|
|
Thread Tools | Display Modes |
#51
|
|||
|
|||
On 22 Mar 2005 04:23:06 -0800, "dkahn400"
wrote: Martin Wilson wrote: Its well documented that the GT triple triangle frame design is more rigid because it supports the seat stays at both the seat tube and top tube with welds. As a heavier rider I'm obviously going to get more movement there. Really? Where is it so documented? This is the design that Sheldon Brown has described in the following terms. : This is not sturdier, it is a bogus design used for cosmetic : purposes, to build brand differentiaton. It is based on : marketing, not engineering. It makes the bike heavier, but has : no functional value. And from Sheldon's glossary (under Hellenic): : It is of no practical value, and often causes un-necessary : complication to brake cable routing, luggage rack attachment : and installation of frame pumps. It is also slightly heavier : than normal frame construction. So your basically saying sheldon brown doesn't like them so the extra welded length of stays to the top tube has absolutely no improvement in strength at all. The fact the seat stays have two welded/anchor points does not add any strength what so ever. Admittedly the well documented statement is referring to mainly GT's own information but real world users seem to accept GTs on this level and they have an excellent reputation for strength. After reading various postings about the unbreakable quality of GT's old triple triangle chromoly and unbutted frames I picked up a GT Timberline FS on ebay to muck about with offroad. The story goes that GT famous for bmx produced early generations of mountain bikes with well over the top strength. There are a few stories of near total abuse and still surviving. It seems everything is open to debate on this forum. I'm not sure I even care anyway but I've read lots of postings where the GT triple triangle was discussed as having a harsher ride and as this would link to GT's own statement regarding strength and more rigidity I perhaps unfairly took it to be true. Anyway my original point still stands the high tensile frame is more comfortable and seems to have more flexing and seems to soften the impact of potholes etc. I had in mind that the oversized main tube created a more rigid main triangle and the chain and seat stays were forced more to flex because of it. The reason I have discounted the saddle from the equation is because often when I see bumps I obviously lift off the saddle to go over them and even then there seems to be a reduction in the impact as the rear wheel goes over it. |
Ads |
#52
|
|||
|
|||
Where are the hordes of people who buy these cheap bikes? Shouldn't we be seeing a massive increase of cyclists on the roads? Ah well, shouldn't feed the Trolls. Cheers Dave R This is what I don't get and perhaps it a local thing but where I live the vast majority of bikes ridden are low cost bikes. Maybe for every 20 bikes I see one will be a fairly new well regarded brand. The other 19 will be low cost bikes are very old bikes like Raleighs. The only Kona or Giant I've seen on the road are my own. Close enough to make out the brand that is as I've perhaps seem them from a distance and not been able to make out the brand. Then again if I think about whose actually riding bikes the vast majority are teenagers or younger. If I was guessing where these bikes are bought from I would say Halfords, supermarkets and mail order catalogues. Then again where I live we never have much in the way of traffic jams or car commuting problems. Assuming that people in this forum are correct and the vast majority of cheap bikes aren't ridden then here that would probably equate to about 200 cheap bikes sold for every 1 high quality brand. |
#53
|
|||
|
|||
On Mon, 21 Mar 2005 23:51:36 +0000, Jon Senior
jon_AT_restlesslemon_DOT_co_DOT_uk wrote: Martin Wilson wrote: So lets get this straight. They have a large collection of high tensile steel frames that have broken in use either the welds or tubeing. What is their motivation to keep these frames? Because we recycle stuff. Those bikes that can be made usable are, and those that can't are collected, sorted by material and sold as scrap. It doesn't surprise me about tourney gears. They are ok and workable but the shimano models higher up in the range have a crisper and faster gear change. While tourney gears are widely used on sub £100 bikes they also feature on higher end models upto £400. I find that disturbing. They are somewhat shaky and when I was budgeting around £400 for a new bike (Ended up revising upwards somewhat!) I was looking at Sora or Sora / Tiagra mix. Last time I googled a womans hybrid came up at £400 with a shimano tourney rear derailleur but can't see it now. There are a few bikes at £400 with tourney front derailleurs. The annoying thing is that if they fit a tourney to a higher priced bike they often won't mention it by name for obvious reasons. They just say shimano gearing etc. Anyway here's a £300 bike with tourney style steel pressed type derailleur Its the silverfox knarly