The problem with a tensioner like that is that since it presses on the chain, it would wear through very quickly on a bike used at high speed (on road) and over any distance - trials bikes by their nature don't cover many miles, and not at high speed...

Jx

We are currently brooding over an adapter solution fitting the inner side of the left swingarm. It should plug into the inner swingarm holes and reach downwards into the chainline. The adapter could probably provide those eyelets to fix a chain guard or just reach down far enough at both sides of the chain to keep it from laterally escaping its natural position.
Probably a carbon solution. No idea. A mate from xt-660.de who is capable of doing CAD work might probably have a look at it. Otherwise I might try to mold something somehow... well no clue right now. I hope we find a feasible solution, and probably without the need to drill swing arm.

Phil

I'd have thought a spinning, polyurethane/nylon wheel would be OK. A bit like a skateboard wheel with a bearing. It would just need a groove machined round it to locate the chain.

rob

rob in a word k.i.s.s. [or acrinom]

the block design has done about 20,000 miles thats 2 salt fest winters, gritty offroads, fortnight trailing in portugal and a blast in sandy stuff to a place called dakar. methinks skate board rollers may have not done it. but hey i'm willing to be proved wrong!

bernard

I agree with Bernard - there is a reason that every enduro bike uses a polyurethywhatsit block and chain slipper to guide the chain, while any rollers above and below the swing-arm are just there incase the chain 'bounces' during suspension travel...

Ideally, the chain (when you are sitting/riding on the bike) is not actually touching any part of the slipper/guide/rollers - it is essentially floating - and only if the chain moves (or is moved) significantly from it's line do the guides keep it in place... If a metal chain is constantly rubbing on a plastic/polyurethane block, it will soon wear though, particularly at road speeds...

This also happens if you run an oversize rear sprocket too close to the lower guide block, and the chain rubs on the trailing edge - in such circumstances, rally bikes can eat a guide block in a day or less...

Jx

This also happens if you run an oversize rear sprocket too close to the lower guide block, and the chain rubs on the trailing edge - in such circumstances, rally bikes can eat a guide block in a day or less...

sounds like the voice of experience!

Hee hee - not me, but I know Tamsin had a lot of problems with the chain guides eating themselves in 2010...

Jx

ps. and I'll say it before anyone else does - guess I didn't get far enough for it to be a problem this year... ahem. (even though I'd ridden over 3000kms x)

..well i got roud to fitting me guide ..and thanks for the great idea

99p off ebay [only bidder ] he he

ive fitted it a little differently or cheated ... depends on you point of view

so far its been fine and a great place for the scottoiler feed

the advatage advantage is its easy to remove if it gets banged up and easy to replace without having to split the chain ..which is a pain in the ass

all i did was punch out the spacers with a 6ml bolt split the guard with a hacksaw ..a bit of wd helps when sawing ..

fitted tyhe brackets as described and put the guard over the chan and repressed the spacers bac in afterwars
[i filed them slightly before so they are flush ]

thats it at the moment its seems to make no difference nice and secure ect ..if anyone was carrying a spare it would only take 5 mins to put it on

http://img62.imageshack.us/img62/7756/img1800i.jpg
By minkyhead at 2011-03-14

http://img220.imageshack.us/img220/7035/img1801v.jpg
By minkyhead at 2011-03-14

http://img97.imageshack.us/img97/5127/img1802pm.jpg
By minkyhead at 2011-03-14

http://img687.imageshack.us/img687/6830/49200133.jpg
By minkyhead at 2011-03-14

hi minkyhead, yup thats the ticket, nice job!

although i havn't done it to the tenere guide, running the saw through the block is the best for replacing/ removing as i always rivetlink the chain

last weekend i was doing a h&h on the gasgas, just a 2 hour event and after 1.20 the chain was derailled with a stony slurry type mud on an overtake out of a slow corner. the chain was so mangled in around the front sprocket it needed the swingarm to be removed. obviously after a long push and retrieval home.
unfortunately it's not just a chain needed it broke 3 teeth off 1st gear and that needs a new shaft as well as a corresponding gear on the output side ho hum and i was leading the expert class passing a backmarker such is life!