Ask Pinkbike: Adjusting B-Tension, Cutting Forks, Making a Full-Suspension Rigid, & Quieting Loud Hubs

Sep 24, 2020
by Daniel Sapp  

Here at Pinkbike, we get inundated with all kinds of questions, ranging from the basic "Can I have stickers" to more in-depth, soul-searching types of queries like if you should pop the question or what to name your first child. Ask Pinkbike is an occasional column where we'll be hand-picking and answering questions that have been keeping readers up at night, although we'll likely steer clear of those last two and keep it more tech oriented.







Adjusting SRAM B Gap Without Tool

Question: @yeahwhy asks in the Mechanics' Lounge: I was wondering how should I set up the B gap on my drivetrain without the tool and where I should be measuring the 15mm difference. I also saw somewhere that 15mm is too much and I should run less, is it 15mm so it works better in sag?


bigquotesThis is a good question. While that little gauge from SRAM is really handy, chances are that a lot of people may not have one on hand and, the local bike shop may not be just around the corner. SRAM suggests the following for chain gap adjustment without the gauge.

1. For an Eagle drivetrain, shift the chain onto the second largest rear cog. For full suspension bicycles, measure the chain gap while the bicycle is in the sag position.
2. Rotate the B-Adjust screw until the gap between the upper pulley and the tallest teeth of the largest cog is 3mm.
3. Check the upper guide pulley alignment in the large and small cogs. Make adjustments to the high and low limit screws as needed.

Following the instructions and measuring the bike while it's at sag, I've never run into an issue with or without the gauge/guide.








Cutting Steerer Tubes

Question: @Pauley asks in the Bikes, Parts, and Gear Forum: I’m currently building a custom Ragley...I am going to get a bike shop to cut the steerer for the fork as I’m not wanting to mess it up. My question is I have no clue what height to cut my steerer to or what height my stem should be. Every bike I’ve owned has been bought complete and I’ve never worried about that. All I know is sometimes on the climbs I would get a sore lower back with bikes so I guess I was overreaching slightly. Any tips or help would be appreciated!


bigquotesWell, this is one you probably don't really want to mess up. Cut your steerer tube too short and it's a pricey fix. For length, I typically dry fit everything. Put the race on the fork, install it all, and decide how many spacers you'll need to get the handlebars where you want them. Typically, 20 - 40mm of spacers should give you enough room for experimentation with stem height. If you want a more in-depth tutorial, @mikelevy did a more in-depth write-up years ago that still applies today.

Any bike shop you trust to cut your fork should also be able to help you settle on the steerer tube length that makes sense. Remember: measure twice, cut once! As far as your sore lower back goes, a higher rise handlebar could help by putting you in a more upright position, and possibly a more comprehensive bike fit could also help detect and other areas that could be adjusted. Some core strengthening exercises wouldn't hurt either.


Tech Tuesday
Leave room for things to tighten up but don't cut it too short...







Making a Full-Suspension a Hardtail

Question: @eatourfoodtina2 asks in the Bikes, Parts, and Gear Forum: Could we in theory stick a rigid shock on a full suspension and turn our full suspension into a hardtail?


bigquotesIn theory, yes. Should you do it? No. You can obviously bolt a piece of metal in place of a shock and the rear end won't move, but it's not recommended. For one thing, the bike wasn't really designed to handle the forces that would go through it in a fully topped-out position. The point where you run out of suspension travel and your frame becomes rigid is at the bottom, not the top, of the travel. In this sense, the frame is in a very different position at full travel than it would be at zero. Bikes are designed to handle these "rigid" impacts at bottom out. That doesn't mean it'll break, but it does mean that you'll be subjecting it to forces it might not be able to handle.

"But what about a bike with a lock out?" Even when a bike's suspension is locked out, or set up a very stiff spring rate (think putting the max air pressure in a shock) it still has some give. You'll also be altering the bike's geometry, since the rear end will have 0 millimeters of sag. Overall, it's much easier (and safer) to run more air pressure, a stiffer spring, or find a shock with a firm lockout if you're trying to make your bike to ride more like a hardtail. 

Bikes are designed to handle hard forces at full compression, not at top-out.







Quieting Down a Loud Hub

Question: @Brendanpedalpusher29 asks in the Mechanics' Lounge Forum: I have a fat bike with Borealis house hubs and when I coast it sounds like a carnival spinning wheel. It is so distracting I can’t hear the people I’m riding with. Short of replacing the hub, any ideas of a quieter hub?


bigquotesLoud hubs are a love or hate thing for most people. A hub so loud you can't hear your homies? That's no good. Many freehubs come with a fairly light oil or grease in them which serves to lubricate the pawls and keep everything working well. That lubrication needs to be light enough to allow the pawls to engage properly, so slathering a coating of thick marine grease in there isn't the way to go.

Dumonde Tech's Pro-X freehub oil or grease are great options for quieting down loud hubs - it works wonders on Industry Nine's extra-noisy Hydra hubs, and it should help quiet down your Borealis hubs too. Once you have the hub nice and clean, put a little bit of grease on the spring under each pawl, and then apply the oil around the drive ring. Put everything back together and the decibel level should be noticeably reduced. 

