Chainring Spider Touches Frame

Hi, when I put the chainring on my BB, the inside part of the spider touches the frame.

Do I have to find a spider that connects the chainring from the 'outside'.

Would this not be a problem with a singlespeed chainset?

In other words, can I get away with purchasing a cheap road crankset from somewhere or do I have to get a proper singlespeed? Thx.

With the chainring like this, on the inside, does this give you a good chainline?

If not, buy a smaller BB and mount the ring on the outside.

BB is not the issue - the crankarm is flush against the frame.

Currently my chainline is off and I need to get the chainring as close as possible to the frame.

PIcture please.... Spider is normally part of the crank, chainring bolts onto spider of right crank by means of 4-5 chainring bolts.

Do you mean that when the right crank (and spider) are installed, you can swing the crank OK- all clear? Then when you attach a ring, it fouls?

Bloody hell Johnny this is turning into a right saga. If the crank is against the frame then it's the wrong bb for that chainset.

Bloody hell Johnny this is turning into a right saga. If the crank is against the frame then it's the wrong bb for that chainset.

Exactly.

Could ask Murtle to use his magic chainline adjusting hammer?

Bloody hell Johnny this is turning into a right saga. If the crank is against the frame then it's the wrong bb for that chainset.

Not necessarily, it may be wrong BB, wrong chainset or a combination of both. What chainset are you using? Fitting too long a bb to give clearance for the chainset will ruin the chainline. Widely spaced chainstays can rub off 144bcd chainsets, particularly where there is a lot of backsweep on the spider arms, my flatmate had just this problem with a set of Campag Super Records on a new frame last week. He switched to a 135 bcd chainset with the same bb and it worked fine.

A 135 or 110 bcd chainset might do perfectly well on the same bike and allow the best size bb to be fitted. Sugino XDs are 110BCD and have pretty straight spider arms, and will give a lot of chainstay clearance. If it's only a matter of a few mills then you might get away with 135mm bcd. There's probably 100 other good cranks for the job out there, loads of BMX type stuff will prob work too if you are ok with that.

Which is why I have said in the past Johnny may have saved time and money buying a new chainset and bb together!

Hopefully that image will clarify issues.

The chainring/crank arm is right up against the frame i.e. there's no space at all between the outer edge of the bottom bracket and the chainring/crank arm.

Now, the spider rubs against the frame. Hopefully you now see the problem.

Have a look at the transmission database for winning combinations of bb / cranks / hubs.

I would link but iPhone makes that hard. Use the search function.

bb is too short. get a longer one and mount the ring on the inside of the spider. if still touches, get a smaller ring.

Something is odd about your hub/sprocket combo if you really need to pull the chainring in that close to get your chainline right.

Is it the actual spider that's hitting the chainstay, or just the support ledge for the inner ring? If it's the latter, it's Dremel time!

The chainstays need the crimping enhanced....

Seriously though.
Need more details (crank model, BB model/lengh, hub details etc.) really. but there's no question that you need to space the rear sprocket out and then the crankset out some (longer BB shaft). Looking at that pic your heels are going to have a hard time passing the chainstays, as it is.

A larger photo:

File them off...

hmm looks like you should get a longer bottom bracket and put the ring on the inside

you know this will work, buying new cranks is another gamble

Longer BB would mean chainline being out.

redish the rear wheel? chainline means nothing if you can't turn the cranks :)

Longer BB would mean chainline being out.
Cant you move the rear sprocket out?

Longer BB + Chainring on inside of spider*. This may also allow you to turn your feet as well as the cranks.

(*basically keep the chainring where it is, and move the spider to the outside of it)

What plastic pedals said actually :)

Longer BB would mean chainline being out.

not if, as suggested you mount the chainring on the inside of the spider rather than the outside.

Edit: beaten to it.

that chainring looks very close to the chainstay. Is that in the position required to get the chainline correct?
Think you have a challenging frame in this case where the chainstay shape wasn't designed to use a 42mm chainline maybe?

Chainring on inside of spider = pig ugly

that chainring looks very close to the chainstay. Is that in the position required to get the chainline correct?
Think you have a challenging frame in this case where the chainstay shape wasn't designed to use a 42mm chainline maybe?

If you look at the crimp in the chainstay. It looks designed for a smaller chainring. Could be a frame designed for a MTN chainline (requires 52mm)*.

(*I actually have the opposite. a MTN drivechain on a cyclocross frame. Cant say its an attractive set-up)

Yes, longer BB with chainring on the inside would work I suppose. The chainring needs to be as close as possible to the frame in order to align with rear cog.

I would just prefer to get a 'proper' solution to this problem.