CCDB it weighs 30lbs 1oz.
So 29lbs is a great weight for sure but if we could get it to that weight even with the CCDB, that would be even better (and perhaps sub 28lbs with the RP23?)
Iíve run the bike before with a 150mm Fox 32 fork (15mm QR obviously) and to be honest, as good as the fork is in the rough (itís a little noodly on steep drop ins/compressions and nose heavy landings) the overall A2C of 520mm dropped the front of the bike just a little too much. It wasnít that the bike became nervous at higher speeds so much as the front end was far too ready to Ďtuck underí, especially on steep tight turns. I gave up in the end but always liked the fact that the fork also helped lose a chunk of weight.
Iíve had a few conversations with Nicolai about using various combinations of the new AM levers and shock mounting plates to adjust geometry and theyíve always said yes in principle but that the problem would be they couldnít guarantee the rear wheel wouldnít fowl the ST. Then just recently I asked another question and it turns out that they were now ready to say that actually this would work if (and only if) the bike was set up in either of the two shorter travel settings. Which was fine by me as that was how I was running it anyway.
So I ordered a set of -7mm plates. These move the head of the shock forwards by 7mm. The net result is about 1.5 degrees off the head angle and seat angle and a reduction of about .5Ē on the BB.
Interestingly it also works in the 157mm setting (I havenít tried it in the full travel setting as yet) although that is with a 2.35Ē Maxxis Ardent tyre. There is about 5mm of clearance between the ST and the wheel on full compression.
The bike doesnít feel right though even it with the fork dropped to 150mm of travel. With 30% sag dialled in to the 157mm setting, the bars feel too high and the bike is kicked back too far. But this is what I wanted because I fully intend to also drop the fork to 140mm and run the bike with 30% sag in the 145mm setting, at which point it should all feel very well balanced.
I realise that what I will have effectively done is create a trail ripping, super beefy Helius AC from a stock AM, but at the same time, a lot of us bought our AMs at a time when the AC hadnít been released. We also bought them with the older style geometry.
The next thing to do then, once Iíve adjusted the fork, is to ride it, which I will do on Saturday and report back along with more accurate measurements.
Oh and the all in cost was about £80 including courier postage from Germany.
You said the BB dropped by 1/2" can you tell me what the actual BB measurement is now please?
Also can you tell me the BB height of your Ragley Ti please, which you posted up on STW recently with your 140/150 forks? Is it around the 13" mark? I currently have a hardtail which has a BB height of 12.3 which I really like.
Gt, with the new levers and the older sized shocks (200x57) you say you get a 66.2ha and lower bb but with what fork a2c? The 520mm you mentioned?
Also I thought the new levers were way more than 80 squids?
My mate is running his AM as a short travel Bike. Actually he does so because he had no money for new parts, so he ended up swapping over the old stuff of his previous frame.
His steup is with a Pike 140mm front and a Fox RP2 with 50mm stroke. he has set reatr travel to 130 mm. Didn't even change levers or shock mounts.
He mainly rides trails up and down. There is no problem with the shorter setup for him. The BB is lower but there is a lot less of sag too. And it does rip trails...
OK so I've had a chance to set the bike up a little better and take some measurements.
Fork is now dropped to 140mm. It's a Fox 36 so the A2C is now 525mm, which is the same as a Pike or Fox 32 150mm.
The head angle measures 66.7 degrees
Seat Angle measures 70 degrees
BB measures about 13" It might even be a bit lower. In fact I'm a little worried it's too low
I cannot see that this set up is going to even remotely work in the 157mm setting because basically unless your pedals were level on full compression, they are going to get burried.
At 145mm travel, they are still 5mm off the ground at full compression.
Note, it's not the levers I've changed, just the forward mounting plates, to -7mm, hence why it cost £80 and not a lot more.
I'll write a report on what it rides like but expect to hear a lot about it being a cruise funken missile!
des[parately interested in your ride thoughts.........
i'm tempted to junk my AM as a one'r ..... unfortunately, i spunkd on new 36 float kashimas and a ccdb custom tune + ti spring so will suffer it for a while longer.....
i expect the pedal strike will kill the ride however - let us know ASAP...!
Brillaint idea and post!
I for see me contacting them myself. I don't see why this wouldn't work for any bike in the helius range? (Correct me if i'm wrong)
Surely this is a great way to change the geometery of the bike? Certainly alot cheaper than an angleset.
When you say the hight of the bars is too high and the bike is kicked back. Does this just mean that you now have it in what I'm going to call dowhnhill mode? And will it put any extra force through the stear tube of your fork? Sorry if those are stupid questions.
Two-tone not stupid questions. If you were to want to run the bike as a DH bike only then I don't think the 'kicked back' layout would be a problem. It's really an issue though if you are intended to ride it as a trail bike.
The problem is this. With a tall(er) fork, say a Fox 36 at 150mm or 160mm and the -7mm mounting plate at the head end of the shock (again, this is NOT the levers, they are considerably more expensive), you feel like you're falling off the back of the bike when seated. The seat tube angle is really slack and you canít really pedal it very well.
