YT Jeffsy 29″ Tuning and Modifications

In september 2016 I ordered my very first own full suspension mountainbike. There was a strong battle between the Canyon Spectral and the YT Jeffsy. In the end I chose a YT Jeffsy.

The exact model was called YT Jeffsy Al Comp 1. During that time it was the highest spect aluminium model and had good specs for the money.

Jeffsy Al Comp 1

Assembling the bike was easy and after a couple of minutes I was ready to ride it. Even though everything was working totally fine, I needed to change some parts to make it individual.

So here we are. I am going to show you how my bike looks today and what has changed since I got it.

First improvements


Tires should be one component that you think about a lot. They should be suited to your style of riding. I startet riding this bike with the factory installed Onza Ibex Tires. They were fast rolling but didn’t give me the support and confidence I was looking for. So at first I switched over to some HighRoller 2 and later on to a Maxxis Minion DHF up front and a Maxxis Minion DHR2 in the back. Those tires are excellent and I won’t think about switching them ever. I am running them in 29″ 2,5inch front tire and 2,4inch back tire. For those of you looking for grip here we go.

Maxxis Minion DHF 3C 29x2,5 WT


Brakes is a topic many people get fairly personal about. In the end it’s all personal preference and all I want is to share my honest opinion about it. My bike got delivered with Sram Guide RS Brakes. For the most people out there they should be fine and deliver well enough braking power for trail rinding and casual enduro rides. On a long trip in New Zealand I made the decision to switch to Shimano Saint Brakes and I don’t regret it. They definitely are a bit stronger, easier to bleed and fairly robust. I think many of you have heard people saying good things about these brakes. I think most of this is true. 

Saint Brakelever
Saint Brake Caliper


Suspension tech and setup kind of splits mountain bikers into two categories. There are the one that check their suspension pressure every ride, and the one that don’t even know how much pressure they are riding at all. I would put myself more in the first group.

I started with a Rockshox Pike RCT3 and a Monarch RT3, the one without piggyback. Riding this setup was fine. Coming back to Germany from NZ I upgraded the shock to a Monarch Plus RT3 on Huber Bushings, and changed the fork to a  Rockshox Lyrik RCT3 Charger 2. The Lyrik got the new Rockshox Debonair Shaft which increased small bump sensitivity and increased the font travel from the standard 140mm to 150mm.

Rockshox Lyrik 150mm
Charger 2 Damper
Lower Legs


I started this bike with a Sram GX 11 Speed drivetrain on a 32T chainring. For alpine riding and 29inch wheels the smallest gear was way to hard to push so I needed to change something. First of all I changed the chainring to an Absolute Black Oval 30T Chainring. Later on I switched over to a GX Eagle drivetrain with a X01 shifter. After destroying my rear derailleur on the trail, a friend helped me out with his spare X01 derailleur. Half a year later I switched to my current XX1 setup that I got fairly cheap from a sponsored rider. Comparing them I can tell you there is a well noticeable difference between GX and X01, X01 and XX1 feel almost identical. A modern 12 speed setup is what I consider the best possible drivetrain right now. Electronic Shifting? Not for me – at least at this point 😉

Picture of a XX1 Eagle drivetrain attached to a 2016 YT Jeffsy
12 Speed Drivetrain
XX1 Derailleur
Picture of Absolute Black Oval Chainring
Absolute Black Oval Chainring 30T


Handlebar, Stem, Triggers. I am running a Raceface Sixc Carbon Bar that I trimmed to 760mm, that’s the width I enjoy the most. Stem is a Raceface Turbine with 50mm length. The most exciting thing about this handlebar setup is the attachment of the dropper post and the trigger for shifting onto the brakes. It’s done with a little adapter called “I-Spec B adapter“. That way you can combine Shimano Brakes and Sram Shifting and dropper into one single clamp. Nice!

Raceface Sixc Carbon Handlebar
"I-Spec B Adapter" Shimano Brakes and Sram Shifting

Details are important:

When you are really passionate about your bike, you care about the small details as well. Details can be Alloy Valve Caps, Carbon Spacers, Custom Titanium Bolts…

Christmas Gift for Mountainbikers: Tune Carbon Spacer
Tune Carbon Spacer
XX1 Eagle Quicklink
CNC machined Valvecap
Rockshox 1x Remote attached to a Sram XX1 Eagle Drivetrain
Reverb 1x Remote

Bike Build:

Combining all those small and big upgrades together this bike transformed from a kind of normal All-Mountain to an excellent enduro bike for bike park laps and trail riding.

Thanks for reading “YT Jeffsy 29″ Tuning and Modifications” on Awesome MTB. If You have feedback to this article or want to contact us feel free to use the Contact Formular or the Comment Section down below. 

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1 thought on “YT Jeffsy 29″ Tuning and Modifications”

  1. Hi, what’s the black frame protector at the lower downtube made of? As far as I know it comes stock without.
    What tune ist the Debonair and how does it compare. Any bottomless tokens installed?
    Thanks and great setup by the way:)
    Best regards Thomas

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