Can You Change Your MTB Rear Shock Size? | Ask GMBN Tech

– Welcome to Ask GMBN Tech
this is our weekly Q&A show. Get your questions in,
in the comments below. Use the hashtag #AskGMBNTech
or alternatively, you can email your questions in to the email address right there. First up this week is from James Doyle. “Hi Doddy, can you
explain rear shock sizing “and can you install a larger travel shock “on a bike?” Yeah, there’s quite a lot
to explain here really. Well first, I’ll look
at the shell of a shock. There’s two real measurements on a shock. There’s an auto wide length of the shock. And then there’s the shaft stroke travel. So you’ll often hear of
a shock being referred to as a 200 eye to eye and a 57 stroke. So the eye to eye refers quite
simply by the measurement between two eyelets,
end to end on the shock. And that refers to if
its actually going to fit in a specified space on a
certain type of suspension bike. The next measurement refers
to the actual shaft travel of that shock and then
within those two measurements that are different variations. Now depending on the layout of a frame, you’re going to have a
certain amount of space in which you can put
that shock and obviously a certain amount of
travel the shock can have and that directly correlates
to my rear wheel travel. So this is how frame designers
decide how they want the bike to ride and how they
wanted to actually feel, out on the trail. So often heard hear the
term leverage ratio applied when bikes and manufactures
are talking about the back end and bikes. So for example, if amount of bikes, got two to one leverage ratio for every millimeter
that the shock operates, the real wheel will move twice that. That is a two to one
ratio nice and simple. Now with that in mind
by manufacturers spec, a variety of different
shocks to give their bikes, different fields and of
course it all comes down to the suspension design
of the bike as well. So there’s lots to factor in that. Now, just for example in
ideal world are manufactured one of us is shock with
the most amount of stroke possible on it because it
simply allows for more tuning and it’s going to actually
cope with what the, what is happening in the
rear wheel a lot more. Just for example, if you had a
bike that had 200 millimeters real travels like a downer bike, if had a little little shocking and I only had 40 millimeters of stroke, that shock is going to be
working incredibly hard the oil in there is going to heat up and as a result of that, the damping is going to be quite erratic, it’s going to be all over the place. Whereas if it had a sharp
travel of 57 millimeters or even longer than that, the longer the shaft is the
more oil that’s in there, the better that the shock
is going to cope with it. It’s all about finding
the best compromise. Now shock sizing itself. There’s what we now call the metric system which is pretty much common
place on most bikes now and certainly all bikes going forward. Once upon a time, shocks would come in a whole
bunch of different variety. I think it’s about nine different options something like that. But the point is that they
were all unusual lengths and didn’t really correspond
to the shaft travel. It was a bit all over the place. So the metric system
basically what it does is simplifies this and takes
it down to about six options that’s far less options there
and within those options they’re actually offers a
chance for manufacturers to spec and more consistent shock that offers more to the consumer and obviously to manufacture bike, to make sure it rides appropriately. Effectively, It gives the
manufacturers bit more freedom because they do know that
whatever shock length they spec in metric, in theory, it should perform exactly as well as any of the other shock sizes. It’s just that picking the
size that correctly fits the bike design have. As for just checking in a shockwave longer stroke length into your bike. Yeah, you can technically do that. But there’s a few things
to bear in mind now. Firstly, is it extends
the back end of your bike, there’s a good chance that
shock could hit your seat tube or depending on the design of your bike. Part of frame could contact
that’s not supposed to contact you don’t need me to say that’s not a very good thing to happen. Then of course with having more travel you might find the wheel
strikes the frame your saddle or even parts of the
frame strike each other there would have been a
nominal amount of clearance to cope with previously. So if you do want to do that, just take that into consideration. Now also if your bike does cope with that and does allow it longer
