Hongfu FM-066/Chinese open mould frame thread

Discuss light weight issues concerning road bikes & parts.
gjash
Posts: 34
Joined: Mon Dec 24, 2012 6:42 am

by gjash

Any more success stores on this frame? I've just gotten mine and in the process of building it up. Size 54 came in at 870 grams. Looks awesome and hoping to hear a few high km stories.

Privateer
Posts: 383
Joined: Thu Feb 03, 2011 2:28 pm

by Privateer

I'm building an FM66SL now, and the entry hole for the rear brake cable housing doesn't have the aluminium cable-stop plate thing that all the other cable entry and exits do. It's just a moulded hole, which isn't large enough to fit the housing.

Has anyone else had this issue?

eric
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Location: Santa Cruz, California, USA
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by eric

Mine has plastic cable stop plate things which fit into place and are held in with a tiny screw. The brake cable housing stops at the entry cable stop thing- the cable runs bare inside the top tube.

If you can figure out how to do it, put some rubber cable noise deadeners or similar on the cable inside the top tube. Otherwise it'll make noise on bumps. I have to take mine apart and do that.

Since you don't have a stop, I'd put a plastic housing cap on the end of the housing.

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53x12
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Joined: Fri Sep 15, 2006 6:02 am
Location: On the bike

by 53x12

Rick wrote:Excuse my ignorance of the subject, but what as an "open mould" and what is a non-open mould ?



Here is a good post by Kazyole: http://www.reddit.com/r/bicycling/comments/16ydvb/new_bike_week_continues_my_notsoinexpensive/
"Marginal gains are the only gains when all that's left to gain is in the margins."

wrcompositi
Posts: 122
Joined: Tue Dec 04, 2012 3:57 am

by wrcompositi

Some alerting findings about FM066SL frames... :cry:

Recently I saw 2 instances of cracked seat tube of FM066 on Velobuild:
http://www.velobuild.com/6-build-photos/5903-cracked-fm066-sl-after-2-rides

The 2 frames in question cracked in similar positions: behind the seat tube and about 12cm down the seat tube.

This seems to be an unusual location of failures, so I removed my seatpost to investigate, and guess what I found:
Image

There's an abrupt transition from a smooth inner wall to a lower "gorge", and the thinner area starts about 11cm down the seat tube, coinciding with the aforementioned cases. My frame has only logged 700km and I 've seen no signs of cracks both inside and outside the seat tube so far, but I'm starting to worry my frame will crack the same way in the future.

My seatpost is cut to 260mm, with insertion depth of 105mm, maybe I should use a longer seatpost to lessen the possibility of cracking?

Has any FM066 user found the same issue of uneven wall thickness of seat tube?

Valbrona
Posts: 1486
Joined: Fri Oct 28, 2011 3:25 am
Location: United Kingdom of Great Britain and Northern Ireland

by Valbrona

A good enough reason for anyone not to buy an Fm066SL:-


wrcompositi wrote:Some alerting findings about FM066SL frames... :cry:

Recently I saw 2 instances of cracked seat tube of FM066 on Velobuild:
http://www.velobuild.com/6-build-photos/5903-cracked-fm066-sl-after-2-rides

The 2 frames in question cracked in similar positions: behind the seat tube and about 12cm down the seat tube.

This seems to be an unusual location of failures, so I removed my seatpost to investigate, and guess what I found:
Image

There's an abrupt transition from a smooth inner wall to a lower "gorge", and the thinner area starts about 11cm down the seat tube, coinciding with the aforementioned cases. My frame has only logged 700km and I 've seen no signs of cracks both inside and outside the seat tube so far, but I'm starting to worry my frame will crack the same way in the future.

My seatpost is cut to 260mm, with insertion depth of 105mm, maybe I should use a longer seatpost to lessen the possibility of cracking?

Has any FM066 user found the same issue of uneven wall thickness of seat tube?


Are the seat tube arrangements of FM066s frames also like this?

GONE4ARIDE
Posts: 46
Joined: Fri May 30, 2008 2:05 am

by GONE4ARIDE

I wrote to Hong-fu about the cracked seat tube issue recently. They acknowledged that this was a problem with some frames. They informed me that changes were made back in July to address the problem and that there have not been any complaints involving frames that have been produced since that time.
Last edited by GONE4ARIDE on Sun Nov 03, 2013 4:11 pm, edited 1 time in total.

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prendrefeu
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Location: Los Feliz, Los Angeles, California
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by prendrefeu

Are those who were affected by this covered with a warranty?
Exp001 || Other projects in the works.

SLCBrandon
Posts: 721
Joined: Fri Oct 05, 2012 3:52 am

by SLCBrandon

Valbrona wrote:A good enough reason for anyone not to buy an Fm066SL:-


wrcompositi wrote:Some alerting findings about FM066SL frames... :cry:

Recently I saw 2 instances of cracked seat tube of FM066 on Velobuild:
http://www.velobuild.com/6-build-photos/5903-cracked-fm066-sl-after-2-rides

The 2 frames in question cracked in similar positions: behind the seat tube and about 12cm down the seat tube.

This seems to be an unusual location of failures, so I removed my seatpost to investigate, and guess what I found:
Image

There's an abrupt transition from a smooth inner wall to a lower "gorge", and the thinner area starts about 11cm down the seat tube, coinciding with the aforementioned cases. My frame has only logged 700km and I 've seen no signs of cracks both inside and outside the seat tube so far, but I'm starting to worry my frame will crack the same way in the future.

