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My Culprit RAD (gravel bike) Build and Initial Impressions
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I got one of these frames from Josh at Culprit about four months ago now but it took me a couple of months to build it up and then another couple of months to finally ride it due to... life. Full disclosure: I paid for the frame though I won't disclose what I paid because I don't know if Josh has set pricing for it yet. I also paid extra for custom paint... which ended up being the wrong color (I was going for Cannondale Green to match my F-Si, the shop matched Cannondale's new "Volt" instead). The parts I bought from independent purveyors (ProBikeKit, Pro's Closet, my LBS, etc).

The build:
  • Frame: Culprit RAD
  • Groupset: Shimano R8000 hydraulic
  • Cassette: Sunrace 11-36
  • Wheels: Reynolds ATR 700c
  • Tires: Specialized Sawtooth 38c set up tubeless
  • Crank: Shimano 5700 (placeholder, I have a Rotor/P2Max combo with a proper narrow/wide chainring I need to unbox, assemble, and install)
  • Bars and Stem: Specialized 40c drop bars with 10mm rise and flared drops, Zipp Service Course 60mm stem
  • Saddle: Selle SMP
  • Pedals: muhahaha

Impressions: first, the build was a comedy of errors which were no fault of the bike but rather the components. I won't go into it here. I originally intended to build this bike with 650b wheels and tires. The Specialized Sawtooth tires set up tubeless very easily with some compressed air (I have the MilkIt tubeless kit) and some soapy water applied to the beads. I've fiddled with pressures a bit and settled on 35psi front and rear for now. The tires themselves roll very fast over pavement and, considering that I've always rode 22-25mm (stated) tires on the road the additional compliance was... nice. You know how you have that rough section of road on your regular route? Coarse pavement, potholes, chipseal, etc? To be able to bulldoze your way through that stuff without a care in the world is refreshing. I don't do much riding on the road but, for training, I don't see any reason to ride "race" width tires again.


All that said, these tires suck off-road. Bear in mind I don't have a lot of offroad experience. I have a hard tail with Schwalbe Racing Ralph and Furious Fred tires and, personally, I prefer fast, buff single/double track. I don't have much gravel experience either. I've rented a Salsa something for a week out in Boulder and a Kona Jake the Snake in Aspen and collectively have about twenty hours of prior gravel riding experience. That said, when something sucks, I know it sucks. The tread pattern of the Sawtooth tires fills easily with sand and they just lack traction in general. Cornering with these tires on loose over hard is... dicey.


These tires are getting changed pronto. They both measure ~40c on the Reynolds rims and that leaves ample clearance both front and rear. I'm not sure what the "official" clearances are for this bike but pretty confident I can fit a Schwalbe G-One Speed in 700x50 in the front... though I'm still looking for options.


Groupset: typical Shimano. Brakes are excellent, shifting is excellent (even with the Sunrace cassette which I'll concede was purchased for aesthetics), and I haven't dropped a chain yet. To be honest, I've been lucky in this regard and need to get a chain guide and 1x ring onto the bike pronto.


Bar/Stem/Fit: I'm 6'1 with a 34" inseam and typically ride a 56cm bike. For the RAD, I sized up to the 58cm, ran a short stem, and a rise bar. This is, by far, the most upright I've ever been on a "road" bike. Heck, I don't think I'm this upright on my F-Si. That said, it's refreshing and it also makes the drops very usable. IMO, one should use the drops more frequently when on "gravel". One change I'm going to make is to add some gel under the bar tape of the drops.


About the bike frame itself: there's not a tremendous amount to write here because, in my opinion, a good frame is sort of "invisible" to the rider. The only time a frame is visible is when it does something wrong IMO. I'm not going to BS you and say the frame is "compliant" or anything like that because it's not and, frankly, I don't think any frame is "compliant" in a sense a human can detect. The Cannondale F-Si was engineered rather deliberately to be "compliant" and, tbh, I can't tell the difference between it and an Aluminum hardtail.