shocking to get that more travel it’s not going to hamper it you might find that it twisted geometry and you’re not gonna like the wet right because it could may
have been bracket to high which in tournaments
deepen your head angle would steepen your see angle. There is various different
effects of doing this. My recommendation, stick with the correct
length shop for your bike. Okay, next up. Forgive me
if I can’t pronounce this. Bartlomiei Kazmierczak. I hope that’s right or even
close to it would be good. Hello Dolly. Is it worth
upgrading aluminum handlebars and supposed to carbon
on an XC hardtail bike. I am worried about durability
when riding in the mountains. Yes and no you’re going to get not that much more performance. But for the same post, there won’t really be
any performance upgrades. You might lose a little bit of weight. But the regards of durability the hourly post is definitely better. carbon bar. Again, you
might lose some weight. But actually there are
some performance benefits to running a carbon
bar and that’s comfort, lightweight carbon handlebars
do absorbs on that buzz. You get out on the trail. But of course, if you’re crashing or there’s any chances
your bikes is going to be grinding against any rock
or anything about that, then there’s a Chartist
can get damaged easier, certainly than aluminum. Perhaps I would look at doing
some upgrades in other areas of your bike instead
using that same money. All right next to geometry related one, from the imaginatively
named Septem Roptem. Can you put 27 and a half inch on a 29? Yeah of course you can. it’s definitely going to have
some adverse effects though. So first up your bottom bracket height. So on a 29 inch wheel bike, obviously your bond brackets
can be high off the deck. So by putting 27 half inch wheels In it, it’s going to be slammed so you’re crying so you’ll
be so close to the ground, you can be hitting them all the time. So not good from that respect. Next up is you’re going to
have some steering problems. So there’s two things you’ll
often hear talked about one of those is offset and
the other one is trail. In fact you’ll hear
trail referred to less. So the offset is the
distance your fork axle is based in front of that steering access. So imagine drawing a line
all the way through your head all the way down to the to the axle, you’ll find quite often the
axle is stepped forward, that is your offset and you
can get different offsets on different forks and that tends to happen by getting a different
crown steer unit assess where the offset actually happens, as opposed to happening
at the actual bottom of The fork there. Now there’s also measurement called trail. Now trail is a distance
between the tire contact patch on the ground and that virtual line going all the way through your head tube where it meets the ground there. One of the problems you
have with 29 is we’ll biases as your actual get high off the ground, the trail measurement basically increases so what they used to
do is change the offset in order to bring it back again. So by putting smaller wheels on your bike your hardly is going to
go all over the shop. next up your chain stay length
is going to feel pretty wacky by putting a smaller wheel in there defect is basically by having
a bigger wheel in there It makes the chain feel shorter by putting a smaller wheel
and it makes you feel longer. The longer chain stay is the more weight you have
to pull back on the bars in order to lift a finger off the ground. As a benefit though, it does bring body weight
further in the middle of the two axles of the bike. I personally quite like
a long chain state, but it’s definitely going to
change the way your bike feels. Now back in 2014. There’s a couple of writers
at the Meg avalanche both writing on the commerce ad team, one of them is Nico quaint and the other was Pierre Charles George. Now they were both running 650b commerce our bikes at the time, but the mud that year was so bad that they both swap to 26 inch wheels in order to get through the frame but you’ve also got bear in mind, the difference between 26 inch
wheels 650 B is a lot closer than 650 B to 29 inch wheels. So I don’t think you want to
be messing around with that when your bike but by all means put in some of your friends wheels and have little play around. Next steps from SB. Is it bad practice to
be sitting on the seat when the dropper is fully down? sometimes I like peddling
around with the seat down maybe when session
features for an hour or so but I’m concerned that it
