Do you have a "dumb" question related to MTB?

Forums Mountain Bike Forum Do you have a "dumb" question related to MTB?


This topic contains 24 replies, has 12 voices, and was last updated by  Aaron Chamberlain 1 year ago.

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    Just to be clear, there are no dumb questions around here. However, I know there are probably folks who read Singletracks who have what they think might be a really basic they’re afraid to ask. The good news is, the Singletracks community and staff are here to help!


    I’ll start this off!!

    I have a Cannondale F29er with a lefty fork and I want to put some wider tires on. What is the easiest way to calculate a maximum tire width and how does my rim width affect things?



    @aes5455 the short answer is no.

    The long answer is:

    Tire brands can measure substantially differently for what is labeled the same size. For instance, one brand’s 2.3 might be another brand’s 2.5. Apart from the diameter, there’s not much standardization in tires. The best way to find out what fits is through trial and error. Which can get spendy.

    Rim width can have a huge impact on tires. A wider rim places the tire beads farther apart which can make the tire measure wider than it would on a narrower rim. It can also allow you to run lower tire pressures, while still having good sidewall support. However, you need to pair the right tire with the rim. For instance, if you tried to put a narrow 2″ tire on a 30mm wide rim, the tire’s profile would get squared off. In that case, the tire would corner like shit. Why? Because the side knobs are no longer on the side of the tire, they’re on the top. When you lean the bike over, there’s nothing to bite into the dirt and you fall on your head.

    Generally speaking a rim around 25mm wide internally is going to work great for a majority of trail tires in the 2.2-2.5″ range. If you want to go with a substantially wider tire, you’ll probably want a wider rim as well. Most plus bikes (2.8″ tires) run rims closer to 35-40mm wide internally.

    However, if you’re not running really wide tires (2.6+”), don’t get too sucked into thinking you need a wide rim. You’ll be pushing around extra weight without a benefit. The more weight you can cut from the outside of your wheel (i.e. the rim and tire) the faster your bike will be.



    What is the purpose of the stem and headset other than the obvious of holding the handlebar on? lol. I suppose my question is how do these affect a rider’s overall ride for the better or worse? Other than seeing so many riders choosing these components to add some “pop” to their bike how could changing these be even more advantageous?

    You asked if we had any “dumb” questions so I’m sure this one rates right up at the very top! But hopefully I’ll learn some really good information!


    I have used 35mm, 40mm, 50mm, & 90mm stems on a whole assortment of bikes. In my opinion, 50mm is perfect for a mountain bike. The 35mm and 40mm made my bikes’ steering feel twitchy. 90mm was just too long for mountain biking and the agility required for it.

    I find that for most of my bikes, I usually end up swapping to a shorter stem to be able to handle the descents better and not feel like I am falling over the handlebar. My sweet spot has always gotten me to around 50mm long stem, raising up the stem with a couple of spacers, and pushing the seat back on the rails around 1/2 inch. On my 26er, I even had to swap over to a riser bar to get my cockpit to where I wanted with my posture a bit more upright and my weight a bit further back.

    That works for me very well and lets me loft the front wheel as needed. The fine tuning is done on the climbs, if I find the front end lifting too much. I then either slide the saddle forward 1/2 inch, or I can scoot forward a bit on the saddle to keep the front down, or in some cases extend the travel of the front fork a bit (by removing spacers internally).

    I have shorter legs, shorter arms and longer torso than average so these adjustments work very well for me. Your mileage may vary.


    What, exactly, is a roller???


    Blundar, thank you for taking the time to share your experiences of what works for you on these components. I am assuming it has to do with the “comfort” of ride. However, I was wanting to know how these 2 things add to or subtract from a ride overall for riders. Could adding to one or both of these enhance my bike and ride, and if so, what would be some of the key factors to look for, etc. Again, I do appreciate you sharing what you’ve experienced and did learn a little from that!


    Hey kenwrightjr, my understand is that a shorter stem makes steering more sensitive or twitchy, while a longer stem slows it down. So increasing the physical distance between the bars and the fork also “moves them further apart” in feel as well.

    But, this has to be taken into context with the angle of the fork. A steeper angle (like a road bike’s) also makes steering more sensitive and twitchy, while a slacker or flatter angle (more like a motorbike’s) slows it down. Older bikes have steeper more vertical forks and long stems, while newer bikes have flatter more raked out forks and shorter stems, so in a way the “sensitivity” of the steering is the same. But the newer geometry almost universally improves the feel, traction, and quality of the overall handling.

