My 13y.o. son's DMR Sidekick keeps losing its chain on any bumpy terrain – which is a tad frustrating for the young'un when he's at the local mntn-boarding/biking place.

We've gone 1×9 with it because we live in a fairly hilly area (he inherited XT derailleur and XTR shifter off me) – but recently the chain has been coming off quite regularly. Is this chain stretch (could remove a couple of links?) or does he need a chain device to add tension at the front end? (eThirteen spotted by him at 70 notes… :cry:)

Any advice appreciated…he's available for car washing duties !

yes you need a chain device.

For a cheaper option, i think you can just keep the front derailer in whatever ring position you run. Not done this myself but pretty sure iv seen it done.

Try Here 😉

I had one of these on my DH bike and my trailstar and it worked really well and is a lot cheaper. Easy to fit too.

No need to spend £70 even. One of these will do just fine:

MRP 1.X

Superstar do a 'full'(ie upper guide plus lower roller) chain device for £35, okay so its not DH race bike weight but its pretty cheap compared to pretty much everything else
The bike will need ISCG/ISCG03, ISCG05 or a Bottom Bracket mounting though
So if the frame doesn't have 3 bolt mountings, or an external type bottom bracket bearing cups, then you'll have to get a special chain device type bottom bracket, or if the frame has a 68mm bottom bracket shell you can use a 73mm bottom bracket, stick the chain device on one side and add an external bottom bracket 2.5mm spacer on the other

There are loads of other ways, but if the bike is for jumping etc then it maybe that a full chain device maybe best

Other solutions include:
Front mech with low limit screw wound out and clamped so it sits low to chainring
Bash guard + inner bash ring (~£16* + ~£28**)
Bash guard + N gear jump stop (~£16* + ~£10)
Pauls components Chain Keeper (I think its called that) (~£50?)
Rohloff Chain Guide (~£50)
MRP 1x/e13 XCX top guides (~£40)
there must be more

*eg FSA polycarbonate on CRC
**eg blackspire on CRC

You have got the correct length chain haven't you? round the biggest 2 rings (only got the one at the front) plus one pair of links overlap

Thanks for the advice all, will check out recommendations…

I wrecked a N-gear Jump Stop today, not sure how but guess a flying rock I had kicked up knocked it out of position & the chain did the rest. It was only 3 rides old. Now looking for a proper chain device 🙄

You are using an unramped chain ring? – it makes it less likely to drop off combined with running the chain as short as possible

TJ +1

ie, get a single speed chainring. Ordinary chainrings are designed to allow the chain to slip off easily for swift gearchanges. If you don't want the chain to come off, use a chainring that is designed for the job.

My record was 13 dropped chains in a 1h 20m race on real rough terrain and that WAS with an UNRAMPED ring.

You need something amongst James spot on list of retention methods.

IME an unramped chainring will make a difference if you're doing "pootling round a woods" style riding. If it's racing or bumpy DH stuff, then you'll still need a chain device.

Superstar do a cheap chain device that gets good reviews.. might be worth a look.

http://www.singletrackworld.com/forum/topic/fs-rohloff-cc-chain-guide-for-1-x-9-ss-1

Use one of these on my setup, works fine, easy to setup too.

… and a shorter cage rear mech?

Thanks TJ, the chainring is unramped.
The bike has been fine for the last 5/6 months, ridden regularly with no 'chain' issues so may be a bit of stretch or his riding is becoming a bit more enthusiatic / aggressive?

How tricky is a typical chain device to fit? One for the LBS or easy-peasy?

I use a cheapo Alivio front mech and the green bit-o-plastic to keep it in the right place. The chain has never come off and it's had plenty of abuse.
EDIT: oh and a medium/short cage as suggested will help

I've just bought the e13 xc chain device thing and its a load of sh1t – how they get away with charging £35 for something that has so little adjustment (and consequently doesn't work) is beyond me. Unless you're running road bike tolerences on your front ring/bb, I wouldn't bother with the XC specific ones (that includes the MRP one as well).

Just wind the adjuster screws out on an old front mech

Proper chain devices can be agro to setup but great when sorted, something like an MRP or pauls chainkeepr or the n gear jump stop and bash are fit in the dark easy…

When I run 1×9 at first it wasnt too much trouble but they do get lots worse as the chain wears its not the strech as much as how much easier a worn one goes side to side,,,,

Just make sure you got it as short as possible, fit a simple device like the Pauls chainkeepes and it should be fine.

I have a barely-used Truvativ Boxguide you could have cheap.

Check them out and drop me an email if interested.

They work good on a 1×9 setup with no bash, I have one on another bike.

I bought the Superstar one for my son, he has an Identiti and 1×9 setup.

Well made and works well.

+1 for the MRP

front mech only will do it. no problemo.

DMR Chaincage is more adjustable than the MRP or E13 offerings!
Cheaper too, here.

Have you checked the chainline. If the chainring is on the outside rather than middle as soon as he goes up gears it will pull it off,

TJ+3
Something with nice long teeth should be ok.
Triple ring 'rings do the chain shed more.

I run an unramped ss ring and bash and I lost my chain too many times at 'degla. I am going the jump stop route to stop my woes.

I finally gave in and got an MRP 1x, fed up of chain falling off during the fun fast parts of the ride. One warning though, the bolt is made of alloy, I managed to ruin mine very easily, had to drill it out and put a proper steel on in there. Works well though.

DMR chaincage back plate with a bashring. I didn't use the full chaincage as it drove me mad rattling at either end of the cassette. So far no problems with this.
[img]http://farm4.static.flickr.com/3055/4563053364_e37dde8a59_m.jpg[/img]

For cheapskates….
One old Alivio derailleur, a bolt, some penny washers and assorted other aluminium spacers (washers would do). Remove cage, add spacers, flip upside down, et voila, one chain retention device.
Take a hacksaw and file to it to remove redundant lumps and it even looks quite slick (from a distance, with mud in your eyes).

i have a dmr chaincage (right size for the DMR) that i'm looking to sell.

£15? email in profile…

crogthomas, that's genius!
Gonna have a go at making one myself 🙂