Derby Carbon TR 40I Disc Rim
The Derby TR 40i is the plus-tire rim from the small American maker who pioneered wide carbon mountain rims: mm inside for 2.8 to 3.0in tires, made in the USA from unidirectional carbon with hookless walls 3mm thick and tubeless retention ridges, in Derby's trail layup. It is the carbon rim for 27.5+ and 29+ bikes that want a light, tough wheel with the widest footprint.
This page covers the Derby Carbon TR 40I Disc Rim in 29in, 27.5in. The Derby TR 40i is not sold bare. You choose the hub and the rest of the build in the configurator, and it ships from our shop in Georgia laced, tensioned and trued by hand.
Design and construction
The rims are simple in the way good carbon rims are: a shallow hookless section with walls thick enough that a rock strike squeezes the tire rather than cutting it, a bead seat with a retention ridge that keeps a tubeless tire on at 18 psi, and a layup that puts the carbon where the loads are. The 30i takes 2.0 to 2.3in tires happily and 2.6in tires without complaint. The TR layup is for trail and all-mountain; the DH layup adds material for enduro and downhill and is rated for riders up to 300lb.
How it rides
A Derby TR 40i wheel with a 3.0in tire floats over roots and rocks and grips on loose climbs, and because the rim is carbon it is far lighter than any alloy rim of its width. The thick walls take the strikes a plus tire at 12 psi cannot absorb. For 2.6in tires the TR 35i is lighter; for 2.8 to 3.0in, the TR 40i is the Derby rim we recommend.
Specifications
| Wheel size | 29in, 27.5in |
|---|---|
| ERD | 584 (29in), 540 (27.5in) |
| Drillings | 32h |
| Weight | 520g (700c/29in), 510g (650b/27.5in) |
| Material | Carbon Fiber |
| Tire type | clincher tubeless compatible |
| Brake | Disc |
| Profile | Triangle |
| Nipples | External |
| Finishes | black |
This listing
This is the 29in, 27.5in listing of the TR 40i, 32h, about 520g, mm inside, mm deep, disc. Pick the size that matches your frame; the profile and construction are the same across the range.
The disc version of the TR 40i has no brake track, so the sidewall is a plain extrusion that saves a little weight and never wears; it is the one to choose for any disc-brake frame. The rim-brake version, listed separately, has a machined sidewall.
Sizes, fit and compatibility
The Derby Carbon TR 40I Disc Rim comes in 29in, 27.5in and 32h drilling. It is a disc-brake rim. We build the TR 40i on Industry Nine Hydra 2 and 1/1, DT Swiss 350, Hope Pro 5 and Onyx Vesper hubs in Boost spacing, usually with Sapim Race or D-Light spokes or DT Competition, and brass nipples.
Tire range on the TR 40i is 2.8 to 3.0in, tubeless-ready tires only on the hookless bead. Pick plus as your bike type in the configurator and it recommends a spoke count and lacing pattern.
Build it with us
We build this rim to order. Open the Custom Wheel Program with the DERBY CARBON TR 40i DISC RIM already selected and pick the parts around it; it is offered for mountain bike, MTB single-speed and fat bike builds, and the configurator will not let you assemble a combination we would not build.
Spoke head is decided by the hub, not the rim: this rim builds equally well with J-bend or straight-pull spokes, and the configurator only offers the spokes that match the hub you pick.
What Derby says about testing
Derby Rims, based in Utah, designs its carbon rims in the US and has a partner factory in Asia make them; Derby states its rims were the first carbon rims strong enough for aggressive mountain bikers when it started in 2012. Derby publishes no laboratory impact or fatigue figures; it relies on ride testing. Derby states the Sol Rider line was tested by dozens of extreme MTB riders over 3 years with zero failures, including DH and Enduro racing and 35 foot gap jumps from 2018, and that the first Sol Rider was cracked in 2023 after more than 5 years. The Sol Rider uses Derby's Solstice layup, alternating a US-designed plastic composite fiber UD with UD carbon fiber; Derby states the plastic layers stretch under hard impacts to stop micro-fracturing, and that it was first with 3 mm thick hookless rim walls and bead seat retention ridges.
Derby's published limits: recommended rider weight 175 lbs / 90 kg for XC (CX and BX) rims, 225 lbs / 100 kg for xc.Trail and 300 lbs / 135 kg for enduro.DH rims; max spoke tension 125 KgF; max mountain tire pressure 32 psi for road use, 22 psi for 2.6 in and larger tires, 30 psi for enduro/DH race, park and shuttle; bead seating 35 to 40 psi; 44 mm minimum valve stem.
Certifications
- Warranty — Lifetime warranty to the original owner: first replacement free within 5 years of purchase, subsequent replacements 50% off MSRP; secondary owners 50% off MSRP warranty/crash replacement regardless of age; receipt, photos and serial number required (source)
Sources on Derby's site:
- Derby Rims - Rim Specs
- Derby Rims - Sol Rider
- Derby Rims - History
- Derby Rims - Terms, Warranty, Returns
- Derby Rims - FAQ
Everything in this section is published by Derby. ProWheelBuilder is the wheel builder, not the tester, and the rim reaches us as the maker ships it.
Building it at ProWheelBuilder
Derby makes the TR 40i; ProWheelBuilder is an independent wheel builder in Georgia, not the manufacturer. Every TR 40i wheel we build gets spokes cut from the rim's measured ERD, is tensioned in stages with a gauge, stress-relieved and trued before it ships. Tubeless tape and a valve are fitted on request.
In the configurator you will only see parts that fit this drilling; combinations that are not made are struck through, and the price updates as you pick.
Warranty
Manufacturer's warranty. Derby warrants this product against defects in materials and workmanship. The duration, conditions and claim process are set by Derby and can change without notice, so ask us and we will confirm the current terms before you buy.
ProWheelBuilder. Our one-year wheel warranty applies to any wheel we build around this part, alongside whatever the manufacturer offers. Inside that year, broken spokes are replaced no matter how they broke, and the wheel labor is ours - truing, re-tensioning or a full rebuild. A rim or hub failure that the maker covers, we claim for you and see through; one the maker declines, we answer with an eligible replacement at 25% off current retail. Shipping both ways is yours, and components you supply yourself fall outside this cover.
Full terms are on our Policies & Warranty page.
Carbon TR 40I Disc Rim questions
Which spokes and nipples suit the TR 40i?
For most riders a double-butted spoke such as Sapim Race or DT Competition with brass nipples; lighter riders can go to Sapim Laser or CX-Ray. The configurator recommends a gauge and count for the TR 40i from your bike type and weight.
TR or DH layup?
TR for trail and all-mountain; DH for enduro, downhill and heavier riders, with a 300lb rider limit and more material at the bead and spoke bed.
Are these rims made in the USA?
Yes. Every rim is molded in the USA in small batches.
Is it tubeless-ready?
Yes. Derby lists the Carbon TR 40I Disc Rim as clincher tubeless compatible; we tape and fit a valve when you choose the tubeless option.
Which spoke count should I choose?
It depends on your weight, terrain and the hub, not the rim alone. The configurator recommends a count from your bike type and rider weight, within the drillings this rim is made in.
How long will the wheel take?
Build time comes down to parts availability rather than bench time. The estimated ship date is shown in the configurator before you check out.
Not sure? Text or leave a voicemail on 470-253-0929 or email info@prowheelbuilder.com — you will be talking to the people who build the wheels.
