Deore 510 9 speed chainrings on 8 speed FCM361 spider?

[Sweep]

Any reason why this shouldn't work before I mount the lot on a build?

I have the 22/32/42 8 speed chainset sitting around.

Don't need another 8 speed spider and can I think use the chainrings as spares on my 8 speed self build tourer which has an old 8 speed Alivio chainset on it.

I already have 22, 32 and 44T Deore 9 speed chainrings and would like to use these on another build.

Pretty sure the BCD is the same for all 3 rings (and in my other thread I proved that the big ring appeared to fit) - and I seem to remember reading (probably Sheldon) that Shimano 8 and 9 speed spiders were effectively the same.

Any reason at all that this wouldn't work in practice?

The 361 is of course square taper - not relevant to fitting of rings - but a big plus for me.

[pwu]

It will work.

[reohn2]

It will work.

+1

[PT1029]

Yes it will work. There will be a slight (small) gap between the crank arm shoulder and the ring because 4 bolt 8 speed and 4 bolt 9 speed have the same bolt hole dimensions, BUT the cranks have slightly different shoulder dimensions, so you can't put an 8 speed ring on a 9 speed crank (I've tried it!).

[mattsccm]

You can with a file.

[Sweep]

Thanks folks - looks like there's no problem.

Nice to have something so simple bike related after a nightmare trying to book a train ticket with bike.

Also happy to have used something from the parts box and I no longer have to lurk on ebay for an old 510 chainset.

thanks again.

[reohn2]

You can with a file.

[pwa]

One of the little compensations for getting older is that your parts bin gets bigger and more useful.

[Sweep]

One of the little compensations for getting older is that your parts bin gets bigger and more useful.

Very true. All i need are some nice second hand frames and i can very easily build some new bikes, only having to buy minimal extra stuff.
In practice if course it will probably be easiest to obtain those second hand frames by buying full bikes and stripping them - more bits

[NetworkMan]

Yes it will work. There will be a slight (small) gap between the crank arm shoulder and the ring because 4 bolt 8 speed and 4 bolt 9 speed have the same bolt hole dimensions, BUT the cranks have slightly different shoulder dimensions, so you can't put an 8 speed ring on a 9 speed crank (I've tried it!).

Being a 5 hole 110/74 person I don't have a direct interest in these cranks but out of curiosity does anyone know why the crank shoulder is different?

[Sweep]

Yes it will work. There will be a slight (small) gap between the crank arm shoulder and the ring because 4 bolt 8 speed and 4 bolt 9 speed have the same bolt hole dimensions, BUT the cranks have slightly different shoulder dimensions, so you can't put an 8 speed ring on a 9 speed crank (I've tried it!).

Reporting back on my efforts. Quoting your post PT so that I can easily address this issue, not as criticism of your post, for which many thanks - and to all the other folks.

It's not on a build yet but all went together just fine and dandy.

In fact there wasn't a gap between the big ring and the shoulder at all - in fact it was all so snug that initially it didn't seem to quite fit as I hadn't got the big ring and the spider properly flat against each other.

I do now have a black crankset with silver rings but that matters not a jot to me.

Thanks again folks.

PS - followed Brucey's advice to grease bolts and sleeves but not the interface between rings and crankset body.

[nirakaro]

Yes it will work. There will be a slight (small) gap between the crank arm shoulder and the ring because 4 bolt 8 speed and 4 bolt 9 speed have the same bolt hole dimensions, BUT the cranks have slightly different shoulder dimensions, so you can't put an 8 speed ring on a 9 speed crank (I've tried it!).

Being a 5 hole 110/74 person I don't have a direct interest in these cranks but out of curiosity does anyone know why the crank shoulder is different?

I imagine it's because the people who design this stuff hate you, and take a sadistic pleasure in imagining you cursing away in your workshop as you find that stuff you thought was compatible, isn't. I take a comparable pleasure in getting out my file (or better still, IIRC I did this particular job - very carefully - with an angle grinder), and thwarting them.

[Sweep]

Update update.

Have now taken the 510 middle and big rings off (will save them as spares for my Hewitt) and put some Alivio 430 9 speed rings (32 and 44T) on - they fitted just as well as the 510. Also black - quite possibly both steel judging by the weight of them.

Life is so simple when you don't go beyond 8 and 9 speed

[reohn2]

.......Life is so simple when you don't go beyond 8 and 9 speed

To a large extent I agree(Shimano) 7,8 and 9sp are,to a great extent,intergangeable,mech,cassettes,chainrings,and hubs plus 9sp chains can be used on 7 and 8sp d/trains.The only flaw is that mtb and road front mechs have differing cable pull,but that isn't a problem with a friction lever.
10,11 and 12sp appear to be each an island of their own with 11 and 12 needing their own specific hubs.