Front fork rake?

Discuss light weight issues concerning road bikes & parts.
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Sirius
Posts: 4
Joined: Sun Jul 08, 2012 7:50 pm

by Sirius

hello,I'm new here and do have a problem with my Litespeed Arenberg it is very nervous on his steering in the way that handsfree riding
is nearly impossible would it be possible to improve the straightoutstability with a frontfork with a greater fork rake ?
Now i have a Pro 1" carbon fork with alu steerer wich I think has a fork rake of 43
Thks

BobSantini
Posts: 292
Joined: Sun Jul 10, 2011 9:03 am

by BobSantini

Sirius wrote:Hello,I'm new here and do have a problem with my Litespeed Arenberg. It is very nervous on his steering in a way that hands free riding
is nearly impossible. Would it be possible to improve the straightout stability with a front fork with a greater fork rake ?
Now i have a Pro 1" carbon fork with alu steerer which I think has a fork rake of 43.
Thks

More stability is achieved with more trail. If you want more trail you need less rake.
I think the Arenbergs are regarded as handling very nicely. Is that the original fork?
r o y g b i v

by Weenie


Sirius
Posts: 4
Joined: Sun Jul 08, 2012 7:50 pm

by Sirius

Thanks for the info and no it isnt the original fork I bought the frame last year brandnew(fair price) but without the front fork so i had to search a 1" fork and the only one I could find was the Pro fork . The original fork was a Look fork yellow with silver and when I look at the history of Litespeed it had a rake of 40 or 43 (depending on the size of the frame) but about the trail nothing was published

bricky21
Posts: 1405
Joined: Tue Sep 14, 2010 3:28 pm

by bricky21

what size is your bike?

bricky21
Posts: 1405
Joined: Tue Sep 14, 2010 3:28 pm

by bricky21

Here is a really informative geometry chart for the Arenberg. They even go on to explain their fork length and headset stack height both which will have effects on the geometry though the effects will be very slight, and unnoticeable to most.
litespeed Arenberg geometry.JPG

lechat
Posts: 260
Joined: Thu Sep 30, 2010 3:32 pm
Location: S.E. TN

by lechat

bricky21 wrote:Here is a really informative geometry chart for the Arenberg. They even go on to explain their fork length and headset stack height both which will have effects on the geometry though the effects will be very slight, and unnoticeable to most.
litespeed Arenberg geometry.JPG

Can't imagine any thing other than a wobble making sans hands riding sketchy. Unless you're negotiating curves. I replaced the 49mm offset, 470gm stock fork on my Specialized Roubaix with a 45mm Reynold's Ouzo and couldn't tell any difference in the steering.

Sirius
Posts: 4
Joined: Sun Jul 08, 2012 7:50 pm

by Sirius

thanks again for the info @Bricky 21 the size of my Arenberg is 55 and besides the nervous steering I am very happy with the riding qualities of the bike @ lechat I never had any speed wobbles but taking something out of your rear pocket is sometimes tricky even at low speed and especially with a little sidewind (Marchisio wheels 28mm high)

bricky21
Posts: 1405
Joined: Tue Sep 14, 2010 3:28 pm

by bricky21

I'm assuming that you're able to ride other bikes no handed and that this problem is isolated to the Arenberg? If that is correct then there is something wrong with the frame, fork, or headset(either not straight or installed correctly. No way a fork offset change of 3mm would turn that particular bike into a poor handling machine. First thing I'd check is the headset adjustment, next I'd try and borrow a fork off a bike that I knew rode correctly, and if all else fails I'd have the alignment of the frame checked. Also, that frame has to be over 10 years old, so are you positive it's new/unused?

Mr.Gib
Posts: 3137
Joined: Fri Mar 18, 2005 4:12 pm
Location: eh?

by Mr.Gib

Check you cable housing lengths. Lift the bike in the air and tilt it forward and back. The bars should stay straight. If your cable housing is wrong it will push the bars to one side. This makes riding no hands very difficult.
wheelsONfire wrote: When we ride disc brakes the whole deal of braking is just like a leaving a fart. It happens and then it's over. Nothing planned and nothing to get nervous for.

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bikerjulio
Posts: 1901
Joined: Fri Dec 11, 2009 10:38 pm
Location: Welland, Ontario

by bikerjulio

I have to disagree with bricky and say that a few mm of rake can make a difference.

I have a frame that originally came with a 43mm fork that was impossible to ride hands off. A change to a 40mm fork made it possible. May not sound much but it translates to about an additional 6mm trail.
There's sometimes a buggy.
How many drivers does a buggy have?

One.

So let's just say I'm drivin' this buggy...
and if you fix your attitude you can ride along with me.

http://www.youtube.com/watch?v=GekiIMh4ZkM

bricky21
Posts: 1405
Joined: Tue Sep 14, 2010 3:28 pm

by bricky21

I would agree if we were talking about a bike already designed to be nervous, but you should be able to read a book while riding that Arenberg.

Since I'm on vacation and my coffee is too hot to drink I decided to mock it up in bike cad using the geometry chart from above with the fork length(368) and headset stack height(12mm) listed in it(1'st picture). Then I changed only the fork offset from 40mm to 43mm(second pic). In the third I kept the additional 3 mm offset, and added 4mm to the fork length 1.7 mm to the bottom stack height.
stock 55 Arenberg.JPG

Stock 55 Arenberg + 3 mm fork offset.JPG

Stock 55 Arenberg + 3mm offset + 4mm fork length + 1.7mm bottom headset cup.JPG

Judge for yourself, but imo when starting out with the stock 55 geometry it would be really difficult to render that bike unstable with such a small change in fork offset.

To the OP do you have or have you had another bike that you could ride no hands( same saddle height/setback and cleat placement)?

by Weenie


Sirius
Posts: 4
Joined: Sun Jul 08, 2012 7:50 pm

by Sirius

@bricky21 yes i do have another(alu) bike and it is possible to read the newspaper on it ,it's also a 55cm frame with the same height of wheels but with a straight blade alu fork so yes I do have the skills to ride handsfree on it thanks again for all the supply of info i will check all the details and if i dont get out off it i 'll be back

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