I'm beginning to feel a lot like Jamey

biondino

When I bought the fixie, the chap told me that he'd had to file off a corner of the bits of the spider where the chainring attaches, as they scraped the chainstay. No biggie, I thought, and indeed, no biggie.

This morning, as I pass Buckingham palace, I notice my right crank/chainring have come loose. So I tighten them back up - and suddenly the ends of the spider are scraping against the chainstay again.

So my question is - what can I do about this? Clearly he managed to set the bike up in such a way that it worked fine, and didn't scrape. I don't think the crank/ring had been loose all this time - though I guess they could have been only lightly tightened. But when I tried to loosen the cap at the end of the axle (which I had tightened to restore the crank/ring to stability) - the crank/ring stayed where they were, and the scraping continued all the way home.

Any thoughts? Will I have to do more filing? Or is there a way I can position the spider so it is tight, but doesn't rub (i.e. like he managed to do)?

jonginge

Sounds odd. What length bb axle you got? May be able to swap it with a couple of mm longer one without compromising the chainline too badly...

Feltup

Wow those tolerance are tight. Perhaps a shim on the BB might be a better way of increasing the seperation between the spider and the stays. What is the line up like with the cog? If it lines up nicely then you really only have two options that I can see:-

1) File
2) Shim the BB

OK 3 options shim the BB and the cog!

redvee

As mentioned above, chuck a freewheel spacer on the BB and maybe on the freewheel. Would a 2mm spacer at the BB need a spacer at the freewheel?

biondino

The chainline has always been excellent and still seems okay now, though obviously the chainring is now slightly (we're talking less than a mm) closer to the bottom bracket. If I could just manage to achieve what the seller achieved I'd be laughing - I wish I knew what it was...

Thanks for the responses, guys - and if other fixie-builders read this and have experience of getting all these distances right, please lend your advice!

always_tyred

Spacer - all the way. Its an obvious and well known solution. The hacking away at the chainstay idea was not the thing to do in the first place.

Its a bodge and if you are the sort of guy to get stroppy with shops, there is a case for getting this sorted by the original vendor for nothing, pointing out that he's hacked a chunk out of your chainstay for no good reason.

Don't get stoppy in a camp way, though, throwing your arms around and stamping and stuff. That won't work.

gtvlusso

Hi Blondie,

It sounds like the BB spindle is too short. It will affect the chainline slightly - only way you will see it is to put the bike upside down and see if the chain is more towards one side of the sprocket/chainring as opposed to running down the middle......takes a keen eye.

What is the rear spacing on the frame? If it is 120mm that breaks down to a 42mm chainline measured from the centre of the seat tube to the chainset. Dependant on your chainset you will need a matching BB to get the correct chainline.

Mine worked out to be a Sugino 103mm BB and chainset:

http://www.italian-solutions.co.uk/prod ... 310&page=1

The chainstays in no way should impede the chainset, so, it kinda sounds like the previous owner did a bodge and used a stripped down road chainset and BB and guessed the chainline?! Especially as you bike is a Bob Jackson track frame.......the geometry should be perfect.

Even with my TT frame some basic calculations and geometry means that I have a 2mm or so clearance on the chainstays.

biondino

gtvlusso wrote:

Hi Blondie,

It sounds like the BB spindle is too short. It will affect the chainline slightly - only way you will see it is to put the bike upside down and see if the chain is more towards one side of the sprocket/chainring as opposed to running down the middle......takes a keen eye.

What is the rear spacing on the frame? If it is 120mm that breaks down to a 42mm chainline measured from the centre of the seat tube to the chainset. Dependant on your chainset you will need a matching BB to get the correct chainline.

Mine worked out to be a Sugino 103mm BB and chainset:

http://www.italian-solutions.co.uk/prod ... 310&page=1

The chainstays in no way should impede the chainset, so, it kinda sounds like the previous owner did a bodge and used a stripped down road chainset and BB and guessed the chainline?! Especially as you bike is a Bob Jackson track frame.......the geometry should be perfect.

Even with my TT frame some basic calculations and geometry means that I have a 2mm or so clearance on the chainstays.

