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Giant Roam D-shaped seat post slipping

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Giant Roam D-shaped seat post slipping

Old 06-05-21, 04:08 AM
  #1  
billyymc
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Giant Roam D-shaped seat post slipping

First of all - Giant, why? Why make a D-shaped seat tube and seat post? Are they going to make a D-shaped wheel next?

Ok - so a friend of mine has a Giant Roam she bought from a LBS near me but about an hour drive from her. She bought three actually - one for her, two for her kids.

The seat post was slipping after she brought it home so she drove it back to the shop and they put some Fiber Grip (assembly paste) on the seat post and cranked the clamp as tight as possible. It held for a bit but when I rode with her yesterday I noticed the post had slipped. So before I call Giant on Monday (or she takes it back to the shop), I wanted to ask here on ideas how to solve this problem?

It's an aluminum bike and alloy seat post, fwiw.

Thanks.
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Old 06-05-21, 07:24 AM
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Would be ugly, but might work--automotive hose clamps have some flex in them. Maybe put one above the seatpost clamp, "mold" it as best you can to the seatpost shape, and tighten it up. With the possible exception of the highest end racing bikes, never understood the need for other than a round seatpost--why mess with success? Personally, I'd be tempted to return all three to the dealer and exchange them or ask for a refund so I could purchase a bike with a round seatpost. If that isn't possible, file a warranty claim. If Giant isn't aware, or riders don't bring to their attention, nothing changes.

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Old 06-05-21, 08:06 AM
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Can you post pics? All the Roam's I'm seeing, even going back several years, show a round seatpost. Photo's may help with coming up with a solution.
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Old 06-05-21, 08:23 AM
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Originally Posted by Crankycrank View Post
Can you post pics? All the Roam's I'm seeing, even going back several years, show a round seatpost. Photo's may help with coming up with a solution.
Not sure what Roam model it is, but they are using a D-fuse seatpost, at least one some--shows it under specs: Roam 2 Disc (2021) | Men bike | Giant Bicycles United States (giant-bicycles.com)
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Old 06-05-21, 09:52 AM
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Stupid design, intended to ensure an aligned saddle. Talk about a solution in search of a problem!

Try making a beer-can shim for the flat side of the D.
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Old 06-05-21, 10:06 AM
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Originally Posted by freeranger View Post
Not sure what Roam model it is, but they are using a D-fuse seatpost, at least one some--shows it under specs: Roam 2 Disc (2021) | Men bike | Giant Bicycles United States (giant-bicycles.com)
OK, I see it now, no thanks to Giant's photos hiding the flat side. It looks like a problem created by Giant where one didn't exist before claiming it was for "damping vibration"???? Anyways it appears to be a common problem with this design and freeranger's suggestion of a secondary clamp would probably work but I also suggest contacting Giant if the bike shop can't fix it since this design seems to be prone to slipping and Giant should offer a fix for this.

Last edited by Crankycrank; 06-05-21 at 10:19 AM.
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Old 06-05-21, 01:52 PM
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Originally Posted by Rolla View Post
Stupid design, intended to ensure an aligned saddle. Talk about a solution in search of a problem!

Try making a beer-can shim for the flat side of the D.
I'd call it an idiotic design. What about the riders who DON"T WANT their saddle pointed absolutely straight!! Great example of what happens when they assume it's a good idea.
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Old 06-05-21, 09:19 PM
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At least they have stuck with it for the time being and they have had it for quite a while. I worry when you start doing silly proprietary stuff like that you stop doing it and supporting it and leave a lot of people in the lurch.

The idea is to give a bit more flex and comfort, yes it also helps with saddle alignment which is nice (and people who want cockeyed saddles probably have some other issues that need to be addressed) but the main reason at least from what I was told from one of the Giant reps was for comfort. It is a silly design because you cannot really upgrade your post or do much without a Giant dealer and they are really not so good to the dealers. I would much rather have a more comfortable frame and use a good ole' fashion 27.2 seatpost or for the bigger stuff 30.9 or 31.6 all of which can be used for dropper posts or Kinekt or Thudbuster style posts.

Also their proprietary racks that did where absolute garbage and really quite dumb. Why does that need to be proprietary it doesn't help anyone and the racks they sold weren't great.
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Old 06-06-21, 02:11 AM
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try beeswax or surf wax. friction coefficient of beeswax is not that small except for extreme pressures - which do not occur on the seatpost-frame interface. if it doesn't work because the gap is too large put some tape and then some beeswax. and put a proper grease on the bolt but don't go for more than 7Nm. you could mix beeswax with a bit of grease or GL4 gear oil or just chain lube added to that wax to get a lube for bolts. you want to have small enough CoF on the bolt head and threads, that's why you mix wax with something else or just get a wax based grease meant for bolts.

avoid straight paraffin wax. it is brittle and less sticky.

