Updating forks on Rockhopper - anybody run longer than 100mm

mac_man

I have 2 bikes in garage at the moment my Saracen Mantra 3 and my son's 08 Rockhopper.
The Hopper comes with a Dart 3 fork which is only ok at best. Am thinking of testing the bike with the 85-130mm U-Turn Toras off the Saracen. These always feel much plusher.

Just wondered if anyone else has run longer forks, or upgraded from their original Darts and what benefits they've found.

The other reason for the swap is the Hopper is a good few pounds lighter than the Saracen so I may end up using it as a main bike if it works.

I know from experience that the Saracen wanders like a drunk if I have the Toras set to max travel on the uphill.

The steerer length seems fine and I'm comfortable in re-fitting the forks.

benpinnick

A buddy of mine took my old F120 foxs and put them on his 08/09 Rockhopper. Improved it immensely. Gave it a much plusher, more relaxed ride that suited the bike alot. The Rockhopper frame is very underrated and can take much better parts that it comes with and not be outclassed by its components.

mac_man

benpinnick wrote:

A buddy of mine took my old F120 foxs and put them on his 08/09 Rockhopper. Improved it immensely. Gave it a much plusher, more relaxed ride that suited the bike alot. The Rockhopper frame is very underrated and can take much better parts that it comes with and not be outclassed by its components.

That's what I'm hoping. The current Darts feel like a road drill on the rocky trails round Calderdale.

The Toras are not much heavier... about 1/3 of a pound extra.

Will probably bung on the larger rotor off the Saracen as well.

Chunkers1980

I run 120mm Reba on my '06

You can feel the difference - I wouldn't go above that though, the seat tube would be too slack (+ I think the manu max is 110mm, so any more you are pushing the capabilities of the frame)

I think it's better for slower technical stuff and going down, but not quite as quick to react as it was with 100mm (Rebas) on.

jayson

130mm is WAY too much for a rockhopper, it'll handle like a canal barge and u risk damagin the good frame.

My old frame was designed around a 100mm fork but i experimented with 110mm but bottled out anymore than that, it handled ok and with the sag taken into account it was barely noticable but i ditn want to damage the frame so stopped there.

mac_man

jayson wrote:

130mm is WAY too much for a rockhopper, it'll handle like a canal barge and u risk damagin the good frame.

My old frame was designed around a 100mm fork but i experimented with 110mm but bottled out anymore than that, it handled ok and with the sag taken into account it was barely noticable but i ditn want to damage the frame so stopped there.

Know what you mean. So how come some bikes ie my Saracen come fitted with these 85-130mm Toras?

The Saracen frame is beefier than the Hopper that's for sure. But how can the frame geometry be right for 85mm and 130mm forks?. As mentioned the Saracen is unrideable uphill with the forks set to 130mm.

Being adjustable forks I can at least have a play around at different settings.. see which works best :-)

Chunkers1980

It depends if the Axel to crown length changes - basically does the 85mm run with the same amount of stanction showing as it would in 130mm mode.

The shorter the wheelbase the more noticable changing the the fork for a longer axel to crown will be.

mac_man

Chunkers1980 wrote:

It depends if the Axel to crown length changes - basically does the 85mm run with the same amount of stanction showing as it would in 130mm mode.

The shorter the wheelbase the more noticable changing the the fork for a longer axel to crown will be.

No.... it winds out more - maybe not 45mm... will have to check.

I understand the geometry aspect of running a longer fork.. lazier steering etc.

But what actual harm could happen... are people saying the frame could snap with an extra 30mm travel????

Am not looking to create a DH machine... just something will swallow the bumps a little better than it currently does.

Chunkers1980

It's the extra leverage the angle and the length of the forks puts on the headtube.

mac_man

Chunkers1980 wrote:

It's the extra leverage the angle and the length of the forks puts on the headtube.

Am with you.... just like using a longer handled spanner to get stuff unscrewed off yer bike.

supersonic

The frame is warrantied for 110mm max.

mac_man

supersonic wrote:

The frame is warrantied for 110mm max.

So how come some manufacturers state 'suitable for forks between X & Ymm'

The Saracen has a fork that has 45mm variation between lowest and highest settings... is it possible to engineer a bike that rides well at both ends of the travel? Or is just the case that the frame is strong enough to handle the 130mm setting, yet will climb ok at 85mm.

I notice that bikes like Ragley's Blue Pig have 140mm forks, a really slack head angle yet testers say it still climbs well. How so?

supersonic

Because bb height, seat angle and wheelbase are other factors. Most bikes though handle fine an inch of front travel either way of what it is 'optimised' for. The hopper works best at 70-110mm of travel for most people and its intended use. The mantra about 90-130.

mac_man

supersonic wrote:

Because bb height, seat angle and wheelbase are other factors. Most bikes though handle fine an inch of front travel either way of what it is 'optimised' for. The hopper works best at 70-110mm of travel for most people and its intended use. The mantra about 90-130.

Cool... I'll have a play.

Will make sure I don't try anything too extreme at the longest setting

FSR_XC

I have a 2003 Rockhopper fitted with 85-130mm Tora U-Turn.

Yet when to comes to climbing, setting the fork to 130mm doesn't help, but otherwise I am happy with the set up. It certainly feels much better than the original Manitou Axel 80mm. The biggest problem to the handling is probably the weight of the fork.

wordnumb

The great thing about U-turn forks is how you don't have to use them at the furthest extension. Toras are far nicer than Darts so use them on the RH at 110 or thereabouts.