To clutch or not to clutch

O

Octain

Member
Feb 15, 2002
11
0
One of my ridding buds and I talked about this on our last ride. I never noticed he used his clutch when ridding till we started talking about it.
I ride a 93 CR250 and hardly ever use the clutch except on stop and go and when I downshift. I dont force it into gear, just let of throttle and shift. He rides a 90 KDX and says he always uses the clutch no matter what. Got me to thinkin'
I was always under the impression that as long as you didnt ram the gears you would be ok.
I ride my XR400 the same way and have had no problems.

I change the lube often
Any opinions?
 
H

Honda26

Member
Mar 17, 2002
139
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use the clutch to upshift, dont worry about it when downshifting..... the most common mistake of beginner riders..- Gary Semics.
 
R

Rockey5000

Mod Ban
May 6, 2002
293
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Up or down, shifting with a load on the transmission is going to cause more wear on it than shifting with the clutch.
 

Jaybird

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Mar 16, 2001
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But minimal wear, Rockey. If one races, there isn't much time to worry about the clutch for shifting. And I don't think not using it during the downshift causes much wear at all.
 
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Rockey5000

Mod Ban
May 6, 2002
293
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Jaybird- So racers don't use the clutch during shifting? I didn't know that, well I guess if you let off the load on the trans (throttle) it would be fine. I just thought that when you shifted w/o clutch the gears would still be turning and when they connected there would be a 30 HP shock put through the gears and it could shear or break off teeth.
 
1

125 rider

Sponsoring Member
Oct 1, 2000
408
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I can understand that when your racing every little shortcut counts, but i dont understand why people who trail ride do this? Are they lazy or just dont care? I dont find it to be an inconvenience to pull a freakin lever when I need to up OR down shift.
 
D

dell30rb

Uhhh...
Dec 2, 2001
1,510
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Once it was really cold and my clutch hand was cramped up so i shifted without the lever. Been doin that ever since!

When you are riding and need to shift gears quickly, if you pull the freakin lever to shift you will get arm pump.

I just counted, and I would pull the clutch 36 times per about 2 minute 30 sec lap. that on top of clutch feathering is a real pain in the arm.
 
1

125 rider

Sponsoring Member
Oct 1, 2000
408
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The only time I get arm pump is when I haven't ridden in 3 weeks or more. Other than that, i could pull freakin levers all day long. :p
 
Last edited:
C

Chili

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Apr 9, 2002
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Originally posted by Rockey5000
I just thought that when you shifted w/o clutch the gears would still be turning and when they connected there would be a 30 HP shock put through the gears and it could shear or break off teeth.
Click to expand...

Correct me if I'm wrong but dirt bike trannys are constant mesh gears therefore always connected.

The MX racing school my son attended this spring they taught him to basically only use the clutch on the race to the first turn i.e. keep it pinned and just bang the clutch as you shift instead of letting off the gas, or just if you need to fan it coming out of a turn or for traction control.
 

Jaybird

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Rockey, on a modern MX bike you can get by without ever using the clutch to shift. However it is a bit harder on them to shift up without it.
My clutch gets used most to help control where my bikes RPM's are. This "fanning" method can actually save you from shifting so much, hence less wear on the gears.
Never let your gearbox go without fresh fluid for more than a few rides.
Oil with particulate in it is harder than anything on the gears.
 

David Trustrum

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Jan 25, 2001
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Strange. Standard road race practice is to clutch only on downshifts - reference Keith Code, (Tarmac equiv of Gary Semics),

Maybe we can get Keith & Gary to fight it out,. . . handbags at 10 paces. ;)

Try it, full throttle, load lever up & blip the throttle off & on again. With a bit of practise you will produce seamless gearbox friendly smooth changes. More so in higher gears as that 1st -2nd is most violent torque change from a ratio point of view.
 
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rc331

Member
Jun 18, 2002
101
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I have used this technique ever since I got my first mx bike in '75 and never had a transmission problem of any sort. ;)
 
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Rockey5000

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May 6, 2002
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Well, you learn something new every day! Im going to try what Chili said about his sons MX school. I rarely shifted w/o the clutch because of fear of hurting something, but as long as oil is frequently changed (and mine is) shifting w/o the clutch does not seem to do much harm?
 
M

ML536

Member
Dec 1, 2001
68
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"Strange. Standard road race practice is to clutch only on downshifts - reference Keith Code"

This is true on both counts: Semics says that the clutch is unneccessary to downshift a dirtbike. Code says it is necessary to clutch to downshift a street bike. I think that they are both correct. Downshifting without the clutch works fine on a dirtbike. Downshifting without the clutch on a streetbike will generally lock up the back wheel, and probably place a huge load on the transmission in the process.

Thinking about this, my guess as to why is 1. the rear tires are runnning on two different surfaces. If you try to downshift a street bike on asphalt without the clutch, the rear tire has a relatively large amount of traction. As a result, it can send a big load through the transmission. On dirt, the rear tire has relatively less traction, thus the rear tire can easily break loose for a split second, eliminating the shock load. (Maybe this is inartfully stated, but I think you guys get the idea). Guess number 2 is perhaps streetbikes generally have wider ratios between the gears, therefore during a downshift the difference in RPMs between the higher and lower gear will be greater, and therefore increase the load on the transmission.

These are just guesses, and are not based on any kind of mechanical expertise. Does anybody know anything about this?
 
1

125 rider

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Oct 1, 2000
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I would believe the gear ratio differences to be true as ML536 stated, especialy on road race bikes that red line at 16 grand.
 

David Trustrum

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Jan 25, 2001
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No in actual fact proper road race bikes have close ratio gearboxes to keep them in the power, this means my YZF750 SP will do ~87mph in 1st gear without crossing redline, so is a pig from starting but easy to keep on the boil thereafter.

ML good point re traction, I had considered it but didn’t want to write a novel.
PS try the quote button in the reply area to highlight quotes.
 
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rc331

Member
Jun 18, 2002
101
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ML536 I think you have the right answer here. ;) (if I was running my mx bike on asphalt I would be using the clutch too)
 

David Trustrum

~SPONSOR~
Jan 25, 2001
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Don’t laugh too loud -I’ve used throwovers on my KDX when we go trail camping.

Have to be real careful they don’t get dragged down into the knobblies though!
 
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