26" frame with 26" wheels but a 650B fork- Will it work?

[sa-shooter]

So my searching skills are failing me and I can't find a good enough answer.

 

I want to upgrade my fork but 26" forks are few and far between. Since I have been told that my bike can be converted to 650b safely (and I may do so in the future) but for now I'm wondering if there would be any negative effects from running my 26" wheels in a 27.5" fork? The one advantage I can see for myself is a slight slackening of the HA which is adventageous to my riding, but I have no idea what it would do to the overall geometry of the rest of the bike.

 

Any advice and/or experience would be appreciated.

[Butterbean]

Slackened head angle, raised bb...

 

Will work though, I can't imagine any fire consequences...

[Grease_Monkey]

A 650b wheel is actually not 27.5", it is closer to 27". So the actual size difference between a 650b and 26" wheel is not that big. A 650b fork will have a slightly higher stack height than a 26" fork - so fitting one will slightly slacken the head angle, in my opinion not to such a degree that it will have a negative effect on the bike - so yes, it will be completely fine.

 

If the increase in stack height bothers you, I would suggest dropping the travel by 10mm. So if your current fork is 120mm, get a 110mm fork. I don't think that's necessary though, try it with the same travel first, and if you don't like it, then drop the travel.

 

Your plan is much better than getting a mew 26" fork - you are future proofing your bike, and allowing yourself to get 650b wheels in future.

 

Go for it.

[Captain Fastbastard Mayhem]

It's fine. No issue at all. Slightly higher bb, slacker head angle and longer wheel base. Slightly. may need to drop your stem a smidge.

[Grease_Monkey]

It's fine. No issue at all. Slightly higher bb, slacker head angle and longer wheel base. Slightly. may need to drop your stem a smidge.

Disregard my previous statement about dropping the travel by 10mm, much easier, cheaper, and more effective to drop the stem by 10mm like cptmayhem suggested...

[sa-shooter]

Thanks guys. I appreciate the input.

[droo]

Do it. Forward compatible so when you go 650 on your next frame you can just take the fork along.

[Headshot]

Just do it already.

[Skylark]

Do you get 650b forks with a 1 1/8" straight steerer?

Probably as rare as the same in 26"

[CdT85]

No issues what so ever. I am running a 650B on my old 26'er. Can't feel the difference. and as Droo said, forward compatibility with you next frame

[droo]

Do you get 650b forks with a 1 1/8" straight steerer?

Probably as rare as the same in 26"

 

RS have a few. All QR though AFAIK.

[Skylark]

RS have a few. All QR though AFAIK.

I would need 20mm thru axle so no dice.

 

Apparently you can use a tapered steerer in a 26" frame as long as you get the outboard headset adaptor, which also essentially extends the fork and slackens the headset angle?

[Me rida my bicycle]

I would need 20mm thru axle so no dice.

Apparently you can use a tapered steerer in a 26" frame as long as you get the outboard headset adaptor, which also essentially extends the fork and slackens the headset angle?

I think those headsets are only 44 or 40mm can never remember which so just check with your lbs if it would work with your frame and those external headsets are quite pricey.

[Tankman]

I think those headsets are only 44 or 40mm can never remember which so just check with your lbs if it would work with your frame and those external headsets are quite pricey.

 

Finding and external headset is waaaaaaaaaay easier than finding an straight steerer 27.5 fork.

 

And if you upgrade the frame later on, chances are 99% its gonna be tapered.

[Tankman]

A 650b wheel is actually not 27.5", it is closer to 27".

 

I would not completely agree with that statement.  Tire choice makes a huge difference.

 

If you measured the waver thin tires that were available 5 years ago, then maybe.  But these days width is the main attraction ... and with width comes volume.

 

The problem is not the fork, since that is being upgraded anyway, but the rear wheel is the problem area on 26" to 27.5 conversions.  Some 26" frames can not take a tire anything wider than a 2.1 tire. 

 

The chainstay narrows down quite a bit behind the bb and that is where your problem lies.

 

I have done conversions on 26" Cannondales to 27.5's ... Lefty = No problem

Chainstay behind the bb = problem for any tire wider than 2.1

[Grease_Monkey]

I would not completely agree with that statement. Tire choice makes a huge difference.

 

If you measured the waver thin tires that were available 5 years ago, then maybe. But these days width is the main attraction ... and with width comes volume.

 

The problem is not the fork, since that is being upgraded anyway, but the rear wheel is the problem area on 26" to 27.5 conversions. Some 26" frames can not take a tire anything wider than a 2.1 tire.

 

The chainstay narrows down quite a bit behind the bb and that is where your problem lies.

 

I have done conversions on 26" Cannondales to 27.5's ... Lefty = No problem

Chainstay behind the bb = problem for any tire wider than 2.1

27.5" refers to rim size, independent of tyre size. 27.5" is not the actual measurment of the rim's diameter, more a marketing term. So the fact that they are closer to 27" than 27.5" isn't really worth debating because a fact is a fact and... if you include the tyre in the measurement you must compare apples to apples, ie thin tyre to thin tyre, wide to wide.

 

Although I do see your point and agree with you - tyre size does make a big difference, a 27.5x2.1 wide Ikon is very different in diameter to 27.5x2.5 Minnion DHF. So the OP will have to be careful when it comes to tyre choice for the rear wheel.