I've been comparing the specs again, and the only difference I can see is the weight (beside really small geo differences according to the tables). The Mondince frame is listed at ~1100g, while the TanTan comes in at ~1300g. That's a pretty big gap for what seems to be the same mold.

Which fork version would you pick (1 - regular; 2 - luggage)? Are there compatible luggage packs available?

Quote from: gribs on July 20, 2026, 07:44:32 AM
If you're going to do it you're probably better off looking for something with fairly aggressive geometry to start with, especially a steep seat tube. From my experience over forking mtb frames having too slack a seat angle made them ride dreadfully when sat down which is much more of a problem for a gravel bike.

Best thing would be a frame compensating longer fork length. Haven't seen much of these frames from china.

Quote from: Tijoe on July 20, 2026, 02:20:46 PM
From my experience and perspective, a suspension fork only shines on descents where there are small drops, roots, washouts, and lots of washboard areas.  (When I ran a 50mm travel on my gravel bike, it was very disappointing overall.)

Quote from: Tijoe on July 20, 2026, 02:20:46 PM
-If you plan on riding on a lot of forest service roads, or smoother trails, then a 29er with a rigid fork is fantastic. 

I'm currently on a XC MTB titanium frame (1.8kg lol) with a 100mm SID /w FA and dropbars and tt bars. I really like the bike. It's comfortable, fast on forest roads, capable on downhills, but also heavy. I did recently a 65km 90% road ride with ~31kph avg.
Agree on what you say. I really wonder how much I sacrifice when I'd from 100mm SID to a 60mm Rudy XL. Weight-wise it's 'only' 110g.

Overall my motivation for the potentially new bike are:

• bigger frame triangle (2 bottles / additional bike packing luggage space)
• to get a bit lower overall (mainly through BB drop)
• frame storage
• lighter frame (which I would also get from a carbon XC MTB frame)
• road standard wheels (currently on boost)

Hi everyone,

I'm currently planning a new gravel build and am looking for some advice on frame selection from the collective knowledge here. I've been digging through the recent threads, but I'm struggling to find the perfect match for my specific requirements.

My "Must-Haves":

• Tire clearance: Needs to handle 57-60mm tires.
• Downtube storage: Essential for my setup.
• Seat tube: Must be a standard round shape (no proprietary aero posts).
• Geometry: Looking for something relaxed/endurance-oriented.
• Drivetrain: 1x12 or 1x13.

The Fork Factor:
I plan to run a RockShox Rudy XL (60mm travel). I am fully aware that this will significantly alter the bike's geometry due to the longer axle-to-crown (A-C) measurement. The Rudy XL 60mm has an A-C of approximately 475mm (compared to ~405-410mm for a standard rigid fork). For reference, the rigid fork of the TanTan GR257 weighs about 780g, while the Rudy XL comes in at roughly 1300g+.

Current candidates & geometry analysis (with 20mm sag):

• TanTan GR206: Looks great on Instagram with a Rudy fork, but specs list max clearance of 700x50C. Out.
• TanTan GR257: Explicitly states 57mm clearance and has downtube storage. I ran a analysis for size 51: the head tube angle drops from 71° to 68.4° and the BB height increases by 20.6mm to crazy high 51.4mm. The reach decreases by 25mm. It seems like it might get quite "chopper-like" with this setup. See attached screenshot from bike-stats.
• Mondince FM356: Promises 61mm clearance and also features downtube storage. Interestingly, the initial BB drop is much deeper here. However, the geometry changes when adding the Rudy XL are very similar to the GR257 (Head angle drops from 70.5° to 68.1°, BB height increases by 19.3mm to acceptable 68.7mm). See attached screenshot from bike-stats.

Are there any other frames (like the newer Spcycle models) that offer downtube storage, 57mm+ clearance, and a round seat tube?

Given the significant BB height increase and slackened head angles, I'm concerned about handling stability. Has anyone here experimented with such a drastic A-C increase on these specific frames? Any input, geometry insights, or alternative suggestions would be greatly appreciated!

I am familiar with the Wolf Tooth GeoShift Angle Headset (+/- 2°) and currently use one on another frame to compensate for geometry changes. While this is a great tool to steepen the head angle back up, I am aware that one has to be very careful with the clearance between the fork crown and the downtube when using such a setup.

Thanks in advance.

Collected some real-world measurements from this thread and some insta posts for reference. Casing width from BRR. All tires mounted on the XMCS rims.

Hier ist die aktualisierte Tabelle. Ich habe den Michelin Pro 5 in 40mm an der richtigen Position (aufsteigend nach gemessener Breite/WAM) eingefügt.





Happy to add more data points if anyone has measured values to share.

I wanted to share some calculations I ran for anyone considering the RockShox Rudy XL 60mm on this frame for the size S (unsagged and 25% sagged).

