MTB Seatpost keeps slipping - help!

[mudda]

Hi Chaps,

 

This has been bugging me for a while - almost every ride I go on with my mtb - the seat keeps slipping down.

 

This happens on both my mountain bikes.

 

I changed the quick release on both to  solid clamps - I thought that would fix the problem good. But it just keeps on happening.

 

I am at wits end.

 

I need a solid solution - at this point I am thinking about getting a spot weld on the seatpost so that it will not be able to drop below the level of the weld.

 

I see on the net - some chaps bolt another clamp onto the seatpost so that it cant drop below that level.

 

O yes - i have tightend the post very tight - it does not help.

 

 

 

 

 

[Baaisikilist]

Carbon compound...?

Or wrap a bit of insulation tape round the post...?

[turtlek]

Most Lbs's have what you call friction paste try that and just coat it lightly and see how it works other than that check that your seatposts are the right size for the frames not likely to be wrong if oem but will happen if you changed the post and mis-measured the original diameter

[Azonic]

Clean and dry the post and inside of the seat tube PROPERLY. You want it to be bone dry.

 

Then spray the seatpost, the area that will be clamped, with hair spray, nice firm hold hair spray. Also, slap on some clear nail polish. Insert the seatpost and clamp it.

 

Give it an hour or so to set. See how that works for you.

 

 

[Johan Bornman]

You don't say whether you have aluminium or carbon bits on there. Nevertheless, why not a) shim the posts with a beer can or b) put some gritty grease on the posts before tightening them.

 

The former can be had by buying any importer beer in all-aluminium cans. Empty contents down throat, snip some strips out of the can using someone else's scissors and fit around post before tightening. All alu cans are far thinner and easier to work with than our local steel cans.

 

I think Foster's works the best.

 

Secondly, if you can find a blob of so-called Carbon Compound grease, use that or make your own gritty grease by putting some gritty stuff in a blob of grease by robbing some sandpaper off its sand. I'm sure good old mechanic's grinding paste will work as well. Get a teaspoon full from your local mechanic.

 

Obviously you've already looked to see that the slot cut out of the frame where the clamp goes doesn't bottom out, preventing the clamp from doing it's thing?

[TheLegend]

dude, it might sound ridiculous, but have you actually checked if the seat post have the right diameter?

 

 

[mudda]

Yes - the diameter is right. Its a tight fit. I tried the insulation tape idea, but the fit is so tight - it sheers off before i get a chance to tighten it.    both are aluminium.

 

I installed a longer bolt - to prevent bottom out.

 

Some good ideas - I will give them a try.

 

I will be able to  mechanics goodies since my brother owns a garage - panel beating and mechanical ,hence the spot weld idea.

 

Thanks Chaps - hopefully I will not be on downhill bike seat position for much longer!!

 

 

 

[joevan]

Hijack on

 

Johan, your description of shimming the seat with a beer can reminded me of this:

 

Adjusting a bicycle seat

The seat (aka saddle) on your bicycle is responsible for carrying your weight and allowing your legs to concentrate on propelling you onward. This seemingly innocuous piece of equipment can make or break your bicycling experience as it can cause you great pain & agony in your nether regions, knees and legs and even impotence, gentlemen, if adjusted improperly. Your cycling efficiency can also go to poo if that seat ain't right.

By and large, most stock bicycle seats are pieces of sh*t. If the simple guidelines below don't soothe your backside and help you from losing that lovin' feeling, replace it. Remember, though - you want to put the pressure on the sit bones in your ass, not the soft tissue such as the taint. Skip the one with Sooper X-Tra Thick Padding and give the Funny Anotomical Seat With The Split Down The Center a try.

To Adjust Your Bicycle Seat

You Will Need:

• one 6mm Allen wrench
• one 4mm Allen wrench
• one framing level
• rags or newspaper (trade show t-shirts work great)
• some variety of pumice soap (like Lava or Fast Orange)
• Vaseline or anti-seize compound (optional)
• one six-pack of your favorite beer (not optional)
• your bicycle helmet (not optional)

Aight, now that you've got all the sh*t, head out onto the

front porch. Crack open a brew. Take a few puffs off your favorite substance to smoke if you're so inclined. Put on a Bad Religion CD. Relax. Now then, the seat on a bicycle has four degrees of freedom. We shall gently adjust these into line one by one.

First, the angle of the seat shall be adjusted. Basically, you want it to be roughly parallel to the ground, aka "level". Stand the bicycle upright and take a gander at the seat from the side. Check it with the framing level. If you have one of the fancy seats with a drop or cutout for your taint, lay a book across the seat. i prefer using my prob/stat book, since i haven't found any other use for it yet. Loosen the seat clamp binding bolt with the 6mm Allen wrench, adjust to level up the seat. Snugly tighten the binding bolt.

While you are dealing with the seat clamp, you might as well adjust the fore-to-aft position of the seat. This one is fairly easy to do. Sit on the seat and with the pedals horizonal, sit on the seat. When it is adjusted properly, your kneecap should be directly over the pedal spindle (axle) of the forward pedal. Adjust and torque the poop out of the bolt. Not so much you strip the threads, Hercules. Drink some more beer.

