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Fitting a 3" Avy shock to a 2004 Norco A-Line

Jan 12, 2005
200
0
Lancashire (U.K)
Bit of advice needed.

I have a 2004 Norco A-Line, pretty much all of the parts have been upgraded by now and the bike suits me down to the ground. The shock is the Fox RC 2.75" stroke. I wasnt happy with its performance when I bought the bike. I had it revalved and re-sprung by Mojo here in the U.K. It is now better but Im looking to change it for something plusher.

Also the standard linkage plates to me are a little thin and undersized and could be causing some flex along with the fastener/mounting hardware.

Personally I do not see the point to 'platform valved' shocks, I would rather have a shock as compliant as possible-I can live with a little 'bob' I hardly pedal the thing anyway! The RC is running Mojo's Works valving which has a platform. It is better than stock but after trying an Avy equipped bike I realise it is still pretty un-compliant and spikes quite a bit.

The above points have led to the possibility (as well as the UK to US exchange rate) of fitting an Avalanche DHS shock.

Whilst I’m changing the shock I am going to get some new linkage plates machined up (F.O.C. courtesy of my work) as the frame will accept another inch of wheel travel, Iv tried with the shock off and measuring everything (taking it up to 9” from its standard 8”). I plan on keeping the BB height and head angle the same but the travel will continue another inch on from its current 8” end position due to using a 3” stroke shock as opposed to the 2.75. This increases the shock ratio from the Fox RC’s 2.87 :1 to 3:1 for the Avy with 9” wheel travel.

I am planning to keep the length of the linkage plate the same as stock to keep the Horst link/dropout angle the same but to have the shock mounting hole ‘¼ “ further away (due to the Avy 9” eye to eye length as opposed to the RC’s 8.75”) but 3” away from the linkage main pivot point rather than the stock 2.9” position.

Please click on the link below to Avy’s fitment chart showing the Norco Team Shore (same frame as a 2004 A-Line) to make a bit more sense.

http://www.avalanchedownhillracing.com/bikes/2004NORCOns.jpg

My question is; how much will this alter the shock’s rising/falling rate? The linkage mounting point will be ¼” further away (towards the rear wheel) than it currently is and 0.1” further away from the linkage main pivot point. (towards the seatstay pivot point)

Admittedly Iv not drawn it up in Autocad yet, but mentally figuring out rising/falling rates is mashing my head up.

Any help or information would be gratefully received. Cheers.
 

banj

Monkey
Apr 3, 2002
381
0
Ottawa, Ontario
The 2004 A-Lines are supposed to have a 8.5 x 2.5" vanilla rc giving 8" of travel. If you've got a 8.75 x 2.75" in there already then you've already upped the travel to around 8.8" of travel as well as jacking up the bottom bracket and steepening the head angle.

My advice would be to sell the frame and get something that has the geometry and travel you're looking for. It will most likely end up costing you less.
 
Jan 12, 2005
200
0
Lancashire (U.K)
err yeah sorry it has got the 8.5*2.5. Id got it in my head it was 8.75*2.75. Im a halfwit at times.

Looks like an 2.75 Avy then with the same problems as per me thinking i was fitting a 3" stroke Avy.

I like the way the frame rides, the linkage plates are being made through work (so therefore F.O.C.), and the GBP/US Dollar exchange is good for us Brits. An avy is only slightly more expensive than a Fox DHX.
 

DHS

Friendly Neighborhood Pool Boy
Apr 23, 2002
5,100
0
Sand, CA
well for one, tell Avy what bike you have. he can make one to fit your bike exactly what it needs. look at the sizing charts of the shocks. get the correct one.

you have new linkage plates made up. just get a new bike. you still have the geo and headangle of your first bike. you add that much travel its gonna feel like crap..