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  1. #1
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    Idea! Moding a DHR to 7 inchs, input needed.

    I have been toying with the idea of decreasing the travel on my DHR from 8.5 to 7 or 7.5 inchs. Couple of reasons

    1. I want to lower and slacken my bike without drilling it
    2. I don't like to run alot of pedal platform, i want a bit less travel so it doesn't bob as much
    3. It would be more fun to ride
    4. It would teach me to ride smoother
    5. It would be a fun play bike with a totem single crown

    My question is, if i change my shock from 9.5x3 to 9x2.75 or 9x2.5, how will i effect the quality of the ride? I will be starting the shock off earlier in the rear suspension curve, will it become too progressive? Changing the shock size is easy, i have any avy and only need a $10 part. Would i need to change my spring and shims setting?

    I don't have time to do an analysis at the moment and was hoping someone could just give me the lowdown, looking at you DT and turner bikes........

    Thanks

  2. #2
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    Just a quick thought...average ratio is still the same (although as you stated, you would be in a different area of the rate curve) so I would think that you could keep the current shim stack (may not be EXACT, but should be close). You will need a stiffer spring. It depends a little on how your spring is now, but going to 7 in travel (2.5 in stroke) would need ~18% increase on spring to keep the same sag percentage.

    Dont you already run a wierd size Avy..like 9.25 inch eye to eye..?

  3. #3
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    Quote Originally Posted by davep
    Just a quick thought...average ratio is still the same (although as you stated, you would be in a different area of the rate curve) so I would think that you could keep the current shim stack (may not be EXACT, but should be close). You will need a stiffer spring. It depends a little on how your spring is now, but going to 7 in travel (2.5 in stroke) would need ~18% increase on spring to keep the same sag percentage.

    Dont you already run a wierd size Avy..like 9.25 inch eye to eye..?
    Yep, i run a 9.375 x 3 inch shock and want to get it lower and slacker. Its at the limit without having to whip out the dremel and drill, and its been a really good frame to me (2 years + ) so i don't want to hack into her, and i have always wanted a little less travel, 7inchs of avy travel is just fine. I also want to mod my boxxer WC down to 7inchs to make it more progressive (i find it a bit linear, guys have done this and it works well) so i need to fix up the rear at the same time.

    I was thinking that the valving should be ok, i was going to get the hi/low adjuster put in so i can fine tune it, and im running a 450lb spring now, and i have a 500 and 550lb spring already so thats all good.

    I am mainly concerned about it become harsh and ramping up too quick. If it starts in the steeper part of the curve then it won't have that nice subtle initial stoke. I don't have the curves to look at so im not sure, and i haven't got time to play with the linkage program atm.

    Thanks

  4. #4
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    What do you weigh? My DHR (05) came with a 450 but I have been running a 411(yes 411) for a while and have yet to notice a hard bottom, and I am 190 195 lbs with gear.

    I compeltely understand the shorter travel deal. I have a RFX at 5" and ~ 5/8 " lower for my "non-DH" bike.

    I have my DHR drilled to lower it as well. For some reason, it it did not need any main frame mods, like your seems to. I also got ahold of Greg @ turner and got a second rear triangle at a VERY reasonable price before drilling, so to be able to return the bike to stock form if needed.

  5. #5
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    Quote Originally Posted by davep
    What do you weigh? My DHR (05) came with a 450 but I have been running a 411(yes 411) for a while and have yet to notice a hard bottom, and I am 190 195 lbs with gear.

    I compeltely understand the shorter travel deal. I have a RFX at 5" and ~ 5/8 " lower for my "non-DH" bike.

    I have my DHR drilled to lower it as well. For some reason, it it did not need any main frame mods, like your seems to. I also got ahold of Greg @ turner and got a second rear triangle at a VERY reasonable price before drilling, so to be able to return the bike to stock form if needed.
    95kg + gear, whats that in pounds, 210lb's. I run the 450lb with 2 1/2 turns of preload, its a little bit soft actually, but thast to make it nice and soft initally, then ramp up.

    I asked turner about that already (probably 7-8 months ago) and they said no dice, although i was asking about getting a cheap second hand one from any warranty returns.

    Yeh, not sure what the deal is with my frame, mine is an early 04 model. If i slacken the bike out anymore the swingarm will hit into the machined yoke area at max bottom out. Due to the problems with 03 cracking around there due to lack of material i am reluctant to dremel there. Maybe i could get a second swingarm and dremel grooves into the swingarm to clear it and do the drill mod..... hmmm......

