Chromag Rootdown & Surface (and maybe Primer) Builds

PB Forum :: 29ers
Chromag Rootdown & Surface (and maybe Primer) Builds
Author Message
flag ronufoh
Posted: Jun 8, 2023 at 8:32 Quote
robbiekane wrote:
I’ve seen folks turning their even older rootdowns and surfaces to gravel bikes. These older versions were even steeper and had straight head tube. Non-tapered. But not your later more progressive Rootdown

I believe 2016 was when the Rootdown 'BA' became aggressive, following the Primer from a an aggressive geo point of view. It also adopted boost rear end starting then.

Prior to 2016, the Rootdown had the mellower geo of the Surface. I think from 2014-2016 they had 12x142 rear ends, and QR rear ends prior to that. They always fit tapered forks though, the earlier ones just had straight 44mm headtubes

IMO turning a 2016+ Rootdown into a gravel bike won't give you a fair taste of what real gravel riding would represent. I mean at the end of the day it's still just riding a bicycle off the beaten path, but for my money I'd rent/demo a gravel bike then make a proper determination into whether you actually enjoy it or not.
flag doomah
Posted: Jun 21, 2023 at 18:00 Quote
Hey guys first time posting here

I just purchased a Rootdown frame in the Clay color directly from Chromag. It arrived yesterday so today I went out today and bought a Wheels Manufacturing BB86/92 Thread Together ABEC-3 BB for 24mm (Shimano) Cranks. I’ve heard other people using this BB on their Rootdowns and I wanted to try it because I use Shimano cranks. But both sides press in by hand, and there’s a bit of slop between the BB and BB shell on the non drive side. No slop on the drive side but it also only takes 1 finger to press it in.

I really don’t want to go buy a Dub BB and new cranks because I have 2 sets of Shimano cranks in my parts bin

Should I just try the Wheels MFG Thread Together?
flag ronufoh
Posted: Jun 21, 2023 at 21:50 Quote
If your BB shell is out of spec, then you'll run into the same loose fit problems regardless of whatever bb you end up buying. BUT

The Wheels mfg instructions for the bb seem to imply that an easy press in fit is ok. Once the 2 sides are threaded into each other, the cups' lips fit tight against the bb shell so all should be fine.
flag doomah
Posted: Jun 22, 2023 at 17:27 Quote
ronufoh wrote:
If your BB shell is out of spec, then you'll run into the same loose fit problems regardless of whatever bb you end up buying. BUT

The Wheels mfg instructions for the bb seem to imply that an easy press in fit is ok. Once the 2 sides are threaded into each other, the cups' lips fit tight against the bb shell so all should be fine.

BB shell measures within spec. I contacted Wheels MFG today and they said they’re purposefully undersized and fit light so it can spin when youre tightening it, they also said once it’s torqued down to the correct spec it won’t be an issue. I’ll give it a try
flag leverfingers
O+
Posted: Jun 22, 2023 at 18:37 Quote
I've always wondered about that. A real press fit would be an absolute bitch to turn, and would probably gall and tear the aluminum. A tight sliding fit makes sense.
flag vermontana
O+
Posted: Jun 23, 2023 at 10:03 Quote
photo

Previewing the Silver Rush 50 course last night up here in Leadville. Finally starting to feel like summer in the high country.

Swapped tires to 2.6 Forekaster V2 up front and 2.6 Rekon Exo+ w Tannus insert out back. Really liking this combo for faster rolling (compared to DHF/Dissector) but with enough grip and a bit of dampening. Been enjoying 19psi for general trail riding but probably bumping to 21 for race, any higher and would be pinging off all the fist size rocks out on the course.

Rootdown def won't be the fastest going up, but will feel amazing on the long, loose descents. Rode with my buddy on a 24lb carbon hardtail and I smoked him going down. Will be interesting to see how I can stack up over 50 miles!
flag tweaked
O+
Posted: Aug 15, 2023 at 15:28 Quote
I recently picked up a primer from Chromag and I thought I’d try to provide some answers to questions I always wanted answered.

First, the wheels manufacturing screw together BB seems a bit loose but once it screws together, it’s fine.

Second, I am running 29x2.6 DHRIIs on 35mm carbon rims and there is enough clearance. I’m 150lbs with gear and with a foam insert I’m running like 14-15psi. Even in Squamish chunk I typically have no harsh bottom outs. A few years ago I had a chromag surface with 27.5x2.8 tires and it feels quite similar in the rear.

