maartendc

Hello all,

Im looking to get a new 650B gravel wheelset built for my Trek Checkpoint ALR5. The idea being to do some serious off-roading, technical MTB trails, and potential bikepacking. Ill be running these with 47mm, 50mm or 53mm tires.

I was looking at:
- DT Swiss 350 straightpull hubs
- Sapim D-light or Race spokes, 28 front / 28 rear
- Dt Swiss XR391 MTB rims or Dt Swiss GR 531 DB.

- So the XR391 is a MTB rim, very shallow, 25mm wide internal, and 415g.
- The GR 531 is a gravel specific rim, 24mm wide internal, a bit taller at 25mm, and heavier at 500g.

Which rim should I choose? Im thinking the MTB rim, since it seems wider, lighter and the riding ill be doing will resemble more MTB than 'gravel riding'. I fail to see any benefit to getting the Gravel rim. Unless the MTB rim is less suited to bikepacking somehow?

Am I missing something? Any other recommendations?

Thanks!

unterhausen

I have always used mtb rims.

maartendc

Thanks for the feedback. Any particular reason for using one over the other?

Metieval

I could be totally wrong here. But I would assume gravel wheels would be closer to road wheels, stiff for efficiency.
Mtb wheels will be more vertically compliant, for a nice ride. Hence shallower.

Based on what you said, I'd pick the mtb wheel. Bonus being lighter weight.

Edit: on the same note, look at capacity. If your going to bikepack then you want to cover you + gear + bike

maartendc

Thank you, this is good info.

Yes I believe you are correct, the gravel rims look more like a wider road rim. The MTB rims are a much different profile. The added compliance would definitely benefit the type of riding I want to do.

It is interesting the MTB rim is rated for 110kg system weight, whereas the gravel rim for 130kg. So the gravel rim would be more suited to bikepacking. But I weigh 70kg, the bike 9kg, and I doubt I'd be packing more than 20kg of luggage, so 110kg should be fine.
But then the MTB rim is rated for ASTM 3 (unpaved technical riding, including small jumps etc.) and the gravel rim for ASTM 2 riding (just unpaved trails, no jumps). So that would make it seem like the MTB rim is the more "durable" one.
Not sure how the system weight and ASTM rating relate to each other...

I'm leaning towards the MTB rim for sure, thanks.

maartendc

Could anyone help me with the SPOKE selection as well please? I'm totally new to this.

For the riding outlined above (MTB trails, up to 100kg load):

From what I've read:
- A thinner spoke like the D-light will give more compliance? But might be weaker / more prone to get out of true?
- A thicker spoke like the Sapim Race will be stronger / stiffer, but less compliant / ride more harshly?

Is this correct?

I do want something I can ride for a 10 day bikepacking trip without having to worry about it going out of true. = Sapim Race
But I also heard 650B wheels are stronger by default, and I don't want something that rides overly stiff... = Sapim D-light.

Which would be the optimal spoke choice? Thanks!

Koyote

Are you building these wheels yourself? If not, I suggest you engage with a shop that builds lots of wheels. They'll know how to guide you to the best components.

Metieval

Too technical for bikeforums.
You might want to try another forum

Sorry I can't help you on spoke selection.

mstateglfr 

Butted spokes are lighter and thinner than plain guage spokes, but they are 'stronger' in that they will flex more easily which is good. The inability to flex means more fragile.

650b is 'stronger' than 700c in that it's a smaller diameter and the smaller radius means shorter spokes. Shorter soles are stronger.


Regardless of spoke used, a wheel that is properly tensioned and tried shouldn't come out of true through normal use, even if 100kg is the full weight being carried on the bike. Proper tension and relief is key to this. A wheel can be true, but have uneven tensioning and break spokes left and right.

Brass nipples. Wasn't asked, but I'll add that anyways. Won't seize and won't round off.

maartendc

You are right of course. Sadly, I don't really have any wheelbuilders near me it seems. I was going to order it with an online wheelbuilder. I guess I will try and e-mail the online builder I was looking at for some guidance. Thanks!

Thanks anyway for replying!

Thanks this is very helpful!

OK, that makes some kind of sense. But I don't think I am fully grasping the complexity of wheelbuilding (yet). From what I gather, flexibility is good, so thinner spokes are good for that (and supposedly more compliant / comfortable). But there must be some reason people use the thicker spokes. It will give a more stiff wheel that can take a larger overall load I suppose? Stiffness is good for pedaling efficiency, but not for comfort.

Thanks, I was tempted to go for alloy nipples and save the 40g or so of weight, but I want the wheels to be durable, so I guess I'll go for brass haha.

mstateglfr 

Psimet is a builder/brand that posts on here sometimes and has a really good reputation. They build solid functioning and conservative wheels. They use their own designed rims a lot.

Prowheelbuilder is an online builder that has a ton of different rim, hub, and spoke brands. I have 3 wheelset from PWB and they are all still excellent.
None were expensive wheelbuilds either - $400-485 for each of them 4-6 years ago.
They are properly tensions and stress relieved, as expected.

You can email PWB with a couple questions before you choose the components of your wheels, or you can ask them for suggested specs, pay, and ride.

Russ Roth

Pick a spoke that has a 2.2mm elbow and is butted from there. The DT alpine for example is 2.2/1.8/2.0, though hard to find affordably. I built mine also using a mtb rim, mtb hubs, and wheelsmith HD spokes which are 2.2/2.0, its the elbow that usually gives first when spokes start to go so a 2.2 there is fine. Its been fine and some of the "gravel trails" I've come across are just single track connecting things like seasonal highways and old jeep roads, so I don't mind leaning towards a mtb rim.

smmeiksa

Considering the mix of off-roading, technical trails, and bikepacking, you may find that the XR391 is more versatile and better suited for your needs. However, if you're leaning towards a more gravel-focused riding style and prioritize durability for bikepacking, the GR 531 DB could still be a solid choice, even if it's slightly narrower and heavier.

Calsun

Start with the tire and then you will know which rim to use. On my mountain bikes I use Maxxis tires and for general use their Rekon Race are a good tire. For gravel I would want a 700x42 size tire which is going to be much better as a multi-surface tire.

Something else to consider is adding a drop post to the bike if it does not have one. On downhill and uphill runs being able to lower the seat is very helpful. My full suspension bike came with one but I paid to have one added to my hardtail bike.

Calsun

Start with the desired tire and then based on that choice you will know the rim that is needed. Mountain bike tires are 50mm or wider and gravel bike tires are usually 700x47 in size. Gravel tires can provide a good deal of traction with less effort to move the bike.
I would also consider adding a dropper seat post if your bike does not have one as it helps to have the seat out of the way to position yourself on the bike when the trail is not flat.