http://www.grattan.co.uk/Web/images/...rge/89W574.jpg I'm sure there are dearer bikes with them fitted it just takes more than a casual search to find them. However there are masses of bikes at around £200-250 with rear tourney derailleurs. The point is these are identical derailleurs to those fitted to the £40 sterlinghouse bikes etc. You don't like them and I don't like them but a massive amount of people are using them. Raleigh seem to fit them to almost every bike they do. I think halfords wanted £15.99 for a tourney rear derailleur when I overheard a conversation from a customer needing a new rear derailleur when some kids had stepped all over his kids bike breaking it. Not sure if this included fitting. It was the only option he was given I think probably because of no gear hanger on the bike. Makes you wonder how a £40 bike can have a rear derailleur that sells for £15.99. I think I've already answered that elsewhere. Sorry. I'll read through the rest of the posts and find out your justification. Jon |
#54
|
|||
|
|||
On Sun, 20 Mar 2005 20:05:19 -0000, "Clive George"
wrote: "Martin Wilson" wrote in message .. . I've never seen a cheap bike with terrible alignment or substandard components. You've described the tourney rear mech (common on cheap bikes) as substandard... clive I see substandard and workable but not brilliant as different. The tourney is usable, its slow to change and for this reason not ideal. the spring is a bit lightweight. Its not unsafe. Its low performance. I see substandard as unsafe and unusable which is different. I'm certainly in 100% agreement though that the higher end shimano's are better. Crisper gear change and faster. |
#55
|
|||
|
|||
On Tue, 22 Mar 2005 18:40:55 +0000, Martin Wilson
wrote in message : So your basically saying sheldon brown doesn't like them so the extra welded length of stays to the top tube has absolutely no improvement in strength at all. Seems fair. Sheldon is a guru, after all. Guy -- http://www.chapmancentral.co.uk "To every complex problem there is a solution which is simple, neat and wrong" - HL Mencken |
#56
|
|||
|
|||
On Tue, 22 Mar 2005, Martin Wilson wrote:
So your basically saying sheldon brown doesn't like them so the extra welded length of stays to the top tube has absolutely no improvement in strength at all. The fact the seat stays have two welded/anchor points does not add any strength what so ever. Absolutely. In fact, by adding local bending top teh tubes by loading them other than at teh node points of the truss, if anything, you'll weaken teh frame. They've taken a nice tidy shape that is intrinsically rigid without introducing local bending in teh elements of teh frame, then converted it to something that relies on local bending. real world users seem to accept GTs on this level and they have an excellent reputation for strength. After reading various postings So they make teh tubes thicker to compensate for poor design - doesn't make teh design good, and especially doesn't make it efficient. regards, Ian SMith -- |\ /| no .sig |o o| |/ \| |
#57
|
|||
|
|||
On Tue, 22 Mar 2005 19:39:50 +0000, Martin Wilson
wrote in message : silverfox knarly I did a quick Google on that. Sterling house sell it (always a bad sign) at £225, much less than the price you stated. A full-sus bike for £225? I'd expect it to be pretty poor. A decent rear shock costs twice that, I know because I can't afford to upgrade my cheap Ballista to a decent airshock. Lots of other generic mail order shops seem to sell the same model. But it's not on places like Bonthrone Bikes. My local MTB specialists don't stock that brand at all (they do Trek, Marin, Gary Fisher, Whyte, Rocky Mountain and Cove). My LBS stocks the following brands (takes deep breath): Bianchi, Cervelo, Colnago, Dahon, Dawes, De Rosa, Electra, Fit, Fuji, Gary Fisher, Giant, Hoffman, Isaac, Kestrel, Klein, Kona, Lemond, Litespeed, Mezzo, Mongoose, Mountain Cycle, Orbea, Pashley, Perv(!), Pinarello, Principia, Quintana Roo, Ridgeback, Saracen, Tifosi, Trek, Vario and Viking. Of these I know that Dawes, Trek, Gary Fisher and Saracen all do competent bikes at the £200 mark, and that's at bike shop prices. £200 should get you a reasonable rigid MTB-style bike. With luck you might even get front sus for that, although it might not be very good. The bike you saw? That's being offered by Sterling House for the same price as a Dawes Tekarra with front sus in my LBS. I would have the Dawes. http://www.awcycles.co.uk/products.p...d=m1b47s2p3632 You can get a full-sus bike from my LBS for that sort of cash: http://www.awcycles.co.uk/products.php?plid=m1b8s1p3127 but I don't really fancy it. Most of the cheap bikes seem to have (Tourney) TX50 rear mechs. These are *not* the same as the old "Shimano SIS" crap seen on early low-end indexed bikes. We have bikes with both sorts; the Tourney style have in my experience two main faults: one, they have plastic adjuster barrels, which tend to strip, and two, the cages bend rather easily. Apart from that they are functional. Actually I have SIS, Tourney, Acera, Deore, Deore LX and Deore