Gravel tyre size.

[nick_the_wheelbuilder]

There are so many options today, and your budget will determine whether you buy an off-the-shelf bike or have something built up, custom.

I recently built the wheels and put together this Nextie gravel bike for a customer, with 47c wide tyres.
I imported the rims, hubs and frame from China.

All-in it cost less than R80k with the new GRX Di2 drivetrain and really nice carbon wheels.
Fully integrated brake hoses and 1-piece bar/stem.

The bike weighed in around 8.5kg without pedals. (with that massive 10-51t cassette)
Perfect machine for gravel racing and long-distance adventures.

[MongooseMan]

Very interesting option coming for those who want the "MTB tyre" but can't squeeze a 2.2:
https://www.bikeradar.com/news/continental-dubnital-50mm-2in

[Michael S]

6 minutes ago, MongooseMan said:

Very interesting option coming for those who want the "MTB tyre" but can't squeeze a 2.2:
https://www.bikeradar.com/news/continental-dubnital-50mm-2in

Stoked on this, can't get the 2.2 RK in the back (If you have not switched bikes were in the same boat)
And I have lost trust in a Thunderburt's ability to hold air. 
Love a Race King so will be on the shopping list as soon as available.

[MongooseMan]

2 hours ago, Michael S said:

Stoked on this, can't get the 2.2 RK in the back (If you have not switched bikes were in the same boat)
And I have lost trust in a Thunderburt's ability to hold air. 
Love a Race King so will be on the shopping list as soon as available.

Yeah, running burts at the moment. No issues yet, and they are frikken fast, but the stories others tell don't fill me with confidence (also they're a mission to get hold of).

Will be very interested to see the rolling resistance tests (both BRR.com and John Karrasch

[guidodg]

I removed my Raceking 2,2s from my gravel bike since they were quite worn and fitted Specialized Air Trak 2,2s...same weight as the Racekings and really impressed so far!

[W@nted]

I just ordered a set of thunder burts for my revolt for an upcoming bikepacking trip. Currently running the pathfinder TLR's in 45mm. 

[guidodg]

what size Burts?

[W@nted]

58 minutes ago, guidodg said:

what size Burts?

I ordered the 2.1"

[cadenceblur]

On 4/17/2026 at 2:39 PM, W@nted said:

I ordered the 2.1"

from where pray tell?

[MongooseMan]

1 hour ago, cadenceblur said:

from where pray tell?

I see Merlin currently has in stock, probably won’t last long

[W@nted]

11 hours ago, cadenceblur said:

from where pray tell?

I ordered from bikeinn in Germany. But I stay in the Netherlands, so I am not sure about ordering from them and sending to RSA.

[W@nted]

Thunder Burts arrived on friday evening, so I installed them. Managed to fit them on the revolt with the flip chip still in the "short" position. Have around 4 mm clearance on each side of the tire to the frame. Probably not ideal for mud, so I will adjust the flip chip this week.

Did two rides this weekend on mixed terrain. Bike felt slower, compared to the pathfinders. Definitely less "snappy" on acceleration. Stopped to deflate the tires mid ride, started on 23 psi ( Silca pressure calculator recommendation), but that was too hard. Once deflated, had more cushioning offroad. Deep gravel and grasspolle are more comfortable with the burts.

 

Looking at the data afterwards, for the same power, speed is almost identical to the pathfinders on the tar sections, so the sluggish feel is not slower actually. Comfort and grip is definitely better than the pathfinders. 

 

I will keep on riding them and evaluating. Had no issues mounting them on my Zipp 303's.

Edited Monday at 05:43 AM by W@nted

[Michael S]

45 minutes ago, W@nted said:

Thunder Burts arrived on friday evening, so I installed them. Managed to fit them on the revolt with the flip chip still in the "short" position. Have around 4 mm clearance on each side of the tire to the frame. Probably not ideal for mud, so I will adjust the flip chip this week.

Did two rides this weekend on mixed terrain. Bike felt slower, compared to the pathfinders. Definitely less "snappy" on acceleration. Stopped to deflate the tires mid ride, started on 23 psi ( Silca pressure calculator recommendation), but that was too hard. Once deflated, had more cushioning offroad. Deep gravel and grasspolle are more comfortable with the burts.

 

Looking at the data afterwards, for the same power, speed is almost identical to the pathfinders on the tar sections, so the sluggish feel is not slower actually. Comfort and grip is definitely better than the pathfinders. 

 

I will keep on riding them and evaluating. Had no issues mounting them on my Zipp 303's.

Are these on the 303 Xplr? If so, what do thet actually measure on those big boys?

[W@nted]

19 minutes ago, Michael S said:

Are these on the 303 Xplr? If so, what do thet actually measure on those big boys?

No, I have the normal 303 firecrest. Measures 53mm