Minor deviation: As the offset is different (55mm frame fork, 45mm Rockshox Rudy XL), I assumed 50mm to simplify the calcs.
Ignore the Front Center value.

Calculator used: https://madscientistmtb.com/sagged-hardtail-geometry-calculator/

Quote from: LittleBobcat on December 15, 2025, 09:27:07 PM
zipp gravel tires are vastly different from normal standard tires on thread width, puncture belt and full bead width. They don't allow just any 40mm tire on their xplr wheels but only their dedicated tires. Using normal 40mm tires on 32mm+ iw wheels is mostly okay in tests (yeah they won't get rip off anyway) but they balloon up too much (meaning the badged spec useless and aero penalties) and the cross section layout would be sub-optimal from the tires' original design which results in RR penalties.

I just checked the Zipp G40 XPLR 40mm. It has the same unmounted tread width like the Michelin Pro 5 at 45mm. Sure the casing width is more (89mm vs. 107mm), due to the 40mm specification. Which looks like more or less average in the 40mm tire cat. I don't see much information on the puncture belt.

From BRR on the G40 Zipp tires:
The weakest point seems to be the puncture resistance of both the tread and sidewalls. The low scores here are probably also partly attributed to the "fishnet" style puncture protection that will only work well on punctures bigger than 3 mm.

Regarding the other claims:
True, the specified tire width is different than the actual one on a wide rim. Acc. ETRTO standards the normal inner rim width for a 35mm wide tire would be between 17-20mm.

Aero penalties of wider tires is rather small (less than aero socks delta). Afaik it's 3,6W for each 10mm of tire for a pair of tires at 30kph. But I could not find any data on aero testing for wide tires with wide aero wheels.

Regarding the RR penalty on the wider rims, I quote BRR again:
Peak rolling resistance performance seems to be reached when the rim width is somewhere between 65% and 75% of the specified width of the tire. Our other conclusion is that a rim width that is within 50 to 80% of the specified tire width results in performance that is within 99% of peak performance. Only when the rim is narrower than 50% of the specified width of the tire, performance starts to drop-off at a faster rate. The drop-off is small as you'll still get 95% of peak performance when the rim has a width of only 30% of the specified width of the tire.
My tire-inner-rim-width combination is at 82% is a bit out of the optimal range (65..75%), but I lose around max. 1% of performance in that regard. This would result in a penalty of 0.276W (for both tires). Is this worth mentioning? I guess not.

Please let me know if you find valuable information on the topic or correct me if I'm wrong.
But other than that your post doesn't include much information and seems like a opinion rather than a facts.

Quote from: radrick_91 on December 06, 2025, 04:50:58 PM
Great build.

Are you satisfied? How do the wheels feel? Aren't 35mm tires almost too narrow?

Did my first ride today (~72km) and I'm really happy with the result. It's comfortable, has lots of grip and is feels quick.
But I don't have any data to back that up. I simply believe the latest research which shows that...

• wider tires reduce rolling resistance
• increasing comfort through greater air volume as suspension minimizes rider fatigue

And all of that without compromising performance.

The widths match quite nice according the 105%-rule (42mm outer rim width; 39.5mm tire width).

The Michelin Pro 5 tires have an unmounted tread width of 45mm, which is even more than the Pirelli P Zero 40-622 at 42mm. This means that even when stretched, the risk of running off the tread is reduced.

---

Regarding ETRTO compliance: I don't really like the concept of regulatory documents being behind a paywall. Additionally, it seems that bicycle tire standards are outdated and not up to current requirements. The complexity also exceeds that of car/motorcycle tire standards. While ETRTO is indeed a technical institution with regulatory purposes and its importance is highly regarded in various forums, threads, and Reddit discussions, this apparently doesn't tell the whole story.

This article provides valuable insights: https://www.cyclingweekly.com/products/will-the-adoption-of-tubeless-technology-finally-force-wheel-and-tyre-brands-to-get-friendly

The most prominent example of deviating from ETRTO standards is SRAM/Zipp. They allow a 40mm tire on their 303 XPLR wheels  (32mm inner width rim) through their 'dual testing' approach, far from ETRTO standards.

QuoteISO Certified tire combinations are within ISO approved standards. These compatibilities are as reported by the respective tire manufacturers.
Dual Tested tire combinations have been tested by both the tire manufacturer and Zipp for compatibility.
Zipp limits the tire size compatibility on 303 XPLR wheels to tires between 40-60mm. Within this range, ISO tire and rim size guidelines allow any TSS-compatible tire sized from 58x622 up to 60x622 (29"×2.3"-2.35").

Finished my long distance build.

Specialized Diverge MY18 Frame 54 with 35-622 Michelin Pro 5 TLR 35 (measured 39,5mm).