"Paraffin wax, colourless or white, somewhat translucent, hard wax consisting of a mixture of solid straight-chain hydrocarbons..."

Last edited by adipe; 06-06-21 at 02:22 AM.
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Old 06-07-21, 04:13 AM
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Thanks all. I'll try a combo of paddle/surf wax and maybe a small shim made of metallic tape or as suggested a strip of an aluminum can.

I asked my friend to call the dealer again so she has the issue on record, but I'm not hopeful there - this dealer did a poor job of setting up her bikes AND charged her $30 per bike for setup. When I asked her about the front shifting she told me "He told me I'd never even have to use it."
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Old 06-07-21, 04:17 AM
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Originally Posted by adipe View Post
try beeswax or surf wax. friction coefficient of beeswax is not that small except for extreme pressures - which do not occur on the seatpost-frame interface. if it doesn't work because the gap is too large put some tape and then some beeswax. and put a proper grease on the bolt but don't go for more than 7Nm. you could mix beeswax with a bit of grease or GL4 gear oil or just chain lube added to that wax to get a lube for bolts. you want to have small enough CoF on the bolt head and threads, that's why you mix wax with something else or just get a wax based grease meant for bolts.

avoid straight paraffin wax. it is brittle and less sticky.

"Paraffin wax, colourless or white, somewhat translucent, hard wax consisting of a mixture of solid straight-chain hydrocarbons..."
Meant to ask in my post above - any thought on warm vs cold surf wax for this use?
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Old 06-07-21, 07:30 AM
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Originally Posted by billyymc View Post
Meant to ask in my post above - any thought on warm vs cold surf wax for this use?
i guess what you refer to as warm wax should mean wax that is best suited for warm environment...
so you should prefer that type as it's more viscous/elastic/sticky when subjected to pressure.

you may use a tiny bit of GL4 gear oil or grease or some chain lube you already got to bring that wax to a creamier consistency. minimize the use of volatile solvents as they won't dry out easily.

wax does not adsorb that strong to metal and it can also oxidise in time so that's one more reason to mix it with just a bit of something having additives to resist that oxidation.

so what you need is something thick, sticky and not necessarily bring down CoF. that's why wax (surf wax being a good example) is good and even better if used as an ingredient in a mixture.

"Surfboard wax is generally composed of a mixture of paraffin, beeswax or other hard waxes; petroleum jelly can also be added to create a softer wax."


also, from wikipedia:

Microcrystalline waxes are a type of wax produced by de-oiling petrolatum, as part of the petroleum refining process. In contrast to the more familiar paraffin wax which contains mostly unbranched alkanes, microcrystalline wax contains a higher percentage of isoparaffinic (branched) hydrocarbons and naphthenic hydrocarbons.[1] It is characterized by the fineness of its crystals in contrast to the larger crystal of paraffin wax. It consists of high molecular weight saturated aliphatic hydrocarbons. It is generally darker, more viscous, denser, tackier and more elastic than paraffin waxes, and has a higher molecular weight and melting point.

Last edited by adipe; 06-07-21 at 07:42 AM.
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Old 06-07-21, 09:57 AM
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These are new bikes, then you need to take it up with Giant before you go about mucking with things that might cause them to say you screwed it up, it's your issue now.

If the dealer that sold it seems too uncaring, then see what another Giant Dealer says about it. Try to contact Giant on the regional level yourself. Though this will be better done by the bike owner. Some manufacturers won't get involved with the customer, I don't know what Giant does.

But as long as this is a bike that was bought and doesn't work correctly from the get go, then Giant and their re-seller or dealer need to handle it.
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Old 06-07-21, 10:24 AM
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Doesn't sound like the dealer is a lot of help, so here ya go: Customer Support | Giant Bicycles United States (giant-bicycles.com)
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Old 06-08-21, 09:17 AM
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Originally Posted by Iride01 View Post
These are new bikes, then you need to take it up with Giant before you go about mucking with things that might cause them to say you screwed it up, it's your issue now.

If the dealer that sold it seems too uncaring, then see what another Giant Dealer says about it. Try to contact Giant on the regional level yourself. Though this will be better done by the bike owner. Some manufacturers won't get involved with the customer, I don't know what Giant does.

But as long as this is a bike that was bought and doesn't work correctly from the get go, then Giant and their re-seller or dealer need to handle it.
Good advice. I will have her contact Cust Support and the dealer again. The only thing I will do will be put some additional assembly paste on the post to try and keep it from slipping until she can get it back to them.
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