Fox 34 rhythms flex?

[Jamsquared]

So took the jam2 to bike park wales yesterday. Rode to to the top in eco used just over one bar which is ok as I weigh 105kgs. The issue is that the forks flex backwards and forwards alot of the time while coming down the runs. Not something I ever noticed on the 35mm Pikes on my old bike. Are the fox forks just that bad?

 

[Richt20000]

Yep, I have fox 34 factory 130mm 29 on my hardtail and they flex on that.

Very very strange choice for an ebike.

I’m thinking of getting a jam2 6.7/8 and would pop some fox 36 on before even riding it.

 

[Beekeeper]

How easy is it to upgrade forks? Do they always need sawing? Seems like a specialist job?

 

[Richt20000]

Yea If you’re handy with a hack saw its a easy 1/2hr job. If that daunts you get a shop to do it....

 

[Mcharza]

How easy is it to upgrade forks? Do they always need sawing? Seems like a specialist job?

Yes, you have to cut the steering tube. So that you get the bar at the same height as the old one.
Easiest is to cut it with pipe cutter.

 

[steve_sordy]

Yes, you have to cut the steering tube. So that you get the bar at the same height as the old one.
Easiest is to cut it with pipe cutter.

To all:
Do not forget "measure twice, cut once!"
Do not forget to include the height of the stem and the spacers!!!

I tell you this because one of the bike skills guys (Jedi of UK Bike Skills) told me that he bought some new high end forks and before he cut the steerer, he not only measured twice, but got his mate to check for him as well. They both checked each other's measurements and agreed all was well and cut the steerer to length. When he put the fork into the frame, the steerer came to the top of the head tube! aaaarrrrgggghhhh!

 

[Mcharza]

To all:
Do not forget "measure twice, cut once!"
Do not forget to include the height of the stem and the spacers!!!

I tell you this because one of the bike skills guys (Jedi of UK Bike Skills) told me that he bought some new high end forks and before he cut the steerer, he not only measured twice, but got his mate to check for him as well. They both checked each other's measurements and agreed all was well and cut the steerer to length. When he put the fork into the frame, the steerer came to the top of the head tube! aaaarrrrgggghhhh!

That's why I always left it a little bit longer first. Easy to adjust with spacers. Some test rides moving spacers under or top and after that cut it again

 

[routrax]

How easy is it to upgrade forks? Do they always need sawing? Seems like a specialist job?

Perfect guide here, don't forget to sand them the same way

 

[dobbyhasfriends]

for me this is a serious consideration... I have been told that the 34 and the 36 share the same internals but the 36 is beefier..
ive never ridden a bike with a 36 but I can certainly feel the 34 rhythm forks on my Levo flexing so my problem is for such an expensive upgrade, is it good value?

 

[Jamsquared]

I have just ordered some bomber Z1s so that should cure it

 

[Stanny_uk]

for me this is a serious consideration... I have been told that the 34 and the 36 share the same internals but the 36 is beefier..
ive never ridden a bike with a 36 but I can certainly feel the 34 rhythm forks on my Levo flexing so my problem is for such an expensive upgrade, is it good value?

hows it feel with -2 in bud???? I'm getting one del tomorrow and in goes a nice set of lyriks to compliment

 

[salko]

Perfect guide here, don't forget to sand them the same way

Wow, this new sanding technique is really convenient

 

[routrax]

Wow, this new sanding technique is really convenient

To be fair, the mock fit, measurement and cutting are all good, the 'sander' and 'hammer' on the other hand....

 

[Robbo746]

So took the jam2 to bike park wales yesterday. Rode to to the top in eco used just over one bar which is ok as I weigh 105kgs. The issue is that the forks flex backwards and forwards alot of the time while coming down the runs. Not something I ever noticed on the 35mm Pikes on my old bike. Are the fox forks just that bad?

I too am having some issues with both ends of my bike (jam2 6.8). I'm 100kg also and basically have no rebound dampening even on full. I think its because of the high pressure I'm needing to run for sag. The rear end is very kicky of booters, and the fork feels like an elastomer fork almost. . ... . So .. whilst not a flex issue as such. .I dont think the valving has been set right for the shock or fork for the weight of the ebike and making it worse is my hefty frame, has anyone else had to re-valve both ends? I'm think I may need to go to a coil and a lyrik ?

AND . . .as the Rhythm is 27.5/29 er fork can I put a Lyrik 29 fork on it with no geometry issues. There are loads for sale in Australia second hand. Might drop a 160mm Lyrik RC2 29 in it.

 

[Jamsquared]

I just fitted a 29" 160mm Bomber Z1 and it doesnt appear to have made any noticeable difference to geometry. With used ones I guess steerer length is something to watch. Probs already been said above with the other good advice already given.

 

[Tamas]

I couldn’t live with the Fox 34 even on my trail bike. From the terrible flex on rough downhills it couldn’t move up and down properly it was like riding with a broomstick. My Meta Power has a Lyrik which is solid so I upgraded the trail bike with a Pike and it’s a different beast...