Thanks guys - the bike's at home so I can't measure, but the chainring is a Sugino 75. And to be clear, the previous owner didn't take a chunk out of the chainstay, he took bits off the back of the spider with a file.

always_tyred

biondino wrote:

Thanks guys - the bike's at home so I can't measure, but the chainring is a Sugino 75. And to be clear, the previous owner didn't take a chunk out of the chainstay, he took bits off the back of the spider with a file.

Whoops.

Okay - less of a bodge, but still a work around and not a real solution.

prawny

Is it a cartridge BB? Is it possible (i'm no mechanic) that when you tightened the crank the BB spun in the shell a little bit and it's brought the spider closer to the frame?

I say this because I think it's happened on my MTB I can see a couple of threads on the non drive side that weren't there when the gears were working properly.

biondino

prawny wrote:

Is it a cartridge BB? Is it possible (i'm no mechanic) that when you tightened the crank the BB spun in the shell a little bit and it's brought the spider closer to the frame?

I say this because I think it's happened on my MTB I can see a couple of threads on the non drive side that weren't there when the gears were working properly.

It's certainly possible as I am also no mechanic and I wouldn't have noticed or even known what to look for! I suspect it's an easy fix for someone who knows what they're doing, but sadly that's not me. I've made myself promise not to mess with bottom brackets as I'm pretty sure my bike will literally explode if I try.

gtvlusso

biondino wrote:

prawny wrote:

Is it a cartridge BB? Is it possible (i'm no mechanic) that when you tightened the crank the BB spun in the shell a little bit and it's brought the spider closer to the frame?

I say this because I think it's happened on my MTB I can see a couple of threads on the non drive side that weren't there when the gears were working properly.

It's certainly possible as I am also no mechanic and I wouldn't have noticed or even known what to look for! I suspect it's an easy fix for someone who knows what they're doing, but sadly that's not me. I've made myself promise not to mess with bottom brackets as I'm pretty sure my bike will literally explode if I try.

Nothing to fear - maybe a mis match of BB to chainset. Suggests a 103 BB for a sugino 75 chainset. 103mm spindle width. Could be that the previous owner has mis-aligned the BB slightly - very difficult to do but it could be in more on one side than the other.....I heave heard of this on the none chainset side.

Bit of maths should sort you out - I guess you have done a t'internet search on the Bob Jackson frame and seen no other issues on other forums LFGSS for example?

biondino

No, I haven't as yet - I trust you guys more! There will be a solution, I'm sure - I just hope it's a solution I can quickly and easily sort out.

gtvlusso

biondino wrote:

No, I haven't as yet - I trust you guys more! There will be a solution, I'm sure - I just hope it's a solution I can quickly and easily sort out.

Sure it can be, will have a look in RP on 18th if you are there with fixie....happy to whack some tools in da mota....

Greg T

Kick at the chain stay until it gives you the required clearance.

Simple.

gtvlusso

it could be bent frame syndrome......will need a jig, brazing torch and allot of water!

Oddjob62

I use a couple of spacers (iirc i got them from velosolo) on my BB to move the crankset a couple of extra mm away from the frame

gtvlusso

Oddjob62 wrote:

I use a couple of spacers (iirc i got them from velosolo) on my BB to move the crankset a couple of extra mm away from the frame

Bodge! :-) if it works though......

biondino

gtvlusso wrote:

Oddjob62 wrote:

I use a couple of spacers (iirc i got them from velosolo) on my BB to move the crankset a couple of extra mm away from the frame

Bodge! :-) if it works though......

Pretty sure this would sort it out - and pretty sure I don't have a bent frame. Oddjob, could you let me know what spacers I should purchase, and I can bring them along to the meetup on the 18th and let GTVL do his magic

biondino

Oddjob, is this what you mean?

http://www.chainreactioncycles.com/Mode ... elID=31698

Oddjob62

biondino wrote:

Oddjob, is this what you mean?

http://www.chainreactioncycles.com/Mode ... elID=31698

Nah... acutally i think I bought these http://www.velosolo.co.uk/ssspacers.html
They are labelled as hub spacers but were the perfect size for my BB as well. Velosolo do BB spacers but there's no pic.

biondino

Blimey - I was hoping for a wee washer-type thing! I don't really want to muck with my chain line more than I have to. Wouldn't I just need a couple of (very thin) spacers, one for the front and one for the rear?

