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 Post subject: Retrobike geometry
PostPosted: Mon May 27, 2013 8:36 pm 
Dirt Disciple

Joined: Thu May 23, 2013 1:04 pm
Posts: 21
I’m in the process of getting my old Saracen rigid mountain bike into a rideable state. There’s nothing really wrong with it, but I’ve not ridden off-road for years, so, being a bit nervous and lacking in skills, I recently had a short session with a mountain bike coach. He was quick to point out the shortcomings of my bike, and explained that things have moved on since it was made. Ignoring the canti brakes, his main complaint with the bike was along the lines of, "the geometry is all wrong". I may have got this wrong, but he said that the older bikes had short top tubes, long stems, tight angles, and a large saddle to handlebar drop. As a result of this, there’s a lot of weight on the rider’s wrists, and that weight is also close to the centre of the front wheel, meaning it doesn’t take much of a descent before the rider reaches a tipping point. He did say it was better for climbing, but at the end of the session advised me never to ride the bike again!

I always thought the saddle to handlebar drop put quite a lot of pressure on my hands, but does he have a point about everything else? When I bought the bike (around the mid 90’s) I think all mountain bikes were similar. It obviously didn’t stop riders then, but is it generally thought of as a less than ideal geometry?

I’m attempting to change the riding position by fitting a swept back riser bar - I’m not sure if it’s ideal for off-roading, but I’ll see how I get on with it.

I’m really interested to know if people generally just ride these older bikes as they are/were, or if there are known tweaks which make them ‘better’.

The other thing I’ve been pondering is – why is there the 1997 cut-off on Retrobike’s MTB forum? Is it because bike design and styles changed drastically around then, or is it just an elapsed time thing, and next year the cut-off will be 1998 and so on?


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 Post subject: Re: Retrobike geometry
PostPosted: Mon May 27, 2013 9:18 pm 
retrobike rider
retrobike rider
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Joined: Fri Aug 08, 2008 2:36 pm
Posts: 16747
Location: Yorkshire, England
He is right, modern setup has change but that is mainly around the increase in suspension fork and little else. It happened because it had to.

As forks get longer, it raises the front end, there is only so short you can make a tube.
This raise means you need to make top tubes longer (virtual tube length) to compensate for the now shorter reach. Also with the increased fork length, that needs to be compensated for by reducing stem length.
Angles ate a difficult one. It depends where you expect the forks to be sitting and I assume how you are aiming the bike. Top end always used to be XCracing focused, lower end slackened them off for longer easier riding.
Sloping top tubes became the norm as the front is now higher and the rear still needs to be as low as it used to be.

Some things are tweaked, but then they also varied bitd.
But it all eve loved around increased fork length. Full sus is a different matter, who knows.


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 Post subject: Re: Retrobike geometry
PostPosted: Mon May 27, 2013 9:49 pm 
Old School Grand Master
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Joined: Sun Sep 05, 2010 1:10 am
Posts: 4756
Location: Heathfield, East Sussex
'Don't ride it again...' huh?

Try telling that to DSP as he's hammering downhill on a 200gs equipped antique, overtaking all the 'Weekend Warriors' on their state of the art full sussers! :roll:


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 Post subject: Re: Retrobike geometry
PostPosted: Mon May 27, 2013 9:50 pm 
Section Moderator & South West AEC
Section Moderator & South West AEC
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Joined: Mon Jun 25, 2007 3:33 pm
Posts: 8163
Location: new forest
personally i think your coach is a bit out of order.

there are a couple of things that are correct but to suggest that you should never ride the bike again? :roll:

early 90's mountain bikes went very race orientated, previous to that they were quite upright with riser bars etc but when mtb's became popular the racing took over so the geometry changed into an almost roadie set up as speed and performance was paramount.

as has been said above the geometry then changed again as suspension became popular the front ends got higher and this meant a change in head angles/stem lengths to compensate.

also don't forget that in the early 90's trail centres etc didn't exist, courses have got deliberately harder because modern full suspension bikes can cope with rocks and drops that early bikes were simply not designed for. back in the day i was riding off road but by comparison with the off road i now regularly ride in wales and the alps is so different.

to sum up, if you're riding the same places as you were 20 years ago you should be fine on the bike, if on the other hand you want to hit a rocky trail centre in the middle of wales then i'd suggest something a little more suited.

personally i have loads of bikes, the retro stuff gets used alot around the new forest, and it's actually perfect for these trails.

:)


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 Post subject: Re: Retrobike geometry
PostPosted: Mon May 27, 2013 9:56 pm 
retrobike rider
retrobike rider

Joined: Tue Jul 10, 2012 11:58 pm
Posts: 2362
Location: Bournemouth
The style of riding has changed. If you try riding an old bike in the modern style, it won't work. However, riding a modern bike with the old style will. Basically, we had to be better riders BITD than the current crop, as our bikes didn't absorb the bumps, we had to ride them. Your instructor may not have the skills to ride the old girl.


