t_e_r_r_y

hi everyone! i've been lurking these forums for years now, but only just recently made an account. this is a great community and i'm hoping to maybe actually be active around here now that i finally did it!

anyway, i was doing some drunk ebay shopping the other day (i always regret this the next day) and ended up probably overpaying a little for an old univega alpina s6.7 mountain bike frame. i'm alright with that, and actually kinda excited, because i've always loved these bikes. my plan is to build it up as either a 26+ or 27.5 go anywhere bikepacking rig.

i got the frame without the fork, which is fine because these bikes originally came with rock shox mag 21 fork (according to what i'm seeing on google) and i'd like to put a rigid front on it, however i'm having a heck of a time trying to find the crown to axle height of mag 21s so that i can start trying to source a correct length rigid fork. i'm hoping someone on here will either know off hand, have a bike in the garage with the same fork, or maybe even an s6.7 they could check out for me!

also, if anyone knows, or knows where i can find out, any of the actual frame geometry for this bike, that would be amazing. according to the auction, the frame size is 21, but i don't have it in my hands to verify just yet.

thanks for any help!

TenGrainBread 

From a quick google search it looks like 403 or 405mm axle-to-crown. No hard proof but that makes sense give 400mm is a pretty typical A-T-C for a late 80s/early 90s 26" mountain bike. A few mm here or there isn't going to do much to the geometry so I would just stay in the 400-420 range. Unless you want to get weird (see next post).

The bike you are talking about has rim brakes and was a 26" bike, probably with clearance for about a 2.3" tire at the most. So not sure how you would do 26+ or 27.5. If you are getting a new fork, then you might be able to run one of those in the front only and then a regular 26x2 in the back, but I doubt you will find a fork that can fit 26+ or 27.5 that has a 400mm A-T-C.

TenGrainBread 

A couple years ago I bought a frame-only 1995 Stumpjumper M2, which probably came with a suspension fork similar in A-T-C to the Mag 21. As an experiment I put a new Salsa Firestarter steel rigid fork on it. This fork is meant for a 29er (700C) wheel, only has a disc brake mount, and has an A-T-C of 483, about 60-70mm longer than the bike's original fork, so the head tube and seat tube were slackened out a couple of degrees and the bottom bracket was raised a few millimeters. I put a 26x2.5" wheel/tire on the front, made possible by the disc brake, and a 26x2.1" wheel/tire on the back, which had a v-brake. The bike actually rode fine. I ended up riding it for a bit with flat bars and then put drop bars on it and used it for a while. It worked well in both guises.

All this is to say, I wouldn't necessarily change wheel size on this, but experimenting with a longer fork could be fun and did work for me.

cannonride15

Go with a fork that accommodates size wheel you want to run, this article may help,
https://velo-orange.blogspot.com/201...t-to-650b.html

t_e_r_r_y

thanks for the comments!

i suppose i was being a bit premature and daydreamy thinking about my tire/wheel combo before even having the bike in my hands, but i've fitted 27.5 wheels on 26ers in the past (fitted, not actually built up and rode, just kinda testing fitment and stuff), and with this frame having the max mudroom stays i was kind of figuring it would fit some pretty fat tires. i've also seen some of these in my google searches built with what looked like 26+ setups, but obviously i could have been mistaking considering i'm just looking at pictures.

the brake reach isn't a deal breaker, i have the means and skill to modify the frame by either moving the brake posts or doing a disc conversion if i have to, but i'd really rather not any time soon, even if it means just rolling 26 with as fat of a tire as i can fit in the frame as is. if i end up loving this bike, i very well may do a modern dropout conversion, possibly even thru axles and disc brake, at some point down the road. doing that would allow me to tweak things a bit to fit fat tires and get the cloud-like ride i'm after. basically, i'm too poor to buy the bike i'd like (maybe a crust evasion? an all-city gorilla monsoon?), but can kinda build what i'd like from an old steel steed if it comes down to it.

having a starting point for the stock atc will let me work out the geometry for the bike once i have it in my hands and compare it to what i'd like to have, from there i can play with the fork length and figure out if this is the frame for me or if i should just build it and romp it for a while while saving for something different. i really appreciate your input!

t_e_r_r_y

that's an awesome stumpy, by the way! i have a 95 stumpjumper fsr that i was originally thinking of converting to my dropbar bike, but it's too rad to hack up!

Classtime 

Classtime 

t_e_r_r_y

that frame isn't quite the same, i can't tell if it has the maxmudroom chain stays or not, but mine doesn't have the dropped top bar at the seat tube junction like that does.

tracking is showing the frame should arrive today, so i'll get some pictures up once i have it in my hands. maybe i'll start an actual thread for it?

as far as atc goes, it's looking like something between 400 and 420 will probably be fine for me. i think surly has some 420 length forks with all the attachment points anyone could ever want, so maybe i'll go that route.

t_e_r_r_y

whoever private messaged me - i can't get into my inbox until i hit 10 posts, haha. i'll get back to you soon!