Front suspension



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davebee

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Jan 15, 2004
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Will putting a front supension fork with an 85-100 mm travel mess up the geometry of my bike which currently has rigid forks? Obviously there will be some change in the geometry and suspension will significantly change the feel, but will the changes "work"?

The reason for the change is that I can't afford a new bike but want to take on more challenging off road courses than I currently do.
 
davebee posted ...

> Will putting a front supension fork with an 85-100 mm travel mess up the geometry of my bike which
> currently has rigid forks? Obviously there will be some change in the geometry and suspension will
> significantly change the feel, but will the changes "work"?

I added a 65 - 85 mm travel fork to my hardtail Dyna-Tech and it transformed it. What used to be
reasonable became a very good bike .. ;) I reckon most half decent hardtail bikes are actually
designed for sus forks these days (last 10 years or so) and the geometry actually improves by retro-
fitting them. I reckon rigid forks, like mine were, are generally just a lower cost option on a
normally suspended frameset.

> The reason for the change is that I can't afford a new bike but want to take on more challenging
> off road courses than I currently do.

I reckon, provided the bike is reasonably new, that they will work and you will feel a great
difference and gain speed, agility, handling and comfort .. ;) My forks cost only about £120 (can't
remember exactly) and they transformed the bike far more than their cost implied.

--
Paul
 
davebee wrote:

> to take on more challenging off road courses than I currently do.

They'd be more challenging without suspension surely.
 
davebee <[email protected]> writes:

> Will putting a front supension fork with an 85-100 mm travel mess up the geometry of my bike which
> currently has rigid forks? Obviously there will be some change in the geometry and suspension will
> significantly change the feel, but will the changes "work"?

Most modern hybrids and MTBs even if sold with rigid forks already have the appropriate geometry for
suspension forks. Look at the distance between the lower race of your headset and the top of your
tyre - if that's more than about 80mm you'll be fine with a suspensiona fork. In any case the bike
won't be unrideable even if the geometry is a bit off - it will just have more caster which will
make it less twitchy.

--
[email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/

;; when in the ****, the wise man plants courgettes
 
"davebee" <[email protected]> wrote in message
news:[email protected]...
> Will putting a front supension fork with an 85-100 mm travel mess up the geometry of my bike which
> currently has rigid forks? Obviously there will be some change in the geometry and suspension will
> significantly change the feel, but will the changes "work"?

It will change the geometry, you may or may not notice it but if you do it will mainly be on
flat ground which is not the natural habitat of mtbs. Also the change of geometry may be
preferable to you.

I've just changed my fork from 80mm (70 more like in practice) to one that adjusts from 63 to 108
and find that leaving it on the longer travel is great downhill and not much of a detriment going
up, you adapt without thinking, so feel a preset 100 travel fork wouldn't cause a problem. I'll get
a better idea of the usefullness of the short travel option when the local, relatively untechnical,
trails dry out and I use them again.

In short, I wouldn't worry unless your frame is very old and/or not designed for suspension forks at
all. AFAIK most decent frames of the last few years have "suspension corrected geometry" i.e. higher
head tube and longer forks. To see if your bike fits this category measure the distance between the
top of the tyre and the underside of the fork beneath the steerer, if there is
>70 mm with fat tyres then the frame is "suspension corrected".
--
Regards, Pete
 
I have just looked at the distance between the fork and the tyre (i currently have fat tyres on) and it is closer to 20-30mm. It is also a threaded headset, so I would need a new headset, but this shouldnt be a major problem. Should it?
It would also mean I need a new stem.

I am just worried that I would spend upwards of £150. (£100 for Marzocchi EXR air, £20 Race Face prdigy stem, £20 Headset, £20 Labour) and then not like the desired result.


I agree that no suspension makes a given ride more challenging, but it would also mean that some rides that I would like to tackle are more challenging than my ability alllows. ;-)
 
"davebee" <[email protected]> wrote in message
news:[email protected]... .
>
> I am just worried that I would spend upwards of £150. (£100 for Marzocchi EXR air, £20 Race Face
> prdigy stem, £20 Headset, £20 Labour) and then not like the desired result.

Unfortunately only one way to find out :-(
>
> I agree that no suspension makes a given ride more challenging, but it would also mean that some
> rides that I would like to tackle are more challenging than my ability alllows. ;-)

It's a couple of years since I rode a non-suspended bike on local baked bridleways. It was fun for a
start due to the liveliness of the bike but after an hour I'd had enough, the discomfort factor
becomes overpowering and I certainly can't imagine doing a 5 hour epic on a rigid bike.
--
Regards, Pete
 
Originally posted by Peter B


It's a couple of years since I rode a non-suspended bike on local baked bridleways. It was fun for a
start due to the liveliness of the bike but after an hour I'd had enough, the discomfort factor
becomes overpowering and I certainly can't imagine doing a 5 hour epic on a rigid bike.
--
Regards, Pete


Thats basically why I want to put a suspension on. The bike is VERY lively, and that is just on toepaths. I can't imagine what it would be like on hilly, rocky terrain which has significant dropoffs. The vibrations through the bike really dig into my elbows, and I am sure that a good fork would take much of that out.
 
davebee wrote:

> Will putting a front supension fork with an 85-100 mm travel mess up the geometry of my bike which
> currently has rigid forks? Obviously there will be some change in the geometry and suspension will
> significantly change the feel, but will the changes "work"?
>
> The reason for the change is that I can't afford a new bike but want to take on more challenging
> off road courses than I currently do.
>
>
>
> --
>
>
It depends ;-)

Bikes made since 1994-ish are designed with "suspension geometry" to accommodate the longer
forks. Most before this time aren't. The non-corrected bikes should ride OK with up to about 80mm
of travel.
 
davebee posted ...

> I have just looked at the distance between the fork and the tyre (i currently have fat tyres on)
> and it is closer to 20-30mm. It is also a threaded headset, so I would need a new headset, but
> this shouldnt be a major problem. Should it? It would also mean I need a new stem.
>
> I am just worried that I would spend upwards of £150. (£100 for Marzocchi EXR air, £20 Race Face
> prdigy stem, £20 Headset, £20 Labour) and then not like the desired result.

Where do you live, roughly ? You maybe can 'have a go' on my originally rigid but now suspended
front end .. ;) I live near Doncaster, but regularly travel to Nottingham so anywhere in between
would be no problem I guess.

Mine was _exactly_ the same setup, threaded head etc

--
Paul
 
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