29 fork on a 27.5 frame with 27.5 wheel?

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Oey12

Well-Known Member
I have a mint condition 2019 Giant Fathom 1 27.5. I was debating selling it…then I thought just use in on the easier trails in the area…

Anywho, I have a Marzocchi Z2 29 34 130 travel with a 44mm offset that I recently swapped off my FS. The bike currently has a SR Suntour Axon 27.5 32 120 travel with a 44mm offset. I realize the 10mm travel difference is going to change the geometry of the bike. But are there any other dimensions that I am unaware of?

Am I going to completely destroy the characteristics of the bike? I would like to run the 27.5 wheel (30mm) because they are wider than my spare 29 front wheel (25mm)

Any incite will be greatly appreciated!
 
Oey12 said:
I have a mint condition 2019 Giant Fathom 1 27.5. I was debating selling it…then I thought just use in on the easier trails in the area…

Anywho, I have a Marzocchi Z2 29 34 130 travel with a 44mm offset that I recently swapped off my FS. The bike currently has a SR Suntour Axon 27.5 32 120 travel with a 44mm offset. I realize the 10mm travel difference is going to change the geometry of the bike. But are there any other dimensions that I am unaware of?

Am I going to completely destroy the characteristics of the bike? I would like to run the 27.5 wheel (30mm) because they are wider than my spare 29 front wheel (25mm)

Any incite will be greatly appreciated!
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What Ryan said, you can do some math here and figure out how much to reduce the travel on the 29er fork to get a similar axle to crown measurement. You could also consider running a mullet, but will need to reduce the travel even more.
 
Oey12 said:
Any incite will be greatly appreciated!
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We all need some incite every now and then, there it goes...Go, Go, Gooo!

10mm (travel) +19mm (29/27.5 adjustment) = 29mm higher axle to crown. If you go with a 29" wheel then you need to add 19mm for the total height increase of the handlebars from the ground (I think).
 
I went to the garage and did some measuring. The Marzocchi is just over an inch longer from the top of the race crown to the top of the axle.

I also noticed there was a sticker on the Marzocchi the said “27.5/29” which is good in my best guess.

I think I got my winter project figured out!
 
Oey12 said:
I went to the garage and did some measuring. The Marzocchi is just over an inch longer from the top of the race crown to the top of the axle.

I also noticed there was a sticker on the Marzocchi the said “27.5/29” which is good in my best guess.

I think I got my winter project figured out!
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I wood go for it, maybe slam the stem if you had spacers (maybe not shorten the steering tube yet, just in case).
 
serviceguy said:
I wood go for it, maybe slam the stem if you had spacers (maybe not shorten the steering tube yet, just in case).
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I have my stem as high as possible because the bike always felt front heavy in the steep stuff. So luckily I have plenty of spacers underneath.

I appreciate everyone’s input!
 
Oey12 said:
I also noticed there was a sticker on the Marzocchi the said “27.5/29” which is good in my best guess
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It's probably referring to cross compatibility of 29" frames/forks with 27.5+ wheels. The outside diameter of a 27.5" wheel mated to a plus tire (2.8 or 3.0) is somewhat close to that of a 29" wheel paired with a more conventional-width tire (2.2 or 2.4). It's not exact, but close enough that some manufacturers label such products as compatible with both setups.

In any case, doesn't hurt to try it out. At the very least you'll have a ton of clearance for mud!
 
serviceguy said:
I wood go for it, maybe slam the stem if you had spacers (maybe not shorten the steering tube yet, just in case).
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But that want account for the BB height change with the longer fork. Best way to handle it is with a travel reduction.
 
stb222 said:
But that want account for the BB height change with the longer fork. Best way to handle it is with a travel reduction.
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With the 29/27.5 out of the way and since he would be using the 27.5 front wheel the 10mm different travel is what, 5mm at the BB? He can probably compensate holding in a couple of farts...
 
@Oey12 just do it. You have all the parts. Slap that fork on, lower your bars and send it.

It will have a slight more head angle which will affect handling.

So it and get back to us on your findings.

Ps origins of your username?
 
knobbyhead said:
@Oey12 just do it. You have all the parts. Slap that fork on, lower your bars and send it.

It will have a slight more head angle which will affect handling.

So it and get back to us on your findings.

Ps origins of your username?
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Oey is short for Joey, a nickname I got from college friends. My first brand new pickup truck was a 20”12”…. Diehard pickup fan…

I will definitely report back.
 
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