Fork Steerer Cutting Anxiety

tl;dr Cut it a tiny bit longer and file it down to the correct length. Cover your fork with an old bed sheet to keep metal shavings off the stanchions. Make sure you're not going to cut into the star nut! Steerer should be 3mm below stem for top cap clearance. Measure top cap clearance after stem is tightened.

I read several posts on mtbr of folks using pipe cutters. They seem to work fine but roll the edge a bit. I was going to try this but my pipe cutter is for copper 1/2" and was too small. So hacksaw it is. First I drew a circle around the steerer at the top of the stem with a sharp pencil. Then I removed the stem and measured 3mm down for top cap clearance.

Next I wrapped a piece of painters tape at the top of the line. The hacksaw blade I had cuts a little over 1mm in width (kerf), so positioned it accordingly. The cut wasn't perfect but it veered out rather than in so that's fine. Next I filed it down so it'd be even with the tape. I recommend wearing gloves when filing since it can get really sharp and you need your fingers to ride your bike. Now I tapped the star nut down to the correct position.

This filing created a huge mess of metal shavings which stuck to my fork, so I spent the next 5-10 minutes cleaning shavings off. I put the stem back and tightened down on the top cap but nope it was still too tall (the compression washer in the stem moves about a 1mm as it is tightened). So back to the filing. This time I wrapped the fork with a cover. Now I could get the headset tight. It did loosen slightly on the first ride which is typical.

Top of stem marked

Measured 3mm down from top and taped

Final length

Lastly, after you preload the headset and tighen the stem, remove the top cap and measure again. The preload compresses the washer and brings the stem down a bit, such that it may be less than 3mm now and bottoming out. If it is, file it down some more

RockShox SID XX Service + Travel Change

I have my fork serviced once a year and this time I thought I'd be super smart and do it myself, saving $150. Well almost, I had to make an initial investment in some tools (crow foot wrench, snap ring pliers, etc). The oil + sram butter alone is about $38 but should last three or more services. The seal kit is $17 but one came with my fork, yay sram! Amortizing the services comes to around $30. And less if you just put in fresh fluids. 

I also need to change the travel from 100mm to 120mm for my Yeti. It seems most RockShox forks can support a travel change. I called RockShox to verify. I only had to get a new airshaft (about $25). 

After a year of riding the only thing that was dirty was the foam seals (under dust wipers). All the o-rings look 100% good. I imagine I could go two years on the seals and once a year just clean everything. The foam seals are the one thing I'd want to replace though.

In general, the sram manual is really good but here are a few snags I hit:

• The service manual states -- All o-rings should be greased but they only say this at beginning of manual -- yet they call out greasing specifically in other sections. So, I didn't grease all the o-rings, dang! But I think I should be okay since they are saturated in oil. I did grease the dust wipers (critical) and the air shaft.
• The say to use a dowel to clean the tubes but don't say what size, so real helpful there. I wrapped a cloth around a air compressor hose and it worked perfectly to clean inside of fork lowers and stanchions
• I should have printed the service manual. Instead I ended up with grease on my notebook
• The red rebound adjuster just pulls straight out the bottom, wut?? How does this stay put?
• Air shaft side required harder blows to free shaft
• Dust wipers were *hell* to remove. Super tight in there. With tire levers they were not budging. Had to ever so carefully work loose from outside with razor blade. This time I greased the seal sockets even though it didn’t call for that
• Measured oil depth to top of fork crown. 106ml was right on 72mm
• A 24mm socket would have been easier for air side but used a crow foot wrench
• The amazon snap-ring pliers deform when squeezed don’t work so well (cheap!)
• For the air shaft I installed the 2 seals inner and outer on air shaft plastic disc. Kit didn’t include other seals.
• Put some air in the air valve to push air shaft out a bit before putting the lowers back if you can't screw in bottom bolts!
• Getting the dust wipers in place was tricky, even with some grease. Can see that tool being worth it.

Before travel change measurement showing 100mm of travel

Legs off

Cloth wrapper around compressor hose to clean insides

120mm air shaft

X-loc (XX) fork requires a crow foot wrench to torque properly

In summary, RockShox forks, at least the SID/Reba, are relatively easy to service. The documentation is excellent and doesn't require any proprietary, impossible to get tools. Take your time, follow the service manual and along with saving some cash, you'll keep your fork running smoothly.