Third, relevant to vermontanas post, I always wondered how a 29x2.6 hardtail feels compared to a short travel carbon xc rig. I can say that in my experience, the rear doesn’t feel that much more harsh than my last 4, 100-120mm downcoutry bikes (all running 29x2.3/2.4 tires on 27-30mm rims). On those bikes I always had the rear shock in ‘trail’ mode for pedalling and they always felt a bit harsh. It’s an on/off harshness vs a dampened harshness on the big-wheeled hardtail though.

However, the one big thing to consider about short travel rigs is that they are really limited by the fork. I’ve had the best short travel forks (like a SID ultimate and a FOX factory 34) and they suck for anything other than XC. Since you’re so over the front on a downcoutry/xc bike, you need to run some compression to prevent pedal bob. That translates into limited, harsh travel on the descents.
On a hardtail with enduro geometry, the fork doesn’t need compression dampening in order to be stable climbing since you’re sitting farther back. Plus a hardtail with carbon wheels pedals better than any downcoutry rig I’ve ever ridden, including an S-works epic evo. Descending is like 80% about the fork and the benefit of 160mm of plush travel far outweighs any slight benefit you’d get from 120mm of rear travel on a short travel bike.

So if anyone out there is torn between a short travel rig vs an aggressive hardtail, a hardtail with a good fork seems to be better at everything (at least around here).

Of course a chromag is like 6lbs+ heavier than any carbon downcoutry bike, so there’s that.
flag ronufoh
Posted: Aug 15, 2023 at 22:02 Quote
That's a nice data point. I've been off Chromag Rooty/Primer/Surface for close to 4 years now. I always ran them with 27.5*2.8/3.0 rear tires for some cush and traction. I moved onto lighter aluminum hardtail frames and settled onto a Norco Torrent now; they give up nothing to the Chromags in how they ride (for me) but the 1-2 lbs saved is notable for me everything else being equal.

I'm trying to spend more time on my FS trail bike of late (2019 Trance 29 overforked to 140mm) and I find it certainly a much more forgiving ride compared to the hardtail despite only 115mm out back, but you're right in that it doesn't pedal as responsively though it is efficient if not ridden like a hardtail

My summary is the hardtail and FS are obviously different but both tools effective at their respective jobs so long as you build them to suit how and what you want to ride
flag tweaked
O+
Posted: Aug 16, 2023 at 9:32 Quote
But, really, who cares how it rides when it looks this good
photo
flag Slackerdude
Posted: Aug 16, 2023 at 18:26 Quote
That looks great ! I'm sure it shreds , My root down is built for riding the gnarly bits and big mountain adventures , It does fine for 6000 ft climbs but if sure great when its time to point it down... been running aggressive 2.5's but may try a 2.6 up front , close to being due for new treads...
flag gubbinalia
O+
Posted: Aug 17, 2023 at 7:07 Quote
tweaked wrote:
But, really, who cares how it rides when it looks this good
photo

Rad! Never thought I'd see a Chromag with a power meter :-)

Agreed on the short-travel trail bike vs. aggressive hardtail comparison. You can still pedal a hardtail as hard as you want without feeling any lost efficiency, or losing the incentive to stand up and really give it on climbs. The overall bike weight is more of a factor when you're timing yourself, or racing.
flag sren
O+
Posted: Aug 29, 2023 at 11:06 Quote
Mine! Not ridden that much the last months. My Santa Cruz Tallboy V4 is just is just so much fun right now and my right knee is not that happy about riding a hardtail back to back. But when I throw a leg over this thing, I'm always fallen in love again.

I have a Fox 36 with 140mm travel which I wanna try the next days and also wanna throw in a lighter wheelset (RF Next SL with Maxxis recon 2.4) to see how this thing rolls and climbs in that configuration.
I also have a Sid Select 120mm which I wanna try with those lighter wheels. Just need to order an "angleset" crown race like the reverse angle spacer to compensate the missing travel a bit. Could be a a fun "monster gravel" bike in this setup.

"Pedal mode"
photo

"DH mode"
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flag flattoflat
Posted: Sep 13, 2023 at 12:29 Quote
I'll add mine to the thread too. Had an older Wide Angle but the stack wasn't good for me, found this frame locally and it fits much better. First bike I've built from a totally blank slate. Happy with the looks and the ride.

Surface Ti
XT 11spd
Stan's Arch 27.5
Magura MT5
Ohlins RXF36
Oneup dropper & bar
Chromag pedals & accessories

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