Seat tube issues

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ridingmakesmehappy
Posts: 10
Joined: Thu Dec 04, 2014 3:34 pm

by ridingmakesmehappy

Hi!

So I've been having some issues with a £1000+ Ti frame I bought back in July, and I'd like to post my story to see what the opinions of the community are.

So the first issue: if using a compact chainset (Red 22), one of the bottle cage bosses on the seat-tube is in the way of the craze-on clamp (Red 22). I contacted the shop i bought the frame from, and the manufacturer of the frame suggested to them I get an aftermarket braze-on clamp that allowed the front mech some adjustibility. OK, fair enough, but still quite annoying considering how expensive the frame is, and the fact that SRAM (and maybe the others) have these important measurements online available for who ever wants to see them.

The second issue: when I first fitted the seat-post, I noticed how loose fitting it was before clamping, but in the excitement of having the new toy, I ignored this. A mistake on my part, becasue for the following week or so, my seat-post kept slipping. Eventually it stopped after many increases in torque on the clamp. I initially though that the clamp-bolt was stretching, so thought nothing of it. However, after about a months worth of riding it, winter set in, so I put it away ready for the next summer and it was at this point that I noticed the top of the seat-tube was pinched in! I got my self an internal bore caliper (digital) and began mearusing the seat-tube. The average diameter at the top was 27.42mm and futher inside it was 27.51mm. This seemed rather large, so to make sure I wasn't going crazy I performed the same measurements on a Specialized Langster (27.30mm and 27.33mm) and on a Cannondale F600 (27.30mm and 27.27mm). Before anyone asks, I am using a Thomson 27.2mm post. In fact, all 3 of my bikes have the same post. So I contact the manufacturer and eventually their R&D team suggest that if I use their Ti seat-post and clamp, the problem should be resolved. They offered it to me FOC but I'm not convinced becasue their post is also 27.2mm, so how on earth will it resolve the "over-size" seat-tube? So I contact the shop, fill them in on all that has been happening and ask for a refund. Their responce was that I should do as the manufacturer suggested, stating that "...their belief (manufacturer) is that becasue Titanium is more flexible than other metals it needs more torque to hold seatpost and clamp together..." and at this point alarm bells start ringing, because Titanium should require LESS torque precisely becasue it is more flexible. The reason I have had to use excessive torque is becasue the seat-tube is too large for the 27.2mm seat-post, so it remains obvious that more torque will be required on my frame becasue the seat-tube clamp and seat-tube will need more deformation just to take up the clearance gap between the seat-tube and seat-post.

Anyway, rant over! So along with your views, my questions to you would be:

1) Can the fact that a seat-post is a loose fit in a frame be the cause of it slipping even if the clamp is done up to normal 5Nm (?) torque?

2) Is 27.5mm an acceptable bore for a £1000+ frame seat-tube specified to take a 27.2mm seat-post?

3) Do titanium frames require more torque on the seat clamp than other materials to hold the seat-post?

4) Would you purchase a £1000+ frame from a manufacturer who claimed a 27.5mm frame bore to “sit perfectly within their quality control parameters” to fit a 27.2mm seatpost?

Any responce is greatly appreciated :)

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ITTY
Posts: 221
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Location: Bremerton, WA

by ITTY

yes no no no
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sungod
Posts: 1702
Joined: Fri Dec 24, 2010 9:37 pm

by sungod

1 - yes
2 - seems like poor tolerance/quality control
3 - that would depend on design as well as material, but their response sounds like bollocks
4 - no

assuming they are not willing to swap it or otherwise fix the situation to your satisfaction, you can go down the route of demanding refund on the basis the frame is not fit for purpose, your contract is with the shop, it's up to the shop to fix it, bodging it is not fixing it, but elapsed time and the fact you've ridden the frame to obtain some benefit of use may limit your right to a refund

have you tried cf assembly compound to increase friction of the post in the seat tube?

mattr
Posts: 4671
Joined: Fri May 25, 2007 6:43 pm
Location: The Grim North.

by mattr

You can probably find the accurate dimensions for a seat post/seat tube fit on the net somewhere.