If you're not seated, it shouldn't be a problem.
But, the BB is really low and you canít use the full travel mode either, youíd be restricted to the 157mm mode and you wouldnít be able to use anything larger than a 2.35Ē tyre either, otherwise the rear wheel will collide with the seat tube on full compression.
That said, the Specialized Demo 8 frame this year comes with a 343mm BB (13.5") and that has 8" of travel! So in theory, if you don't intend to pedal, then the Helius, in 157mm mode with 2.35Ē tyres would rip as a mini-DH bike (possibly). But then itís not designed to do that really.
All of this is a bit academic because Iíve not even ridden it yet in its current guise. I think pedal strike will almost certainly be an issue and most people would have to seriously adapt their riding style to make this set up work. I tend to ride more by carrying speed than regaining it and where I ride mostly doesnít tend to be too rocky anyway. Iíve ridden a bike with a BB almost this low before and in the end, I did have to move to 165mm cranks, which may be something i have to do here also. But we will see. Besides, a low BB, slack HA and long wheelbase Ė man this bike is going to be a cruise missile!
Interesting and thanks for the clarification.
GT I know its not what you bought the new mount plates for, but could you or do you know the rough Geo using the full fat 160 up front and the old style (200x57) shock out back?
Also what are you measuring the angles with? Pen + Paper + Maths or iphone App? If the latter which one?
It would not work because the wheel collides with the seat tube. The measurements I've given here were using the Plain Code 'clinometer' application on an iphone, calibrated to zero on the floor where the measurements were taken. Changing the travel setting on the AM does not change the static geometry so the geometry in full travel mode, with a 160mm fork, would be the same but 1 degree slacker on the HA and SA, which is the effect of raising the front end by 20mm. It would also raise the BB maybe .5"?
Thanks GeeTee. I agree it's not been desgined to be a full downhill ripper but certainly has the travel to do it.
looking forward to hear how it rides!
This sounds sweet, excited to hear how she rides, a low slung single track slaying machine...
The_Lecht_Rocks: whafe - cheeers - may i offer an official apology for the wagon wheeler "dis-belief"
Interesting post, GT...
Isn't a bit conflicting that the SA becomes too slack when you want to drop the hammer?
The rest of numbers sound great but I'd be concerned about it getting a bit nose happy on the climbs and for sure it will lose some efficiency when pedaling. Also, you need to keep the bike riding high in tis travel when uphill or it will bog you down.
As Whafe says, though... sounds like an awesome nini-DH bike. It's going to rail corners with the weight so low and the geometry all laid back.
For numbers sake, the AC is around 1.5 degrees steeper in HA and 3 full degrees steeper in SA. However, you AC-Killer is a full 0.5" lower at the BB.
You can recover some effective seat angle by moving the seat forwards on the rails as much as you can but that also shortens your cockpit.
How amenable are Nicolais to making chimeras similar to what pre-DW Link Turner owners were doing a few years back. For instance, can you run an AM front triangle with an AC rear, and if so, what would the expected result be?
I have asked this question before and the answer is no you can't because they build the rear end to specifically align with the front. So all front and rear triangles are matched to each other in order to ensure perfect alignment.
Damn those exquisitely tight tolerances!
Originally Posted by geetee1972
Originally Posted by geetee1972
Doesn't that just mean they couldnt send you an off the shelf rear triangle...but if you sent them your front triangle they could build a rear (AC) traingle to match your AM front?
I sent my CCDB off to Stendec on the recommendations from TLR. I got the unit back a few days ago and managed to get out on it yesterday for a few hours so I figured now would be a good time to update on project Hades, so named because the bike has been lowered all round, and actually is now almost subterranean, lower than Hades in fact.
The results then are a combination of the tuning work that Dave at Stendec did to the CCDB and the overall changes to bike geometry.
What Dave has done is really positive and I can genuinely feel the changes he’s made.
One of the suggestions Dave put to me was to increase the oil flow and thereby reduce the need to have as high a spring rate as I was previously running (or something long those line). This means I’ve gone from a 550lb to a 450lb spring, which has meant a reduction in mass that is always welcome. It’s not much but it all adds up. I also asked him to make the unit more ‘dynamic’. I said that what I wanted was to be able to pop the bike off and over stuff when I wanted, without having the bike constantly wanting to buck me off and certainly not have it get twitchy on the take off of fast jumps and hard landings.
On first ride he really does seem to have managed this very well. When compared to a boost valve RP23, the bike now feels alive, sprightly and super fast; my experience with the RP23 is that it was either far too ‘flaccid’ and mushy, especially on landings, or following the increase of the compression damping to the higher tune, dead and inert. The compression tuning seems to have has firmed up a bit overall so the bike doesn’t feel as ready to push into its travel and it is sitting higher in its travel when riding. But this is actually a good thing because when combined with the new shock shuttle that moves things forwards 7mm and therefore lowers the BB, it means that the bike is still relatively low to the ground but not so low as to cause major problems with pedal strike. I have ridden the bike with the new shock shuttle on the RP23 and found that even with the sag set to 20%, the bike was still getting seriously low and the pedals catching. So with the CCDB, things are sitting a little higher but and more constant but the bike doesn’t feel harsh or choppy. Indeed, the tune on the CCDB is now giving more feedback so while it feels firmer, the added information it’s communicating seems to give you more control. It’s sort of like the bike is using only the bare minimum of travel it needs in order to keep the wheel in contact with the ground so outright grip is not really suffering although it took me a little while to adjust my expectations of when and how the back end was going to break. It’s doing so at about the point in any given situation, but it’s a little quicker in the snap of the arc – does that make sense?