 

[Jamsquared]

I couldn’t live with the Fox 34 even on my trail bike. From the terrible flex on rough downhills it couldn’t move up and down properly it was like riding with a broomstick. My Meta Power has a Lyrik which is solid so I upgraded the trail bike with a Pike and it’s a different beast...

I had a pike on my reign, awesome fork. And yes my 34 flexed rather than compressed.

 

[Waynetta]

I weigh 65kilos. Do think a fox 34 would flex with a dwarf on board ?

 

[Ivan]

The 36 is significantly stiffer than the 34. A stiffer fork inspires confidence in rough or steep terrain, and hard cornering and braking.

IMO, the 34 is not the right fork for any trail bike >=140mm.

This is one of the major turn-offs of the new Levo SL. Forks are not cheap to upgrade, especially if you already paid a small fortune for the bike.

 

[knut7]

I weigh 65kilos. Do think a fox 34 would flex with a dwarf on board ?

Depending on how hard you ride, you might be happy with a Fox 34. And not all 34's are the same. The Rhythm 34 can have a bit of play between the uppers and lowers, it can have quite some flex. The ebike specific Fox Float 34 is much better.

 

[Stanny_uk]

OK so.... For those asking lots of questions.... Jam2 2019.... I've just fitted 650b lyrik ultimates.. The boost size 650b lyrik take a tyre up to 81mm so with my 2.8 e wilds loads of room.. Ya do not need a 29 fork if rockshox... Only if fox.... So on subject of length.... A 170mm lyrik is 555mm axle to crown my 34s were 551mm so exen though 20mm extra travel only 4mm longer.. So minimal change to chassis... I,ve also fitted a works components 2 degree offset h/s which originally would drop my BB 3MM but with slight fork length change I see no issues.... Will try this week.. If feels bit top heavy I. Ll go to 160mm airshaft in fork.. But doubt that....

 

[Winryn]

Any feedback on the lyriks? I’ve done 50 miles on my 2019 jam2 6.8 plus the past week and I can’t fault anything apart from the terrible fork. No plushness at all, cannot cope with small bumps, feels like a pogo stick. Thinking fox 36 with the better damping or rockshox pike or lyrik. Assume I need 51 offset and 29er forks (as that’s what’s written on current fox forks )for my 27.5+ wheels ?

 

[Stanny_uk]

Any feedback on the lyriks? I’ve done 50 miles on my 2019 jam2 6.8 plus the past week and I can’t fault anything apart from the terrible fork. No plushness at all, cannot cope with small bumps, feels like a pogo stick. Thinking fox 36 with the better damping or rockshox pike or lyrik. Assume I need 51 offset and 29er forks (as that’s what’s written on current fox forks )for my 27.5+ wheels ?

Plush as plush could be.. Like night and day..

 

[Stanny_uk]

Any feedback on the lyriks? I’ve done 50 miles on my 2019 jam2 6.8 plus the past week and I can’t fault anything apart from the terrible fork. No plushness at all, cannot cope with small bumps, feels like a pogo stick. Thinking fox 36 with the better damping or rockshox pike or lyrik. Assume I need 51 offset and 29er forks (as that’s what’s written on current fox forks )for my 27.5+ wheels ?

In fox ya need a 29+ in rockshox ya can run plus rubber in 650b fork.
I've dun it... Only small issue.. My mudguards bit close..

 

[sdcoffeeroaster]

I made two mistakes when replacing my air shaft on my 2018 Focus Jam2 C with Fox Rhythm 34. I wanted to increase the travel to 150 mm and use a 29" wheel. As flexible as this fork is I decided to go back to 140 mm to try to minimize flex. I'm also unsure as to if this version is OK with 150 mm. I used it that way for months without any apparent issues.
The other mistake is to try to duplicate the huge amount of grease that the factory used on the end of the air shaft. That resulted in plugging all holes as shown in the picture. Months of riding like this did not unplug the holes so I've now cleaned it out and re-installed the stock 140 mm and I'm using one volume spacer. I weigh about 65 kg but still wish I had a higher end, stiffer front fork. No way to test any of this right now since all the trails are closed here in SoCal but someday soon I hope. Stay safe out there!

 

[PJ27]

I too am having some issues with both ends of my bike (jam2 6.8). I'm 100kg also and basically have no rebound dampening even on full. I think its because of the high pressure I'm needing to run for sag. The rear end is very kicky of booters, and the fork feels like an elastomer fork almost. . ... . So .. whilst not a flex issue as such. .I dont think the valving has been set right for the shock or fork for the weight of the ebike and making it worse is my hefty frame, has anyone else had to re-valve both ends? I'm think I may need to go to a coil and a lyrik ?

AND . . .as the Rhythm is 27.5/29 er fork can I put a Lyrik 29 fork on it with no geometry issues. There are loads for sale in Australia second hand. Might drop a 160mm Lyrik RC2 29 in it.

Hey Robbo746, thanks for the post. I am also 100kg and have same bike 2020 Jam2.