User avatar
breezerboy
Shop Owner
Posts: 279
Joined: Fri Jun 22, 2007 8:14 pm
Location: Bristol, UK

by breezerboy

If they've offered a replacement post and clamp free of charge it may be worth trying. Another alternative is to request that they supply a replacement Thomson post in 27.4mm which should be used in the dimensions you have measured.

Butcher
Shop Owner
Posts: 1917
Joined: Sun Jan 03, 2010 4:58 am

by Butcher

The price of the frame does not dictate the quality [although common sense would think it does]. If they are offering you free parts to fix a problem, then it should not be turned down.

The name of the frame manufacturer would also help. Some people here may have solutions to your same problem.

Valbrona
Posts: 1629
Joined: Fri Oct 28, 2011 3:25 am
Location: United Kingdom of Great Britain and Northern Ireland

by Valbrona

A framebuilder that TIG welds could weld a mech hanger on to the seat tube obviating the need for a clamp.

What type of seatpost clamp are we talking? If it is a traditional binder-type clamp, well then there is every chance that it might break with a little more usage. A removable clamp would be better, and these come in different designs. Some have wide bands and two fixings screws to provide a better hold.

The seat tube ID has been reamed too large and the frame sounds plain defective. Do not apply a grease-based anti-seize compound to the seatpost because that will only encourage slipping - use a sprayable/lighter type of anti-seize compound(Loctite do one).

Having your seatpost knurled would probably sort the problem. But you shouldn't be having to faff around like this. An old time framebuilder would have a knurler and aluminium seatposts are more receptive to knurling than steel or ti.

Or, yes, try a Thomson 27.4 seatpost.

ridingmakesmehappy
Posts: 10
Joined: Thu Dec 04, 2014 3:34 pm

by ridingmakesmehappy

Thank you for your replies :) Sorry I havent said anything sooner; I've been moving house! I needed some reasurance that I wasn't going crazy. And I know I'm not, but still, you never now :P

So I agree to the YES/NO responces.

As for the other points mentioned:

    Getting the offical mesurements WITH their tolerances would be pretty hard unless if the manufacturer has put them online, which looks like they haven't. The only thing you can get from their website is that you should use a 27.2mm post.

    I don't want a new seatpost from them, the frame is clearly defective, especially if I would have to use a 27.4mm post. I would have been quite happy to have had the frame replaced, but since there are issues with the bottle cage placement, then I'd rather have a refund. Else, why would I bother paying £1000+ for a poorly designed frame? I might as well have bought a second hand frame on ebay for £300-£400. By the way, the frame is actually really nice, and in my opinion, it's the nicest design in the market. Just a shame this has happened really. If these issues were sorted, I wouldn't hesitate in getting another one!

    It's a modern Ti frame, so I'm using a removable clamp.

Speaking to my bike buddies, some of which have, and have had Ti frames, and some which are mechanical engineers(one of them is a Physicist who works on Ti-6Al-4V!!) say that this is unacceptable.

I haven't had a reply from the bike shop yet. Fingers crossed something gets sorted out :)

mattr
Posts: 4671
Joined: Fri May 25, 2007 6:43 pm
Location: The Grim North.

by mattr

I didn't mean the manufacturers tolerances, I meant the industry standard tolerances.

Valbrona
Posts: 1629
Joined: Fri Oct 28, 2011 3:25 am
Location: United Kingdom of Great Britain and Northern Ireland

by Valbrona

mattr wrote:I didn't mean the manufacturers tolerances, I meant the industry standard tolerances.


There aren't any regarding the internal diameter of seat tubes.

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Rick
Posts: 2034
Joined: Sat Aug 29, 2009 4:30 pm

by Rick

It sounds like the frame might be categorized as "defective" and if they would give you a refund, that would be great.

