Australian Cycling Forums - Bicycles Network Australia

For all the wise and knowledgeable sages I have a quick question about Shimano 600 cranks and chainrings, specifically this style: http://www.ebay.com.au/itm/Shimano-600- ... 500wt_1414" onclick="window.open(this.href);return false;

Is there any trouble with removing the existing two chainrings and installing a single, probably 46t?
I want to run it with a 6-7 speed cassette.
Thanks.

Bobbybobson wrote:For all the wise and knowledgeable sages I have a quick question about Shimano 600 cranks and chainrings, specifically this style: http://www.ebay.com.au/itm/Shimano-600- ... 500wt_1414" onclick="window.open(this.href);return false;

Is there any trouble with removing the existing two chainrings and installing a single, probably 46t?
I want to run it with a 6-7 speed cassette.
Thanks.

Assuming you can get a 46T in the right BCD it'll work fine - you will need BMX / track chainring bolts though:

http://www.ebay.com.au/itm/Vintage-Shim ... 500wt_1289
Those are overkill but you get the idea. My local bike shop generally sells a set for $10-$15 for a set of 5, not coloured or dura-ace though.

The 46T 130BCD is common enough so it won't be a problem.
Thanks for advice on the bolts Drubie.
Cheers.

Bobbybobson wrote:The 46T 130BCD is common enough so it won't be a problem.
Thanks for advice on the bolts Drubie.
Cheers.

It will be a problem if you are going sans front derailleur.
The chain will come off sometimes, maybe not that often but enough to be a real problem.
To go without front derailleur you need to use an INNER chainring, and i suspect that the largest you will find is probably 44 tooth.

Agree with much of the above. What I understand you're trying to do is run a 6/7 speed cassette/cluster which is designed for lateral movement through the use of a derailleur and which dictates the use of a chain that is also designed to derail. You want to now pair this with a front chainring that is also designed to derail, and as you move across the gears, the chain will most likely do just that.

As standard chainrings are designed to derail in a single direction i.e. the big ring from the outside to the inside, and vice versa for the small ring, I'd actually suggest (in contrast to Elantra) the use of a big (outer) ring up front. Using an outer ring means that when the chain inevitably derails, it should do so inwards towards the bottom bracket and not outwards and into your pedal/onto the road.

Cycle Underground can cut chainrings to run with 3/32" chains - I'd suggest using one of these up front, as its designed specifically not to derail - has higher profile teeth, no ramps, etc.

I hope this is helpful in some way?

Single chainrings are pretty popular in MTB and CX. There are heaps of them around.

Personally, I run a 1x8 setup on my Raleigh without any issues. Haven't dropped the chain yet. I'm using a 42t ring with an 11-28 cassette, and the chain is probably a link or 2 shorter than you'd run normally.



This bike is a hoot to ride. I love it. It was initially set up this way as a temporary thing, but after I rode it the first time, I decided to keep it this way. It looks neat and goes well. Yes, I am going to upgrade the crank. I know that one's ugly.

Anyow, there are people getting around with 1x10 setups, so I'm sure chain derailment isn't that much of an issue. It should be even less so with a narrower cassette/freewheel.

If you're worried, Surly make stainless steel chainrings which are designed for single speed [3/32"] and have a taller tooth design. There are also special chain tensioners you can buy, which make the chain wrap the chainring a bit more snugly. I've not had the need for anything like that though.

Another option is to use an inner ring, plus a "blank" outer to match your 46t - could be called either a chain guard or cyclocross bash guard.

Brendan

I don't think you'll have much of an issue on a roadbike with dropping the chain, I run 1x9 on my MTB with a small top guide and it can take a lot of abuse before dropping the chain.

If you want a little more protection without going to full bash guards consider one of these which stops the chain from dropping on the inside for under $10 and very subtle
http://www.ebay.com.au/itm/New-DOG-FANG ... 3cc4fbd023" onclick="window.open(this.href);return false;

Or the next step up is this but it's a bit of overkill
http://www.paulcomp.com/chainkeeper.html" onclick="window.open(this.href);return false;

after that there's lots of MTB options but they're going to ruin the simple look of the 1x setup

These are all excellent ways to prevent or mitigate any damage which might occur when the chain derails. However, should the OP decide to use a SS specific chainring, they're all largely redundant.

Thanks for all the replies everyone.
Dan, a Cycle Underground chainring is my number 1 preference. I came across them on the FOA forum a year or so back but haven't had a reply to my email which I sent a week ago.
Rkelsen, that set up is pretty much what I'm going for. What cassette are you using exactly?

It's an Sram PG850. It's classified as an MTB cassette by Sram, but works fine with all the other bits on there.

The RD is a Shimano 1050 which I chose specifically because of its ability to work with bigger cassettes. It is one of the few short cage "road" RDs rated to handle a 28 tooth cog.

Since taking that picture, I've installed a Campagnolo Ergopower 10 speed brifter. It works perfectly with the 8 speed parts.

The downtube shifter in the picture is a 7 speed A500 unit. The 8th shift didn't 'click' but it didn't matter since it was against the limit screw anyway. I've kept this one. It may return to service if the Campy brifter breaks.

A 44 or 46 tooth chainring seems to work better on paper. I haven't tried it, so I can't comment... but what I can say is that in practice the 42t is a lot of fun.