might damage the dropper since It was designed for dissent when you’re not when you’re
supposed to be stood up. No it’s absolutely fine
basically drop a post. what they do is they move oil
from one chamber into another and I have air basically
that when you Open, the portal allows all to flow back in and the air basically helps extent so pretty simple system of
course there are intricate parts on the inside but when
it’s lower and slam down You are absolutely fine
to use it in that position in fact you are ok to
use it in other positions as well within there don’t
feel confined to using it fully extended all the time. So job done it’s a drop the
post enjoy being dropped Next steps from Mick gearing. Hey Doddy thanks to you and the team for providing us with great content, I love tuning in and learning
new things every week. Thank you. Thanks Mick.
I really appreciate that. And my question is about
volume spaces in forks and rear suspension cans. I’m on a slightly heavier side but not too out of shape
body wise thanks to riding frankly again at the moment I find myself on the upper limits of the fox 36 performance elite and a DPX2 float evol
pressure charts for my bike. will adding volume spaces to my suspension helping reducing? How much psi is needed
for my targeted sag range between 25 and 30% or a primary designed for getting the suspensions
to ramp up quicker Do I need to look into suspension products that cater for higher psi requirements my bike is a 2018 giant rain advanced one. I’m riding as much as possible to continue reducing
my weight to come down in required psi for Fox gear on my bike. Okay so there’s there’s a lot to this. So first let’s look at the
air pressure recommendations for your fox and shocks. So looking on the fox site, they say evolve equipped
DPS and DPS two shocks, they’ve got maximum pressure of 350 psi. So that’s quite significant
amount of pressure people need shock but something that you really
need to take into account this is the amount damping that
you’re putting on that as well. So with more pressure put in a shock you think is stored energy you
really need to control that as much as possible. That can have an effect
on how the bike feels even if it is slightly over the sect. now also take into, account now this is
foxes recommendation here that the pressure measure
in ambient temperature of 70 to 75 degrees Fahrenheit normal operating temperature
range of Fox products is 20 to 140 degrees Fahrenheit. now Fox I’ve got a pretty
helpful way of checking the maximum volume spaces
which will definitely help with your ride because they
do of course affect the end of the stroke and how it ramps up but they do have a slight overall feel and you do tend to have to
run slightly less pressure with the I’m talking maybe like five psi it can be enough to make a difference so if I should definitely
try a ramp them up with as many volumes basis
as you can have a product. So I’m just throwing
you a link on the screen now is a link to the right folks website and you’ll fall your forks and your shocks will have a little four
digit ID code on them. So if you put that into the
search product information, bet it will bring up all
the information about your particular focus shock. I’m guessing you probably know this because you had referred
to the pressure charts so it’s the next step up from that. But also the other things
to take into account the suspension design on bikes. Now your bike is a linkage bike. So for example, a single
pivot bio code orange, you’re gonna need to be
slightly lighter rider in order to use out over a linkage bike just because the amount of pressure you end up using in those shocks. I don’t quite know what
the max is on yours. But the truth is, is something you’re going to
need to play with yourself to get exactly right on there. I’m almost certain whatever your weight you can get the bike chained
in to feel just right for you, but it might require a little
phone call for some tips to a dedicated suspension tuner, someone like videFoxUK or
TF chewed or sprung over enforce a thing and there are
a number of those in Europe, in Asia in America
wherever your base as well I hope you can get that figured out. Sorry. It’s a bit of a vague answer on air like the volume spaces will
definitely make a difference. But its Definitely something
you can need to play with to see how they feel. She might also not like the way that they change the
characteristics of your body. And then we go there’s another
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91 thoughts on “Can You Change Your MTB Rear Shock Size? | Ask GMBN Tech

