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ok ive got an old iscg lg1 on my dh bike and decided to put it on my 125, the holes didnt line up so i assumed it must be iscg05, so i ordered a new backplate which arrived today and also doesnt fit at all, am i missing something here? i thought there were only 2 types of iscg! thanks in advance

matt

There are, ISCG and ISCG 05

get a pic of your (iscg) holes.

(http://img80.imageshack.us/img80/9927/dsc01025zp4.th.jpg) (http://img80.imageshack.us/my.php?image=dsc01025zp4.jpg)

(http://img379.imageshack.us/img379/6185/dsc01026hu6.th.jpg) (http://img379.imageshack.us/my.php?image=dsc01026hu6.jpg)

in the second one i have the chainguide lined up the way i want it but only 1 bolt hole lines up. Possibly a manufacturing problem?

Whats the distance between the centres of the holes?

Compare it with this http://www.e13components.com/support_iscg_explained.html (http://www.e13components.com/support_iscg_explained.html)

there are standards:

ISCG OLD

and

ISCG 2005

the '05 arrived because the royalty-free standard of ISCG (not originally called "OLD" but just ISCG) was misunderstood by designers and frame fabricators and therefore frames arrived with the ISCG mounting holes "rotated" to suit the width or height of particular chainstay / swingarm tubes

ISCG 05 was designed to improve this by increasing the BCD (bolt circle diameter) and also indicating the mounting holes relative to the frame geometry to ensure that a chain device could be bolted straight on

HOWEVER....certain frames which use chunkier tubesets will still not accept certain ISCG chain devices as the thicker chainstay or swingarm will not allow the mechanic or home builder to rotate the backplate to line up with the mounting holes

for example, the Mythic Scythe will accept an E13 SRS ISCG 05, but not the E13 STS ISCG 05, because the STS takes up to 36T chainrings and the Scythe's thicker swingarm does not allow the smaller STS to rotate sufficiently to line up with the mounting holes - this is also true of other brands

with a frame like a Specialized SX Trail the ISCG OLD mounts are actually rotated forward to clear the low slung swingarm, and an E13 SRS ISCG OLD will not fit unless raped with a file and hacksaw....

E13 are actually pretty good in providing a "fitment" chart to help people get the right device, for example the old banshee scream frame required a "wide" backplate rather than the std. E13 backplate

this is why its good to have an experienced. bike mech. fit your chain device, the best £20-30 you will ever spend ;)

thanks for the help guys, my mate has a srs iscg old on his 125, so i guess ill just have to get one of those and fit the lg1 conversion kit, the 125 isnt listed on their fitting chart, so its kinda hard to tell, may have to just go for an mrp or another bb fitted chain guide.

thanks for the help!

BTW I think that your problem is that all the holes should be rotated around.
Check out...
http://www.iscg.org/INTL_STD_MTG_LOCATIONS.pdf
Thats bad from norco (i'm guessing tis a norco 125)

A little bit off topic but my LG1 came from chain reaction the otherday and the bolt hole slots on the backplate werent countersunk??

yeah it is, my mates srs fits on his no problems, but i dont wanna have to get that then get an lg1 kit for it, too much £££

you may be able to use a bb-mounted iscg adaptor, I don't know if it would interfere with the current mounts, but may be worth checking out.

simple option is just drill 2 or 3 new holes where you want it mounted.

you can't use a b/b adapter in conjunction with a frame which has ISCG mounts as it interferes...

you can always cut off the ISCG mounts and run the b/b adapter (which does the frame no harm if done carefully) but its kinda easier and "cheaper" to sell off a chain device and buy the correct one for your frame ;)