Some people like to turn their hub volume up to 11. Many prefer nature. A slightly heavier oil or freehub grease will go a long ways in quieting things down.







96 Comments

  • 99 0
 What about making my hardtail into a full sus?
  • 75 0
 easy. angle grinder to the seatstay, take out around 5 inches each side, weld in a coil spring. chainstay flex will provide progression, i promise
  • 9 0
 theres a guy somewhere on the gram who made a full sus BMX bike, coolest thing ever.
  • 4 0
 @GumptionZA: I saw that. I still like @arrowheadrush flexy chainstay though.
  • 1 0
 Matt Macduff had the dj/slope frame where a shock was part of the top tube. pretty spiffy design
  • 3 0
 Didn’t understand that question. Why not just get a rigid?
  • 5 0
 You and @eatourfoodtina2 need to get together. Take the piece you cut out of your hardtail and install it in place of eatourfoodtina2's shock. Perfectly balanced, as all things should be.
  • 2 0
 @R-M-R: you must be a jedi...bringing balance to the Force...
  • 73 2
 Quieting down a loud hub, that's great, but how would one (hypothetically) go about quieting a loud wife who is upset that riding bikes is a higher priority than home repairs? Obviously asking for a friend....
  • 216 0
 Same instructions. Add more lube
  • 20 0
 @adrennan: best response I've seen in 11 years on pinkbike
  • 7 30
flag TRG22 (Sep 24, 2020 at 16:54) (Below Threshold)
 @adrennan: I find the dryer they are the more they squeal
  • 2 0
 @adrennan: PB comment of the century
  • 4 0
 Does anyone know where I can turn in my internet points for money?
  • 2 0
 @adrennan: It's where you buy bitcoin
  • 18 1
 I ride an Onyx hub and I love it. Totally silent. You wind up getting noticeably closer to animals.
  • 25 1
 Like bears and cougars?
  • 9 0
 @h82crash: did someone say cougars Wink
  • 1 0
 Love my onyx! I’d rather have a noisy bottom bracket than a loud hub!!!
  • 2 0
 @h82crash: haha! thx for that. lol'd
  • 18 0
 Brilliant idea. I’ll go turn my dropper post into a rigid seat post.
  • 11 0
 "a higher rise handlebar could help"

Why wouldn't you suggest just trying setting the stem higher (not more than 25-30mm of spacers is a common upper limit) first, since they're got a full steerer available. Sure more spacers also means slightly less reach, but that might help too. Definitely worth a try before spending on a new handlebar, and can always trim the steerer again if they decide to go riser bar instead of tall stem (to gain back the reach, or for looks: slammed stem & riser bars does look way better than a stack of spacers and a flat bar)
  • 11 0
 Sounds like @eatourfoodtina2 needs a Straitline Quickie Stiffy - vimeo.com/21775503
  • 1 0
 That was awesome. I cant believe I've never seen that before.
  • 1 0
 dang what a great way to market your shop though I instantly googled Dunbar Cycles out of pure curiosity
  • 11 3
 Hear ye. The best way to adjust any and all current SRAM components is best done with with proper tools. Simply remove entire drivetrain, place it in the garbage, and replace it with Shimano. This method has been proven effective for worry free, optimal performance. You are welcome.
  • 4 0
 For the steerer tube cutting, don't forget that there are high-rise and low-rise headset caps, which can make a considerable difference with how much room you have to play with.
  • 6 0
 Remembering any money spent on trying to make a full suspension hardtail is a down payment on a hardtail.
  • 6 0
 You can cut your steer tube with a pipe cutter... good tool to have in your toolbox for handlebars and seatposts too
  • 3 0
 19hours, no complaints yet it seems. Just waiting for the first one to come back here and complain that he followed your advice and now he's seeing stars and his dropper post has gone orbital.
  • 1 0
 Yeah if you make sure to file off the damage it causes so it doesn’t gouge out the inside of your stem.
  • 3 0
 We had a customer back in the mid 90s with a Cannondale Super V that he made rigid by swapping the shock for a block of wood. Surprisingly the front shock mount cracked all up the side of the weld.
  • 1 0
 Was the piece of wood made exactly the right width? If he made it slightly thinner and tightened the bolts, he must have introduced a lot of stress into the shock mount. Add to that the cyclic loading when riding and of course it would fail from fatigue eventually. But when doing those lab tests on new frames, don't they already install a rigid beam in the shock position? I thought it should be up to that. I think I have seen more pictures of frames tested in labs with an aluminum beam in place of the shock than an actual shock.
  • 1 0
 @vinay: sadly my memory of it does not extend to the dimensions of the wood block. One would hope it wasn’t six millimetres too narrow, hence causing him to pinch the tabs together.
  • 1 0
 @jaame: Do at least remember if it was a softwood or a hardwood?
  • 1 0
 @iamamodel: If I had to guess, I will go for pine. The pine leg of an old sideboard.
  • 1 0
 "chances are that a lot of people may not have one on hand"

Doesn't it come with the mech? Or with new bikes? If it doesn't come with new bikes, don't you trust the assembler?

