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Changeing Forks... Effect on handeling ??(11 posts)

Changeing Forks... Effect on handeling ??CraigVM
Sep 6, 2001 7:51 AM
I am anxiously awaiting for the UPS person to drop off a new bike I just ordered "my first road bike". I am have been thinking that I will quickly want to replace the straight blade chrome looking aluminum forks which the bike has now, with some carbon type. If I replace them with a fork that isn't "straight blade" in design and have the typical curvature to them, will it greatly effect the way the bike handles? I have seen one or two carbon forks that do state to be "straight blade" design and wonder if I should stick with them.
Thanks...
re: Changeing Forks... Effect on handeling ??Jofa
Sep 6, 2001 8:13 AM
This specifically will make no difference. It is the relative positions of the fork crown and the dropouts which affect handling: this is the same on all modern forks, irrespective of the shape of the blades. Additionally, most of the flex in forks is contained in the crown- not the blades- so this makes no difference to the forks' response to road shock, a value of which it is difficult to detect variations anyway. The reason for the curve is aesthetic.

My question is why do you want to change the forks? I'm sure the ones the bike comes with are fine.

Jofa
curved blades won't change handling...C-40
Sep 6, 2001 8:21 AM
If you change forks, be sure that that overall length does not change by more than a few milimeters or the head tube angle and the steering response will change. Most forks are similar in overall length, but it's always good to check.

The rake of the fork is what affects steering response. Rakes of 40, 43 and 45mm are common on new carbon forks. These rakes are available in straight or curved blade models. The more rake the quicker the steering (for a given head tube angle). You may want a slightly different rake, if you want to make the steering a little quicker or a little slower. You will need to get the manufacturer's specs to determine the rake of your current fork, in order to determine the rake that you may want to purchase.
curved blades won't change handling...mackgoo
Sep 6, 2001 10:45 PM
Actually won't more rake put the wheel farther out thus make the bike a little slower steering but more stable, bring the wheel in and the bike will steer quicker but be a little more twitchy?
curved blades won't change handling...Leisure
Sep 6, 2001 11:51 PM
Longer rake, such as 4.5, is supposed to equate to slacker handling in the same fashion as mountain bikes. And different forks will change your ride character, though not to the extent that it does in mountainbiking. I went with a Woundup 4.5, which my LBS equated to being the most "Mazocchi-like" i.e.-precise handling, fabulous dampening, though with a weight-penalty (and wallet-penalty). So far, it feels unflappable, pretty much the same at 40 mph as it does at 4. I'm fairly new to roadie stuff, but I've heard (and expect) other forks don't maintain composure as well at speed. Shop around, and be picky.
got it backwards...C-40
Sep 7, 2001 3:12 PM
More rake reduces the amount of trail, and the less trail, the quicker the steering. A fork with no rake at all would produce a huge amount of trail and very slow steering. The formula for trail is (tire radius/tanH)- (rake/sinH), where H is the head tube angle. From this formula, it's obvious that the maximum trail occurs when the rake is zero.
got it backwards...Leisure
Sep 12, 2001 12:29 AM
That does sound familiar...I think I just confused rake with head tube angle. But then I'm wondering why I perceived more relaxed handling when I used a 4.5 as opposed to a 4.0. Perhaps it's the wheelbase, since the equation as is doesn't appear to factor that with the rake simultaneously (i.e.-assumes wheelbase is constant for all rakes). It could also be that the handling is faster early in the turn and slower later (or vice-versa, what have you), because in the end they all start at 0 degrees and stop at 90, which could change how intuitive differences in handling at low and high speeds are. What a bugger...does anyone have input on this? I guess the universal fallback is to test each situation with your frame and body geometry. The final analysis is always what feels best for you.
But like I said, be picky, take your time. A couple of people already mentioned that changing the fork on a bike you've ordered and haven't even ridden might be spend-happy; I'm given to agree, especially when you may change other things as well to suit your geometry and riding style (think stem!), that will also influence the feel of the bike. Just like that the fork you spent $300 can feel all wrong. Ouch.
and the designers talk about balance between the stiffness ofbill
Sep 6, 2001 11:58 AM
fork and the stiffness of the bike. You may want to research a little before you change.
re: Changeing Forks... Effect on handeling ??davidl
Sep 6, 2001 2:07 PM
What kind of bike is it? My Univega got its straight blade aluminum fork replaced by a Profile Design BSC straight blade w/ alloy steerer. The results are amazing. Better handling, smoother ride. You can expect the same. I'd change it out as soon as possible if I were you.
offset is offset and some sage adviseclub
Sep 7, 2001 12:56 PM
doesn't matter if the fork is straight-bladed and offset at the crown, or uses curved blades. It's the amount of offset that matters, not what happens between the steerer and the dropouts. But ride the bike as-is first, I think this whole carbon fork thing is overrated. They're a tad lighter, but the difference in ride feel among steel, aluminum, and carbon is not a dramatic one at all. As this is your "first road bike" I seriously doubt that the subtle differences among forks will be an issue at all.
Go put 10k miles on it and then you'll have a better idea of the bikes high and low points. Even better, ride other bikes so you have some basis of comparison. The contact points between the rider and the bike are likely the most appropriate places to start looking to make changes. Saddles, stem lengths, and pedal choices are all individual decisions and it's possible those choices made by the bike maker aren't necessarily the best ones for you.
Gearing is another place you might find the stock setup wanting for your terrain, riding style, and fitness level. If you find yourself always struggling up climbs in the lowest gear, than a wider-range cogset would make a lot more difference than a new fork. Or if your riding is flat and you find yourself not using the largest cogs at all, you can change to a tighter rear cluster that would provide smaller jumps between gears without hauling around large cogs you don't use.
It's your money, but spending several hundred dollars on a new fork without even forming an opinion on how the bike rides and handles stock seems a tad spend-happy to me. If you really have several hundred dollars burning a hole in yer pocket, consider a second set of wheels. Yours probably has clinchers. A nice light set of tubular wheels will give you a difference you will definitely feel, much much more so than swapping forks.
very subjective differencesDog
Sep 10, 2001 9:43 AM
Funny, but I have exactly the opposite "feel" for some of these things. To me, an all carbon fork cuts road buzz quite a bit compared to a carbon with aluminum steerer or a steel fork. To me, the difference was fairly dramatic. I also notice a bit of difference among different brands of forks, whether carbon, steel, or some combination of materials.

Also, I can't tell much of a difference between clinchers and tubulars. While I certainly can tell some difference between different makes and sizes of tires, and certainly based upon air pressure, I cannot generally ascribe a bit of difference between clinchers and tubulars. The closest comparison, I say, that I've done is between Vittoria Open Corsa and Corsa tubulars. The Opens are a bit wider, I think, but at similar pressures I could never tell them apart.

I think these differences perceived are very subjective, and largely tainted by the preconceptions we have.

Dog