Carbon 490 mm Fork?

[Ray Young]

Anyone know of a carbon 490 mm fork. The cheapest I have been able to find so far is the White Brothers Rock Solid on Wiggle at £236.99 ?

[Bearbonesnorm]

That's a pretty long fork Ray, all my 29ers run something 460mm - 470mm with no problems. If you can drop a bit of length I'd certainly consider some eXotics.

http://www.carboncycles.cc/?s=0&t=2&c=43&p=1056&

[Taylor]

I might have a pair of those laying idle in the garage as the wife now has a bouncy front(fnar fnar).
I'll check on them later.

[Ray Young]

That's a pretty long fork Ray, all my 29ers run something 460mm - 470mm with no problems. If you can drop a bit of length I'd certainly consider some eXotics.

http://www.carboncycles.cc/?s=0&t=2&c=43&p=1056&

My forks measure 510mm c to a. The frame is adsjusted to take 100mm travel forks.



I have emailed Charge Cycles to find out what the minimum length fork I could safely run but have not had a reply yet. If I can run 465mm (exotics) or 470mm (on ones) then I would happily do so but I think the change in angles would be just too much. What do you think?
Thanks flatfishy.

[Bearbonesnorm]

Are you sure those forks aren't meant for a 36" wheel ?

Have you got anyway of measuring the headangle ... as a rule of thumb / rough guide a 20mm reduction in fork length will result in gaining 1 degree in headangle.

[jameso]

Ray, 30% sag less a bit (my r-o-t for converting sus to rigids with a similar length as the 'working height' of the sus fork) from a 505mm 29er sus fork (eg Reba 29) gives you 475mm or less, so 470mm would be ok as long as the bike's not fairly steep angled to start with. Sag's often set at 25% but 35, even 40% isn't too much if working out a rigid equivalent. I may be off, but it may open up your fork options.

[Ray Young]

Have you got anyway of measuring the headangle ... as a rule of thumb / rough guide a 20mm reduction in fork length will result in gaining 1 degree in headangle.

Head angle is 70 degrees according to stats on bike radar review so fitting a 470 fork would give a head angle of 72 degrees, is that correct and more to the point would it be OK. Happy to have faster steering but would it put undue pressure on the frame?

Ray, 30% sag less a bit (my r-o-t for converting sus to rigids with a similar length as the 'working height' of the sus fork) from a 505mm 29er sus fork (eg Reba 29) gives you 475mm or less, so 470mm would be ok as long as the bike's not fairly steep angled to start with. Sag's often set at 25% but 35, even 40% isn't too much if working out a rigid equivalent. I may be off, but it may open up your fork options.

Would Charge not have fitted a rigid fork that took into account of the working height of a sus fork, if not did they c**k up their measuring then!

[restlessshawn]

A longer fork will generate more stress than a shorter one so no worries there.

Are you just looking to save weight or something else? I'd have thought a skinny steel fork that long would be pretty comfy anyway.

[Bearbonesnorm]

Head angle is 70 degrees according to stats on bike radar review so fitting a 470 fork would give a head angle of 72 degrees, is that correct and more to the point would it be OK. Happy to have faster steering but would it put undue pressure on the frame?

It will quicken things up a touch Ray but nothing to worry about. There's a few possible reasons why the standard fork is 490mm not all of them are obvious.

[Ray Young]

Hi restless and thanks, looking to save weight mainly but I'm sure I could cope with a bit more steering speed without undue tiredness over distance.

[Bearbonesnorm]

As Jameso says, once you consider fork sag then the numbers start to stack up ... but besides preset sag there's also the dive / sag caused by braking. Obviously due to you running rigid you don't need to factor that in but imagine if some one fitted a set of 100mm forks to your bike.

Static = 70 degrees
Allow for sag = 71 degrees
Add a little braking = 72 degrees
Now hit a bump while braking = 74 degrees

The above is correct If the new suspension forks are 490mm A to C to start with.

[Ray Young]

Thanks guy's. So basically what your saying is that a shorter fork will not put extra pressure on the frame and replacing the 510mm fork fitted with a 470mm or 465mm will steepen the head angle by about 2 degrees which will increase the steering speed a bit but not make it twitchy. If that's the case you will be saving me lots of money, thanks again.

[Bearbonesnorm]

Thanks guy's. So basically what your saying is that a shorter fork will not put extra pressure on the frame and replacing the 510mm fork fitted with a 470mm or 465mm will steepen the head angle by about 2 degrees which will increase the steering speed a bit but not make it twitchy. If that's the case you will be saving me lots of money, thanks again.

Correct, but I've just thought ... at present are you anywhere close to toe overlap ? A shorter fork (with the same offset) will put the wheel closer to your pinkies

[Ray Young]

About 2 to 2 1/4 inches at the closest point.

[Bearbonesnorm]

About 2 to 2 1/4 inches at the closest point.

It'll be fine then.

[Ray Young]

Thanks guys, :D .

[ScotRoutes]

I have a set of the Exotic 465s currently sitting unattached in the garage (the EL Mariachi is sporting 100mm Rebas atm). You're welcome to borrow them if yo want to try out the geometry change before buying.

[Ray Young]

Scotroutes, that would be most welcome but can't do it until towards end of September due to decorating then going on holiday. Would that still be OK with you, Ray.

[ScotRoutes]

It would, but by then I will be somewhat more distant. We move to Aviemore in a couple of weeks!!

[Ray Young]

Doh! But thanks very much for the offer. Good luck on the move.