If you look at the downtube, you'll notice it's not round or flat but instead has a bit of an "aero" shape to it. Is it aero? I don't know. I'd wager it's more aero than either of the previously mentioned shapes but I can't say much beyond that. I've seen an Exploro in person a few times and I can say the shapes aren't similar. The Culprit's downtube appears to be a larger than normal "conventional" Kamm shape but perhaps a bit wider at the rear than normal. The Exploro's downtube is massive and just... a different shape. More bulbous I'd say. Honestly though, this is just idle speculation. There's no way to know how a shape will perform in a system unless you test it.


If you look inside the frame (literally inside the tubes) you can see the walls are very smooth. I tried to get photos but it was a futile exercise. From my understanding, smooth = quality. Shane Miller (aka GPLama) has some excellent videos on his YouTube channel where he cuts open frames and wheels and discusses them with a composites expert and they touch on this point. They're definitely worth watching.


Where this bike really shines is the mounts. They're everywhere! You can mount bottles on the downtube, seat tube, and under the downtube. The bento box on the top tube (comes with the frame) is really quite cavernous and, honestly, Josh should sell it separately. You could easily hold 10+ gels in there and it's just really well made. The frame has mounts for both fenders and panniers. My one suggestion for Josh is to add an extra set of bosses to the downtube in the XL size. There's certainly enough room inside of the frame.


These are just initial impressions thus far. I've only had it out for a few quick ~10 mile rides (3 road, 4 off-road, 3 road). You can see some pictures below. I'll update this in the coming weeks with some more pics and impressions from a longer ride.






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Re: My Culprit RAD (gravel bike) Build and Initial Impressions [GreenPlease] [ In reply to ]
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I just finished putting together my Culprit RAD a couple days ago and have taken it for its first 2 rides. I figured I would add my thoughts about it here as well. This frame is the last of the pre-production ones and the same as what is available from the Culprit Indiegogo (this was used for pictures before it was sent to me).

To get it out of the way (like GreenPlease) I did pay for the frame but won’t disclose the price. It is close to what the Indiegogo pricing is. I had been considering a gravel bike and when I saw this posted I reached out to Joshua on ST to get some details and pricing. Everything was inline with what I was looking for so I went ahead with it.

My build is a little different than GreenPlease. It is:
  • Groupset: Shimano Di2 with R785 Hydro Brifters / RX805 Rear Derailleur / RS805 Brakes
  • Cassette: Shimano XT 11-40
  • Crankset: Quarq Riken AL with 40T ring
  • Bar / Stem: Salsa Cowbell 3 with Rotor S3X stem
  • Wheels / Tires:

    • Culprit 50 AD with Continental GP4000SII 700x23 tires
    • White Industries CLD hubs laced to HED Belgium Black with WTB Nano 700x40 tires

It took me a little while to get this built but not due to anything with the bike itself (2 little kids and the holidays eats into your time!) The frameset and wheelset took 2.5 weeks to clear US customs. The bike built up very easily. Neither I nor my LBS (who ran the hydro lines and bled the brakes for me) had any issues. I do also have the Culprit aero drop bars (which seem really nice) but I have had these Salsa bars sitting and waiting for me to try on something so I decided to go with them for now. I wasn't completely sure at first if RX derailleur would clear the 11-40 cassette I wanted to run until I saw a few people doing it here on the gravel bike thread. No issues at all and I might switch to something with a 42 for a little more range if I decide I need it. I like that this gives me the option of putting on a FD if I want one.

The first ride I did was to some local cranberry bogs which have some trails behind them. Everything was pretty muddy and wet. The RAD definitely didn’t seem to mind the conditions. The mud didn’t build up much on the tires or bike but there would have been plenty of clearance anyways with the 700x40 tires (40mm measured width on the Ardennes rims). Depending on how much clearance you would want between the frame/fork and the tire I think a 700x50mm would fit with at least 2.5mm clearance on the sides and more on the top. The handling seemed just like my cross bike but it is a little tough to say with the wider bar / shorter stem I am running on this.

