Bash gaurd help!

Corners R Us

I've recently removed the outer ring on my chainset and replaced it with a bash gaurd as I never use the outer ring. When I'm using the middle ring and the bottom 3 sprockets on the rear cassette the chain just snicks the inner edge of the gaurd making an irritiating clicking noice!

I plan to use some spacers and longer chainring bolts to resolve this issue but can't seem to find anywhere to buy them. My usual CRC and online outlets don't seem to list anything suitable. I've not been to my LBS yet but will later in the week time permitting. Anyone point me in the direction of a suitable online supplier or a solution!

Cheers, Corners

nicklouse

what size is your new big ring? and what size is the bash?

Corners R Us

nicklouse wrote:

what size is your new big ring? and what size is the bash?

I'm starting to think I bought the wrong size bash. Its a Hope 36-38 and the middle ring I currently have is a 32. I suspect thats more my issue? Not sure why I didn't buy the 32/34 bash......costly mistake?

Corners

nicklouse

correct. you will not space that out. and people wonder why bash rings are sized.

put it is the classifieds or what about a 36T ring?

Corners R Us

nicklouse wrote:

correct. you will not space that out. and people wonder why bash rings are sized.

put it is the classifieds or what about a 36T ring?

Bought in haste and got lured in by some red Hope bling! I think I might well go to a 36T setup as you suggest as I'll get a nicer spread of ratios for my needs. Now I need to wander through another minefield and identify what 36T middle rings are compatible with FCM580 Hollowtech II cranks! And hopefully buy right this time...

Thanks for clarifying.

Corners, learning all the time!!

bikaholic

Hold the 44T chainring (that you took off) against the bash and post whether or not the diameter of the bash is greater than that of the chainring - contribute some useful data to other potential buyers of bashguards.

Chunkers1980

Corners R Us wrote:

nicklouse wrote:

correct. you will not space that out. and people wonder why bash rings are sized.

put it is the classifieds or what about a 36T ring?

Bought in haste and got lured in by some red Hope bling! I think I might well go to a 36T setup as you suggest as I'll get a nicer spread of ratios for my needs. Now I need to wander through another minefield and identify what 36T middle rings are compatible with FCM580 Hollowtech II cranks! And hopefully buy right this time...

Thanks for clarifying.

Corners, learning all the time!!

BCD 104mm and see if it fits on, some times you need yo file a bit off as the shoulders are different, but you should be alright with just a middle.

Corners R Us

Chunkers1980 wrote:

Corners R Us wrote:

nicklouse wrote:

correct. you will not space that out. and people wonder why bash rings are sized.

put it is the classifieds or what about a 36T ring?

Bought in haste and got lured in by some red Hope bling! I think I might well go to a 36T setup as you suggest as I'll get a nicer spread of ratios for my needs. Now I need to wander through another minefield and identify what 36T middle rings are compatible with FCM580 Hollowtech II cranks! And hopefully buy right this time...

Thanks for clarifying.

Corners, learning all the time!!

BCD 104mm and see if it fits on, some times you need a file a bit off as the shoulders are different

I'm also running 9-speed too so it needs to be compatible with a 9-speed chain. Oddly I can't find any Deore Hollowtech M580 specific rings. I presume any of these would fit?

http://www.chainreactioncycles.com/Mode ... elID=38192

http://www.chainreactioncycles.com/Mode ... delID=5699

http://www.chainreactioncycles.com/Mode ... elID=24653

Corners

The Rookie

Chain rings are all the same width....the chains get narrower externally not internally!

Corners R Us

bikaholic wrote:

Hold the 44T chainring (that you took off) against the bash and post whether or not the diameter of the bash is greater than that of the chainring - contribute some useful data to other potential buyers of bashguards.

32/22 rings and 36/38 bash (what was I thinking?!).



You can see the witness marks where the chain is clipping the bash periodically.

I've put the 44T outer ring back on for now whilst I ponder my next move some more.....

Corners

The Rookie

Right size bash.......

I have a couple of 32T bashes going spare (just horrid boring black! - one ally off a GT and one a Truvativ plastic) PM me if you are interested!

bikaholic

Corners R Us wrote:

bikaholic wrote:

Hold the 44T chainring (that you took off) against the bash and post whether or not the diameter of the bash is greater than that of the chainring - contribute some useful data to other potential buyers of bashguards.

32/22 rings and 36/38 bash (what was I thinking?!).



You can see the witness marks where the chain is clipping the bash periodically.

I've put the 44T outer ring back on for now whilst I ponder my next move some more.....

Corners

What I was getting at was if the diameter of the 44T ring is larger than that of the 38T bash, then you should be experiencing ticking noises from the chain periodically catching on the 44T shifting ramps - meaning the chainline is too far inboard.