The caveat to that is that the riding around here is less rocky, more rooty and loamy and I don’t tend to pedal through stuff as much as I pump and try to carry speed. But still, there wasn’t one instance of pedal strike on the whole ride, even when pedalling around some tight corners.
Hitting some reasonable sized gap jumps, say 10ft at speed and the bike feels fantastic on takeoff; no squirming, no wobbles, no bucking, either on takeoff or landing.
So the overall set up is now 140mm Fox 36 fork, with an Axle to Crown of 525mm; 145mm rear with a 2.25”/57mm stroke and 7.75”/200mm E2E, regular levers and the -7mm front shuttle. A more accurate measure on the BB puts it at 13.1” or 333mmm, HA is as stated previously 66.7 degrees, SA 72 degrees (not sure where I got 70 degrees from in my previous post!)
So far, my experience is hugely positive. You can feel the bike turning in quicker, is more stable and settled even with the lowered front end and is just carving corners like a short travel 4X bike. I think you could perfectly run the bike with a 150mm Revelation or Fox 32 and loose over 1lb in weight. With an air damper and the most judicious parts selection you can make without going mental (and by mental I guess I mean carbon fibre wheels) you could have a bike that would weight easily 27-28lbs, depending on whether you’re running 1x10/9 or double/triple set up, but wouldn’t feel compromised for doing DH runs. It would have the stiffness and strength of the AM, the weight of the AC but the ride characteristic and handling of a mini DH bike.
In honesty it probably feels not too unlike a contemporary AC so the point of this exercise is really for the benefit of those of us that have an older AM. The new AM for example is much slacker at the front and so could probably more readily accommodate a 32mm fork without compromising the handling on steeper switch backs (which is where mine suffered with this fork). However, the lower BB in the shorter travel mode is also a bonus and actually is not something I think you could achieve with the new AM? Of course, you could just buy the AC but for me, being a heavier rider, the strength and stiffness of the AM is preferable to the AC anyway.
So in conclusion, the tune/service by Stendec is excellent and genuinely makes a difference. I can well imagine that whatever he’s done to our respective units (mine and TLR's), having the bike sit slightly higher in its travel and not be so ready to blow through would definitely cure pedal strike issues. If you wanted now to have a bike that was more trail ready, like an AC, then I really do suggest you look at the alternative shock mounting plates. There is a big bonus to running the bike in the 145mm setting which is greater sensitivity, feedback/feel and better pedalling efficiency but you will need to lower the front end to make it work and even then, it is a little compromised for in the saddle hammering (although it is only a minor compromise). Although it would be an experiment for you, it would only cost you £80. You could also try the -3mm plates for a slightly less extreme result. That would probably put the BB around 13.4” HA maybe at 67.5 degrees? Again, bear in mind this is all with a 140mm/525mm A2C front end.
Finally, you’re concern with pedal strike in this set up should be allayed partly by the better tune of the CCDB and partly by the fact that you’d be running the bike in the much shorter travel mode, so with the same percentage sag, the bike is actually higher off the ground anyway.
Hope this is interesting and of help and thanks to TLR for bringing Stendec to my attention.
So in conclusion, the tune/service by Stendec is excellent and genuinely makes a difference. I can well imagine that whatever he’s done to our respective units, having the bike sit slightly higher in its travel and not be so ready to blow through would definitely cure pedal strike issues.
NO PROBLEMM GEETEE - I LIKE YOU AM A FUSSY BUGGER AND KNOW EXACTLY WHAT WAS NEEDED TO RESOLVE the issues i had with the AM.
Dave is a cracking guy and he's transformed my AM.
I might try this out some time, the -11 shock mounts were a bit too much 12,5" BB
The AM is just so immensely versatile.
Set it up like a 140mm trail ripper or 170mm mini DH bike!
I think I'll try and get a hold of some light weight air forks and just use the Boxxer for DH duties.
from 0 - sideways 3.2 sec
Jesus i leave for 5 minutes and Gee and TLR's are a couple WTF?
P.S. great post, shame about the pedal strike...............
LOL we do seem to have 'kissed and made up'. Probably just in time as from the response on other threads, it looks like TLR needs as many friends as he can get right now!
Jesus i leave for 5 minutes and Gee and TLR's are a couple WTF?
I think tolerances are about the same, but they have this clever idea of specifying 5 different offset for the right dropout mount - to compensate for the possible misalignment. And those are set for each individual frame after measuring.
Originally Posted by stymie
Nicolai does that instead of the normal practice of just forcing the tubing into alignment after welding, at least on the rear triangle.
Originally Posted by Axe