The second ride I swapped on the Culprit 50mm wheels and went for a road ride. I don’t normally ride a road bike much other than the occasional group ride – it is usually either the tri bike or I will take my cross or mountain bike off road. I don’t have a lot to say other than that it road like a road bike. I would like to put some wider road tires on these wheels as I think the ride would be even more comfortable than it was. I definitely didn't notice anything that felt weird to me handling wise as a road bike but I might not be the best person to evaluate that.

In the end I was looking for a bike to give me the ability to ride anywhere I wanted with possibly just a wheelset change. I also wanted something with more tire clearance than my cross bike (the Nano 40s barely fit between the chainstays on that). I think this accomplishes that. I really like the looks and details of the bike and so has anyone else who has seen it. I definitely see this as the bike I choose to ride all the time when I am not wanting to ride in the aero position. I am really impressed with the fit and finish of the frame. I also have a set of Shimano XTR 650b wheels with Byway 650x47 tires I need to try.

If anyone has any questions or would like some measurements or pictures of anything just let me know. Here are some pictures:






With Culprit 50AD Wheels:


WTB Nano 700x40 Chainstay Clearance:
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Re: My Culprit RAD (gravel bike) Build and Initial Impressions [m.medeiros] [ In reply to ]
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Man that bike looks slick in black.

I have to disagree with you about one thing: how the bike handles. It has endurance road bike geometry and handles accordingly. It’s very stable at speed but going slow it’s s bit “floppy” which is exactly what you’d expect given its geometry. Every cross bike I’ve ever ridden has had quite sharp handling at lower speed but was a bit twitchy at higher speed. We’re talking subtle differences here. You could definitely “cross” the RAD but that’s not really what it’s meant for.

Personally this has become my “do most stuff” bike. I commute to the gym on it in the morning during the week and on the weekend I pull off the rack and do a long gravel ride on the Lake Apopka trail. I run the 45c WTB Riddlers (tons of clearance) both front and rear tubeless on Reynolds ATR wheels and they are very capable tires.

I had the same rims built up with Bitex straight pull hubs with internal nipples. I have 28c GP 4000S IIs on them now with latex tubes. It’s a pretty nice compromise of comfort vs speed if one wanted to do a group ride but, alas, it’s quite rare that I do.

Honestly I’m a bit bummed about two things:

1. that this is basically a modified open mold bike. I didn’t know that going in. Seeing Planet X carry a version with a few fewer mounts (and supposedly lower quality paint... which I do actually believe given how nice the paint is on my bike) is a bummer. That said, it doesn’t diminish that it’s genuinely a great bike.

2. that there wasn’t enough interest to get Josh to invest in the full internal cable routing. Oh well.

Other notes: Ultegra 8000 is reaaallly nice.
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Re: My Culprit RAD (gravel bike) Build and Initial Impressions [GreenPlease] [ In reply to ]
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Yeah the handling is probably different to my cross bike but for me it's different tires, bar width, stem length that (at least to me) it was tough to tell. Probably need to do some back to back rides to compare. The only drop bar bike I normally ride is my cross bike - almost never a road bike.

The 28c GP4000 setup is what I am considering switching to or maybe some of the new GP5000. I'm the same way with group rides.

On your 2 points at the end I definitely agree with the first one. Depending on if the Covert Ops stem gets produced and the routing from the bar is completely internal through the steerer that might make up some of the price difference but that's going to be different for different people. The second point didn't matter to me but I definitely understand it.
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Re: My Culprit RAD (gravel bike) Build and Initial Impressions [m.medeiros] [ In reply to ]
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I’d just go with the GP5000. Personally I’m going to wear out my GP4ks and then try out the 32c tubeless G5000s :)
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