Making a 27.5/26 mullet out of 2006 Jamis?

SpeedoJosh said:

Have a 2006-ish 26" Jamis Dragon. Front shock is equally as old (SID) and in need of some almost non-existent parts. So got me thinking of just buying another. Which got me thinking about a mullet since 27.5 stuff seems more available than 26".

The Jamis set up with the factory 100mm Fox32 has a HA of 70.5 and Seat angle of 74. Non-tapered steerer, hydraulic disc brakes.

I've read up on changing over and how it could raise the front end more than desired. So my first thought was finding a 80mm 27.5 fork to offset the extra tire meat. But that seems to limit one to cheap Suntour forks only. I did find a rough estimation in an old article that said for every 20mm of added travel, reduces the HA by 1 degree. With my factory HA being 70.5, it seems I have a little play room. A 100mm travel 27.5 non-tapered seems to have a little more options as far as forks go. Maybe putting the HA in the 68-ish range once you add increased tire size.

I know axle to crown measurements also factor in, but those are tough to find unless you have the fork in-hand.

Anyone done a 27.5/26 mullet on an older frame and have some insight? Or maybe someone with more geometry sense to shed some light. Am I onto something that could work, or am I misunderstanding everything and should just buy an old used 26" ROCKSHOX off eBay for $300+ and hope it doesn't break?

Since riding style/location plays a role. Mostly just single track/trail. Roots, some rocks, sand, short hills with incline and decline.

Click to expand...

SpeedoJosh said:

Have a 2006-ish 26" Jamis Dragon. Front shock is equally as old (SID) and in need of some almost non-existent parts. So got me thinking of just buying another. Which got me thinking about a mullet since 27.5 stuff seems more available than 26".

The Jamis set up with the factory 100mm Fox32 has a HA of 70.5 and Seat angle of 74. Non-tapered steerer, hydraulic disc brakes.

I've read up on changing over and how it could raise the front end more than desired. So my first thought was finding a 80mm 27.5 fork to offset the extra tire meat. But that seems to limit one to cheap Suntour forks only. I did find a rough estimation in an old article that said for every 20mm of added travel, reduces the HA by 1 degree. With my factory HA being 70.5, it seems I have a little play room. A 100mm travel 27.5 non-tapered seems to have a little more options as far as forks go. Maybe putting the HA in the 68-ish range once you add increased tire size.

I know axle to crown measurements also factor in, but those are tough to find unless you have the fork in-hand.

Anyone done a 27.5/26 mullet on an older frame and have some insight? Or maybe someone with more geometry sense to shed some light. Am I onto something that could work, or am I misunderstanding everything and should just buy an old used 26" ROCKSHOX off eBay for $300+ and hope it doesn't break?

Since riding style/location plays a role. Mostly just single track/trail. Roots, some rocks, sand, short hills with incline and decline.

Click to expand...

RETROROCKS said:

or I may have a sid thats working ill check my storage
If your interested

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phantoj said:

Just rebuild the SID, looks to me like the parts are available and it's all just o-rings anyway.

With a longer fork, the problem isn't so much the slacking of the head angle as the raising of the BB, IMO.

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Grinchy8 said:

I spent some time and quite a bit of money this summer restomodding an FSR from the 90s. Even with a custom angleset (-1.5 deg) and 130mm fork (vs 100mm), it still only got down to 68 deg. Of course I did raise the backend with more travel there too . . . It was a fun project, I learned an immense amount about bicycle mechanicing, standards, building and fabbing shock links, etc, so I not trying to discourage you, but if you don't have a bunch of parts on the shelf to reuse it'll probably cost more than you want it to.

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SpeedoJosh said:

Have a 2006-ish 26" Jamis Dragon. Front shock is equally as old (SID) and in need of some almost non-existent parts. So got me thinking of just buying another. Which got me thinking about a mullet since 27.5 stuff seems more available than 26".

The Jamis set up with the factory 100mm Fox32 has a HA of 70.5 and Seat angle of 74. Non-tapered steerer, hydraulic disc brakes.

I've read up on changing over and how it could raise the front end more than desired. So my first thought was finding a 80mm 27.5 fork to offset the extra tire meat. But that seems to limit one to cheap Suntour forks only. I did find a rough estimation in an old article that said for every 20mm of added travel, reduces the HA by 1 degree. With my factory HA being 70.5, it seems I have a little play room. A 100mm travel 27.5 non-tapered seems to have a little more options as far as forks go. Maybe putting the HA in the 68-ish range once you add increased tire size.

I know axle to crown measurements also factor in, but those are tough to find unless you have the fork in-hand.

Anyone done a 27.5/26 mullet on an older frame and have some insight? Or maybe someone with more geometry sense to shed some light. Am I onto something that could work, or am I misunderstanding everything and should just buy an old used 26" ROCKSHOX off eBay for $300+ and hope it doesn't break?

Since riding style/location plays a role. Mostly just single track/trail. Roots, some rocks, sand, short hills with incline and decline.

Click to expand...