Forking hell

[BigdummySteve]

I've been looking at various forks for my ecr, the main reason is to reduce weight. The ecr fork is 468mm A-C with 47mm offset, I'm looking at the on one fatty fork, it's 470mm and 55mm off set so a tiny bit longer but more offset. I can't get my head around how this will affect the handling, my gut feeling is it will end up quicker due to the offset?
My only other option is a 490mm fork (mrp rock solid)

[sean_iow]

Having just drawn the 2 sets of dimensions on my CAD I measure the change as 0.94 degrees slacker (assuming the offset is forwards) which would make the handling slower?

Sean

Edit, Thinking about it though I'm not sure that's how it works? The head angle will be the same but the offset moves the wheel in a larger arc around the steerer? This may help

http://www.mbr.co.uk/news/fork-offset-h ... ail-342679

[Jurassic]

You probably know this but just in case, remember that the hub spacing is 135mm on the Fatty fork so a front wheel rebuild may be needed. The fork itself is pretty nice though (I ran one on my Fatty for a couple of years), very light, flat(ish) surfaces on the fork legs for mounting Gorilla Clips if required, tracks fine and isn't too harsh, I liked mine.

[BigdummySteve]

Yeah it seems like a nice fork, light and I've ditched my anything cages anyway so no bother there. It's just the offset increase I'm not sure about.
I was looking at tapered forks and a new bottom cup but the ecr has 38mm head tube so it's not possible. The options are limited......

[Jurassic]

Yes spookily enough I just noticed yesterday (while browsing for 29er carbon forks) that they are selling a version with a straight steerer (mine are tapered). Hope you get sorted out anyway.

[jameso]

The differences between the length A-C (assuming it's measured as fork height along the steerer line, not direct) and offset cancel out so the frame will still sit at the same geometry. If both are direct A-C heights the 55mm offset / 470mm fork will steepen things up ~0.1 degree, ie no real difference worth worrying about.

The 55mm offset will lower trail ie lighten the handling, generally in a good way esp. for loaded riding, unless it's a twitchy bike to start with. Most current MTB geometries would benefit from a bit less trail for loaded riding imo though.

[Jurassic]

Ooh, just thought of something else, my one's are RDM brake spacing as well (not sure if the straight steerer version is the same).

[Bearbonesnorm]

I can't get my head around how this will affect the handling, my gut feeling is it will end up quicker due to the offset?

On paper, (and everything being equal) the increase in off-set will reduce trail and make the bike turn quicker / easier or become less stable in a straight line.

Edit: sorry, hadn't noticed James had already answered ... must pay more attention

[BigdummySteve]

So this would be a good fork? The ecr is nice and stable, in fact it needs a bit of body English to turn at speed. My other option is the exotic/ mrp rock solid, both are available in 465 and 490 at 44mm offset. Assuming at 29+ will fit the shorter fork the result would be similar if slightly more stable handling? The 490 is longer with smaller offset so where does that leave me....I might have to go for a ride my head hurts

[BigdummySteve]

I can't get my head around how this will affect the handling, my gut feeling is it will end up quicker due to the offset?

On paper, (and everything being equal) the increase in off-set will reduce trail and make the bike turn quicker / easier or become less stable in a straight line.

Edit: sorry, hadn't noticed James had already answered ... must pay more attention

Cheers stu, I do get that but I'm not sure how it would feel in the real world, although the fork is reasonable a 135mm hub (maybe another dyno) and build are going to add to the cost. An added bonus of The fatty fork is I can spray it MRE green to match and I may just get away with it

[Bearbonesnorm]

Cheers stu, I do get that but I'm not sure how it would feel in the real world

IMO ... no worse and hopefully better. Altering stem length by 20mm would likely be more noticeable.

[BigdummySteve]

Ok that makes real world sense
Think I'm going to go for this, looking at 1kg saving.

[fatbikephil]

I'd avoid - Surly know how to make a bike handle and reducing the trail by that amount will wreck it. The weight saving will be unoticable and largely offset by the extra wide hub and the longer spokes.

[jameso]

Surly know how to make a bike handle and reducing the trail by that amount will wreck it

Could equally be said that they make bikes with high trail that some think feel a bit lazy, more so when loaded, and a longer offset that reduces trail a bit is a good thing?

ECR is 69.5 HTA and 47mm offset - with a plus tyre that adds trail also. A Stooge is a shade under 70 HTA dep on tyres fitted and uses 55mm offset - a popular bike. My Jones outhandles anything else on 29" wheels imo (and this is all just feel and opinions, in case I'm sounding like a geometry nobber ) and that's 70 degrees HTA and 55mm offset - again, less trail.

[Bearbonesnorm]

geometry nobber

Ooh, I feel a T shirt coming on ... could sell loads on STW

[fatbikephil]

Aye I know all that however my Krampus handles sweet as, loaded or unloaded

[ctznsmith]

I played this mental game for a bit last year and came to the conclusion that a straight steerer, 29+ compatible fork for a 100mm hub doesn't exist.

[BigdummySteve]

Well I've ordered a fork, I looked at a few and settled on one which is fitted as standard to a production 29+ bike
I'm saying nowt until it's working as I'll just look like a general nobber

I've also ordered a pair of Bontrager chupacabra's saving a useful 300g an end

[Bearbonesnorm]

I played this mental game for a bit last year and came to the conclusion that a straight steerer, 29+ compatible fork for a 100mm hub doesn't exist.

I was going to suggest asking Andy at Stooge?

[Mart]

I played this mental game for a bit last year and came to the conclusion that a straight steerer, 29+ compatible fork for a 100mm hub doesn't exist.

Singular Swift fork does that

[ctznsmith]

Sorry the missing word was 'Carbon'.

I have an ECR fork on my bike. I 'solved' the 'problem' by giving myself a talking to about being a weight weenie.

[atk]

How much weight are you actually saving (actually weighing the forks rather than trusting PX/OO to have accurate online info... and including new hub and spokes) and what's the overall cost (fork, wheelrebuild, bits etc.) if you don't mind me asking?

[BigdummySteve]

Sorry the missing word was 'Carbon'.

I have an ECR fork on my bike. I 'solved' the 'problem' by giving myself a talking to about being a weight weenie.

I largely ignored weight, I told myself that I'm bike packing, an extra 500g here and there didn't matter. Lugging 62lb around wales on the WRT proved me wrong, next trip after I had trimmed 12lb, the bike handed better, I had more fun, I was less beat up and I was still carrying everything I needed.

[ctznsmith]

Let us know if the fork you ordered works and what it is. ;-)

[BigdummySteve]

Let us know if the fork you ordered works and what it is. ;-)

I've ordered a MRP rocksolid, 465mm a-c 44 offset. Half the weight of the standard fork, plenty of clearance with a 3" chronicle in a 47mm rim. I've a set of chupacabra'a to put on so should be looking at about 1kg off the front end and hopefully a bit more compliance. I'll post up some photos and thoughts when I've fitted them. My only concern is the max disk size, I've a 203mm on the ecr fork, with a 180 the calliper would contact the spokes.