Replacing front forks, offset discussion

[sdcoffeeroaster]

I've decided that no matter what I do to my Rhythm 29" front forks they are just very harsh, especially on washboard surfaces. The resulting vibration and shock is very hard on my wrists and upper body at the ripe old age of 71. So I've been researching a replacement. At first I stuck to Fox products but I've now come to realize that the Rockshox 2021 Ultimate Lyrik is the very best option for me. The 2021 model in particular has made hand/wrist/arm fatigue reduction a goal. From all accounts they have done a great job. So that decided, what about offset? I currently have my 2018 Jam2 C set up with 2.6" tires front and back, reverse mullet with stock 140mm travel in the back and 150mm front (bumped from 140mm). That results in a fork angle of about 65 degrees, slacker than the 66.5 stock with a wheelbase of about 1209 mm for medium, 1202 mm stock.

For the past decade the "golden" advice has been to use a 51mm offset for a 29" front fork to reduce some of the added trail from a 29" setup. Trail has increased even more as bikes become more slack with modern designs. But the latest current advice goes a bit contrary to this with offsets for 29'ers now trending lower to 44mm or less adding even more trail but reducing the overall wheelbase somewhat and maybe the twitchiness. Maybe it depends on the type of riding you do a lot? The increased trail adds to the straight line stability but my worry is that if I go from 51mm to 44mm the bike will be more difficult to turn on slower flow type trails. All the articles on this say this is not the case and that's really got me confused right now. They try to explain the why of this but for my more moderate riding style (not a crazy fast downhiller) I'm just not convinced of their reasoning yet. Any thoughts on this out there? I'm ready to cut lose on the Lyrik Ultimate but just don't know if it's 44mm or 51mm I want. I suppose the differences might be very subtle and I won't notice anyway?

I ran this thru the Yojimg trail and flop calculator (Bicycle Trail Calculator | yojimg.net) and found that I now have approximatel 102mm of mechanical trail and that would go to 111mm with the 44mm offset. The flop value came out to be 43mm now and 47mm with the 44mm offset. I don't really understand how much "flop" is too much before the bike becomes noticeably difficult to turn on slower corners like switchbacks. Maybe I'm over analyzing this but being a mechanical engineer leaves me little choice. Pray for me or help if you can, lol.

 

[Gary]

No "maybe" about it

 

[sdcoffeeroaster]

No "maybe" about it

I'm pretty much decided to stay with 51mm, no real complaints but thought I'd go thru the numbers for the hell of it anyway. They are only numbers and at end of the day the improved Lyrik Ultimate performance would overwhelm the subtle difference of the offset, lol.

 

[themoon]

I've switched from 51mm offset from my stock rockshox recon to 44 on dt swiss 535 on jam2 with 2.7 plus wheels. Really liked the change - bike became much more stable, esp. when landing after a jump and when riding on a rough terrain, such as roots. I know that these are different forks price-wise and I'm yet to experience downhill on a new fork, but in the end for me this change in offset was well worth it.

 

[flash]

I went from 51 to 44 on my previous bike. Definitely noticed the difference. Also got used to it in about a month and appreciated the high speed stability. New bike has 51mm offset. Have got used to it. Maybe at the top end of rider ability it's critical. For me as a shitty rider it's just a small adjustment.

I have a 2021 Lyrik. Great fork. Plush. But not as nice as my Fox38 Elite. If you're going up. Maybe consider the new 38's (Fox or Zeb).

Also I'd explore new grips. Lots of tech to help sore hands and wrists out there now. Also cockpit set up and consider Carbon bars, which are more compliant than Aluminium. Maybe some riser bars to get some of the weight off your hands. There's a LOT you can do before you drop money on a new fork.

Gordon

 

[sdcoffeeroaster]

I went from 51 to 44 on my previous bike. Definitely noticed the difference. Also got used to it in about a month and appreciated the high speed stability. New bike has 51mm offset. Have got used to it. Maybe at the top end of rider ability it's critical. For me as a shitty rider it's just a small adjustment.

I have a 2021 Lyrik. Great fork. Plush. But not as nice as my Fox38 Elite. If you're going up. Maybe consider the new 38's (Fox or Zeb).

Also I'd explore new grips. Lots of tech to help sore hands and wrists out there now. Also cockpit set up and consider Carbon bars, which are more compliant than Aluminium. Maybe some riser bars to get some of the weight off your hands. There's a LOT you can do before you drop money on a new fork.

Gordon

I did get the 2021 Lyrik Ultimate and is so much better than the Forx 34's. I do have carbon bars, Salsa (only 15mm rise but using a Giant 3deg stem that add some too) and Ergon GA3 grips too. The 38 or ZEB is probably overkill for my Focus Jam2 but the Lyrik is just what I was looking for. And 51mm is what I was after too. I don't do huge jumps and don't even ride that fast since my collar bone break. Tight turns and trials type moves are easier with less trail and less tendency to flop. I don't need the increased stability at high speeds and like you said the differences are small and easy to get used to.

 

[sdcoffeeroaster]

went from fox 34/150mm/51mm to fox 36/160mm/44mm and I absolutely love it. bike is more playful and fork feeling is amazing.

Going from the Fox 34mm Rhythm to any higher quality fork is such a huge improvement, lol.

 

[SGS]

I've gone from the stock Fox 34 to a Fox 38 non ebike 44 offset 160mm - just waiting to get the bike back with it installed

 

[SGS]

Fox 38 now installed - best conversion