HD MtB Wheels, Tires and Rims – and the wide open desert…

Greetings.

For the last few weeks I have been thinking quite a bit about how to build a robust MtB Wheel that can handle long-distance touring and abuse. It began with buying a skinny set of tires for my 9C 2806 hubs; fine for city, but in the greater Seattle area we also have potholes. I fear taco’ing at 25mph. Thus it began the hunt for a good solid solution both for town and for trekking. Currently I have a study on tire size here on tire width:
What is your tire width?

In my search I have narrowed the rim selection down to DT Swiss F 630, or possibly the Mavic EX 729 Disc Downhill 26" x 36mm wide; both good solid rims ready to take abuse. Then it came to me last night that although bicycle tires with rare exceptions, pretty much limit out at 2.5” wide, there might be motorcycle tires in like-sizes that could resolve my durability concerns. The last thing I want when I’m satisfying my high-speed lust, WOT out in there in the open desert between Tucumcari and Timbuktu is to blow a flat or taco the tire. Know what I mean?

The wild-child crazy KF-part of me starts to thinkin: What is the smallest motorcycle tire I can put on my MtB? Small meaning skinny. Turns out that options begin to appear at 18”, 19” and 21” rim diameters, though good luck finding anything narrower than 2.75” tire. Calculating at that size a dual-sport tire on a 21” diameter rim comes to roughly 26.5” in diameter, whilst a 19” rim translates to 24.5” diameter. Both of these are doable. BTW - some info suggests not going larger than 3” wide for any tire/rim combination due to clearance with the rear derailleur.

Pensive, I reviewed my frame and it can take 2.75” wide no worries. My Marzocchi Bomber front shock though is a problem; I’ll need to deflate the tire to get past the V-Brake mounting pins. I was planning on going to disc in the front anyway (er... that’s another project).

OK, now to sort out the rims: Turns out that there are few options here. Rims in this size run between 1.6” to 2.15” and are mostly 40-spoke. However – in diligence I found this source offers 36-spoke rim which is exactly what we need for the 9C hub:
Warp 9. They're a little cheaper here...
Spokes are about 10-gauge; forgive me – we really need to refer to spoke diameters in millimeters. Anything 2.3mm or larger is good.

Cost: With exception to custom-builds (spoke-cutting, rolled, laced) the costs for motorcycle wheels is on par or may be cheaper than going with the high-end downhill bike route. Throw in rim balancing; which is easier?

Conclusion: There’s really quite a gray line between these two worlds. In theory I think I have researched the beefy-arse high-speed tire spec to the nits-end. But more rhetorically, are there a lot of folks out there doing something similar? If I stayed local I think I would be happy in the bike world, but my gypsy soul craves the open sky radical road trip… off the grid, natch.

Imagine: Road Warrior. Rebel Solar-Powered Stations linking the desert expanse! Junk yards and clandestine machine shops. Forget about oil; the war’s about water rights, tofu, and livin’ on the edge…

Give me steak!
Happy Fried’aye. KF

I know what you mean about wanting wider tires. In the desert here, it's hard to have wide enough tires on anything, trucks, motorcycles, bikes. Part of why I bought my specailized was that it came with 2.7 inch maxxis mobster tires. Yeah baby! not quite 3 inch wide, but definitely floats well on loose sand.

But one thing I realized pretty fast, was that the fat tire on the front was actually making it a bit hard to ride. It just grabbed so much dirt that I could easily over turn it, and then the big scoop of dirt would force the wheel 90 degrees without a lot of force to stop it. I ended up putting a 2.3 inch tire that still floats ok, but steers much better on the front.

Motorcycles are built that way usually, with a fatter tire in the rear and something a bit narrower and less knobby on the front. So you may want to just use a motorcycle rim and tire in the back, and go with a good DH rim and 2.5 inch tire in front.

Check out the aluminum rims that the vintage small displacement racers use. If there is anything lighter than your typical aluminum motorcycle rim, they will be the ones using it.. For street tires see what they use also. Probably some nice sticky compounds. IIRC they use the 17" '21 inch' moped size tires and rims. Motocross rims are strong for sure, but maybe a little overkill. I want to try one of the 14's I have around here someplace..

Here is one link where a guy was trying to find a light strong rim for a little vintage racer.
http://www.jrbranson.com/hondaracer/honda/alloyrim.htm from http://www.jrbranson.com/HondaRacer/mainpage.htm

Thanks for the feedback guys! It’s really had my noodle working overtime 8)

Yesterday I rode out to the Seattle Bicycle Expo which was out on Pier 91 in the Magnolia district. The Noon ride was 25 miles in length from Redmond via I-90 Floating Bridge and Seattle Waterfront. There were two levels of all kinds of bike stuff in the warehouse; I was there for about 3 hours networking.

Off-Topic:

• Frankly I was surprised at the number of electric bike dealers/booths; they just about equaled one-for-one every traditional bike booth. Bionix was there in force; I counted three booths: Upstairs and Down, and at the Entrance.
• The most interesting item I discovered was an Electric Shifter on a speed racer: Uses a 7.4 Li-Ion 3.5Ah battery for power, and has a worm drive that ratchets the F/R derailleurs.
• There was also one local (in-State) Bike Bag manufacturer: I have been trying to source someone to fab a custom bike bag for my P1 triangle area; it makes for a separate subject.

Tires:
Because my time was limited I tried to focus on the unique items, and my most-pending issues. If I saw a bike that had eye-catching fattys mounted then I stopped to investigate. One place had a 2.3” MtB knobby mounted on a carbon-fiber rim with carbon-fiber flat-spokes which I thought was interesting, though I’d wager to be very expensive.

Near the end, I found that Specialized had a booth on the ground floor. They had three people working, no – sitting there, and I didn't glean anything new; they seemed pretty tired.

Schwalbe was the only-tire manufacturer there and they had in-State distributors there in a tour de force booth on the ground floor. The guys there were busy; very knowledgeable gents willing to invest the time explaining their product. The part I really liked was their hanging rack of various models mounting on rims without hubs that allowed a person to quickly evaluate the merits of each tire. I walked away with a beefy technical catalog duly impressed.



Leaving, I took the Burke-Gilman/Sammamish Trail, 31 miles back to Redmond and ended up at Claim Jumper for a carnivorous feast pouring over the catalog of Schwalbe’s product line, exhausted but geeked!

Here are other related threads on tires, assembled for completeness.

Poll: What is your tire width?
TYRES !!! ~ Which do you use ?
Tires - Balloon/Urban type
Tire size. What size do you use and why?

Enjoy, KF