More mountain biking

qslim said:

Gotcha, so instead of finding a taller low gear one has to change the front chain ring which affects the overall ratio? So it's a tradeoff then on all gear settings...

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Is it a 3x system? Yes the smaller front chainring will change the gearing on the whole cassette, but how much does he use the small ring anyway? Most of the time you're in the middle ring on a 3x, and that won't change.

qslim said:

climbing
I'm not sure what you mean by 3x. His bike has one cog up front, 8 in the rear, so I'm assuming that's a 1x? My only concern is with him having a taller 1st gear on his rear gear set to help with climbing in the lowest selection. Sorry if that doesn't make sense, I'm a car/aircraft guy, don't know a lot about bikes.

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You got it right. I assumed it would have three chain rings up front (3x) and not one. Yeah, get him a smaller front chain ring... Or, depending on the rear hub, you might be able to switch the shifter and derailer to 10 speed. Then you can go with a 11-46 (sun race) high range cassette. Might have to change the chain too.

Look here
https://www.thebikesmiths.com

qslim said:

Makes sense. I'm going that far for a 7 year old's bike. He'll just have to pump it out and complain.


I set the tires up on my new Specialized for tubeless today, I've read it's all the rage and it was super easy. How often do y'all replace the sealant in these things? The LBS says every 3 months but some guys I know say they just add some every once and awhile. Is it a good practice to clean the old sealant out and replace it every so often?

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I set my bikes up tubeless last fall and haven't added sealant. They all hold air pretty well Now, I did true a wheel last week. I pulled the tire to do so and the sealant was all dried up, so it doesn't last forever. Once they are sealed, I don't think you really need to worry about it, unless you think you're gonna get punctures from thorns or whatnot. I have a better chance of blowing a bead than getting a puncture, so I'm ok without sealant. Been riding 25 years and I've only had one flat that I can think of...and that one was because I taco'ed a wheel. Had to stuff the tire with leaves, disconnect my brakes and smash the wheel on the ground to get it sorta round to ride out!

qslim said:

Another question for you braniacs: How does the length of the stem affect handling? I did some googling and think I got it worked out, but wanted to double check.

I didn't like my old hardtail because I thought it handled like a tank. It's an entry-level to begin with, but on the tight trails laden with rocks on the side of a mountain I felt like I had a hell of a time getting the front wheel where I needed when I needed.

After getting my new FS, I love the way it feels - it's snappy, responsive, and I can yank that front tire wherever I need to put it. However, it feels cramped on the climbs. I second-guessed myself as to whether I should have gotten an XL frame instead of the L like my last hardtail, but I measured the distance from the seatpost to the handlebar stem and they are indeed both the same. Then I noticed that the bar stem on my new bike is about an inch shorter than my old bike:

New:
View attachment 154730

Old:
View attachment 154731

What I've gathered is that this could explain why my new MTB feels so much more confident on the technical bits but less so on the climbs? I was thinking about swapping the two and seeing how it feels.

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Stems and bar width are related. Your correct that a shorter stem will make it feel snappier, but you also need wider bars to increase the leverage. GMBN and Worldwide cyclery both have some good videos on bar width and stem length.

I've been experimenting with my bars too. I have three bikes with three different length bars. 760, 780, and 800. Its interesting putting different bars on different bikes. For instance I had the 800mm bars on the bike with the shortest stem (50mm). I took the 760's off my bike with the longest stem (around 110 mm) and put them on the short stem bike. Haven't ridden much more than around the yard, but I like it. I also like the reciprocal, the 800 mm bar on the 110 mm stem feel pretty good. We'll see though. I'm getting a lot of shoulder cramps from my new bike, and its the one with the wide bar/short stem combo, so I'm trying some different stuff out.

You also mentioned something about the new bike feeling more stable on technical stuff, but less so on climbs. I don't know how old your hardtail is, but "modern" geometry can contribute to that too. Mountain bikes have been getting more and more slack and they've shortened the rear chainstays almost as much as possible. The slack head angles make them more stable in decents...but too slack can make it feel lazy at slow speeds. The front end will want to flop over (like a 70's chopper...think Easy Rider). The shorter chainstays and brings the rear wheel under your butt more, so more weight is on the rear...it lightens the front on climbs. Makes it tough to keep that front wheel planted.

I love this stuff. I'm still a newb, but I find bike geometry fascinating. Just like jeep suspension...SO much to learn. My buddies laugh at me because they are all convinced that I'd rather spec and build a bike vs riding them. I don't know if they are wrong...My dream is to take a class and build a Steel frame trail bike. Hard tail, kinda slack, 29'er with a Carbon fork and 2.6" wide tires. Not sure I'm ready to drop 5-7K on a bike yet...someday though...

qslim said:

Interesting. I looked up the specs on my old vs new bike, looks like the bars are different too.

Old:

STEM	Stout 3D-forged alloy, 31.8mm, 6-degree rise, 70mm length
HANDLEBARS	Stout double-butted alloy, 18mm rise, 8-degree backsweep, 4-degree upsweep, 740mm width, 31.8mm

New:

STEM	Specialized Trail, 3D-forged alloy, 4-bolt, 6-degree rise, 45mm length
HANDLEBARS	Specialized Trail, 6061 alloy, 8-degree backsweep, 6-degree upsweep, 27mm rise, 780mm, 31.8mm clamp

Geometry wise my new bike has 15mm on reach, so I'm thinking the reason it feels cramped to me on climbs is that shorter stem. I think I'm going to swap it for the longer one and see how that combo feels with the wider bars & longer stem.

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Won't hurt. The nice thing about accumulating that kind of stuff is that you can swap it around, and figure out what really works for you. If you don't like it, you can try something else. Once you get a group of riding buddies, you can share stuff between you too, so you can really get dialed in without spending a bunch of money

qslim said:

Another interesting thing - this Specialized has a 'flip chip' thing that changes the geometry of the bike:

"All models irrespective of travel or price will come with a flip chip in the rear shock yoke which allows the geometry to be adjusted by half a degree steeper or slacker. It will also raise or lower the bottom bracket by 6mm and change the reach by 5mm. The chip is made of two steel parts inserted in the shock extension and depending on its orientation will change the geometry accordingly."

I changed it a few weeks ago to the higher setting and thought that I noticed it was more twitchy, which is what I liked for technical descents. I wan't sure if it was just my own bias from reading on it though, so I brought some tools along today and changed it a couple of times during my ride. I was really surprised how raising it made it easier to negotiate tight downhill switchbacks with rocks & roots. Having it raised like that makes it feel a little cramped on climbs, but I didn't mind that so much. I had no idea that such a small change could affect handling like that.

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That's pretty cool!