Mountain Bike Reviews Forum banner
1 - 11 of 11 Posts

·
Registered
Joined
·
485 Posts
Discussion Starter · #1 ·
For those of you who missed the "frame geometry experts" thread, i emailed BETD last night to inquire about a swingarm conversion for my Stumpy to make it a 29er.

"Yeah it seems the 29ers are getting popular now, we dont do a kit at the moment but we may consider making if we get the demand. At the moment it wouldn't be worthwhile. If you have any questions dont hesitate to ask. "

Dan

Is there anyone else that would be interested in this?
if so, get this guy by the collar and tell him!
[email protected]
 

·
(was) Big in Japan
Joined
·
1,008 Posts
rryyddeerr said:
For those of you who missed the "frame geometry experts" thread, i emailed BETD last night to inquire about a swingarm conversion for my Stumpy to make it a 29er.

"Yeah it seems the 29ers are getting popular now, we dont do a kit at the moment but we may consider making if we get the demand. At the moment it wouldn't be worthwhile. If you have any questions dont hesitate to ask. "

Dan

Is there anyone else that would be interested in this?
if so, get this guy by the collar and tell him!
[email protected]
I am. Bedtime now, but I'll compose an email tomorrow and send it on to them. They make good stuff.

Thanks for taking the initiative! I might yet get a cheap FS 29er....

Chris
 

·
Registered
Joined
·
4,040 Posts
I think this is totally

doable for any of the Horst link designs out there - Speshy, Turner, etc. You could fabricate a seatstay that positions the rear wheel a little further and a little higher back. This would allow you to not drastically alter BB height and angles if using a 80mm 29er fork.

My primary concern is rear mech/chainstay clearance.
 

·
Recovering couch patato
Joined
·
14,019 Posts
As long as the headtube's relative position to the BB is fixed, I think it will be very hard to make a good 29"er from a purposely designed 26"er. A 29"er has a 2.5" taller headtube and a 1 1/4" taller rear axle. Hard to have both work with the same frame. Fork will have to suffer some serious travel, and rear to gain some.
 

·
Registered
Joined
·
650 Posts
Cloxxki, do you remember an MSN conversation we had about using BETD earlier this year.

I did some calculations and I don't think it makes sence. Longer forks will be needed, slackening the head angle, the back end will need to be longer.

With the slacker head angle and the longer bike it will be a really slow handling bike.

The BB height will be higher to which could be OK if you run longer cranks.

I would love to see it done. I put a lot of thought into this but it was not for me.

Specialised make a lot of different designs, you are going to have to make sure that everyone wants to convert the same model (and year)

Now a 2006 S-Works Epic Carbon Frame 29er would be ace, but how many other people would be coverting that bike.

P::..
 

·
Recovering couch patato
Joined
·
14,019 Posts
Duh, why didn't I come up with that in this case? Normally I use everything as an excuse to try longer cranks.
So it can be done, but it's does take some preferences to line up, taller BB, longer cranks, slower handling, less travel. Spend lots of money on a new rear end, and you have something more or less rideable. If you do a smart group purchase for a complete 29" frame less damper, you may spend the same and have a better package.
Way to make a long nose to Specialized though. "You're not making any, but we're enjoying your front end for our FS 29"er anyway!".
 

·
Blanco
Joined
·
1,353 Posts
The main problem I see is that you either end up slacking your STA/HTA, raising your BB, or going to a shorter fork -- probably some compromise between all three. And your wheelbase will get longer.

I wouldn't mind because I like slack HTAs, but the type of people who want a Stumpjumper (versus, say, an Enduro) might find it sluggish.

Personally, I'd want the Enduro conversion.
 

·
Registered
Joined
·
4,040 Posts
Okay.

If you can replace the seatstay with one that repositions the axle both rearwards and upwards you should, putting all other things aside, be able to keep the BB height static while lengthening the stays. I would think the final length would be no longer then all the other 18" CS lengths you see on other FS 29ers.

Sooooooo, to the front. Running an 80mm 29er fork on a bike designed for 100mm 26er forks seems to be about as ideal as you're gonna get. Not perfect math, but you drop 20mm in travel and pick up an incremental 18mm in A-C [(1.5 x 25.5) - 20]. The net effect at the BB could be about a .5" increase in BB height that could be partially offset by running long(er) cranks. As for HT length/bar height it sound like low to neg rise stems would be in order.

Is all this worth it? Sure, to see if it can be done. It seems like the net effect would be a taller bike with slacker angles (<70d HTA?). Sounds free-ridey but using an XC frame...

Don't be mean. I'm just a simple caveman.
 

·
Registered
Joined
·
485 Posts
Discussion Starter · #10 ·
bb height

stumpys have really low bbs ANYWAY. since ive had mine ive wished for a way to raise it a bit.
so this conversion would cost probably about 3 bills, wheels could be about the same and the fork would be about five give or take. so the whole deal could be done for probably about 1200 beans. thats a ton less than a whole new stumpjumper with all the upgrades and trinkets that i like. have you SEEN the prices of these bad boys this year? 1200 bucks is PEANUTS! A PITTANCE I TELL YOU! MY GOD MAN! THEYRE PRACTICALLY GIVING THEM AWAY!!!!
now all we gotta do is convince sombody to make the damned thing.
 

·
Shamisen Appreciator
Joined
·
2,098 Posts
rryyddeerr said:
stumpys have really low bbs ANYWAY. since ive had mine ive wished for a way to raise it a bit.
exactly my thoughts. I went from riding a hardtail with a 14.5" high BB to an Epic which sits at about 13" unsagged. I personally love a high BB bike. I bought an Enduro around the same time I got my Epic. With a 14" (unloaded) BB hight and 6" of travel, I was banging my pedals all the time. An extra inch an a half would be welcome.
 
1 - 11 of 11 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top