    The offset of the axle, called the fork rake, is really important too, but that generally can’t be changed, so people don’t talk about it. Interestingly, the Santa Cruz DH team reckons that the perfect stem length for handling is about 50mm too, and is a consequence of the rake and head angle of their downhill bikes. Generally, the 30-60mm range would be normal.


    Thanks for that info jagungal. That helps. I guess if I am reading the specs on my Santa Cruz it says I have the Cane Creek 40, Integrated for a headset. And I really can’t tell if it’s too sensitive or not. So I guess if it’s not broken then there’s no need to fix it! lol


    @kenwrightjr in regards to the headset itself, the biggest benefit between a low and high priced headset is going to be the quality of the bearings. After all, they’re quite simple. In most cases, aluminum cups are pressed into the frame’s head tube, although there are some frames (carbon in particular) that have the cups molded directly into the head tube. As you can imagine, there’s not a ton of difference or weight to be saved between one aluminum cup and another.

    The real difference will be in the bearings. More expensive headsets will use nicer bearings that should last longer because the machining is more precise and the seals are better. Personally, I go with something like Cane Creek’s 40 series headset. They are readily available and fairly inexpensive. Once the included 40 series bearings wear out, I’ll upgrade to a nicer bearing, like their 110 series. That way I can get the best of both worlds – inexpensive cups with nice bearings.


    My Santa Cruz has those Cane Creek 40 series Aaron so that’s good to know those are a fairly popular and trusted headset. On average for someone who rides approx. 25-35 miles per week in northern Georgia how long could one expect these Cane Creek 40’s to last? Is that a legitimate question or is the unknown too large here to answer that? Just curious as to what I could expect.


    It’s hard to say how long a headset will last. It totally depends on the conditions you’re riding in. Obviously, the more you ride in the wet and slop, the faster the bearings will wear out. Check your headset at least once a year and keep it greased. If you do that – and also make sure it’s properly adjusted – it should last years.


    The length of the stem does a couple of things:

    1. Adjusts the quickness of your steering (long stem is slow, short stem is fast steering)
    2. Positions how far forward your upper body is over the handlebars

    For the first one:

    Slow steering is more stable (great for long distance XC cruising). Fast steering is great for tight and technical singletrack and downhills.


    For the second thing:

    If the stem is very long and most of your upper body weight is far forward over the handlebar, then down hills are going to be really sketchy. Hitting the brakes hard will make you feel like you are going to go flying over your handlebars. Another thing is that it will be more difficult to lift the front tire over an obstacle. If the stem is very short and your weight is too far back, then every time you start climbing up a steep hill the front end will feel like it lifts, loses control, and wanders too much.



    “What, exactly, is a roller???”

    Pump tracks started out from the BMX days. Berms, jumps, flat tops, and rollers are terms used to describe features on a pump track. Rollers is a series of humps that you “roll” (not jump) your bike through at speed, where you pump your bike repeatedly to maintain speed without losing momentum.




    Alright, here’s one.


    When should you replace your helmet? Obviously after any kind of impact, that’s a given, but I am on season 3 with my Smith Forefront helmet, and I am wondering when I should replace it. No impacts, just wearing it or storing it in my closet. Manufacturers say 3 years, what do you guys do?


    Hey Christopher94,

    I don’t know if this will be helpful or not but here is what I do, I race MTB so I replace my helmet when I have a bad crash, but given that you haven’t crashed yet (if you haven’t) I would replace the helmet after the manufacture date if the helmet was less than $200, if it is over $200 I would keep it for 1 more year.



    When should you replace your helmet?

    This is my personal opinion – no need to replace it if it’s in like new condition. Better use that money for something else.


    What do you guys think on cornering technique differences when riding MTB and motorcycle? On MTB I try to stay on top of bottom bracket while motorcyclists shifting their body in opposite direction, closer to the ground. Is it just because of heavier bike and greater g-force? Or there’s something else?


    @stumpyfsr – that’s a good question.

    I *think* it’s partly due to the weight of the bike, but also because of the tire’s contact patch – if we’re talking about a street motorcycle. You want as much rubber on the ground as possible, and that rubber is found in the middle of the tire. To make best use of that contact patch, you want to lean your body and not the bike. Which is the opposite of mountain biking. On a mountain bike you want to lean the bike more than your body so you are pressing the side knobs into the dirt.

    Or something like that.

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