  1. #askgmbntech Maybe a dumb question but I have Shimano Hydrolic dis brakes on my Big Honzo. The rotors say "resin pads only". Why is this and what would the effects be if i choose to use sintered? Thanks!

  2. No, measuring is from center of the eye, to the center of the other eye. Not as in the video. That can make 10mm difference.
    For the rest good video.

  3. #askgmbntech Hi Doddy, I wondered what would happen to my fork if I keep it locked out while riding down a trail for more than just one ride and how the lock out system works

  4. #askgmbntech
    Hey Doddy!

    I got a SID World Cup 15×100 fork with the OneLock remote installed from factory. is it possible to uninstall the OneLock remote and put on new top cap, or do i have to buy a new damper unit?

  5. #askgmbntech hey doddy, loving the channel!!. What difference in the bike behavior would make a 140mm fork on a hardtail designed for a maximum of 120mm travel? A friend of mine wants to sold me a brand new 140mm rockshox pike rct3 at basicly half the price than any other place i can find it (it came with with his new bike). My bike is a specialized rockhopper pro, it came with a 100mm manitou markhor. I find my self out of shock travel pretty frequently, i would love to have a little bit more. Greetings from Argentina!

  6. To answer the last guy there, it sounds like you have set your sag and found you were bottoming out so have countered it with more air and are now running a lower sag. I'd definitely go for volume spacers and keep the sag between 25-35%. Countering bottoming out with more air just makes the back end stiffer. You've got a damn good bike there with some high-end suspension but you're not using it to its fullest.

    Defo spacers and correct sag.

  7. #askgmbntech Hi Doddy, I plan on upgradig my 120mm 26" Fox 32 fork to a 27,5" Fox 34 since there are no Fox 34 26" forks for sale. Can I run this larger fork on my bike with my 26" wheels without major consequences. I am aware that it will slacken my headangle a bit but thats fine.

  8. #askgmbntech can I put a 27.5 wheel on the front of a 29er and counteract it with a longer travel fork? while keeping the rear wheel a 29er

  9. #askgmbntech I have just bought myself a new 2019 Giant Trance Advanced 1 and am looking to slacken the headangle a bit. I have looked at some angled headsets but no one seems to make one that will fit an intergrated headset. Is there any other way I can slacken off the head angle ?

  10. #askgmbntech Hey doddy, i have a trek slash and the metric shock sizing is 230×57.5. i want to know if i can use a fox x2 with 230×60, there is some procedure to reduce the stroke of the shock?

  11. #hellogmbntech Please can you pass this link to martyn please as im hoping that this can help your injury

  12. Should have used a picture of a Foes for the 2:1 leverage ratio – Brent was the big advocate of 2:1 (versus the 3:1 or higher of most bikes). Tons of Foes bikes with 2:1 ratio.
    And, he did have a good point. The lower the leverage ratio the better off you are.

  13. Rs debonair plus is a real peach. You can Only mod 1 chamber, can use only a few drops of oil, any grease or access oil plugs up the chamber equalization holes and you end up with a stuck down. Pop off the cap to service and you chance ripping the upper bump stop oring. If you do that you need a full shock rebuild which is pointless due to cost. Complete nightmare design.

  14. Get a breezer supercell frame. Install 27.5 wheels, a 140 to 160mm 29er fork and you now have a burley trail bike thats super fun to ride on the cheap.
    120 rear and 160 up front with flat handle bars. Sounds dumb but it all works out and its super fun, cheap and not very expensive.

  15. I took a 2016 trance 27.5 and dropped in a 157×2 shock, a 160 lyric with a 2 degree slacker works headset. Bike is so much fun to ride. Super supple. Looks good and fun as f to ride. If your American and buy used from canadians you get a currency discount. Picked up a xl frame for 300 and a 2016 lyrik for 300.
    Do the service ur self and score giant lol.

  16. Hi Doddy! I own a 2019 Fox Float X2 and I was wondering if rear dampers have a "dead zone" of some sorts because I can't use the last ~7mm of stroke. Loving the show and greetings from Germany! #askgmbntech

  17. #askgmbntech How can I get rid of stiction? My fox 34 isn't feeling the same as back when I got it. Will a simple lower leg service help, and what can I do to keep it running smoothly on the daily?

  18. Hi doddy. How are 26" wheels closers to 650b than 29" wheels? Obviously they're both are 1.5" different, but the difference between 650b and 29" is less as a percentage? Cheers, Adam.

  19. Changing my aluminium bars to carbon made so much difference on my bike and reduced a lot of that nasty vibration that tired out my hands after a while.

  20. thanks for giving such a thorough answer to something i've been wondering about for a long time! Shame i cant just give it another 10mm travel. Guess ill have to get myself some spacers and see if that helps

  21. #askgmbntech hi Doddy I have recently decided to build a dirt jump bike, could u explain the rear axels on them for horizontal drop outs, thanks

  22. #askgmbn Hi Doddy, I would like to ask about the compatibility issues with Shimano’s new 12 speed freehub that is silent when coasting.