The seat angle adjustment has a great deal with how your nether regions will feel on a ride. Some people prefer a slight upward or backward tilt. Level is the best place to start and will be most comfortable for most people. The fore-to-aft position (in conjunction with the height adjustment, below) helps with making sure you get maximum efficency and protect your knees from nasty grindy sounds.

Now then, adjusting the seat height. Loosen the seatpost collar binding bolt with the 4mm Allen wrench (or just loosen the quick release lever) and remove the seatpost. That's right, grab the seat and take that entire f**ker out. You will notice what a tight fit the seatpost has in the seatpost tube and how gritty it feels coming out. Wipe the seatpost clean with the rag or newspaper. NOW IS TIME TO GET DIRTY (so drink the rest of that beer and have another smoke before proceeding). With the vaseline or astroglide anti-sieze compound, grease up the bottom quarter of the seatpost. Spread it around if you're so inclined. Reinsert the seatpost into the seat tube and put the seat back to its previous height. Tighten up the seatpost binding bolt. Go wash your hands, you filthy pervert. Get another beer and continue.

To find out what the proper seat height is for you, sit on the bike seat while remaining stationary (having a wall or couch or friend nearby is helpful). Try to wear the shoes and funny bike shorts you'll be wearing when riding the most. Put the heel of one foot on the center of a pedal and rotate it backward to the bottom of it's excursion. When the seat height is adjusted properly, your leg will be straight when your heel is on the center of the pedal. Got it? Good. Adjust the seat up and/or down until this is the case. Torque the poop out of this bolt as well.

Some of you may be thinking "But jbo, this seat seems awfully goddamn high! I can't touch the ground while on the seat." There is a reason for that, Gentle Reader. It's because you're not supposed to be able to touch the ground while on the seat. If you have adjusted the seat height as described above, you will get the maximum pedaling efficency when the ball of your foot is on the center of the pedal. This also helps your knees. Pay attention to them; They will tell you if the seat needs to move up or down. If your knees hurt in the front, raise the seat. If your knees hurt in the back, lower the seat. If your lower back hurts, find a member of the appropriate sex to rub it. By this point, you should be about halfway through your six pack. If not, play catch up. NOW, son!

One last thing to check - the seat alignment. Sight down the seat, in line with the back wheel. Would a line drawn through the fore-aft axis of the bicycle also be coplanar with the seat down its respective axis? If not, just bang on the seat from the side with the palm of your hand until it is. Don't bother with loosening the seatpost collar binding bolt.

Time for the moment of truth - finish the beer you're currently drinking, put on your helmet and take it for a test ride. Some fine-tuning and tweaking may be necessary, but you should be very close to the optimum seat position for your unique body geometry and bicycle.

Go hit the streets. Ride to work. Ride to the store. Ride to your friends' houses. Ride to school. Ride Out There and Back. Ride Ride Ride.

Now please realize that your mileage may vary.

Albert Herring promises me that all his seatpost binding bolts are a whole millimeter larger than what i specified here. i would speak of a vast left-wing conspiracy headed up by the British, but instead i'm going to get another beer.

Hijack off 

 

[Little-Ben]

buy a new bike

[Tumbleweed]

I think Foster's works the best.

i'm curious. why do you reckon this works best?

[ddakin]

I sent Mudda a PM about this, but I have a small bike parts company (www.chasebicycleproducts.com) and we now have a Seat Post slippage solution It's a simple lock ring that sits above the seat collar and stops the seat from slipping back into the frame.

 

I've got them in 27.2mm and 31.6mm sizes and they'll work with carbon or aluminum posts. They weight only eight grams.

 

Please let me know if anyone is interested. They would be $12 including shipping to South Africa, or anywhere in the world.

 

Dan

Chase Bicycle Products

[philip.maree]

I am interested but I don't understand how this works? what would prevent the post from slipping through the lock ring?

 

[ddakin]

When you look at a seat collar, it 'squeezes' the frame (for lack of a better description). With these rings, they're completely against the seat post itself.

Secondly, it's similar to having two nuts on a bolt. These are in addition to the seat post collar, so it's like a backup system, except that these are stronger than the collar itself.

 

Hopefully that answers your question.

[Johan Bornman]

When you look at a seat collar' date=' it 'squeezes' the frame (for lack of a better description). With these rings, they're completely against the seat post itself.

Secondly, it's similar to having two nuts on a bolt. These are in addition to the seat post collar, so it's like a backup system, except that these are stronger than the collar itself.

 

Hopefully that answers your question.

[/quote']

 

Hmmmm... it sounds a bit like two layers of Elastoplast to me. Look, I'm sure your product works but this is hardly an elegant solution. I still recommend the OP gets himself some of that friction paste or grinding paste. I also think he should have his seat post measured by someone with a vernier calliper and post the measurement here. We'll soon know whether then post needs shimming or just a bit of friction.

 

Push comes to shove, he can just take a stainless steel hose clamp and fix it until he's had time to find some good imported beer in an aluminium can.

 

I'm also suspiscious of that bolt. I bet it is flimsy and needs a few millimeters in girth. I also smell anodising in the mix. That stuff is so slippery that it is widely used in politics.

 

Not so long ago our biggest fear was the post seizing in the seat tube, now we're battling with sliding posts.

 

 

 

 

[Red Zone]

Mudda how much to you weigh, perhaps that is the problem

[Piernas Flacas]

A little bit of Locktite for threads may do the job.