My 29er came wit a ridged fork with a AC of 480mm. Looking at putting on the RST M29 80mm which has a ac of 490mm. Is this about right? or is it far to short. Im running 2.2/2.0 tyres front/rear if that's significant.

Thanks

anybody?

i would suggest that the suspension fork should sag around 10mm, leaving you with a similar ac height.
thats the size i would go for.

what kind of rigid fork? fancy selling it to me? (see giantxtcghetto69er thread) 😉

it should sag around 25% of travel, so subtract that from the 490mm. Assuming it's a 80-100mm fork, the length will be 465-470mm, and the head angle will be ~0.5-1.5 degrees steeper. 1.5 May be a bit much, esp of the frame is steep/twitchy just now.

Trail is another factor…

Where does one get the RST's from?

I'm finding it hard to understand your writing. Spelling is good. Why not try it?

I haven't seen an RST fork for about 10 years, and they were always on low budget bikes then. Has anything changed? Can they be serviced? I don't think RST still exist.

I've seen one review that says their geometry (80mm M-29er) is a little bit "sharp" from a steering point of view and given that on full compression they will be 70mm (nearly 3") shorter than your current fork, I think you might find the front wheel will feel like its disappearing underneath you if you hit a hollow at speed.

Normal sag is 25% btw, that's 20mm.

rst m29 are a well regarded fork, were on sale at on-one a few months ago.
Earl, what 29er do you have and what is the offset on your rigid fork?

BJ – is it not the accepted wisdom to use a fork that matches with your rigid fork? (with sag rather than under full compression)

I think the accepted wisdom is to find out what fork the bike was designed for and use that.

I was just saying that a fork with a reputation for being twichy (something about the trail being 5mm more than a Reba) AND being 3" shorter might be a bit of a handful.

I ride a Soul with a 130 Menja fork which has A-C of 498mm. If I was going rigid I think I would use the recommended Pace RC31 with 440mm A-C.

Its a DB Mojito 29er. Its comes with a cromo rigid.

DB also does the Absinthe 29er which is same frame with gears and a sus fork. The 08 had a RST M29 100mm. The 09 model comes with a RST M29 80mm fork. Don't know if DB (Raleigh) changed the frame between 08/09 – no detail or contact info on the website.

I can't find the RST M29 100mm on sale anywhere but On-one are doing the M29 in 80mm. Could look at something else but don't want to spend the cash and the M29 gets good reviews all things considered. The other option I was looking at was the on-one carbon with a AC of 470mm – 10mm shorter than the current ridged.

Does if the current ridged fork length perfect for the frame? If I knew that then I could probably answer this question myself.

earl, i wouldn't worry too much about having the perfect geometry. the a-c measurement is in the ball park, so to speak. the rst has 45mm offset, this is now considered normal on a 29er fork.
as an example i have a singular rigid fork (485mm 48mm offset) on a niner. niners own rigid fork was different (490mm 40mm offset)but they have changed them (shorter with 45mm offset). i have no problem at all with the singular fork and don't believe putting the rst on your bike would result in problems.

keavo – to answer a prev question, as the fork came with the bike I don't have a clue what the off set is. Pretty entry level – heavy and strong.

Thank very much for all the replys.