My gravel project - Charge Plug, with Schwalbe Big One 27.5x2.35 tires

[Birdman]

I would like to share my project with you WeightWeenies.

Background:
My wife allowed me to get a new bike if it is capable of carrying my 2 year old on rides, so the two of us can go get lost in the woods somewhere for hours without bothering her. Obviously I have no objections to that.

Project requirements in order of priority:
1. Road (gravel) bike geometry
- BB drop = 68mm min
- Chainstay = 440mm max
- head angle = 71.5 max
2. Tire clearance = Schwalbe Big One 27.5x2.35
3. Road crank compatible, so no 73mm wide BB.
4. Realistic price! So no boutique frames.

The Bike:
Charge Plug 2, it was on super duper sale. Around $440 USD.
11.54kg (25lb 7oz) stock, size medium, no pedals.
1.88kg frame + bolts + rear caliper ISO bracket, no headset no BB no






The MODS:
1. Surly Straggler 700c fork (for the tire clearance and 1.125" straight fork)
2. Schwalbe Big One 27.5x2.23 Tubeless Easy
3. Stans Crest MK3 on DT Swiss 240 hubs
4. Shimano Ultegra Di2 1X kit with R785 hydraulic.
5. Wolf Tooth narrow wide chaining.





The Clearance:
The Big One on Crest MK3 (23mm internal) measured at 57mm wide.
Fork clearance = 2.5mm on both sides
Chinstay (drive side) clearance = 2.0mm






Issues:
1. This bike can only take a straight fork. I wanted to use the 3T LUTEUS II fork but that's 1.5" taper. I also explored some mountain 26" rigid forks but nothing jumps to me that would work well with this bike. I stumbled upon the Surly Straggler 700c fork, some Google image showed it cleared some giant tires, so I ordered it. It fits!!! Very happy so far.
2. Di2 wiring. I have no problem drilling, and I have plenty of wire plugs. However I was having a hard time routing the excess wire from the junction box to the rear derailleur. I can't really stuff the wire into the chainstay, so I had to tape it on the rear. That'll have to do until I get some shorter wires. No big deal.

Other Bikes I've considered:
1. Fuji Jari. I saw it in the store today. The chainstay inner width measured right at 57mm. So it won't fit the Big One. Is such a shame because the frame set price is very reasonable, and it has all the awesome features one would look for in a modern gravel bike. If the Big One isn't a major requirement, then this bike is a clear winner!
2. Otso Warakin
3. Kenesis Tripster ATR version 2
4. Diamondback Haanjo... This bike has 73mm BB, not compatible with standard road cranks.
5. Bombtrack Hook EXT... This bike has 73mm BB, not compatible with standard road cranks.
6. Mason Bokeh... sooooo sexy, soooooooo expensive...
7. Open U.P.. I read somewhere the tire clearance is slightly overrated. Also, kinda expensive.

[Tomstr]

Cool build! I can imagine it will be comfortable with those tyres. How are you planning to have your son ride along? I'm thinking something like a tubus carrier with seat could work if you don't go offroad too much. In my case I decided on a regular aluminium TCX but with a single-wheel trailer. Haven't tried it on the roads yet but it seemed like a good idea.

[Birdman]

Thanks Tombstr, yeah it floats over poor roads nicely.

I have a cheap rear rack mounted child seat for my daughter. I also have a Thule Chariot but not a big fan of it. It is super safe for the little one but it is a big heavy thing to toll around. Plus my daughter likes to be up high near me.

Single wheel trailer make sense though. Never thought about it. It will certainly be lighter with less rolling resistance.

[jemima]

I like those big tires on your bike , even if the clearance is tight.

Very nice.
Will add the Big One to my list of potential tires for my new build (Curve Grovel v2).

[Tomstr]

I assumed it's a boy, my apologies

The reasoning behind a trailer is that they can be attached to a bike quickly but don't require a large setup change. Most of them accept regular tyre sizes meaning comfort and speed can be tuned for. I'm hoping to adjust or build one later this year. Ideally with some suspension and a brake. If you ever go down that route too, Schwalbe makes a 2.0 Big Apple in 12" and larger. Should work nicely on gravel.
https://www.schwalbetires.com/node/4410

[Birdman]

No problem, my daughter didn't look like a girl until very recently

So I took this bike on a short ride yesterday, this thing self steers a lot... It didn't used to self steer at all with the original carbon fork and 700c 33mm Clement LAS tubulars.

Charge Plug carbon fork = 400.0 axle to crown, 45.0 offset
Surly Straggler steel fork = 400.0 axle to crown, 44.0 offset

Approximate tire circumference by Schwalbe:
32-622 = 2170 mm
57-584 = 2215 mm

The two forks and tire combo have very similar geometry, so I don't think is that.

From what I can gather around the web, seems like a possible issue with tire choices. 27.5x2.35 slick tires on pavement will likely self steer a bike, (due to the large contact patch?) I'm going to change my front tire to Nobby Nic or Rocket Ron (since I have those laying around), and see if the reduced contact surface area will change things a bit, just as an experiment.

[Marin]

Or ride a bit more, you'll get used to it

[Birdman]

Giving up the Schwalbe Big One tire. The tire clearance is already very tight when the tires are brand new. After a couple of months of stretch, they officially rub. These tires now measure at 60mm wide, compare with the original measurement of 57mm when they were first mounted. All at the same 40PSI pressure.

I'm using Schwalbe Thunder Burt now. 27.5x2.10. So far so good. Also, no more self steer.

[TheKaiser]

Giving up the Schwalbe Big One tire. The tire clearance is already very tight when the tires are brand new. After a couple of months of stretch, they officially rub. These tires now measure at 60mm wide, compare with the original measurement of 57mm when they were first mounted. All at the same 40PSI pressure.

I'm using Schwalbe Thunder Burt now. 27.5x2.10. So far so good. Also, no more self steer.

That is a bummer that the Big Ones didn't work out. I had been thinking they could be a sweet and underrated rough terrain gravel tire, given how low Schwalbe says their rolling resistance is. Running those at lowish pressure seems like a great alternative to messing about with all of these gravel bike suspension systems that are coming out.

I wouldn't have expected you'd get self steer at 40psi but, as you say, slicks do have a heck of a continuous contact patch. I have experienced self steer on fatbikes and plus size MTBs and it does seem to be partially tread pattern specific, but also will get a lot worse, regardless of the tread pattern, as pressures drop (in this case, below 13psi or so). Glad those Thunder Burts are working out for you. They ought to roll nearly as well and be much better if you get out into the soft and dusty shoulder of the road.