[Closed] 20mm longer rigid fork on 90s frame?

I bought a 425mm salsa cromoto for a hardtail that was originally specced with Marz Z2 Flys. Z2s were 432mm A2C, so I figured it would have sagged shorter than 425mm just riding along.

It's very quick steering! It was always that sort of frame though. I could easily have gone for 445s. Pfff. A Hugo and a Dirt wizard up front have taken a little of the edge off now. Could be just right.

I'd be less keen on adding fork height to a big dummy - loaded up, there's going to be more force to cope with. Personally, I wouldn't worry about 2cm, but 4-5, maybe I'd worry a bit.

But in percentage terms, it's adding 10% to the moment - are you in the heaviest top 5 percent of riders Surly designed the bike to cope with, and loading it with the heaviest 5% of loads they considered?

Probably not, so you're probably fine adding 4-5cm

IANAE.

Stuck a 29er rigid carbon fork on my orange evo - difference of 20mm. Can't say i noticed the difference except the reduction in weight and loss of suspension.
Rides fine.

I'd be less keen on adding fork height to a big dummy - loaded up, there's going to be more force to cope with. Personally, I wouldn't worry about 2cm, but 4-5, maybe I'd worry a bit.

But in percentage terms, it's adding 10% to the moment - are you in the heaviest top 5 percent of riders Surly designed the bike to cope with, and loading it with the heaviest 5% of loads they considered?

Probably not, so you're probably fine adding 4-5cm

IANAE.

Hi - think you've misunderstood - I'm just getting the fork, not the Big Dummy bike - and putting it onto a 1997 rigid Trek MTB, so my worry is adding to the original fork length and stressing the head tube / really terribly altering handling. Everything I see online about getting longer sus forks warns against adding more than 20mm fork length due to head tube stress, so I wondered if the same applied to rigid (maybe even more so as there is no suspension to absorb some of the force). (I'm 10 stone, which is 140 pounds in US language).

I was wondering if I could safely go even longer than the 20mm extra length the Big Dummy fork will add, as there is a greater range of forks at the 445mm+ length, including a cheaper Nashbar one!

I'm also curious as to the effect on geometry - putting the numbers into an online bike geometry calculator suggests that it will [i]increase[/i] the effective top tube, but [i]decrease[/i] reach...

I bought a 425mm salsa cromoto for a hardtail that was originally specced with Marz Z2 Flys. Z2s were 432mm A2C, so I figured it would have sagged shorter than 425mm just riding along.

It's very quick steering! It was always that sort of frame though. I could easily have gone for 445s. Pfff. A Hugo and a Dirt wizard up front have taken a little of the edge off now. Could be just right.

The Cromoto is a super looking fork - I love the silver dropouts - but (a) a but pricey for my second hand bike (b) not very available at the moment

So you reckon frame-wise it's a do-able job to go up to roughly 450mm? There was a sus-forked version of this Trek bike in 1997, but on looking it up, the fork was only 56mm travel! RST 161b: Similar to what I insisted was fitted to my totally-suspension inappropriate Dawes Saratoga when I was about 11 one Christmas. Old Mr Scott in the LBS rolled his eyes and my dad (rides a 1970s custom built Fuji road bike) had to look away in embarrassment. They were ace and turned my paper-round bike into a dirt machine.

Rose bikes have a fork that shouldbe up your street IIRC.

Rose bikes have a fork that shouldbe up your street IIRC.

Hey - they do a perfectly decent looking canti-only fork, which I reckon is the same as the one I picked up from my LBS (unbranded, black, chunky tubes) but haven't installed. However my thoughts were, while I could spend £35 on this, and still need a new fork when my front wheel goes and I end up getting a disc wheel, I might as well spend £65 on a disc-ready fork.

http://www.rosebikes.com/products/bike-components/forks/mtb-forks/stiff/

Yeah, their forks are stiff...

Sorry sb, I could have swore those had a disc mount too.

I can't answer any of your questions directly, so this post is of no direct use whatsoever (it is the internet after all!), but ...

I have a 29er PII fork on the front of my '92 Kona Fire Mountain, with a 26" wheel (a 29er wheel in there would be too much).

The original PII would have been ~425mm A-C, and the 29er version is 470mm A-C. I run a 2.3 x 26 Bonty mud tyre on a Mavic 721 rim, so I've got a bit more volume in the tyre (than I would have used with the original fork).

Frankly ... it's bloomin 'awesome!

[img] [/img]

I wonder if the Big Dummy fork *might* be a tiny bit harsh (fatter tyre there too perhaps)? It *looks* pretty tough (in a good way), but that aside, and based on my experience only - what's not to like?

As you've found, once you go up to / above 440mm A-C there is lots more choice (as that's ~100mm suspension fork equivalence).

I wonder if the Big Dummy fork *might* be a tiny bit harsh (fatter tyre there too perhaps)? It *looks* pretty tough (in a good way), but that aside, and based on my experience only - what's not to like?

As you've found, once you go up to / above 440mm A-C there is lots more choice (as that's ~100mm suspension fork equivalence).

Uh oh.... No-one's told me my frame's gonna snap... am I going to go for a longer fork in the end...?

Also, are those Jones H bars? I've just been ogling them...

Honestly I doubt it will make THAT much difference. It will lift the front and bottom bracket height a bit and slacken the head and seat angles a tiny bit.

If it helps I have a late 1990's race hardtail that came with 80mm forks that ran for years with 100mm suspension forks in it. I've also run it with 26" rigid forks that were equivalent to a sagged 100mm fork and with a big 29r wheel up front too in those 26r wheels. All those things had an effect but none were problematic to ride with.

Hmmm, well I'll stick with the Big Dummy's when they arrive - will use 5-6cm-ish of steerer tube to add bar height, shouldn't be a problem with a steel steerer for touring on roads / light tracks. Though the bike's gonna end up looking like this...

http://www.thorncycles.co.uk/bikes#thethornsherpa

Sweet...

Glad I've not gone shorter though - nearly went with Identiti tuning fork at 395mm

My instinct says you'll be fine for the kinda riding that frame would ordinarily be fine for.

🙂

The bars on the Kona are the Titec versions of the Jones bars. I think Titec [also] refer to these as H versions, (they did a J too, which doesn't have that bit of rise). You might struggle to find them now tho' as they aren't a current bar.

I do have Jones (fully looped) H-bars on my (rigid) Swift, and I am equally, if not [i]more[/i] fond of them. The newer versions are a bit longer too, which gives a bit more versatility. 'Alt' bars come wholly recommended (for rigid bikes).

None of them look like a letter H.

This does: http://store.velo-orange.com/index.php/casey-crazy-bar.html

Drool.

I can maybe see where they are going there, the backsweep on the ends makes sense, and I guess the 'horns' would be ok in a kinda aero-position, but I'd still miss the multiple options you'd otherwise get with a curved bar. They'd be ok for mounting a bag on tho'.

Yeah, they need angling in more.

What I really want is a bar like a reversed mustache bar, but with flat portions instead of the sharp curve, to give 3 positions:

(From inner-most to outer-most)
1. Angled inner portion for 'aero' position that doesn't drop you too low.
2. Flat, close portion for upright riding (possible brake position)
3. Bar end type horns for climbing that aren't actually too far forwards as the bar has already swept back (possible brake position)

Maybe like an angled back riser bar with bar ends, but less ugly.

This is nearly it but doesn't angle back in the centre

http://www.sjscycles.co.uk/humpert-comfort-revoshift-handlebars-254-mm-clamp-silver-prod28189/

That would be sweetness.