Changing Fork Travel and Tribal Knowledge

It's pretty awesome that Rockshox forks (some) can have the travel adjusted. This will be saving me gobs of money as I go from a frame that requires 100mm to 120mm of fork travel. All you need supposedly is a longer air shaft, and it's only about $25! The stanchions are already long enough, how cool! The tribal knowledge aspect of this adventure is I can't find any documentation that describes how to convert and what parts you need so I called rockshox. The rockshox guy was super helpful; he took my serial number and gave me the part number to go to 120mm travel on a solo air SID XX fork 2015 (also for reba too): 11.4018.021.000

RockShox documentation lists the air shaft sizes for wheel/travel sizes. Part numbers would have been nice here

But almost no retailer lists the part number. The first airshaft I bought was listed incorrectly and was for a 26" fork, ugh. Universal cycles does list the part number: https://www.universalcycles.com/shopping/product_details.php?id=67483&category=701

Now I'm waiting for this airshaft to arrive and I'll report back on the conversion.

Here's the photo of the 26" airshaft. There is no marking on the shaft but it's it's 7 1/4" long, then it's a 26", not 29". Notice the part # ends in 005, not 000, but who could be bothered putting that anywhere in the website description!

Here's the correct (I hope) air shaft

Yup, I measured and it's just a hair over 8 5/8" so matches up with 222mm in chart.

1x vs 2x Range and Weight Savings

All the cool kids are riding 1x setups these days and it makes sense for a lot of folks but I'm not yet ready to give up on 2X. I have been racing XC and many of the races have flat fire road sections where you would simply spin out on 1x. It's true you can go with a bigger ring in front but then you are going to suffer (maybe) on the climbs. Of course more powerful riders may not experience this situation so 1x just works for them.

Also it's important to note that with the Shimano 11-speed line, they have reduced the max difference in chainrings in 2x to 10 teeth, so you can have 26/36 or 28/38, but not 24/38 as they offered in the 10 speed lineup.

I did some research into the ranges that are possible with 1x vs 2x and 3x (Shimano only). In short, 2x10 offered 518% range, while 2x11 only offers 493%. With 1x11 it drops to 407%. There are some aftermarket options (OneUp 50T) that could get you to a 10x50 and maybe even 9x50, which would best 2x11. I didn't look at SRAM since the cassettes are OMG expensive.

Of course there's some weight loss to be had with 1x systems. I couldn't find any concrete numbers so I did a little bit of research and came up with:

XT Front Derailleur adds about 137 grams

XT Shifters are 237g, so subtract one to get 119g

Small chainring weight? I'm guessing 60g, maybe it's less

But 1x increases cassette weight: 11-36 (268g for 32) cassette vs 11-42 (433g) + ~60g

Total 255 + chainring - 60g. 

So I'm calling it just under ½ pound of weight savings for 1x (Shimano XT). XTR should be less

Lots of noise in this table but the number to focus on is the range in the far right column. I wasn't able to paste the column headers, the second from the right is the number of feet the bike travels per revolution of crank.

3x10	22	32	25.73	80.7922	4.63	555.37%
3x10	22	28	25.73	80.7922	5.29
3x10	32	11	25.73	80.7922	19.59
3x10	42	11	25.73	80.7922	25.71
2x10	24	36	28.68	90.0552	5.00	518.18%
2x10	24	32	28.68	90.0552	5.63
2x10	24	28	28.68	90.0552	6.43
2x10	24	11	28.68	90.0552	16.37
2x10	38	13	28.68	90.0552	21.94
2x10	38	11	28.68	90.0552	25.92
1x11	30	42	28.68	90.0552	5.36	407.27%
1x11	32	11	28.68	90.0552	21.83
1x11	32	50	28.68	90.0552	4.80	500.00%
1x11	32	10	28.68	90.0552	24.01
2x11	28	40	28.68	90.0552	5.25	493.51%
2x11	28	35	28.68	90.0552	6.00
2x11	38	11	28.68	90.0552	25.92