Ask MBA – Big Ring and Chain Woes

 What bike should a big guy be riding? How much travel do I really need? How fat is too fat? The MBA wrecking crew uses its combined expertise to address these questions and more every month here at “Ask MBA.” All you need to do is visit our web- site—www.mbaction.com—and click the “Ask MBA” tab. Scroll to the bottom of the page and click the link to ask your question.

CHAIN-STRETCH FRUSTRATION

Q: I just recently upgraded to a 1x sys- tem, which is awesome, but I have had to replace the chain twice in less than 500 miles of use. That seems a little excessive to me. Do you have a suggestion of a prod- uct that will last longer than 250 miles? I am 6-foot-4 and 220 pounds and am cur- rently using the SRAM PCX1 chain.

—Bob, who doesn’t want to buy more chains

A: That sounds excessive to us too. We’ve had excellent luck with longevity with these chains on all of our test bikes. Your stature certainly isn’t helping limit the wear, but we’re pretty confident that’s not the only culprit here. If you’re running your drivetrain dirty, all that grit and grime could be wearing the rollers quicker than normal. Think of what happens when you get a rock in your shoe. It’s not a big deal until you put pressure on it, and your chain must withstand about a thousand times the pressure that the bottom of your foot does. We’d recommend being more diligent about keeping the drivetrain clean as a starting point.
It’s also possible that you’re installing a new chain on a worn cassette. Since chains and cassette cogs tend to wear together, the spacing on the teeth gets stretched with the chain. When you go to put a new chain on, the cassette soon wears that worn-out spacing into your otherwise new chain. If it’s been a while since you’ve replaced your cassette, that’s likely the culprit.

TAKE IT LOW!

Q: My trusty three-ring circus has a lowest gear consisting of a 22 up front and 36 in the rear. It gets me up steep stuff. If I go with the SRAM Eagle 1x drivetrain with 50t in the rear, what front ring would be needed to equal my current low?

—Michael, who wants to climb

A: We ran the calculations on this one, but we’re not going to show our work like this is a high school math test. Basically, a 30-tooth ring with a 50-tooth cassette cog will be almost identical and even a touch lower than your current 22/36t setup. There are plenty of ring options in this size and even some that are smaller than that if you want to really go crazy crawling up the steep stuff.

BIG-TIRE DILEMMA

Q: I have a Yeti 575 with 2.3-inch tires. I was wondering if I could use a 2.8-inch plus-sized tire, assuming, of course, there was sufficient clearance. If not, would it be a matter of the stock rims not allowing proper tread profile?

—Jeff, who wants to go bigger

A: A bike that’s not specifically designed to accommodate plus-sized tires will probably not work with them. Your Yeti is one of those bikes. Even if you get the tires to clear the frame when the bike is in the work stand, the rear wheel will flex slightly while riding and almost certainly buzz the inside of the chainstays, seatstays or both. This would also leave you with almost zero mud clearance—and that’s not the worst of it. As your rear wheel moves through its travel, it moves up and forward towards the seat tube. If you run a tire that’s too big, it may be possible for the tire to contact the back of the seat tube at full compression. We’ve seen some horrible crashes caused by this exact issue, because the wheel can come to a complete stop when landing a jump or drop and eject the rider unexpectedly.

There’s no rim profile we know of that could solve this problem. Our advice would be to save your pennies for a bike that’s designed to handle plus-sized tires.

Have a question for the MBA crew? You can send your brain busters to [email protected].


“Ask MBA” peeve of the month:

Online MTB videos that are laced with profanity, drug and alcohol use, and lewd acts. You don’t need a ton of curse words to make a sick riding edit. At MBAction.com, we screen every video to make sure it’s on the up and up. Feel confident if your kids are on our site. They’re going to get everything about bikes without any of the vulgar filler.


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