X-Caliber project

The bike

Trek X caliber 7

As I am quite tall and unable to find a large frame “cross country” bike at local bike shops. I was on top of the world when I found a Trek X-Caliber 7 Frame size 23″ at Probike. I brought the bike home and started riding on it. I got the bike for a bargain price, so there was budget left to improve it. The X-Caliber 7 is after all the entry model, and slightly heavy. The frame is great, so time to look for upgrades. Initially I considered upgrading the group set to Shimano SLX or XT, but I must say the Acera 9-speed shifting is great, and I have no issues with the brakes, so these will probably stay on the bike until they break. The Wheels are rather heavy and I would love to ride tubeless. The plan was to upgrade the wheel set.

New Wheel set – DT Swiss M1700 boost

The X-Caliber has a weird rear axle, it is a Quick Release (QR) but in “Boost” size: Boost141. Local bike shops could not help me, I googled and was kind of lost on what to get. Having emailed both Mavic and DT Swiss, DT Swiss came back with a clear message. With the Boost wheel, I could replace thru axle end-caps with a 5mm QR conversion kit. Great! So I ordered a Boost wheel set and the suggested end-caps. These wheels provide an upgrade path for when I may get a different frame with thru axle. The M1700 with its “350” ratchet system hub has 18 engagement points which is superior to the M1900 “370” with a 3 pawl engagement hub.

Conversion kit to 5mm QR HWGXXX0001528S (Boost141)

When it all arrived, I could fit the back wheel right away. However installing the front wheel was a disappointment because it turns out that the standard rockshox XC32 was not boost?! my bad. What to do… return the boost front wheel and replace it with a regular one. That would work but I had already looked at the fork which is rather heavy, and has no remote lock, I also would love to have a fat 15mm thru axle to replace the thin 5mm QR.

Weight improvement so far: 350 grams.
Stock rear wheel (complete with XR2 tire) 2950 grams
DT Swiss M1700 rear wheel (complete with XR2 tire) 2600 grams

New Fork – Fox Float 32 Rhythm

Fox Racing32 Float Rhythm 29″ 100 Grip Tapered Boost Remote

Well this part is tricky. There are so many forks available, and I have no way of trying out different ones, so I have to learn from online reviews. I contacted a Fork service company in the Netherlands and they suggested Fox Racing. These are not cheap, but I managed to find an OEM fork on sale in Germany (which is usually sold with a bike, not separate). The “Rhythm” is an economical version of the “performance”. Here is an article and here a vlog on the Rhythm. The Fork is in the mail as we speak, hopefully it will arrive before my next cross country trip early march.

New Tyres

Bontrager XR2

The Bike comes with Bontrager XR2 tires which are heavy and look rather simple compared to Schwalbe tires which I use to buy. I did a long ride last weekend with lots of technical sections, climbing and downhill, and I must say that they roll great, and the grip is fantastic. I did order lighter tires (Rocket Ron 2.25 for the front and Racing Ralph 2.25 for the back to setup tubeless, but I may only mount these when the XR2’s are worn out. The weight penalty is big because the XR2’s are with over 350 grams heavier than the Schwalbe combination.

Expected weight improvement with Schwalbe setup another 350 grams, the fork will also be lighter (300 grams?) as will the front wheel (another 300 grams?) resulting in an expected total of 1300 grams compared to the stock bike. We will see.

to be continued..

Well, things did not work out as planned, the ordered FOX fork and other goodies got lost in the mail, and when I got my money back this fork was not available anymore. By now, my local bikeshop could source a Rockshox Reba RL, so I got this instead and had it installed.

Since I will not be using the MTB a lot in the summer, I plan to move to tubeless only after the summer, and keep the Bontrager tires on the bike for now. These tires actually started to grow on me. I have done a few rides with the new setup, and am still playing with the air pressure of the fork and the tires. If you ask me if I can feel the difference in weight (The bike is more than a kg lighter than stock, I can say it reacts better, I get more easily off the ground at bumps, and the cornering is more direct.

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