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Post by Radchenister on Jul 9, 2015 12:09:35 GMT
Come on, red frame issue that was fixed on the white frame ? I've got both red and white frames sat behind me right now, as well as a Trek MTB and the FC700 - the most flexible in overall frame length is the FC700, which I've compared to other carbon and metal frames of various price bands, as it is something I'm into ... but guess what, the carbon ones flex more than the alloy ones, so far I've found this true across the board with all I've looked at, not done all that scientifically, just by pushing at the BB from the side; but it's clear that there's loads of nonsense out there on this topic, so I can't take this sort of thread seriously. If the OP returns then fair play, but perhaps they can show us some Strava so we can see their power output and also a little vid of the frame / BB flexing, so we can take it more seriously as a first post?
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Post by chas on Jul 9, 2015 12:16:43 GMT
My view is that the frame is stiff enough but the bottom bracket and chainset are about the cheapest you can get and it's not unreasonable to expect some flex if pushed hard.
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Post by Radchenister on Jul 9, 2015 12:28:25 GMT
Yep.
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Post by william39 on Jul 9, 2015 13:18:20 GMT
Movement not anything to worry about in terms of losing power. I changed my BB yesterday and didn't put the non drive crank arm on properly realised afterwards it was sticking out nearly a centimetre and wobbling. Didn't stop me getting 8th on this segment, www.strava.com/segments/2174433or setting a PR (30th place) on this one, www.strava.com/segments/1675191With regards frame movement when on the turbo full gas sometimes I can see a bit of movement around the crank area but this could be down to the turbo not being rigid or just a trick of the eye.
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Post by Radchenister on Jul 9, 2015 13:34:14 GMT
You will get some movement on all bikes, it feels a lot sturdier on a turbo with alloy than carbon - I've had carbon fishing rods go twang and snap on me, it's not a nice feeling and the rear stays on carbon bikes aren't all that different so don't fill me with confidence when braced in place, I simply don't trust strapping carbon onto a turbo but am far happier with metal.
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Post by william39 on Jul 9, 2015 13:42:02 GMT
Pro golfers are virtually all still using steel shafts in irons rather than graphite as they are sturdier despite the weight handicap. I've still not ridden a carbon bike so not able to compare but some of the aluminium bike seem to be coming in at very low weights these days.
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Post by Deleted on Jul 9, 2015 13:42:39 GMT
Wow I had no idea my question would cause this sort of defensive stance but alright I just want to point out I was looking for advice on my specific bike and google landed on this community. First the comment about something being fixed in the white version came from here citycyclingedinburgh.info/bbpress/topic.php?id=10929 but it might be bs as some mentioned. I'm new to cycling and the red 3 is my first bike, which I bought second hand. If it sounded like I'm knowledgeable in any way it's because I've been looking into this problem for quite a bit and I have read a lot of stuff on Sheldon's webpage. But I was looking for some advice from people that own this bike as perhaps this is a common issue. Now that we got past that part, I see that some suggestions involve fixing the fd or looking into the crank set which might be flexing. For the first one, as I mentioned I have looked into many guides for aligning the fd (height, angle, cable tension) and I just can't get it to jump into the largest chainring without excessive cable tension (except in my current configuration which causes some rubbing). As a side note I had a size 60 triban 3 red before this one and I didn't run into this problem but turned out that the bike was too big and was lucky to find a person selling a 51 size that wanted to swap with mine. So it might be a problem in the smaller versions? Do you also find that your cable tension needs to be very high for your fd to work properly or is it juat me? Maybe I'm doing something wrong. I'd appreciate some advice here. The other issue would be the crankset bending. Now I'm not saying I'm doing some ridiculous power, as I mentioned I'm quite new but I still get this problem when pushing hard (I don't know how hard I'm also not very heavy ~70kg). Is there any way I can pinpoint what is the thing that is flexing? I believe you that the frame is less likely to be the problem so I want to see which part of the crankset is responsible. I of course don't have a trainer so it's a bit difficult for me to reproduce the problem inside (I've tried pushing with my hand but it doesn't happen then). While riding it's a bit difficult to see what's going on while trying to not crash with something.
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Post by Radchenister on Jul 9, 2015 13:59:37 GMT
Ah you are real - so welcome, we like a good debate, it's just this one looked fishy - apologies . So, some more clarity, probably over thinking the issues though. First, if the limit screws are set right and the front mech' is in good working order, then the cable shouldn't be stiff, the clearances should be manageable and the noises will go away. Sometimes if the cable is over the lug wrong or the tension is wrong, you can have the problems you suggest with changing but this may or may not be related to 'perceived flex' - see this for FD triban3owners.freeforums.net/thread/5461/alur-chain-rub-front-derailleur?page=1&scrollTo=94829 ... different bike but the principles still apply. Then it's either the BB, cranks or even a misaligned chain ring. The BB needs replacing over time, so that's not a bad place to start, perhaps also new cables if they're old, frayed, gunky, as they can cause issues, lastly consider new cranks, Sora appear pretty decent but they also need a different BB (and even spacers if you want to get the offsets even). I'll say it again though, it's not the frame - unless it's cracked or something .