Oddjob62

biondino wrote:

Blimey - I was hoping for a wee washer-type thing! I don't really want to muck with my chain line more than I have to. Wouldn't I just need a couple of (very thin) spacers, one for the front and one for the rear?

The small ones (ones i use) are 1mm. How much thinner do you want?

biondino

Nope, that'll do

Oddjob62

biondino wrote:

Nope, that'll do

Actually the bottom of this page
http://www.velosolo.co.uk/shopchain.html is the set i've got 3x2.5mm and 2x1mm

Handy to have in the toolbox in any case.

biondino

Okay, so, I think I've figured out the problem. I noticed when trying to figure out what to do that the bottom bracket is not exactly centred in the bottom bracket shell - it's slightly poking out on the non-drive side and slightly recessed on the drive side, about a couple of millimetres.

Now, if it were properly centred, the chainring would, I think, no longer rub on the chainstay.

So - how do I achieve this? Should I just ask the LBS (Holdsworth)?

prawny

biondino wrote:

Okay, so, I think I've figured out the problem. I noticed when trying to figure out what to do that the bottom bracket is not exactly centred in the bottom bracket shell - it's slightly poking out on the non-drive side and slightly recessed on the drive side, about a couple of millimetres.

Now, if it were properly centred, the chainring would, I think, no longer rub on the chainstay.

So - how do I achieve this? Should I just ask the LBS (Holdsworth)?

Yes! I was right I am a mechanic! Get the right BB tool and screw it back in a bit i spose

Paulie W

prawny wrote:

biondino wrote:

Okay, so, I think I've figured out the problem. I noticed when trying to figure out what to do that the bottom bracket is not exactly centred in the bottom bracket shell - it's slightly poking out on the non-drive side and slightly recessed on the drive side, about a couple of millimetres.

Now, if it were properly centred, the chainring would, I think, no longer rub on the chainstay.

So - how do I achieve this? Should I just ask the LBS (Holdsworth)?

Yes! I was right I am a mechanic! Get the right BB tool and screw it back in a bit i spose

Why do BBs always need a special tool?! We are just whores to the bottom bracket tool makers.

lost_in_thought

Paulie W wrote:

prawny wrote:

biondino wrote:

Okay, so, I think I've figured out the problem. I noticed when trying to figure out what to do that the bottom bracket is not exactly centred in the bottom bracket shell - it's slightly poking out on the non-drive side and slightly recessed on the drive side, about a couple of millimetres.

Now, if it were properly centred, the chainring would, I think, no longer rub on the chainstay.

So - how do I achieve this? Should I just ask the LBS (Holdsworth)?

Yes! I was right I am a mechanic! Get the right BB tool and screw it back in a bit i spose

Why do BBs always need a special tool?! We are just whores to the bottom bracket tool makers.

Is it really one BB one tool? A Park Tools spanner I have maintains that it does lockrings and BBs.

It's this one:

Paulie W

lost_in_thought wrote:

Paulie W wrote:

prawny wrote:

biondino wrote:

Okay, so, I think I've figured out the problem. I noticed when trying to figure out what to do that the bottom bracket is not exactly centred in the bottom bracket shell - it's slightly poking out on the non-drive side and slightly recessed on the drive side, about a couple of millimetres.

Now, if it were properly centred, the chainring would, I think, no longer rub on the chainstay.

So - how do I achieve this? Should I just ask the LBS (Holdsworth)?

Yes! I was right I am a mechanic! Get the right BB tool and screw it back in a bit i spose

Why do BBs always need a special tool?! We are just whores to the bottom bracket tool makers.

Is it really one BB one tool? A Park Tools spanner I have maintains that it does lockrings and BBs.

OK maybe I'm exaggerating a bit but I have two different tools for two different bikes! And that's the spanner not the tool itself isnt it? You'd still need the hexagonal thingy.

prawny

lost_in_thought wrote:

Is it really one BB one tool? A Park Tools spanner I have maintains that it does lockrings and BBs.

It's this one:

I think that'll do one type of BB, but it depends if it's an old style one, of a cartridge on, or and external one or BB30 yadda yadda yadda, I have no BB tools, thats one reason my MTB hasn't moved in about 3 months