    Still wouldn't mind a travel reduction though. I saw the new "progression" movie the other day and it had me lusting after a 6inch burly travel bike......

    Did you find the mod changed the feel of your bike at all? I know that when i changed my eyelet 0.125" it did seem to make it ever so slightly more harsh. Maybe i might have to machine up some custom links, could be a fun project

  6. #6
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    Bumpn' it up

    I had some spare time so i plotted my DHR's rear wheel travel (as traced by an arc around the pivot) vs shock shaft travel. Red is the DHR curve, black is a linear line starting at the start,

    It is slightly progressive, but not as much as i thought it would be. DT, is this close to realistic? Obviously there is some slight errors due to measureing with a tape measure. Looks like a shorter shock won't be effected much at all, can you shed some light on this Dave??

    Thanks
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  7. #7
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    If you switch from a 9.5 x 3 to a 9.0 x 2.75 the shock will be 1/2" shorter but get only 1/4 less travel causing the linkage to compress further which may have clearance issues and cause the rising rate to fall off and bottom easily. Probably not good.

    Going from a 9.5 x 3 to a 9 x 2.5 you shorten the shock 1/2" and also the stroke 1/2". Sounds good.
    1/2" less stroke would yeild 7.5" travel at 3:1, but don't the DHR's get 8.5" (?)so that's 2.8:1 yeilding 7.0" travel. Also good.

    But you have a slightly shortened shock and it doesn't hit anything at bottomout(?) so maybe you could squeeze in the 2.75 stroker.

    Krispy
    Currently enjoying life Giant Trance Advanced 27.5/Rockshox Pike/Sram XX1
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  8. #8
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    Buy a highline you cheap bastard.

    I know US built frames are like half price where you live.
    STRAVA: Enabling dorks everywhere to get trails shut down........ all for the sake of a race on the internet.

  9. #9
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    Quote Originally Posted by krispy@go-ride.com
    If you switch from a 9.5 x 3 to a 9.0 x 2.75 the shock will be 1/2" shorter but get only 1/4 less travel causing the linkage to compress further which may have clearance issues and cause the rising rate to fall off and bottom easily. Probably not good.

    Going from a 9.5 x 3 to a 9 x 2.5 you shorten the shock 1/2" and also the stroke 1/2". Sounds good.
    1/2" less stroke would yeild 7.5" travel at 3:1, but don't the DHR's get 8.5" (?)so that's 2.8:1 yeilding 7.0" travel. Also good.

    But you have a slightly shortened shock and it doesn't hit anything at bottomout(?) so maybe you could squeeze in the 2.75 stroker.

    Krispy
    I have an avy, so i can shorten the eye to eye the same amount as the total reduction in travel, meaning nothing will hit. I

    So i will go from 9.375x3 to 8.875x2.5 which will yeild approx 7 inchs of travel and not result in any contact.

    Also going to mod my boxxer airs to 7 inchs by putting a 1inch spacer in the -ve air chamber.

    So i will end up slightly slacker, lower and more nibble and fun. Most of the tracks around here where i ride (in australia) are tight and technical, i think this would suit the conditions better.

  10. #10
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    Quote Originally Posted by kidwoo
    Buy a highline you cheap bastard.

    I know US built frames are like half price where you live.
    Hmmm....... tempting, but i like my DHR, its been so solid for the past 2 years so i see no need to get rid of her yet, and i still want a DH frame, the highline is too upright and the BB is a tad high for my liking.

  11. #11
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    Sounds Hot! Do it up!

    I watch Super 8 a lot-seems all exotic here! (in USA). a 7" bike looks just right for the Aussie nats courses or general screwing around there.
    Currently enjoying life Giant Trance Advanced 27.5/Rockshox Pike/Sram XX1
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  12. #12
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    I don't see why this should be so complicated. Remove shock, compress suspension, measure distance between shock mounting eyelets at the point where something starts to interfere in the swingarm/linkage. This is the minimum length of the shock at full bottom out. Add to this length the desired stroke to get the eye-to-eye length, no?

  13. #13
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    Quote Originally Posted by big-ted
    I don't see why this should be so complicated. Remove shock, compress suspension, measure distance between shock mounting eyelets at the point where something starts to interfere in the swingarm/linkage. This is the minimum length of the shock at full bottom out. Add to this length the desired stroke to get the eye-to-eye length, no?
    The question is not about frame interference, if you read what i said its already been checked.

    The question is how will starting the shock further into the shock curve effect the suspension feel. ie will it ramp up to much, be too harsh etc etc.

    krispy, thanks for the egg on, might have to do it now

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