(I have one 11sp and one Eagle, can't remember where the Eagle came from though. 11sp came with a mech.
  • 1 0
 OEM stuff and full builds don’t come with it. I’m sure your LBS will have one
  • 1 0
 I just replaced mine and it came with the gap tool.
  • 11 7
 If you want quiet hubs, take up knitting.
  • 2 0
 I tried knitting, it is pretty noisy actually.
  • 4 0
 you can also remove a pawl or three.
  • 6 1
 i hope you're kidding and don't do this
  • 5 0
 @Bikerdude137: Hell, remove them all! Take the chain off too!
  • 1 0
 @Bikerdude137: not kidding.
  • 1 0
 @owl-X: have fun when you snap a pawl or break the drive ring...
  • 1 0
 Some Stan's hubs ship without all their pawls. Ahead of the game for sure.
  • 1 0
 @Bikerdude137: taking 3 out of a 6 pawl hub ain't gonna do nothing but quiet it down (empirically) and speed it up (theoretically).

Snapping a pawl? That's above my leg grade, even on an eeber. But I'm flattered you think I could! Definitely able to use too thick a grease and gunk up a spring, but snapping a pawl? Snapping? A pawl?
  • 3 0
 Is the 3mm gap just for the 52t? In the diagram it's showing that cassette, not the older 50t.
  • 3 0
 It's the same. Note that the derailleur was also updated.
  • 5 0
 Setting at sag is the trick. If no friend around I have aired down the shock an used a tie strap. I found it makes a ton of difference and why it will be fine on the stand but not on the trail sometimes.
  • 1 0
 Is the 3mm gap a common gap for all gearing systems or only for SRAM Eagle? I always thought as long as the upper pulley clears the biggest sprocket I'm good. So that's typically less than 3mm for me. I'm using Shimano Zee with an 11-36t cassette. Or does Shimano also have a very specific gap prescribed?
  • 3 0
 Inanimate carbon tube should stiffen up that squishy bike. vimeo.com/161058261
  • 2 0
 Wow, is that for real?
  • 1 1
 why isn't there a for that's on-the-trail travel adjustable but works the other way?
as in, when I put it in 130mm 'trail' mode it will sink in by 30mm, steepening the head and seat angles and then when it's time to decent, I'll put it in 'enduro' mode full send 160mm configuration and fly off into the sunset!
I don't get why it's so hard!
  • 2 0
 Eh? That's what most travel adjust forks do? Fox and rockshox definitely do.
  • 1 0
 @inked-up-metalhead: I was under the assumption that when travel is reduced they just stand more upright, like there is more compression resistance. I might be wrong though as I've never owned one
  • 2 0
 @ShortJeffsyOwner: well, I have owned multiple, coil u turn, air u turn, dual position air from rockshox and at least 2 generations of talas from fox and they all drop when you drop the travel. There'd be literally zero point in making the air spring more complex if it only did the same as a lockout.
  • 1 0
 @inked-up-metalhead: thanks for the information, I had no idea! so why did they stop making them??
  • 2 0
 @ShortJeffsyOwner: I don't know for sure, but it's possibly to do with the fact they were only really ever good for over forked bikes, if you got a modern 160mm bike with a 160mm fork, dropping that to 130 would make the bb way too low. I used them for that exact purpose, hardtails mainly but also a kona bass dj full suss, it meant they had a monster truck mode but could also be dialed back to almost stock for handling purposes if it was actually being used for dirt jumping or street riding.
  • 2 0
 I used an old American made Schwinn full sus mtb for winter commuting use. After several years the rear shock was so clapped the bike was damn near rigid
  • 1 0
 Ditto but it’s the cheap elastomer fork on my Specialized that froze solid and now I have a rigid fork.
  • 2 1
 Making a full-sus bike rigid? Why on earth would you even want that? Also you do know that you could just lock out the rear shock, right?
  • 1 0
 But how do you get the pike in the sag position to measure b gap? Last time I put a bag of concrete on the saddle; I dont want to resort to such stupidity again
  • 5 0
 release shock air surely?
  • 3 0
 I H A T E loud hubs... Gearbox is the future, or maybe not!
  • 6 6
 I ride with a guy with an i9 hub. If our Tuesday night ride wasn’t a standing open invite he’d be cut!
  • 2 2
 They're annoying as hell. Shame, since they're beautiful hubs, and the engagement is great, but I won't be a customer too soon.
  • 4 0
 I also hated the loud pawl noise on my DTSwiss so contrary to what was said above I packed it full of wheel bearing grease and reassembled it. 4 years later and its still running completely silent and the pawls and ring and still In great shape. Gotta love ghetto fixes that work...
  • 1 0
 5-deg, 60mm Truvativ aka stem - NOOOOICE.
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