Corners R Us

bikaholic wrote:

Corners R Us wrote:

bikaholic wrote:

Hold the 44T chainring (that you took off) against the bash and post whether or not the diameter of the bash is greater than that of the chainring - contribute some useful data to other potential buyers of bashguards.

32/22 rings and 36/38 bash (what was I thinking?!).



You can see the witness marks where the chain is clipping the bash periodically.

I've put the 44T outer ring back on for now whilst I ponder my next move some more.....

Corners

What I was getting at was if the diameter of the 44T ring is larger than that of the 38T bash, then you should be experiencing ticking noises from the chain periodically catching on the 44T shifting ramps - meaning the chainline is too far inboard.

Ah right, with you now. Not noticed it doing similarly or any evidence of it doing so. I'm out Sunday locally so will report back. I think the main issue is the bash is quite a bit thicker than a chain ring at the outer edge but I understand your point about chainline.

Cheers, Corners

Corners R Us

4hr rideout Sunday with no contact made between chain and 44T ring whilst on the middle ring. Decision made; 36T middle ring order and I will run 2x9 36/22 with a bash.

Corners

Corners R Us

So the plot thickens...again! The 36T chainring and new red crank arm bolt arrived today. I managed to get my work done early for the day so got the allen keys and spanners out late afternoon.

I've never taken a Hollowtech II apart so was pleased to navigate that simple task without any disasters! Chainrings off, give everything a bit of a clean. 32/36 rings on and bash on. Re-fit cranks to BB and bugger!

First issue. The left hand crank bolt (item 1 on the exploded PDF diagram below) I have seems to be a small 15mm diameter item. The new shiny red item I have is 20mm as they all seem to be?! What cranks do I have them?! Bike is circa 2007? Very odd? Anyone any thoughts? The standard bolt extractor tool works with it?







So undeterred I refitted tha cranks and rattle rattle rattle! 36 ring is worse than the 32! And no I had the chainring on the right way. The small tab that you use to line up the ring with the crank was in the right place etc etc.

So disassemble, rebuild in 44/32/22 format, re-apply cranks one more time and retreat to the interweb for guidance from those more knowledgable than I.

I'm out Thursday evening with my riding buddies again and one is an uber techy geek so I'll pick his brains too if he's there.

Someone mentioned chainline in an earlier response. Does this relate to the spacers left/right on the external BB? I note I have one on the chainwheel/right side and two on the left side? Could this be the culprit? The PDF below shows 1 x 2.5mm spacer on the left crank and 2 x 2.5mm spacers on the right (items 13).

http://techdocs.shimano.com/media/techd ... 608889.pdf





If I get time tomorrowI might go pick my LBS brains too as the mechanic/owner there's a helpful, knowledgable sort!

Any thoughts appreciated.

Confused Corners

The Rookie

No 1 is not a bolt it is the preload adjuster.

Just use the one you had already?

Did you find what was rattling on what?

cooldad

Read 'Read this first' below and fit the cranks properly.
But if you have a 68mm BB it should be 2 spacers on the drive side and one on the non drive, so that's wrong.
Which the doc you linked to clearly shows.

Corners R Us

The Rookie wrote:

No 1 is not a bolt it is the preload adjuster.

Just use the one you had already?

Did you find what was rattling on what?

The problem I have with the existing crank arm fixing bolt (as Shimano describe it)/the crank preload adjuster (as everyone else describes it) is that the recess where the removal tool fits is very shallow (see pictures added to previous post) and eventually it will cry enough. I appreciate they aren't meant to be done up tight but the reason I bought the red one is that a. the extractor tool sits all the way in it and its a way snugger fit and b. its made of alloy not Japanese plastic/Swiss cheese! and c. it looks perdy!!

I think my chainring/bash rattling issues might be incorrect external BB spacer application left and right by the previous owner (see previous post with additional pics). I'm just about to nip round to a mates and have a look at his external BB to see what spacers he's got where if he's in!!

Corners

Corners R Us

cooldad wrote:

Read 'Read this first' below and fit the cranks properly.
But if you have a 68mm BB it should be 2 spacers on the drive side and one on the non drive, so that's wrong.
Which the doc you linked to clearly shows.

I think I have fallen victim to a previous owner incorrectly installing the spacers :roll: Just measured the BB shell and it's a 68mm so it looks like the spacers are the wrong way round. Thought I was going mad! I will run a bash and 2/9 setup if it kills me!!!!

Corners

cooldad

The preload adjuster is just that - to preload the bearings. Once the pinch bolts are done up on the cranks, it serves no purpose and takes no strain. The fitting/removal tool is plastic so unless you are a gorilla it won't do any harm. And it just needs to be tight enough to remove play.

I still suggest you read the Parktools link.

