Jeffsy 29er Thread

PB Forum :: YT Industries
Jeffsy 29er Thread
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Posted: Mar 9, 2022 at 21:20 Quote
Hey, I'm building up a large 2021 Jeffsy and am trying to find a fork for it. I was wondering what the minimum required steerer tube length would be. I don't have a stem picked out yet so I have just been kind of eye-balling it. Would 6.5 inches be too short?

Sorry if this has been covered already. I tried searching through the thread but never found an actual length.

Thanks!!

Posted: Mar 12, 2022 at 22:30 Quote
I currently have a Jeffsy Core 2 in a size Large. Would upgrading to a Fox 38 Factory Fork (170mm) and a Fox Float X2 shock (165mm) work with this bike’s geometry? Reason why I’m considering upgrading is because my buddy got a new YT Decoy MX Core 4 and he’s changing out the suspension right off the bat. I would say my riding style is all mountain/enduro with the trails we have here in SoCal (Orange County). Thank you.

Posted: Mar 13, 2022 at 5:44 Quote
mindzeye wrote:
a Fox Float X2 shock (165mm) .

Do you mean mounting a longer shock? That does not work.

Posted: Mar 13, 2022 at 7:23 Quote
mindzeye wrote:
I currently have a Jeffsy Core 2 in a size Large. Would upgrading to a Fox 38 Factory Fork (170mm) and a Fox Float X2 shock (165mm) work with this bike’s geometry? Reason why I’m considering upgrading is because my buddy got a new YT Decoy MX Core 4 and he’s changing out the suspension right off the bat. I would say my riding style is all mountain/enduro with the trails we have here in SoCal (Orange County). Thank you.

The Decoy has a 230mm x 65mm rear shock and the Jeffsy needs a 210mm x 55mm so you won't be able to do it on the rear.

On the front, people (including me) have had success going to 160mm but I have a feeling 170mm might be too far. You can always change the travel of the fox 38 with a new air shaft though which isn't too expensive (about £50 here in the UK).

O+
Posted: Mar 13, 2022 at 7:48 Quote
38 is overkill and defeats the purpose of the Jeffsy. It’s like some guys who bought the Izzo and put a 36 on it.

Posted: Mar 13, 2022 at 8:16 Quote
Thanks for the input! You guys are what makes this place rock!

Posted: Mar 22, 2022 at 10:25 Quote
Anyone know the max clearance for the rear tire on a 29er jeffsy 2022?

Posted: Mar 22, 2022 at 11:50 Quote
Planning a similar angle headset conversion as what @appltn has discussed.

I have the 2019 YT Jeffsy CF Pro XL, which is a 140mm/140mm setup.

- 1.5 degree Works headset
- Rockshox Lyric 160mm with same 42mm offset

Not sure I have all the numbers right but using the same synGeo site it gets the head angle to a more modern area, while not affecting the seat angle too much (I do a ton of long climbs and I love the STA on the Jeffsy). Does raise the BB a bit, which should have benefits since I get some rock strikes a bit more often than I'd like.

Comparing current Jeffsy geo with update.

appltn wrote:
You can always email them to ask which you’d need, I did and they were super helpful.

For the carbon Jeffsy they sell an EC44 top cup which creates about 18mm of stack in total. In my case that was fine and I even had room for one more spacer. I found this awesome geometry calculator which helped me decide to go for a -1.5 degree headset and increase my fork travel to 160mm. This has left the geometry basically unchanged except for the head angle.

Posted: Mar 22, 2022 at 17:10 Quote
Mike-Gambino wrote:
Anyone know the max clearance for the rear tire on a 29er jeffsy 2022?
29x2.6 is best bet… I did 27.5x2.8 on MK1 29er with minor rub…

Posted: Apr 1, 2022 at 1:44 Quote
objectuser wrote:
Planning a similar angle headset conversion as what @appltn has discussed.

I have the 2019 YT Jeffsy CF Pro XL, which is a 140mm/140mm setup.

- 1.5 degree Works headset
- Rockshox Lyric 160mm with same 42mm offset

Not sure I have all the numbers right but using the same synGeo site it gets the head angle to a more modern area, while not affecting the seat angle too much (I do a ton of long climbs and I love the STA on the Jeffsy). Does raise the BB a bit, which should have benefits since I get some rock strikes a bit more often than I'd like.