My seatpost is cut to 260mm, with insertion depth of 105mm, maybe I should use a longer seatpost to lessen the possibility of cracking?

Has any FM066 user found the same issue of uneven wall thickness of seat tube?


Are the seat tube arrangements of FM066s frames also like this?




This is the Internet and forums at its/their finest.

So a small sample size of people have an issue and now no one should ever buy the frame again. But by all means, keep buying the major brands (full disclosure, I am employed by one) because they've never had a single failure.

Also, disregard the guy that has 4000 miles on one with zero issues. That's not headline making and doesn't make for good convo when the topic inevitably comes up about open molds.

Just checked my frame. Not a single sign of a crack. Again, 4000 US miles. But that's boring....

wrcompositi
Posts: 122
Joined: Tue Dec 04, 2012 3:57 am

by wrcompositi

prendrefeu wrote:Are those who were affected by this covered with a warranty?


The guy reporting the cracked frame on VeloBuild said Honor Bike would send him a replacement, which hasn't shown up yet.

GONE4ARIDE wrote:I wrote to Hong-fu about the cracked seat tube issue recently. They acknowledged that this was a problem with a some frames. They informed me that changes were made back in July to address the problem and that there have not been any complaints involving frames that have been produced since that time.


If this issue has existed for quite some time and was only rectified as late as this July as Hongfu says, why don't we see more such cases since FM066s were put to the market last year and have been very popular? If any FM066 owner can find the same scenario of uneven surface inside the seat tube, but his frame has been used long enough and shown no sign of potential failures, it would be reassuring for me to know! :roll:

GONE4ARIDE
Posts: 46
Joined: Fri May 30, 2008 2:05 am

by GONE4ARIDE

wrcompositi wrote:
prendrefeu wrote:Are those who were affected by this covered with a warranty?


The guy reporting the cracked frame on VeloBuild said Honor Bike would send him a replacement, which hasn't shown up yet.

GONE4ARIDE wrote:I wrote to Hong-fu about the cracked seat tube issue recently. They acknowledged that this was a problem with a some frames. They informed me that changes were made back in July to address the problem and that there have not been any complaints involving frames that have been produced since that time.


If this issue has existed for quite some time and was only rectified as late as this July as Hongfu says, why don't we see more such cases since FM066s were put to the market last year and have been very popular? If any FM066 owner can find the same scenario of uneven surface inside the seat tube, but his frame has been used long enough and shown no sign of potential failures, it would be reassuring for me to know! :roll:


I am not sure what the answer is to your question. Perhaps the issue only affected a certain production run. Whatever the case may be, I became a bit concerned when I saw the reports involving the FM-066SL on Velobuild because I have a pending order with Hong fu for the new FM-069. When they acknowledged the issue with the FM-066SL and said that it had been addressed, I left it at that.

chalkie
Posts: 31
Joined: Sat Apr 20, 2013 11:01 am

by chalkie

Just checked the inside of my seat tube. Smooth all the way down. Frame was delivered mid July.

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WMW
in the industry
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Joined: Sun Jul 29, 2012 2:59 pm
Location: Ruidoso, NM

by WMW

Can you describe what is shown in the photo a little better? Hard to make out... but it looks like a hole facing rearward.

If it is really a place where the wall of the seat tube gets abruptly thinner, it wouldn't help to use a longer post... the part that goes below that point would not be touching anything.
formerly rruff...

wrcompositi
Posts: 122
Joined: Tue Dec 04, 2012 3:57 am

by wrcompositi

WMW wrote:Can you describe what is shown in the photo a little better? Hard to make out... but it looks like a hole facing rearward.

If it is really a place where the wall of the seat tube gets abruptly thinner, it wouldn't help to use a longer post... the part that goes below that point would not be touching anything.


The border between two different thickness is not regular and the transition starts at various depths down the seat tube, so the affected areas are not like holes, but more like cliffs or ramps.

My picture only shows half of the affected area with the arrow pointing the most severe drop of thickness , below this area the inner wall gets thinner but the thickness is uniform around the circumference.

I think it's understandable for the thin-walled seat tube to have a thicker portion at the top to accommodate a 27.2mm seatpost, but the transition from thick to thin walls should be gradual to avoid stress risers. I wonder how they make the seat tubes of these frames. In my cases, some places inside the seat tube look as if carelessly carved rather than molded.

And Ron you're right, I think a longer seatpost won't help, since it's only in contact with the thick part.

I bought my FM066SL early this year from Miracle Trade, and it's the older version with a riveted FD mount, machined cable ports and plastic cable stops. I tried searching the web using "FM066 cracked seat tube" as key words but the Velobuild post is the only evidence, and I've seen no one mention the same issue as my frame has. (Of course I haven't read every post in every forum! :oops: )

Valbrona
Posts: 1486
Joined: Fri Oct 28, 2011 3:25 am
Location: United Kingdom of Great Britain and Northern Ireland

by Valbrona

You really do not have to be an expert in carbon fibre frame design to spot a weak design element. The thick part of the seatube will act as a lever against the thinner part, especially in the case of a heavy rider with lots of seatpost showing.

Said by the very pleased owner of an FM-028.

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