Carbon fork question : flex?

[ifouiripilay]

I purchased a Nos edge 1.0 fork. I installed it. And did a brake test to check for headset play. No play but I can see some flex. Anyone have experience with this fork and can give me some insight? I'll might just go to the lbs. I did torque it properly. The shop that cut it actually recommended a glue in nut rather than a compression nut.
I had a full carbon bike with a full carbon fork and i don't recall this much flexing.

What should I recheck?

[eddief]

what length headtube, how heavy a rider?

[wallymann]

are u seeing this flex?

[ifouiripilay]

I'm 155. From the top of the headset to the the top cap I have 2.5" steerer. Total steerer is 9 3/4". It's on a Gunnar roadie.

I see the flex. I'm not actually riding the bike. I'm just merely holding the front brake Down and moving the bike forward and back.

[cfox]

the type of compression plug / glue insert you use won't have anything to do with seeing the fork legs flexing (which is what I'm guessing you are seeing). Forks are designed to flex, to some degree. If they didn't they would just snap. The 1.0 is a super light fork, so I'm not surprised you see some flex. If it seems excessive, have someone you trust look at it.

[eddief]

is that you are talking about the lightest weight fork Enve makes. that means they probably saved the weight in the walls of the steer tube. my guess is also that you are able to put so much leverage on the system when you apply the brake and rock the bike, that the steer tube/fork is flexing. but if there is no play in the headset parts then my guess is you have a modern, high tech lightweight fork that probably rides as good as it gets.

watch out for guys who do nothing but guess :).

[Peter B]

I'm at ~150 and have a 1.0 on both my Marcelo and Speedvagen. No issues here with excessive flex. If there's no play at the headset then go for a ride and decide. I suspect you'll like it.

[William]

I can't comment on your particular situation but....Go to a cross race and stand on a part of the course where there is a bumpy downhill section with a tight turn at the bottom. You will be amazed by how much flex you can see in carbon forks under loads like that.





William

[Grant McLean]

I had a full carbon bike with a full carbon fork and i don't recall this much flexing.


stuff flexes. it would be unrideable if it didn't, some flex is necessary.

You'd be surprised how much the top tube and downtube 'bow' when
a force is applied to the front wheel. it's not the fork flexing.

good visual example:

http://www.youtube.com/watch?v=IEHq67sy-5s

[William]

stuff flexes. it would be unrideable if it didn't, some flex is necessary.

You'd be surprised how much the top tube and downtube 'bow' when
a force is applied to the front wheel. it's not the fork flexing.

good visual example:

http://www.youtube.com/watch?v=IEHq67sy-5s


I don't doubt the frame flexes, but in my example what I saw was definitely forks (as well as frames) flexing. One fork blade snapped sending the rider to the hospital in an ambulance.



William

[Chance]

It's both. Both have to flex. Whatever load makes the fork flex will also make the frame flex. Different amounts perhaps but each flexes some.

[Ken Robb]

I'm 155. From the top of the headset to the the top cap I have 2.5" steerer. Total steerer is 9 3/4". It's on a Gunnar roadie.

I see the flex. I'm not actually riding the bike. I'm just merely holding the front brake Down and moving the bike forward and back.

Most if not all manufacturers recommend 25mm of spacers on 1" carbon forks and 40mm on 1 1/8" forks. 2.5" x 25.4=63+mm of spacers so you are pushing the envelope.

[Ken Robb]

I think most makers of carbon steerer forks recommend up to 25mm of spacers on 1" forks and 40mm on 1 1/8" forks. Your 2.5 inches=63.5mm so you are pushing the envelope.

[Peter B]

I think most makers of carbon steerer forks recommend up to 25mm of spacers on 1" forks and 40mm on 1 1/8" forks. Your 2.5 inches=63.5mm so you are pushing the envelope.

If he's truly measuring from top of headset to top of stem cap as stated then deduct ~40mm (stem) from the 63.5mm (2.5") to determine spacer stack. At ~23.5mm he's fine.

[ifouiripilay]

Thanks for all the input.

As far as steerer and # of spacers I followed the recommendation of enve per their website:
The spacer stack below the stem must not exceed 50 mm (2 inches).

Also thanks for the video link. I'll look for a fork specific one or perhaps I'll make one myself.

[monkeybanana86]

stuff flexes. it would be unrideable if it didn't, some flex is necessary.

You'd be surprised how much the top tube and downtube 'bow' when
a force is applied to the front wheel. it's not the fork flexing.

good visual example:

http://www.youtube.com/watch?v=IEHq67sy-5s

that video for sure could have been shortened lol. cool to see.

my steel fork vibrates a good amount when I do the thump on the ground check to see if stuff is loose. this bike rides really well too in terms of feel and comfort. in fact i'm going to swap the fork while waiting for my new bars and see if that fork plays a big part in the good ride

[Chance]

I think most makers of carbon steerer forks recommend up to 25mm of spacers on 1" forks and 40mm on 1 1/8" forks. Your 2.5 inches=63.5mm so you are pushing the envelope.

This may be important to safety but probably has little to do with test he is performing where he notices flex. By holding the front brake and moving bike back and forth the part of the steerer above the top headset bearing isn't doing much of any flexing. At most it depends partly on where he is pushing the bike back and forth.

If he is rocking the bike back and forth by mostly pushing on the saddle or part of the frame then the steerer extension up to stem doesn't do anything. And if he is pushing back and forth on the bars themselves (while holding the back of the bike from lifting up) then additional steerer flex caused by pushing on the bars is in the opposite direction which would tend to offset other flex if anything.

[oldpotatoe]

I purchased a Nos edge 1.0 fork. I installed it. And did a brake test to check for headset play. No play but I can see some flex. Anyone have experience with this fork and can give me some insight? I'll might just go to the lbs. I did torque it properly. The shop that cut it actually recommended a glue in nut rather than a compression nut.
I had a full carbon bike with a full carbon fork and i don't recall this much flexing.

What should I recheck?

VERY light fork, legs DO flex more than the 2.0. Unless the rider is a buck 25 or so, we just sell the 2.0.

[Grant McLean]

VERY light fork, legs DO flex more than the 2.0. Unless the rider is a buck 25 or so, we just sell the 2.0.

I've had the 1.0 on my Parlee for the last 3 years,
it is plenty stiff, stiffer than any steel fork i've ridden.
It's stiffer than the Reynolds Ouzo forks.

-g

[soulspinner]

The difference from the 1.0 to 2.0 includes the longer steerer the 2.0 has. That makes the difference of 55 grams more like 35-40.