- The “SRAM GXP Bottom Bracket Cup Set English Thread” which comes as part of the SRAM Force Groupset is as soft as butter (for want of another word!) be super careful when applying torque to the cup ensuring your wrench does not slip off causing cosmetic damage in the least or mechanical in the worst case. I had this issue and even though it didn’t affect the performance I replaced it with a new Cup Set ~ AUD$29.13 from Wiggle
- Hongfu sell a Seatpost (1 xHF-SP003 $38.00) – it appears their is no adjustment for the pitch – mine was pitched at about 5-10deg to the horizontal – no good I simply could not use it – no great loss at US$38 but just be warned.
- The HF-SPC001 seat post clamp works well but is heavy and can be opened by hand – I initially replaced this with a Hope clamp as above however this is made of a very weak aluminium and I ended up splitting the bolt – Hope sent me a replacement no questions asked and I am currently using it but would like to replace it with the more robust Thomson Seat Collar.
- I used the Neco headset from Hongfu, so far so good – I didn’t have too many issues installing it but used a different technique (Not PVC) for installing the race onto the fork. I used a plank of wood – drilled a 2-3inch hole, supported the plank of wood between two chairs, placed the race onto the fork and banged the race down onto the fork through the hole as opposed to the PVC method where you may be putting excess pressure on the fork and will have to support he fork somehow. (comprendez vous?)
- My frame did not come with any cable barrel adjusters – I purchased these from my LBS.
- No issue with the FM015 Top tube internal cabling however I found the SRAM rubber gromits used between the end of the gear/brake cable and top cap made the brake/grear change spongy – I ended up not installing these – I will have to be vigilant of water ingress but so far so good
- Underneath the BB there is a plastic gear guide – this was screwed into place with a factory screw and didn’t look very durable – I replaced this with a decent Stainless Steel screw for good measure.
- The 3K black Matte finish is better than I expected – it’s actually a paint finish ontop of the raw carbon so water et al beads off without worry. I have protected the underside of the down tube with psuedo 3M Helicopter tape – stones flicking off the front tyre made quite a noise however produced no noticable marks – the 3M tape is just for insurance!
Most cheap carbon bike frames come in both 3K or 12K versions. Many people ask which is best.
Firstly, what is the difference between the two types?
Carbon fiber is made of thin carbon “threads”, each of which is made from even smaller carbonÂ filaments. 3K or 12K refers to the number of filaments per thread – ie, 3ooo or 12ooo filaments per-thread.
Originally, most carbon fiber was woven using 3K fiber. During the early to mid 2000′s, though raw carbon fiber increased in price as more and more of it was consumed in military and aerospace applications.
New carbon fiber manufactures developed processes to use 12K fiber instead of 3K. This new fiber could be manufactured cheaper, but had the disadvantage of being more difficult to handle andÂ mold, especially on tight circumferences
as well as being not as strong as 3K filaments. For example, cstsales.com lists the strength of 3K fiber at 7400 ft/lb while 12K is listed at 1800 ft/lb. (Edit – it has been pointed out that these measurements are actually for weight per length, not strength at all. Doh!)
Now, most handling problems have been overcome and for bicycle frames the molding problems are not an issue. The finish on the frames looks different though, because 12K filaments cannot be woven as tightly as 3K fiber.
Unfortunately, for most bike frames it can be difficult to know how much of the frame is manufactured from each type of carbon fiber. Carbon fiber frames are manufactured by laying down layers of fiber weave with resin, and we can only see the outer, cosmetic layer. Without destructive testing and/or a forensic investigation of a cut up frame it’s impossible to know what (if any) effect weave has on a frame’s riding characteristics.
In conclusion, you are probably best off buying the type you like the look of, or whatever is available.
Update: I found this document from hexcel which lists the strength of various fiber type. It gives some useful information, but really shows how the exact grade of fiber used has a much bigger effect than if it is 3K or 12K.
The FM027 (aka TP-R813) Â is one of the newer frames available. I haven’t seen any built up yet, but judging from the curves in the seatstays it should be a pretty comfortable bike to ride.
55 cm Frame Geometry:
I think the reason most people buy a cheap carbon frame from ebay or whereever is that they cost less than non-generic brands. Usually buyers have already owned a bike for a few years and are looking to upgrade and find the economics of saving 50% on the frame difficult to argue with.
Often that means being able to afford a groupset higher than they would otherwise (Ultegra instead of 105 is something that seems to be common) or the ability to purchase the exact parts they want (many would like to experiment with a SRAM build, but can’t find one in a bikeshop they like.)
One question many people ask when they discover carbon frames are available for under $400 is “are they safe”? I don’t think anyone can answer that in every case – it really is a case of buyer-beware.
There seems to be plenty of evidence that the well known generic frames (ie, the Hong-Fu/Greatkeen FM004, FM015 & FM028) Â are no less reliable than any common brand. The RoadbikeReview.com forums have threads going back to 2008 about them with no cases of broken frames.
The other argument against them used to be that people thought they were just copies of generic frames.Â FortunatelyÂ it looks like this argument is dying out as people realize that – while some frames do have some superficialÂ resemblanceÂ to other well known frames, they also have enough differences to make it impossible that they are copies. After all, many bike frames look pretty similar if you take the paint off.
At the moment it isÂ increasinglyÂ common for people to find FM frames being house-branded by large bike shop chains or mail-order resellers.Â Ultimately, if you are concerned about the reliability of one of these frames that may be the best of both worlds for you.
Here is the Hong Fu FM028 carbon bike frame geometry chart for 50cm, 52 cm, 54 cm and 56 cm frames. (Thanks to some readers for the 50cm, 52cm and 54 cm drawings. Does anyone have any other sizes? [email protected])
I also found a sizing chart from an ebay listing that appears to be for the FM028:
A few people on the roadbikereview.com forums have recently bought bike frames from Miracle Trade. A copy of their catalog was posted recently (22 July 2010) too. It contains a good selection of carbon bike frames as well as wheels.
Here are the geometry charts for the HongFu FM015 bike frames, in the 53 cm, 55 cm & 58 cm sizes. (Update: A reader sent in the non-integrated seatpost drawing and a sizing chart. Thanks! Update 2: And now we have a 51cm drawing.)
55 cm (non integrated seatpost):
Here is a sizing chart:
anybaby8088 is one of the better know ebay sellers of carbon fiber road frames. A number of people from the roadbikereview.com forums have purchased from them (him? her?) without problems. (Update: A reader has commented that anybaby8088 is the ebay account of Jenny from Hong-Fu, who most people deal with when buying bikes from the Hong-Fu website)
This one is known as the FUll CARBON FIBER MONOCOQUE ROAD RACING BIKE FRAME, and is available in 3K or 12K weave.
This carbon TT frame looks similar to the Hong Fu FM029 TT frame:
The Hong Fu FM004 is an older (compared to the FM015) frame from Hong Fu. It remains popular because of its different fit and ridingÂ characteristics.