But they might also argue that the water-bottle boss location is just the way they do it and it is not compatible with compact cranks. And if Thomson makes a 27.4 seatpost as a standard part of their lineup, there must be a reason for that, so maybe these types of seat tubes aren't all that uncommon. Maybe it is a standard tube size. I really don't know.

If it were me, I would probably just use a 27.4 seatpost (or the one they supplied) and then use a clamp-on bottle cage and get on with riding and enjoying.

But I would be more careful about what frame I chose in the future.

Is the manufacturer refusing a refund, or are you just gathering background info for future use ?

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CharlesM
Posts: 5759
Joined: Tue Sep 26, 2006 12:37 am
Location: Phoenix Arizona

by CharlesM

You have what sounds like a bad frame.

the seat post needs to be more snug as part of the clamping strength is down to friction on the length of the seat post. Also most seat post makers want the stress of flexing to be spread over the length of what is inserted into the seat tube, not all loaded up on the clamp point.

You got a bad frame.

Who made it?

ridingmakesmehappy
Posts: 10
Joined: Thu Dec 04, 2014 3:34 pm

by ridingmakesmehappy

I'm telling my story here so I can get people's opinions on this matter, but I have already been in contact with the manufacturer, and later with the UK bike shop I bought the frame from. And what the manufacturer has said, along with the bike shop, is that the measurements I have supplied them with are within their design tolerances, and they beleive that if I were to use their Ti seatpost and clamp (FOC), the slipping would stop (somehow). Thus, they are not going to give me a refund, and will only replace the frame is their Ti seatpost slips too.

So you think Thomson makes the 27.4 post precisely for situations like mine? How nice of them :)

In regards to the bottle cage bosses...they should state on their site that it is not compatible with compact cranks then. And if I can find a document like this...

https://sram-cdn-pull-zone-gsdesign.netdna-ssl.com/cdn/farfuture/7Kz2bnB9nCK7Hg9bFHXk-WeY3vi2Ydl0OC5WuEIn7jw/mtime:1376068950/sites/default/files/techdocs/road_frame_fit_specs_gen0000000004410_rev_a.pdf

...on SRAM's site, then why can't their designers? I haven't looked but I assume Shimano and Campag have something similar.

Valbrona
Posts: 1629
Joined: Fri Oct 28, 2011 3:25 am
Location: United Kingdom of Great Britain and Northern Ireland

by Valbrona

ridingmakesmehappy wrote:So you think Thomson makes the 27.4 post precisely for situations like mine? .


No - they just happen to make one in 27.4, and it is surely worth a try.

ridingmakesmehappy wrote:... the bottle cage bosses...they should state on their site that it is not compatible with compact cranks then..


When you first saw the bike on their website (or wherever) did it show the frame with a welded-on FD mount? If so, whoever made the frame perhaps took a short cut and didn't weld one on, hence the fact that you have to use a clamp-on FD. Perhaps they ran out of FD mounts?

You would think that even a novice framebuilder would manage to fit the bottle bosses so that they don't foul an FD clamp in the case of both compact and regular cranksets. However, one possible explanation is that your frame is very small and the framebuilder wanted to mount the seat tube bottle bosses low to allow easy removal of the bottle.

ridingmakesmehappy
Posts: 10
Joined: Thu Dec 04, 2014 3:34 pm

by ridingmakesmehappy

Sure, I could give the 27.4mm a try, but that's no really the point. I shouldn't have to be doing this on a brand new £1000+ frame....right?

These frames are designed to take a braze-on clamp, so any picture of it, including the ones on the manufacturers website, is shown with a braze-on clamp. And you're exactly right...the designers felt compeleded to add the second bottle cage...no matter what!

I haven't had a reply from the bike shop to my last 2 emails (the first was sent 2 weeks ago!) so it seems like I'll have to phone them up, and accept their proposal to use the manufacturers Ti post (FOC), or else nothing will get sorted.

I guess it's not that bad, it's a nice looking post! But I'm still feeling sore because in my eyes, and in a lot of everyones eyes, I'm stuck with a defective frame :(

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