  23. Would it be feasible to put a reduced offset 29” fork in a bike designed around a 27.5” wheelsize. Specifically a 160mm 29” fork in a 2017 Stumpjumper 650B. Thinking of upgrading the fork, but would also like to future proof.

  24. #askgmbntech great content I am new into mtb and i love all the gmbn channels, I am always learning new things from you guys and improving my riding because of your helpful videos. So is it a big no no to ride with goggles without a full face helmet? would this make me look like a noddy and would I be breaking the mtb dress code if i did!?!? I find that the goggles look much better then the glasses and they provide more comfort

  25. #askgmbntech hi doddy, my rear shock rockshox monarch model R is have some squeaky sound , which kinds of annoy me. anyreccomadations on what i can do ?

  26. A carbon seatpost on a hardtail is a GREAT upgrade, as it eliminates a lot of the shock and vibrations coming up from the back wheel!

  27. As an Alaskan winter rider, I've seen people reduce wheel size and increase tire size for a much larger contact patch for more float in the snow. If the guy is going to go to a taller 27.5 or even a 27.5+ tire, his bike handling characteristics may end up fairly neutral and he gains the benefits of more air volume allowing him to run lower pressures for more float/patch.

  28. #askgmbntech Im going to buy a new yt capra al. Should I take 27,5 or 29. I heard that 29" is faster but 27,5 takes better the corners and it is more fun. I'm not a racer so the time is not that important. Also the. 29" climbs better but are the differences that big? I'm actually riding 26" and I think 27,5 will be a lot of fun. Could you give me advice?


  29. #askgmbntech hi guys, i’d like to know if it’s possible to put the right arm and the spindle of a gxp crankset apart so i can clean it properly, since is sand in there? excellent content as always, cheers

  30. Great job, Doddy: very clear and very accurate, as usual. Would you mind to come to Italy and apply for Prime Minister, please? 😉

  31. Hey mate . Awesome video and very interesting 🤙. Just wondering what the advantages are to upgrading to the 35 mm stem and handle bars ? I ride meloish enduro style trails 2-3 times a week and am buy no means a pro rider. Will I be able to notice any performance improvements or is it just that they look sick?

  32. #askgmbntech Hi 👋, I’m purchasing a 2013 giant reign, and would like to change the stock stem, but I have heard that giants steerer width is 1-1/4, would this make a difference to the stem that I choose to buy?

  33. What is fork offset? I own a 2018 Transition Patrol. Transition says that they use a shorter fork offset. I’m confused on what this means?

  34. I have a few questions?I want to get back into mb and loose some weight, my ride is gt avalanche 1.0 with disc brakes from around 2005 I think. what tire pressure should I go with being 340lbs, and do I need to have my fork tighter then usually? what shoe would you recommend for flat pedals? all I have are skate shoes. is there a bike rack for A 2012 Dodge Challenger? And just any advice you could give me thank you for your time. #askgmbntech

  35. #askgmbntech I am looking to buy a downhill bike but I'm not sure about which size to get. I am 1.88m tall and currently riding a Nukeproof Mega 275 in size L. It has the standard stem (which is 50mm i think) and a reach of 470mm. The Bike I am looking to buy is a Commencal Furious which I'm mostly going to use for bikeparks, jumps, tricks and stuff. So the question is: Should I get a L size frame with a 440mm reach because maybe a downhill bike has to be a little bit smaller or should I get a XL frame with the same amount of reach as my enduro?

  36. I am curious if you wanted more fork travel without messing with bb heights, if you could swap out for a dual crown fork on an enduro or am bike? Could you explain please?