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Post by Radchenister on Jul 9, 2015 14:14:33 GMT
Oh and I vaguely recall someone having a problem with their shifter in similar circumstances - a little vid off your phone might help if you can't crack it from the above, you have to YouTube it (or similar) and link it.
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Post by r0b1et on Jul 9, 2015 14:39:54 GMT
... but is it the crank or the BB or the frame - they couldn't possibly tell and it's more likely the BB and crank than the frame. Much, but then you've previously denied they flex too. PS, 800W for 20s isn't that high, given I'm much lighter: www.strava.com/segments/933262154.9km/h 151bpm 986W Powermeter - 23s BUT, I do agree that first post screamed troll to me.
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Post by r0b1et on Jul 9, 2015 14:50:53 GMT
Should say I expect Rad has it covered - I'd look at the cables and check for cleanliness and fraying and then confirm the limits cause no rub on the stand.
Another thought, is the rub consistent? (i.e. on the whole way around the crank movement?) I'd think flex in the cranks or BB wouldn't be.
Then if you think you'll do a lot of riding think about replacing the chainset too (what ever Rad says, it feels like it flexes relative to my tiagra, 105 and SRAM rival chainsets and I sprint less effectively with it). If not huge mileage, the bottom bracket is a cheap swap and might make a noticeable difference.
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Post by Radchenister on Jul 9, 2015 15:00:23 GMT
I do have a bee in my bonnet on this of course, I thought we determined it wasn't the frame and was likely the BB or cranks in all of these similar discussions? ... which is what I said as the first response on this thread, it is one with a title saying 'frame bending' after all - my response is that somebody has to be having a laugh here, as I simply can't get my head around this perception, as it doesn't gel with things I see with my own eyes, my own experience and the things that I feel by flexing various frames when out and about. The ongoing issue here being the 'flexy frame' joker card, the common theme to the ongoing debate that @germcevoy , you and others have banged on about in the past, particularly re carbon / alloy v power output. FWIW, I'm still quite happy with my Ounce and a stiffer BB on the T3 as a winter bike, I don't think it's such an issue that it warrants all this hot air, the over zealous concern for marginal gains is a bit OTT here - Rocket has demonstrated similar findings, as has our man in the Alps above. I just find this association of clunky gears, rubbing chains and then the mental leap to conclusions about flexy frames being 'the problem' as being totally bonkers, particularly when the people rolling it out as a principle are posting rides averaging 100 - 120 watts (Strava figures, not actual) and haven't even got their heads round the basics of gear set up. I genuinely believe that the T3 frame is up there high on the rigidity scale, it's not much different to my old tank of a Trek MTB (not cheap in its day or more recently - look up the model 8500). I've been flexing frames all over the place over the last few months, as I'm more curious about how much carbon flexes than alloy - I simply can't gel with this talk of 'flexy metal frames', as the carbon ones are all flexing more. Try it next time you're out with mates (if they don't mind), just lean the bike over a bit holding onto the saddle firmly and push the crank set towards the road with your palm.
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Post by r0b1et on Jul 9, 2015 15:12:56 GMT
Agree, I generally don't have comfort issues, and so went for stiffer aluminium.
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Post by Radchenister on Jul 9, 2015 15:29:16 GMT
If I was buying now, I'd have to have a serious think about alloy v carbon - light alloy and stiffness are appealing, as long as they're comfy enough. If we get really geaky on power and movement when sprinting, I get more rear wheel skip out of the T3 than the FC700 when gunning it, I need to be smoother on alloy, as that flex across the wheel base on the carbon can help keep road contact. If we liken the rear end to a car's suspension, some degree of movement can assist in keeping the back planted in contact with tarmac, if things are skipping about because it's all too stiff, then you're in danger of losing traction. This is a different principle to the movement through the localised area of the BB and cranks of course. On a similar vein, the overall frame flex is an issue when descending, it affects tracking and control at speed; with a flexy frame, you're required to be careful with your lines and body weighting, as sudden jerky corner maneuvers mean the bike can suddenly feel mushy up front, just when you don't need it; probably only a concern for the ex superbike speed freaks, who are used to occasionally forcing a bike through a change of line in a corner but it's also worth bearing in mind, if people get in a panic going too fast in a corner and need to correct their line, the bike may not comply if it's done too aggressively - the amount of wheel and tyre flex also comes into this.
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Post by mark072 on Jul 9, 2015 19:28:52 GMT
Unless is Uri Geller or puts out 10 times more watts then Cav in a sprint finish I cannot see it been the frame bending, maybe gears need adjusting to prevent chain rub
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