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PostPosted: Thu Aug 15, 2013 12:33 pm 
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Joined: Sat Apr 02, 2011 11:16 am
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Location: Camden, London
I'd see if you can ride the larger frame, funnily enough I've been having this debate with myself only the other way with Marins, dropping a frame size and playing with stem length, but with the Marins, there is only limited impact as while the size on seat tube goes 17.5 to 19, the top tube is only 22.5 to 23. A bigger impact seems to be the change in head tube means the bars sit lower with a smaller frame so more bent over, I've been looking at Kona's for a change - do drop us a line if you do change frame :D


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PostPosted: Thu Aug 15, 2013 12:53 pm 
retrobike rider
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Joined: Sun Sep 23, 2007 11:22 pm
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Location: Hove
FluffyChicken wrote:
1993 the 18/19 used 130mm stems. 20/21 used 150mm stems on the Kona. So steering shouldn't be to effected with 135/140 lengthening it a bit over the targeted average for that size. They where certainly not uncommon length. Your arm length and position is possibly quite different to Anthonys so would find the larger swing better over the shorter twitchy 125 length.
Still proof is in the pudding and riding it. I have 130/135's on my 17/18/19/20 frames, rigid to period suspension. The only one shorter is the newer Kona but it has longer forks on. Still its down at 120mm ('97 era). The 17" needs to be shorter as its for them wife, but for me its good.

Just because Kona themselves specified 150mm stems for the large sizes doesn't mean they don't adversely affect the handling. Fitting a long stem *always* adversely affects the handling. A 150mm is an abomination that should never be used, but in those early days designers hadn't worked out how to design mountain bikes properly and were still just adapting road technology (and road riding postures).

There is however room for variations in taste. If you find a 125mm stem short and twitchy, then your personal taste is obviously way out in the dead end of the handling spectrum - and that's fine for you, especially if you have a lot of skill to overcome it, as I'm sure you have. Most people though prefer responsive steering and that's why you won't find a stem anything like that long nowadays, even on rigid bikes.


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PostPosted: Thu Aug 15, 2013 1:12 pm 
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Is the fork shape not also a factor along with head angle, ie fork "rake" (to reduce the "trail", being the amount the axle is in front of the line of the stem and something to do with steering line and where the wheel touches the ground respectively), with the shorter the rake the twitchier the steering, and less forgiving the ride which is why tourers had lots of rake and racing bikes had a lot less ?


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PostPosted: Thu Aug 15, 2013 3:21 pm 
retrobike rider
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Joined: Fri Aug 08, 2008 2:36 pm
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Location: Yorkshire, England
and that's the point Anthony. EVERYTHING is preference. People I ride with seem to always have the 130 to 150 stems that the bikes used BitD.
You like short stem, small framed bikes.
I don't
Plenty of other don't
I was not assuming anything about what anybody else would like, just showing what was used BiTD when the frame was designed and came out.
Hence proof is in the pudding when he rides it.


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PostPosted: Thu Aug 15, 2013 4:36 pm 
retrobike rider
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Joined: Sun Sep 23, 2007 11:22 pm
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daugs wrote:
Is the fork shape not also a factor along with head angle, ie fork "rake" (to reduce the "trail", being the amount the axle is in front of the line of the stem and something to do with steering line and where the wheel touches the ground respectively), with the shorter the rake the twitchier the steering, and less forgiving the ride which is why tourers had lots of rake and racing bikes had a lot less ?

Fork offset, stem length, bar sweep, wheelbase and wheel size all affect the responsiveness of the steering. I can never understand why people focus so much on head angle, as if it was the only factor, when it's just one of many.


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PostPosted: Thu Aug 15, 2013 5:29 pm 
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Joined: Mon May 07, 2012 10:30 pm
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Location: Lochaber
As ever, all thoughts appreciated. Yes, lots of things affect steering and handling. I know this from my motorcycles, retro pedal bikes being a rather recent affliction! I run my old Voodoo Erzulie in two guises, one with long stem, narrow bars and short fork for cross country rides and pub and one with longer Z1 Bombers, short stem and wider bars for steeper scary stuff. Both work well in their way, its horses for courses.

Funnily enough I just this minute got a black Velocity stem of the correct vintage in 100 mm (cheers Marc two tone) that I bought before I'd 'faked up' the build, sat on it and thought "this is a tad short". So now I have a range of stems to try from 100 to 135. If nought else it'll be entertaining trying them out. The wee black 100 mm one with yellow and white logos undoubtedly looks the best though :(


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