Have you found good settings for front and back on forks/ shocks that came with bike? What were they? Or have you upgraded? If yes to what?
I have really struggling with the rear shock Fox DPS Evol

Cheers

 

[Tooks]

Hey Robbo746, thanks for the post. I am also 100kg and have same bike 2020 Jam2.

I have really struggling with the rear shock Fox DPS Evol

Cheers

I’ve recently purchased and installed a Fox DPS Evol LV on my bike, a 2019 Jam 2 6.7+.

I‘m 95kg in my riding kit, and to get the right sag I’m running 220psi, rebound damper six clicks from fully closed, Open on the blue lever (compression damping), and position 1 on the Open Mode Adjust.

It‘s performing a lot better than the stock Rockshox Deluxe R, doesn’t blow through the travel nearly as quickly, feels more progressive and controlled.

I like the fact I can lock it out for the long road sections before I get to my trail start point.

What are you struggling with, in particular?

 

[sdcoffeeroaster]

Hey Robbo746, thanks for the post. I am also 100kg and have same bike 2020 Jam2.

Have you found good settings for front and back on forks/ shocks that came with bike? What were they? Or have you upgraded? If yes to what?
I have really struggling with the rear shock Fox DPS Evol

Cheers

Same here with the Fox DPS Evol. Setting the sag to 30% for me (155+ psi, and 150lbs), removed volume spacer that came stock, results in about 14 mm of unused travel. I'm going to try 150 psi tomorrow (probably be too soft initially then) but I have a DVO Topaz T3 on order (210mmx55mm not in stock but coming) since they had a sale for $375. The trails here are open again as long as you can ride to them...no parking.

 

[PJ27]

I’ve recently purchased and installed a Fox DPS Evol LV on my bike, a 2019 Jam 2 6.7+.

I‘m 95kg in my riding kit, and to get the right sag I’m running 220psi, rebound damper six clicks from fully closed, Open on the blue lever (compression damping), and position 1 on the Open Mode Adjust.

It‘s performing a lot better than the stock Rockshox Deluxe R, doesn’t blow through the travel nearly as quickly, feels more progressive and controlled.

I like the fact I can lock it out for the long road sections before I get to my trail start point.

What are you struggling with, in particular?

Hi Tooks,

Thanks for the detailed reply. It feels too stiff and like I am floating above the terrain. I adjusted from standard settings which were way off (air pressure was 190PSI).

This was my first ride after adjusting to Fox's recommendations at SHOCK- 2019 FLOAT DPS and DPX2 | Bike Help Center | FOX the first point Fox suggest (as I read it) was to set the air PSI to your body weight in pounds = 227 PSI (I am 6'4 and approx 103kg's with riding gear). To get 28% sag approx 14mm movement when sitting on bike I need to increase PSI to 330 and then rebound to fully closed according to Fox guidelines (as I read/ understood them). Way to stiff and just not a good feeling.

I have let further air out and increased rebound to 3 and it is starting to feel better. (Note: when I let air our of the chamber on the rear shock, oil also came out. In quick research this is normal. Is that correct?)

More trial and error is required this weekend, based on what you are running I am way off and probably need to go down to 237PSI and maybe 5 clicks from closed on rebound. Thoughts?

Thanks again

 

[sdcoffeeroaster]

Hi Tooks,

Thanks for the detailed reply. It feels too stiff and like I am floating above the terrain. I adjusted from standard settings which were way off (air pressure was 190PSI).

This was my first ride after adjusting to Fox's recommendations at SHOCK- 2019 FLOAT DPS and DPX2 | Bike Help Center | FOX the first point Fox suggest (as I read it) was to set the air PSI to your body weight in pounds = 227 PSI (I am 6'4 and approx 103kg's with riding gear). To get 28% sag approx 14mm movement when sitting on bike I need to increase PSI to 330 and then rebound to fully closed according to Fox guidelines (as I read/ understood them). Way to stiff and just not a good feeling.

I have let further air out and increased rebound to 3 and it is starting to feel better. (Note: when I let air our of the chamber on the rear shock, oil also came out. In quick research this is normal. Is that correct?)

More trial and error is required this weekend, based on what you are running I am way off and probably need to go down to 237PSI and maybe 5 clicks from closed on rebound. Thoughts?

Thanks again

I'll just comment on the oil. Let the air out with the pump connected. There is only a little bit of fluid in the DPS to keep the seals lubed. If you let the air out without the pump connected it will come out too fast and pull the oil out too. I set mine for 30% sag which for my light weight do no allow me to use all of the travel. I'm going to try 145 psi my next ride since I'm using almost all of the travel now, weight is 160 lbs with all my gear on. So I'm sort of at the opposite extreme to you. I had to take out the one very small volume spacer that was stock, you might in fact have to add a larger one to make everything work.

Oh I forgot to add it's important that for every 50 psi change that you remove the pump and cycle the shock up and down about 10 times to equalize pressures. The put the pump back on and continue/repeat until you reach whatever set point you are after.