|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
Straight line instability?
I have a stock 1998 Cannondale R300.
Ever since the bike was new, the front end has always felt very twitchy and requires a conscious effort to keep the front wheel perfectly straight. I find myself pushing forward on the bars to force it to go straight. Although it's not something I normally do, today I sat up and took both hands off the bars to stretch my back while having a drink from the bottle. The front wheel started swerving back and forth, not greatly, but enough that I didn't dare leave my hands off the bars for more than 5 seconds. Is this normal? If not, what is the cause of it? Is it specific to the bike, geometry, and/or setup? - Mike |
Ads |
#2
|
|||
|
|||
Straight line instability?
Is this normal? If not, what is the cause of it? Is it specific to
the bike, geometry, and/or setup? Nope. And all of the above could be culprits. 1. Check/adjust the headset preload/bearings. They could be too tight. 2. Check/adjust the front and rear dish. I'm not sure what happens when the front wheel is off, but when the rear is off, the bike will constantly drift. 3. Check/adjust the front wheel bearings. This probably isn't the problem. 4. Check/adjust the alignment of your ass. Maybe you're sitting funny? 5. A long shot: is your seatpost too high, and so you have to rock side to side to pedal, thus causing weight shift? This isn't likely, but maybe your form is too jerky? (no offense) 6. Check if the frame is bent. 7. Check if your wheels are all the way in the dropouts, and if the rear wheel has the long slot-type adjustment for aligning the wheels. -- Phil, Squid-in-Training |
#3
|
|||
|
|||
Straight line instability?
On 16 Aug 2003 14:16:02 -0700, Mike Reef wrote:
both hands off the bars to stretch my back while having a drink from the bottle. The front wheel started swerving back and forth, not Is this normal? If not, what is the cause of it? Is it specific to the bike, geometry, and/or setup? I'd expect this on a road bike except at higher speeds. Bike, setup, and especially geometry could certainly do it, and would certainly have an effect. If it steers to one side, then your frame is probably bent. - Mike -- Rick Onanian |
#4
|
|||
|
|||
Straight line instability?
On Sat, 16 Aug 2003 17:49:32 +0000, Rick Onanian wrote:
On 16 Aug 2003 14:16:02 -0700, Mike Reef wrote: both hands off the bars to stretch my back while having a drink from the bottle. The front wheel started swerving back and forth, not Is this normal? If not, what is the cause of it? Is it specific to the bike, geometry, and/or setup? I'd expect this on a road bike except at higher speeds. Nonsense. Bike, setup, and especially geometry could certainly do it, and would certainly have an effect. If it steers to one side, then your frame is probably bent. I'd be quicker to assume the fork would be misaligned, since that is common (with steel forks at least). But the description seems to be more of someone who is uncomfortable riding no hands -- or riding that bike at all -- than of a mechanical problem. -- David L. Johnson __o | If all economists were laid end to end, they would not reach a _`\(,_ | conclusion. -- George Bernard Shaw (_)/ (_) | |
#5
|
|||
|
|||
Straight line instability?
I have a bike with no rake to speak of and it rides no-hands as
described. It comes from no countersteer at the start of a correction. With a decent rake, moving the seat right turns the front wheel left _then_ right as the front of the wheel is late in following (opposite of the gyroscope effect). The left-then-right is the countersteer that makes a right turn work when you tip the seat right. -- Ron Hardin On the internet, nobody knows you're a jerk. |
#6
|
|||
|
|||
Straight line instability?
I saw this on my CD. I found the headset preload too loose. I also had a
slight "rattle" in the headset. After tightening, the problem was much improved. Chris "Mike Reef" wrote in message om... I have a stock 1998 Cannondale R300. Ever since the bike was new, the front end has always felt very twitchy and requires a conscious effort to keep the front wheel perfectly straight. I find myself pushing forward on the bars to force it to go straight. Although it's not something I normally do, today I sat up and took both hands off the bars to stretch my back while having a drink from the bottle. The front wheel started swerving back and forth, not greatly, but enough that I didn't dare leave my hands off the bars for more than 5 seconds. Is this normal? If not, what is the cause of it? Is it specific to the bike, geometry, and/or setup? - Mike |
#7
|
|||
|
|||
Straight line instability?
On Sun, 17 Aug 2003 03:33:04 +0000, jobst.brand wrote:
But the description seems to be more of someone who is uncomfortable riding no hands -- or riding that bike at all -- than of a mechanical problem. Let's clarify whether the complaint is shimmy or that the rider must lean to one side to ride straight ahead while riding no-hands. From what I see, it's shimmy which has nothing to do with frame alignment. I saw no complaint abut aversion to riding no-hands. From the original post: "Ever since the bike was new, the front end has always felt very twitchy and requires a conscious effort to keep the front wheel perfectly straight. I find myself pushing forward on the bars to force it to go straight." This certainly does not sound like shimmy. I don't understand what he means by "pushing on the bars", though. He continues: "Although it's not something I normally do, today I sat up and took both hands off the bars to stretch my back while having a drink from the bottle. The front wheel started swerving back and forth, not greatly, but enough that I didn't dare leave my hands off the bars for more than 5 seconds." Again, "swerving" is not how people tend to describe shimmy. Perhaps the idea of an over-tight headset or some other mechanical glitch would make sense. -- David L. Johnson __o | And though I have the gift of prophecy, and understand all _`\(,_ | mysteries, and all knowledge; and though I have all faith, so (_)/ (_) | that I could remove mountains, and have not charity, I am nothing. [1 Corinth. 13:2] |
#8
|
|||
|
|||
Straight line instability?
On Sun, 17 Aug 2003 09:57:48 +0000, Ron Hardin wrote:
I have a bike with no rake to speak of and it rides no-hands as described. It comes from no countersteer at the start of a correction. My first good bike had lots of rake, and the next one, a track bike, had almost none. But I could always ride the track bike no hands, while the road bike would always veer to one side. Eventually I found out that the fork was misaligned on the road bike, but certainly a lack of rake is not a cause of this instability. -- David L. Johnson __o | You will say Christ saith this and the apostles say this; but _`\(,_ | what canst thou say? -- George Fox. (_)/ (_) | |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Riding to right of white line | mary | General | 19 | June 18th 04 06:53 PM |
Knee to pedal plumb line | MJ | General | 7 | November 18th 03 09:18 PM |
RFI:700c carbon fork - straight vs curved legs | Mark Hickey | Techniques | 4 | August 8th 03 02:02 AM |
Difference Between Handlebars 0 ~newbie~ Straight vs slight bent | whatup | Mountain Biking | 8 | July 26th 03 09:30 AM |
Braking Technique | asqui | Racing | 55 | July 25th 03 04:16 PM |