Chain guard almost scrapping side wall of tire, possible cause?

[kaiq]

I recently changed new chain, sprocket and tires together. All changed to factory default recommendations. Ride for about 1000km and I now noticed my chain guard groove area is almost touching the side wall of the tire. The tire is too near to the end of the groove.

 

What could be the possible reasons? Chain not stretched yet, axle position before half point. Chain also don't feel too tight, basically everything feels ok when riding.

 

My bike is a Honda, guard is similar to S4's chain guard.

 

I've been thinking of a few:

i) Chain guard defomed due to plastic deform over old ago (bike more than 10 years)?

ii) Tire too small even though I use according to the spec? My spec says 140/70. I'm using BT 140/70.

iii) Tire pressure too low?

 

More importantly, is there any countermeasure I can apply on it?

[Raptor]

A picture paints a thousand words.

[ezzyoiler]

note....tyresof different made..made not be exactly the same size...

 

i suggest to check new tyre actual size compred to what you had before...the difference in size may be apparent..

did you change from a low profile tyre to one normal road tyre..if it is...clearances with tyrewould be apparent.

 

sometimes worn shocks ...the bottoming of your shock may come into contactwith your new tyre..

[kaiq]

 

Images attached. Btw, my bike's a VTR250, hence it's a mono shock. Chain also correct size, counted myself, got 52 => 104L as according to spec.

 

Tires have been pump up again, problem still persist as shown in these pics, so it's not a tire pressure issue.

 

The tire size is smaller than previous now. It's a BT39, 140/70. Previous using Dunlop 150/70 and it's almost hitting the bottom of the shock, hence I change back to default size. Both are road tires as I am neow, haha, save money. Now It does seems too small...

 

I suspect 2 problems:

- tire too small

- Plastic chain guard shape has deformed (shrunk) as I don't think the guard is designed such that it crosses the path of the wheel rotation.

 

I see 2 solutions:

- Cut groove, extend it longer OR

- Add brackets, pulling entire guard backwards

 

Anyone got other suggestion?

[ezzyoiler]

check clearance of tyrewall to swing arm...make sure both are the same..

at mudguard area and rear of swing arm..tyre to be centred or else during tyre change ..miss out a washer oe two...

if not the tire is not aligned with the chasis...

[ezzyoiler]

there is a cut relief at the chain

guard....it seems that you havethis problem before...

 

the chain guard may be the culprit

[ezzyoiler]

wrong size chain guard..

[ulysses_sc]

Check if the mech installed the wheel spacers correctly... Usually left and right sides have different lengths.

[kaiq]

The cut is I diy one, cos last time when using 150/70 tire the top of the side wall cuts into the guard as it's too wide. Hence I cut the groove to make the groove bigger.

 

After changing to new tire the chain guard could be wrong size? Might be possible even though this guard is the original guard, but changes in tire seems to render it out of spec... but is it common?

 

Think I should go back to workshop to give them a look.

[kaiq]

 

Bigger pic here http://img571.imageshack.us/img571/2472/rearwheel.jpg

 

Attached is the rear wheel disassembly of my bike. Which part you guys guess is giving the problem?

Edited November 6, 2012 by kaiq

[ezzyoiler]

check if the tyre isaligned with the chasis...then you can decide

[ezzyoiler]

you chage from 150/70 to 140/70...the tyre is even smaller. the width is narrower by 10mm.. means your smaller tyre should have more clearance now...to be exact 5mm.from chain guard..

.and it still hits the chain guard...obviously something is not right..

the chain guard relief is to solve rubbing issues...now with smaller tyre ..the issue still exist..

it look like a installation issue to me.

 

back to where you installed tyre..ask them to do it right.

Edited November 6, 2012 by ezzyoiler

[ulysses_sc]

[ATTACH=CONFIG]261650[/ATTACH]

 

Bigger pic here http://img571.imageshack.us/img571/2472/rearwheel.jpg

 

Attached is the rear wheel disassembly of my bike. Which part you guys guess is giving the problem?

 

Check that items 4 and 5 are in the right places.

[kaiq]

Ok. Will look for 4 & 5. Btw just now went to see the distance between the tire and the swing arm. I use the front, upper end of the tire and the sides of the swing arm as gauge. Both sides the the distance looks the same, at least a 2cm distance apart.

 

It seems to me the wheel is center-aligned.

 

Current possible solutions:

- Cut groove, extend it longer OR

- Add brackets, pulling entire guard backwards

- Check for wheel to make sure it's in center alignment

- Change chain guard

[ulysses_sc]

Dude... the sprocket looks too close to the swingarm... Check 4 and 5 now... Highly possible the mechanic got the left and right sides mixed up.

[kaiq]

Dun think the sprocket is too close close to swing arm, take a look at this setup - same model, different year.

 

http://upload.wikimedia.org/wikipedia/commons/7/76/Honda_VTR250_2009_Sprocket.JPG

[CSV]

vtr250????

 

ducati monster lookalike eh.....rare bike.

 

anyways, cheapest option is to cut the rubbing plastic material off. doesnt seem to be too uch so once that is cut off, should be ok.

[kaiq]

 

Yep, VTR250 still exist here, haven't extinct yet .

 

Last night went browsing at other VTRs, think my wheel gap is correctly spaced, so the problem seems to be at the chain guard. I attached the pic of the guard's rear view, from the shape it's now, looks like the plastic warpped or something until the right side is being pushed closer to the wheel.

 

Perhaps by adding another nut/spacer at the rear bolt to push the guard out might solve the problem, haha, just thought of this this morning.

[ezzyoiler]

you chage from 150/70 to 140/70...the tyre is even smaller. The width is narrower by 10mm.. Means your smaller tyre should have more clearance now...to be exact 5mm.from chain guard..

.and it still hits the chain guard...obviously something is not right..

The chain guard relief is to solve rubbing issues...now with smaller tyre ..the issue still exist..

It look like a installation issue to me.

 

Back to where you installed tyre..ask them to do it right.

at least ask why?

[kaiq]

You mean why change to smaller tire? Not actually, the 140/70 is the original size, but I previously using a wider 150/70.

 

I think installation no issue though.

[CSV]

your plastic defintely looks warped.

 

can get new one maybe?

 

let me know if you're selling. interested in it.

[kaiq]

 

Final solution: added a 1cm rubber spacer (made from thick rubber hose) to the rear bolt.

 

The gap is now widen, and the guard isn't too near to the chain, so the chain fling also won't hit the guard. Only disadvantage is that the guard looks slightly bend.