  37. #askgmbntech Hi Doddy, I have just swapped my brakes on my bike to Sram Code R Hydraulics, ever since the swap over no matter what I try I cannot get the pads to stop rubbing, my rotor is the standard Sram 203 on the front, the rear is fine, other than purchasing new rotors do you have any tips for stopping the rubbing as I'm tempted to return and buy new brakes. I had re bled them 3 times, purchased different pads and tried every adjustment method under the sun, any help is appreciated!

  38. I ride a 2008 giant reign size medium, I'm 6ft with a 32 inch inside leg and I don't feel comfortable on it when I do any sort of jump ( it feels a bit small and cramped ) the rest of the time it feels ok do i need a 19 inch frame instead of my 18 inch.

  39. #askgmbntech I recently bought a new coil on my dh went from a 450 to 500 but I’ve bought a shorter coil than the original but the original shock says 3.25 and the one I have just bought is just 3 and the shock length is 3 will this cause a problem and would this coil have the same strength as a 500×3.25 as it’s 500×3 or are they equal

  40. #askgmbntech Hi Doddy, I'm looking for a new bike and i'm strugling to decide wether to get a good frame and upgrade the components or get a better frame and keep the stuff thats on there.

  41. #askGMBNTech I got 40mm rims and running 3.0 inch tyres. I like them, but I‘m thinking of changing to 2.6 inch tyres, so my question is: will they fit normally like on a thinner rim or will they be flat on the upper side ( so the area that’s rolling on the ground)? My english is not the best, so it’s difficult to explain, but I hope you can understand what I mean

  42. #askgmbntech Hi! Long time listener first time caller. Can you add a lock-out remote lever to a fork that has just a standard lock out? It’s a general question about all forks but I have Suntour XCR forks.

  43. #askgmbntech is it possible/easy to spec out a wheel and tire combo to get the same rolling diameter on both 27.5 and 29? Put short/skinny tires on the 29 for fast rolling days and big fat rubber on the 27.5 for big grip days, without changing the bike geometry, bb height, etc?

  44. I'm a fairly big guy 6"6" 340 pounds and I got a Trek fuel ex 7 29 2019 model. What are some upgrades that you would recommend

  45. #askgmbntech Hello there, I ride a 26” 2014 ragley blue-pig and have really knocked my rear wheel out of shape, it is not really repairable so I’m on the lookout for a new wheel. My question is if I should build up a new wheel on the same 28 hole dtswiss hub or go for an all new wheel. The wheel should be as bombproof as possible, but also affordable so probably aluminium. Weight doesnt really matter too much.

  46. #askgmbntech
    Hi Doddy, love ur video’s, jealous of how many bikes u all have and also love how Martin can be treated like the rest of you having as much fun on the trails as much as you and he rest of the team do.
    Is there any type of oil or grease I can use on my fork suspension as it is literally glued shut??

  47. #askgmbntech Hey doddy, thx so much for all your expertise! I have a question concerning tubeless setup: does the bead of the tire has to "POP" into the rim? i have a new bike and wanted to convert to tubeless, just as i did with my 2 previous bikes. I can inflate the tubeless tire with a standard floor pump, but i just won't get the initial pop from the bead, no matter how much bars i put into it. It holds the air for 2 days now, but i'm concerned of rolling the tire of the rim when i ride it. Couldn't find help anywhere else online – so maybe you can(: cheers

  48. #askgmbntech Why do pinion gearbox bikes like the Deviate Guide use grip shifters instead of traditional trigger shifters?

  49. Fox float rear shocks. During cold weather psi recommendation settings, adjusting at room temperature or at outside cold temperature?! Any affects?

  50. i would like to know can i change my front suspension fork….it an old judy xlc double crown fork100 mm travel…probably from early 2000… i would like to have a bit more travel and a single crown…so it doesnt look to bulky…. is it ok.. or does it mess up everything about geometry…. bike is an stumpjumper fsr also from about 2005… tnx !!

  51. Hi do you have any suggestions to an online company where I can order stuff that deliver to South Africa.
    Kind regards

  52. #askgmbntech hi Doddy, just wondering what issues you see in running shorter travel than standard. The shock length is still the same as factory (210) but going from a 55 to a 50. Cheers

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