140mm forks on a Blur classic « Singletrack Forum

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140mm forks on a Blur classic

17 posts & 12 voices | Started 1 year ago by catfishsalesco | Latest reply from Saccades

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Blur Magura gnarr

catfishsalesco - Member

Hi, I have a sc Blur classic, currently running Magura thor (100-140mm) forks on it. Reading around, it looks like the sc was designed for 100-130mm forks at the most, so how likely am I to shear the headtube? I got the Thor forks as I knew I could adjust the travel, but didnt realise (unlike the RS U-turn) that it was either the 100 or 140mm travel options with nowt in between. I run them at 100 when I can, but they do usually creep out again. Does anyone make a Angleset for 1&1/8s head tubes? Or would this not solve the problem? I don't do too much GNARR riding, but have started doing the odd jump now & then, so hence the concern...

TLDR- Big forks on a blur classic, how soon is it going to break, can I do anything about it (without changing forks)

Posted 1 year ago #
V8_shin_print - Member

I've been running a 130mm revelation on an old SC Superlight (100mm) for a couple of years and it hasn't snapped yet. Not exactly conclusive, but it has taken everything I have thrown at it so far including crashes. It has made it super slack though and steep climbs can be awkward...

Posted 1 year ago #
BadlyWiredDog - Member

Does anyone make a Angleset for 1&1/8s head tubes?

Yep, Works Components has just started producing them in the UK, slackens the head angle by 1˚
http://www.workscomponents.co.uk/index.asp

Or if you want more slackness, may be possible using this guy, Saar, who posts on mtbr and does it as a sideline. Really helpful, great customer service:
http://www.ofanaim.net/has.html

I'm about to slacken my Pace RC405 by 2˚ - headset's in the post right now. Slackening your steering isn't going to massively change the forces going through your headtube, but the way I read it, at the same time as slackening the head angle, you'll also drop the bottom bracket slightly and steepen the seat angle by the same number of degrees which will move your weight further forward on the bike and stop it turning into a wandery nightmare on climbs, which tends to be what happens if you just stick longer forks on and tip everything back.

If you thihnk it through, lifting the front of the bike tips the seat angle back, moves your weight over the rear wheel and changes the balance of the bike - less weight on the front, wandery on climbs, lifts front wheel more easily etc.

The Pace is designed around a 130mm fork, works okay with a 140mm Pike, but sticking a 150mm Revelation on it really screwed up its ability to climb, thinking is that slackening it off - while using a shorter, 50mm or 60mm stem to keep the steering sharp - should drop the front enough to make a 150mm fork feasible or be lower with a 140mm, plus the steeper seat angle - you can adjust a bit with saddle position - should move rider weight forward, weight the front wheel and keep the front down on steep ups.

Which is why an angleset or similar makes a lot more sense than simply throwing a set of long forks in there. Of course you might end up with more pedal strikes thanks to the lower BB, but the lower c of g should also help with cornering and the slacker front end, ought to be more stable at speed and on the steeps.

Posted 1 year ago #
BigJohn - Member

You might like to check your Magura's axle to crown length and compare that to a Marz 130 of similar vintage to your frame.

Posted 1 year ago #
Blurboy - Member

If you do decide you have to change the forks I have just put a 140/120/100 Talas on my Blur Classic and find that the 120 setting is spot on. Don't think I would chance the 140 as the frame, like mine, must be getting on a bit now?

Posted 1 year ago #
catfishsalesco - Member

I've been running a 130mm revelation on an old SC Superlight (100mm) for a couple of years and it hasn't snapped yet. Not exactly conclusive, but it has taken everything I have thrown at it so far including crashes. It has made it super slack though and steep climbs can be awkward...

Good to know, I have been running the travel down to 100mm for climbs & it goes up nicely then.

Yep, Works Components has just started producing them in the UK, slackens the head angle by 1˚
http://www.workscomponents.co.uk/index.asp

Ta for the link I see what you mean about it not really changing the force thru the headtube though.

If you do decide you have to change the forks I have just put a 140/120/100 Talas on my Blur Classic and find that the 120 setting is spot on. Don't think I would chance the 140 as the frame, like mine, must be getting on a bit now?

Yep, its 2004 / 2005 vintage I think- the one that had the improved tyre clearance. Yep, it rides so nicely I dont want to break it!

You might like to check your Magura's axle to crown length and compare that to a Marz 130 of similar vintage to your frame.

I'll look into that, ta

Posted 1 year ago #
Blurboy - Member

Yeh I run 100 on the uphills as well. Just out of curiosity what rear shock are you running.

Posted 1 year ago #
catfishsalesco - Member

Yeh I run 100 on the uphills as well. Just out of curiosity what rear shock are you running.

Its a Fox RP3- not sure what vintage.

Posted 1 year ago #
chickenman - Member

Run a 110-140 Rev on my Blur Classic. Definately rides best at the 110, but for fast gnarly descents the longer setting is great, and slackens the HA by about 2deg over a 100 fork. Not broken it yet (in 2 years)!

Posted 1 year ago #
catfishsalesco - Member

Run a 110-140 Rev on my Blur Classic. Definately rides best at the 110, but for fast gnarly descents the longer setting is great, and slackens the HA by about 2deg over a 100 fork. Not broken it yet (in 2 years)!

Thats good to know. Yeah, it is very nice on the descents with the forks run out fully.

Posted 1 year ago #
Paceman - Member

I'm about to slacken my Pace RC405 by 2˚ - headset's in the post right now.

BadlyWiredDog

Let us know how you get on with that. I run 140mm Floats on my RC405 and would be interested to hear what a slightly slacker HA and lower BB feels like.

Posted 1 year ago #
DaveyBoyWonder - Member

Surely the last thing you want to be doing on a frame designed for a 130mm fork and running a 140mm fork is throwing an angleset into the mix and slackening it all out even more = more stress on the frame??

Posted 1 year ago #
Paceman - Member

Surely the last thing you want to be doing on a frame designed for a 130mm fork and running a 140mm fork is throwing an angleset into the mix and slackening it all out even more = more stress on the frame??

Not keen on doing it to my 405, just interested in how the 405 rides with 150mm and slack geometry up front

Posted 1 year ago #
younggeoff - Member

think the classic was designed for 105mm forks, my old one was ok with a set of revelation swound out to 130 on the downhills, steering was a bit slow though. on the uphills anything other thatn being wound down to 100mm and it wandered all over the place

Posted 1 year ago #
coolfurcats - Member

Hey Catfish S, The Thor forks should go from 140mm down to 110mm including any hieght in between. There isn't a scale, but you get used to how much the fork sinks down to with the amount of weight you put on them. It isn't an either or travel fork, you should have a range of travel adjustment at your diposal. If this isn't the case get in touch with Mike at the Magura service! tel: 07773453681.

Posted 1 year ago #
fatmax - Member

I've got a 2005 Classic, and have an email off Jungle saying that it was designed for 100mm, but was fine up to 120. I've got some 115 Fox on the front and it wanders all over the shop on the climbs, but is great on the downhills...

Posted 1 year ago #
Saccades - Member

Ran mine at 150mm for 2 years with no bother, went to the north wales trail centres, les gets, peaks etc as well as the normal irish stuff with no bother - only got rid because I had a chance to get a LRS which needs bearing once a decade and is faster...

Posted 1 year ago #