Corners R Us

cooldad wrote:

The preload adjuster is just that - to preload the bearings. Once the pinch bolts are done up on the cranks, it serves no purpose and takes no strain. The fitting/removal tool is plastic so unless you are a gorilla it won't do any harm. And it just needs to be tight enough to remove play.

I still suggest you read the Parktools link.

Read the link, digested and book marked for future use; ta muchly. I understand the preload concept and why its made of plastic. I don't want to swing off a 6ft bar to tighten it more wanted something more aesthetically pleasing and less likely to round off when done up gently Looks like I might be stuck with it a while longer....

Thanks for you helpful pointers and links. Much appreciated.

Corners

cooldad

It's a very useful site.

bikaholic

Corners R Us wrote:

I think I have fallen victim to a previous owner incorrectly installing the spacers :roll: Just measured the BB shell and it's a 68mm so it looks like the spacers are the wrong way round. Thought I was going mad! I will run a bash and 2/9 setup if it kills me!!!!

Corners

No, the previous owner installed the spacers correctly for his own setup. Swapping the spacers around is a legitimate fix for chainline issues - it's typically done where the FD cage can't reach far enough outwards without getting chain rub or where pedalling backwards causes the chain to drop into a smaller cog.

The FD-M580 has a working chainline of 50mm but in many instances it really needs to be 51mm.


I've worked on every model of Shimano HT2 external type crankset at one time or another and on some of the road and mtb cranksets, as you've discovered, the plastic preload bolt is recessed deeper into the crank arm than the tool can reach - that is why I use the metal one:

buckmulligan

I thought all of the Shimano crank arm fixing/pretensioning bolts were the same until I had the same problem on my road bike.

I believe the smaller plastic one is an older or lower range design (M15 thread I think), but your shiny new one is for newer and/or higher range cranks (M20 thread I believe). I don't think you'll find an M15 one where the tool can pass through, because of the size of the threaded bolt bit behind where the tool engages. They have to have a shallow engagement (perhaps why Shimano changed the design?) but you can probably still find a nice alloy one on eBay or somewhere.

Corners R Us

BuckMulligan wrote:

I thought all of the Shimano crank arm fixing/pretensioning bolts were the same until I had the same problem on my road bike.

I believe the smaller plastic one is an older or lower range design (M15 thread I think), but your shiny new one is for newer and/or higher range cranks (M20 thread I believe). I don't think you'll find an M15 one where the tool can pass through, because of the size of the threaded bolt bit behind where the tool engages. They have to have a shallow engagement (perhaps why Shimano changed the design?) but you can probably still find a nice alloy one on eBay or somewhere.

Yep, all seem to be M20 ones that I can find. time to look to the darker corners of the web. Failing that as the previous respondee says, use a good metal tool to avoid failure.

Corners

Corners R Us

bikaholic wrote:

Corners R Us wrote:

I think I have fallen victim to a previous owner incorrectly installing the spacers :roll: Just measured the BB shell and it's a 68mm so it looks like the spacers are the wrong way round. Thought I was going mad! I will run a bash and 2/9 setup if it kills me!!!!

Corners

No, the previous owner installed the spacers correctly for his own setup. Swapping the spacers around is a legitimate fix for chainline issues - it's typically done where the FD cage can't reach far enough outwards without getting chain rub or where pedalling backwards causes the chain to drop into a smaller cog.

The FD-M580 has a working chainline of 50mm but in many instances it really needs to be 51mm.


I've worked on every model of Shimano HT2 external type crankset at one time or another and on some of the road and mtb cranksets, as you've discovered, the plastic preload bolt is recessed deeper into the crank arm than the tool can reach - that is why I use the metal one:

Thanks for clarifying. My setup clearly needs the two spacers on the drive side and a single one on the non drive side. All much happier now and no nasty chain/bash rattling. I needed to turn the front mech adjuster several turns to tighten the cable and make the front mech go further out when on the middlle ring to stop chain rub in the smaller rear sprockets. Ideally I need to move the front mech down a few mm's to avoid the chain rubbing on the bottom edge of the rear end of the cage when in the small rear cogs but I'll do that once I'm happy that 36/22 is actuallly for me. I might have a 24 inner sprocket somewhere and that might go on if I feel the gap between the front chainrings is too great gearing wise. All go learning fun and experimentation!

With regards to the preload bolt. Its not how far its recessed in the crank arm, its how shallow the actual engagement is for the tool. On th eM20 bolts the tool goes all the way in. On my M1 version it only goes in about 3mm. does tha make sense?

Anywho thanks to all for your thoughts, pointers and links; we got there in the end!!!! Roll on thursday evenings rideout! I might just have a quick punt up and down the street tomorrow evening to ensure I'm happy.....

Clued up Corners