Comparing current Jeffsy geo with update.

appltn wrote:
You can always email them to ask which you’d need, I did and they were super helpful.

For the carbon Jeffsy they sell an EC44 top cup which creates about 18mm of stack in total. In my case that was fine and I even had room for one more spacer. I found this awesome geometry calculator which helped me decide to go for a -1.5 degree headset and increase my fork travel to 160mm. This has left the geometry basically unchanged except for the head angle.

I went this road and really like it. I have a 2020 Jeffsy and changed the fox with a lyrik ultimate 160mm and a Work -1.5 angleset. I wouldn't go back. Specially on the descents i like it more slack! Also changed the shock with a Rockshox deluxe ultimate coil.. That really changed the bike!!

O+
Posted: Apr 1, 2022 at 9:32 Quote
RobK1979 wrote:
objectuser wrote:
Planning a similar angle headset conversion as what @appltn has discussed.

I have the 2019 YT Jeffsy CF Pro XL, which is a 140mm/140mm setup.

- 1.5 degree Works headset
- Rockshox Lyric 160mm with same 42mm offset

Not sure I have all the numbers right but using the same synGeo site it gets the head angle to a more modern area, while not affecting the seat angle too much (I do a ton of long climbs and I love the STA on the Jeffsy). Does raise the BB a bit, which should have benefits since I get some rock strikes a bit more often than I'd like.

Comparing current Jeffsy geo with update.

appltn wrote:
You can always email them to ask which you’d need, I did and they were super helpful.

For the carbon Jeffsy they sell an EC44 top cup which creates about 18mm of stack in total. In my case that was fine and I even had room for one more spacer. I found this awesome geometry calculator which helped me decide to go for a -1.5 degree headset and increase my fork travel to 160mm. This has left the geometry basically unchanged except for the head angle.

I went this road and really like it. I have a 2020 Jeffsy and changed the fox with a lyrik ultimate 160mm and a Work -1.5 angleset. I wouldn't go back. Specially on the descents i like it more slack! Also changed the shock with a Rockshox deluxe ultimate coil.. That really changed the bike!!

Thanks so much for the feedback! The numbers look really good. I was considering going to a Rocky Mountain Instinct to get the slacker geo I wanted, but the BB height and drop is too low on their slack settings. Definitely cheaper to up the fork and add an angleset! I did like that the Instinct could have 448mm chainstays though.

Posted: Apr 7, 2022 at 9:46 Quote
I am seriously considering getting a Jeffsy Core 4. I'm looking at new bikes and for the price nothing comes close spec wise, and it comes in an xxl while not many bikes do. I also think they look next level.

But I am wondering, have many people had issues with the full carbon frames cracking? Any issues with the frame quality or durability? I am 240lbs and I am curious about the long term reliability of the frame. Are there many cracked ones around? (I could only find a few instances online)

O+
Posted: Apr 7, 2022 at 9:52 Quote
HVrider wrote:
I am seriously considering getting a Jeffsy Core 4. I'm looking at new bikes and for the price nothing comes close spec wise, and it comes in an xxl while not many bikes do. I also think they look next level.

But I am wondering, have many people had issues with the full carbon frames cracking? Any issues with the frame quality or durability? I am 240lbs and I am curious about the long term reliability of the frame. Are there many cracked ones around? (I could only find a few instances online)

I'm 6' 6" and 220+ with riding gear, no issues with mine. I've had it for almost 2 years now.

Posted: Apr 9, 2022 at 8:53 Quote
PACNW-MTB wrote:
I'm 6' 6" and 220+ with riding gear, no issues with mine. I've had it for almost 2 years now.

Thanks for your reply! I’m 6’5, do you find the xxl a good fit? How has it been with bearing life? I also can’t seem to find an exploded parts diagram anywhere online

O+
Posted: Apr 9, 2022 at 15:24 Quote
I'm 6' 4" on an XXL and I love it. I changed the 50mm stem to a 35 because we have some very tight, steep switchbacks here and I definitely prefer it now. Pedals really well even with the super deluxe coil I've put on it. Frame bearings still feel good and I will have had it 2 years in June. Email YT and they will send you the very detailed exploded drawing


 
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