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 Post subject: Re: Retrobike geometry
PostPosted: Mon May 27, 2013 11:44 pm 
Geoff Capes
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Joined: Sun Feb 12, 2012 10:33 pm
Posts: 956
Location: On my laptop somewhere..
true & well said^^

He actually said 'don't ride that'?....... RUDE!

There's a certain type of satisfaction to be had, OK, largely at trail centres, on a rigid bike. When going past these knights in shining plastic armour with more hydraulics that you can shake a stick at..Seen some of them even get off and walk down - that makes me believe in the effectiveness of my bikes geometry, its kit (and my nerve). It all works & always will. It's down to the rider.

Critiquing skills and techniques is a given.. Open to that. But dissin' the bike?!?

In the nicest possible way:' Ta for your advice on my bike.. But shove up it your @r¤€!'


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 Post subject: Re: Retrobike geometry
PostPosted: Mon May 27, 2013 11:52 pm 
Section Moderator & South West AEC
Section Moderator & South West AEC
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Joined: Mon Jun 25, 2007 3:33 pm
Posts: 8163
Location: new forest
reading the above reminds of 2 rides, the HONC a couple of years ago, me and graveymonster were riding most of the course together, we were mid field but going quite well, we overtook more guys on the downhills than elsewhere and most riders were on 5 inch full suss bikes, i was on a rigid vitamin t2 and graveymonster was on an ealry E stay saracen.

the other ride was the cannock turkey twizzler a few years ago, towards the end of the ride there was a steep drop in, i came round the corner (having never ridden there before) on my rigid 1993 orange elite, saw 2 guys stopped on full suss bikes eyeing up the this drop, i just rode straight in to it shouting "come on you pansies!!!" :lol:


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 Post subject: Re: Retrobike geometry
PostPosted: Tue May 28, 2013 2:06 am 
Dirt Disciple

Joined: Thu May 26, 2011 6:03 am
Posts: 82
Location: Singapore, formerly Luton
My wife is looking to buy a new road bike, and through her work got a free bike fitting and recomendation. We regularly ride 150 k in a weekend and her 95 Trek 970 is showing its age. It does have a LOT of new parts on it, but is still an old bike, it's also getting rusty. But it's triple butted frame means it weighs in at 10.5 kg, not bad for an old girl.

We turned up at the bike shop last Saturday, complete with the old girl, to find a brace of very high tech williers in there with some other super expensive machinery. The guy went through fitting her out and finding best geometry for her future purchase, and after two hours got her on the Trek to see what improvements could be made. Shorten stem ,by 20-30mm was conclusion.

Despite the fact that the Trek currently needs a good service, he didn't make one comment about its age or pedigree.


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 Post subject: Re: Retrobike geometry
PostPosted: Tue May 28, 2013 12:50 pm 
retrobike rider
retrobike rider
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Joined: Wed Apr 15, 2009 1:08 pm
Posts: 3117
Location: Woking
jonnyboy666 wrote:
to sum up, if you're riding the same places as you were 20 years ago you should be fine on the bike, if on the other hand you want to hit a rocky trail centre in the middle of wales then i'd suggest something a little more suited.

personally i have loads of bikes, the retro stuff gets used alot around the new forest, and it's actually perfect for these trails.

:)


Yep, what he said.


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 Post subject: Re: Retrobike geometry
PostPosted: Tue May 28, 2013 1:38 pm 
Dirt Disciple

Joined: Thu May 23, 2013 1:04 pm
Posts: 21
Thanks for all the comments, and the info on the changing geometry and riding styles. I hadn't realised the rides/routes had changed.

I wasn't offended when he commented on my bike - at the time I thought it was a good excuse to buy a new bike! However, older bikes have always appealed to me, and I'm not even sure I'm going to take to mountain biking, so I just thought it would make sense to do whatever I can to this bike to make it better suited for the sort of riding I'm planning to do. I don't think I'd ever have the skill or confidence to ride down anything extreme. In fact, I'd probably walk down a lot of routes even if I had a downhill bike! I'm just looking to pick up enough skills to get by and ride safely, mainly to do a bit of bike-packing here in northern Scotland. If I get on okay then I'd be tempted to buy a fancier steel frame from the same era.

The first thing he did at the start of the lesson was to hop on my bike and try the brakes, which didn't impress him! He tried to persuade me to hire a bike for the lesson from a nearby shop. He then twisted the adjusters to remove the play in the levers, and during the lesson I found I was squeezing the brakes for all I was worth and barely slowing down on the descents - at times there was no way I could have stopped even if I'd had to. Last night I had another look at the bike, and decided to back off the brakes to where they had been - it meant the lever moved much closer to the bars, but I think the brakes are more effective now. I suspect he was trying to get the same lever movement as his hydraulic brakes, but perhaps the canti's need to have more lever travel.

After telling me not to ride it again, he did say that the purple paintwork was beginning to grow on him!


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