XT. Of these the only one which is actually crap is the SIS. Oh, and I had some trouble with the Deore but that was 9-speed job and on the recumbent with very long cable runs. After I'd replaced it I found that the real problem was simply that the hanger was too thick - I ground 1/16" off it and it's fine now, so I think even base spec Deore probably works OK. My experience with Tourney is that if they (and the chain) are kept well lubricated they work as well as anything else, but they are intolerant of abuse, especially mechanical abuse. On the plus side, the cages are made of cheese so straightening them out is a job for fingers not the vice. The most dependable bike in our house is my wife's 2001 Dawes Saratoga, Tourney rear mech, Cr-Mo frame. I put Alesa XPlorer rims and a Deore XT rear-end on because the trailer bike was taking its toll. Cassette rear end - there's a must for the heavier rider. Avoid screw-on blocks! That's the same price now in aluminium with front sus as it was then in Cr-Mo with a rigid fork. Incredible, really. Guy -- http://www.chapmancentral.co.uk "To every complex problem there is a solution which is simple, neat and wrong" - HL Mencken |
#58
|
|||
|
|||
Martin Wilson wrote:
[snip several paragraphs about cheap bike frames, one of several posts in this thread on the same subject by Martin, and it's not the first thread where he's engaged on the subject]... I'm not sure I even care anyway ....[snip another couple of paragraphs] I can hardly wait to see what you'll do for a topic you really care about. -- Joe * If I cannot be free I'll be cheap |
#59
|
|||
|
|||
JLB wrote:
Martin Wilson wrote: [snip several paragraphs about cheap bike frames, one of several posts in this thread on the same subject by Martin, and it's not the first thread where he's engaged on the subject]... I'm not sure I even care anyway ...[snip another couple of paragraphs] I can hardly wait to see what you'll do for a topic you really care about. Do you think he might...gulp....contribute to the FAQ? Naaaah, too much bother. James |
#60
|
|||
|
|||
in message , Martin Wilson
') wrote: On 22 Mar 2005 04:23:06 -0800, "dkahn400" wrote: Martin Wilson wrote: Its well documented that the GT triple triangle frame design is more rigid because it supports the seat stays at both the seat tube and top tube with welds. As a heavier rider I'm obviously going to get more movement there. Really? Where is it so documented? This is the design that Sheldon Brown has described in the following terms. : This is not sturdier, it is a bogus design used for cosmetic : purposes, to build brand differentiaton. It is based on : marketing, not engineering. It makes the bike heavier, but has : no functional value. And from Sheldon's glossary (under Hellenic): : It is of no practical value, and often causes un-necessary : complication to brake cable routing, luggage rack attachment : and installation of frame pumps. It is also slightly heavier : than normal frame construction. So your basically saying sheldon brown doesn't like them so the extra welded length of stays to the top tube has absolutely no improvement in strength at all. Martin, I am _not_ deliberately having a go at you. But it doesn't seem likely. The conventional diamond frame geometry makes each element either a relatively pure compression element (the seat stay, seat tube, top tube) or a pure tension element (the chain stay, down tube). Bonding the seat stay to the seat tube at 75% of its length and to the top tube at about 70% of it length means you are inducing bending loads in both the seat tube and the top tube, and thin-wall tubes are not particularly good at resisting bending. Also, the tubes need to be thickened around the joins so that the heat effects of welding don't unduly weaken the tube. So at a first analysis I would expect it to be weaker, heavier and/or less rigid. It seems everything is open to debate on this forum. I'm not sure I even care anyway but I've read lots of postings where the GT triple triangle was discussed as having a harsher ride and as this would link to GT's own statement regarding strength and more rigidity I perhaps unfairly took it to be true. The harsher ride might simply be the thicker tubes needed to stand up to the extra welds. -- (Simon Brooke) http://www.jasmine.org.uk/~simon/ Das Internet is nicht fuer gefingerclicken und giffengrabben... Ist nicht fuer gewerken bei das dumpkopfen. Das mausklicken sichtseeren keepen das bandwit-spewin hans in das pockets muss; relaxen und watchen das cursorblinken. -- quoted from the jargon file |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Go Faster New Bike Recommendations ? | Mike Beauchamp | General | 50 | December 16th 04 04:13 PM |
Go Faster New Bike Recommendations ? | Mike Beauchamp | Techniques | 0 | December 9th 04 12:57 AM |
How much faster and I supposed to go? | ChangingLINKS.com | Unicycling | 7 | May 31st 04 01:23 PM |
Scottish Cycling Fund | Smithy | UK | 148 | April 29th 04 12:56 AM |
this newsgroup's URL | Steve Fox | Recumbent Biking | 20 | August 21st 03 03:34 AM |