Hi there, I’ve been playing around with a new project idea which is like so:
I have an old Saracen Myst 2015 complete bike (the one Manon Carpenter became World Champ on…) in my shed, and I would like to build a new front triangle for it. It is a size XL but still a bit too short for my liking, so I started doodling around a bit in CAD…
so, there are a few challenges with this particular layout:
the fixed shock mounting is somehow exactly in the middle of the whole frame, which makes this unusual main tube arrangement necessary
the linkage points make a straight seat tube impossible so I need to bend or segment that one as well, not the biggest fan of that…
The fork I have (an old Intend inverted DC, actually a fork Nina Hoffmann used to ride in 2018 ) only allows for a maximum of ~130mm headtube length, which makes the stack height a bit low for my liking
so, opinions please!
Is this weird front contraption going to hold up, especially with that tiny head tube? Or does anyone have a better Idea for attaching the shock in a mechanically sound way? Or should I maybe hang up the “vintage” fork on my wall and get a 29" fork instead?
I rarely ever ride DH these days, but when I do, I really enjoy having a DH bike. It does make a huge difference over my enduro rig. It’s just so much more fun to plow through rock gardens…
I would follow the original shape of the frame with the steel tubes, and add a gusset instead. For the shock mount, I’d also try to recreate the original lines of the frame with that.
Deity makes a “highside” bar thats 80mm rise and 760 wide, I ride 'em on my trail bike and dh rig. I’m trying to post a link but can’t for some reason. That would definitely give you an option if you wanted to do the 130 ht.
When YOU (the master of custom front ends for production DH frames…) of all people say go, it shouldn’t be a problem and must be done I was a bit concerned about the structural side of things with such a short headtube and long frame…
ah yeah got a bit distracted posting about the track bikes
ill sling some details about once i’ve got some photos of David riding it!
back to the saracen. (edit side note; knowing the meaning of the words saracen and myst, there’s a BUNCH of good wordplay names you could make for this thing, depending on how carefully you want to tread.)
id be prone to suggest that if you build this thing, it WILL RIP, and thus you should make it a total battle axe. Also the whole, shock mount/tt/tt2.0/dt/HT situation makes me yearn for some big ol straight gauge tubing and a /massive/ headtube thats angleset capable.
I’m 1.90m tall and weigh in around 85kg race ready, so not a featherweight.
I have some 40x1.0 straight gauge tubing around which I’d use as DT, the other tubes are open for discussion
Straight gauge all around sounds like a sensible option since there is so much going on that it’s probably not wise to use any butted tubing.
HT will be straight 44mm ID one from paragon and afaik there is no angle adjustable headset available that fits into this. I don’t want to build a tapered headtube mitre Also, I can build the HTA I want, and I’m not a tinkerer once on the bike, so I think I’m fine with regular ZS44/1 1/8" cups on both ends. The fork has 1 1/8" stubs on each crown…
fair shout on the no-angleset, though works components make em for 1-1/8’ steerers in 44mm HTs which is all I really meant.
that is a super cool fork with extra cool provenance. sometimes it feels like celebrating stuff like that is becoming a smaller part of mainstream cycle culture as “new=better” thinking seems to swell, so I applaud you for that!
in the frame above I used similar tubing (44x0.9 and 38x0.9) and in the end decided to silver solder all the suspension-mounting-hardpoints to try and minimise the heat going into the tubing, though i’m not sure how much of a difference this will have made, or if it will have helped at all: im definitely a novice when it comes to FS mtb design so i’m interested to hear how you’ll lean.
how are you thinking that upper shock mount is going to look?
next iteration… When building a tank I might just as well build a tank
I’ll have to check if the linkage/lower shock mount can actually wrap around that tube in that manner.
Upper shock mount might look something like that:
As for all the other suspension hardpoints, I have to yet disassemble the frame to see how that actually works. But brazing these in is probably a good idea, Ive done that on all my other fs builds so far. It is a lot easier to join dissimilar wall thicknesses with brass than tig welding. And a thin wall bearing seat is going to stay neither round nor pressfit post welding.
You could leave some material on and spindle out the final dimension with a boring head, but that setup is quite complicated
The continuous line running from the HT through the shock actually looks quite pleasing!
Have you thought about moving all the suspension points back a bit to lengthen the rear centre? How much longer is your front centre compared to the original?
Have I thought about it: Yes, definitely! Is it possible? Not really, the lower shock mount in the rocker link is pretty close to the seat tube, there is not really a lot of wiggle room…
That’s what I do. For teh boires are left about 0.25 undersized and once teh hard points are brazed into teh frame I set it up flat on teh mill and boring head the finish in. BUT it’s sper easy to over shoot that final bearing fit dimension. Ideally you’d have a ream for each size. The other way is to machine the bore to size and run with a really thick wall and silver them in so you are unlikely to distort the bore. I’m using flanged bearings so don’t need a ciclip or a seat in teh bore for the bearings to sit against so running a ream through at any stage is easy enough. Though flanged bearings are not the easiest to source unless you go budget Enduro bearings and then only in a couple sizes. So may end up going back to a circlip system.
) only allows for a maximum of ~130mm headtube length, which makes the stack height a bit low for my liking
