B9er thread

Author Message
flag 700pirate
Posted: May 12, 2019 at 5:31 Quote
Thats a 27.5 frame right?
flag tene
Posted: May 12, 2019 at 5:39 Quote
700Pirate wrote:
Thats a 27.5 frame right?

Yes.
flag Dimebolt22b
Posted: May 27, 2019 at 11:33 Quote
Just trialling a 27.5 on the back of my Swarf. Only done a few miles on the flat with my boy but it definitely manuals easier. It's a 1285mm wheelbase so every little helps. Hopefully getting out for a proper ride on some trails tomorrow.
photo
flag rickyvic
Posted: May 28, 2019 at 10:03 Quote
tene wrote:
Fastbiker1998 wrote:
What do you guys think of making a b9er of the gt force 2019. Would it be good to go after just swapping to a 29'er fork and wheel?(Still 160mm travel). Alot of reviews is saying the front end feels a little bit low(stock 27,5), so putting a 29 wheel and fork would probaly just help this. Obviously bb height will be higher, head angle slacker, seat tube angle slacker and a bit shorter reach. Is any of the things mentioned above going to change too much or will the bike probaly feel just fine? If so, what are possible modifivations to fix the geometry?

I think that the bike will slacken too much with those modifications. Maybe 140mm 29er fork would be in the sweet spot for that bike. There are examples in this thread for swapping bigger fork & wheel in 27.5 bike.
Correct me if I am wrong but a force 19 with a 170 fork has a 64.5 head angle in low position, with a 160 29er fork in high position should be in the region of 63.5 roughly. Or 64 in high position.
If it is too slack one could always use a longer stem to bring you more in the front and a bit more sag in the fork.

I think what maes did is sound, not sure how much advantage would a normal rider gain. On slow sections with big rock gardens you should be able to not get stuck as much but the rear wont follow and speedwise it wont be faster.
Also a bit more traction on steeps.

Obviously if geo changes too much it will need to be tweaked but the idea is to reduce travel in the fork and adapt it without altering the geo too much.
flag rickyvic
Posted: May 30, 2019 at 10:36 Quote
I checked also axle to crown of the rockshox lyrik 27.5 180 vs 29 160 and they are the same.
I dont know the fox 36 but I guess similar.
If one also uses a short offset in the 29er they will end up with the same exact geometry.
Oh except 1.5 inch difference in wheel diameter, so it will be run 1.5/2 =0.75 in = 19mm higher, so about 1 degree slacker, you need to run more sag in the front to offset it or use a 150 but then it wont be enough travel I think.
A much higher bb too to take into account unless you use more sag.

Most enduro rigs run a 170 upfront but some use a 180 so you can run a bit softer too.
flag Fastbiker1998
Posted: Jun 1, 2019 at 7:56 Quote
rickyvic wrote:
I checked also axle to crown of the rockshox lyrik 27.5 180 vs 29 160 and they are the same.
I dont know the fox 36 but I guess similar.
If one also uses a short offset in the 29er they will end up with the same exact geometry.
Oh except 1.5 inch difference in wheel diameter, so it will be run 1.5/2 =0.75 in = 19mm higher, so about 1 degree slacker, you need to run more sag in the front to offset it or use a 150 but then it wont be enough travel I think.
A much higher bb too to take into account unless you use more sag.

Most enduro rigs run a 170 upfront but some use a 180 so you can run a bit softer too.
Martin Maes actually only use 150mm travel on his fork, seems to work for him atleast. Source: https://www.vitalmtb.com/features/WINNING-BIKE-Martin-Maes-GT-Force-69er,2683
flag rickyvic
Posted: Jun 1, 2019 at 8:37 Quote
Fastbiker1998 wrote:
rickyvic wrote:
I checked also axle to crown of the rockshox lyrik 27.5 180 vs 29 160 and they are the same.
I dont know the fox 36 but I guess similar.
If one also uses a short offset in the 29er they will end up with the same exact geometry.
Oh except 1.5 inch difference in wheel diameter, so it will be run 1.5/2 =0.75 in = 19mm higher, so about 1 degree slacker, you need to run more sag in the front to offset it or use a 150 but then it wont be enough travel I think.
A much higher bb too to take into account unless you use more sag.

Most enduro rigs run a 170 upfront but some use a 180 so you can run a bit softer too.
Martin Maes actually only use 150mm travel on his fork, seems to work for him atleast. Source: https://www.vitalmtb.com/features/WINNING-BIKE-Martin-Maes-GT-Force-69er,2683
It makes sense as the geo would be extreme with a 150 instead is similar to a 170 27.5 in low position. Plus fox 36 runs higher in its travel.
For a spartan you would probably be able to run a 160 upfront
flag ronan29
Posted: Jun 7, 2019 at 8:02 Quote
My first try at a mixed wheel combo: 27.5x2.8 at the back and 29x2.25 up front, it went well I cannot wait to test it again. Especially on a hardtail it makes sense because the plus tire helps for cushioning things a little, and in the front the 29 one allows to choose more precise lines.

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flag undescended
Posted: Jun 7, 2019 at 19:36 Quote
Mullet+ is awesome, ain’t it!
flag tene
Posted: Jul 14, 2019 at 14:35 Quote
SlipperySEAL wrote:
photo
Best looking b9er that I have seen!
flag ktm87
O+
Posted: Jul 14, 2019 at 15:27 Quote
that commencal is so hot!!

this is latest b9er im working on
170mm front and back. log and slack. gearbox with high pivot. very progressive. hopefully be fun

rough 3d drawing. material is on the way to bring it to life
flag dagzin
Posted: Jul 17, 2019 at 11:40 Quote
Hey
I have a 29er hardtail, and thinking of trying a 27.5 out back. Well thinking is a lie.. I pick up a cheap 27.5 wheel just waiting for it to be delivered.

My question is..
At the moment I used 29x2.6s front and rear if I put a 27.5 wheel out back what tyre would be best suited. 2.6 or 2 8?.

Thanks
flag dagzin
Posted: Jul 18, 2019 at 1:05 Quote
Forgot to mention I'm useing a sunringle duroc 40 with a Id of 36mm.

The tyres I'm looking at are.
Wtb ranger 2.8
Wtb ranger 3.0
Wtb trailboss 2.65
Wtb trailboss 3.0

But looking at the reviews and posts it seems wtb comes up a tad small.
flag telephunke
O+
Posted: Jul 30, 2019 at 12:22 Quote
does anyone have any thoughts on 'ideal' bikes to do this conversion to? I'm in the market for a new frame/setup, and want to end up with a 160mm rear and 170mm front. (I know about the dedicated liteville and Foes bikes, but not that into them)

It seems if I convert a 27.5 bike, I have to find one with a 20mm difference in travel at either end, and accept having the same travel at either end as the final result. Is this correct? Not what I want in any case. (based on this anyway: https://www.bikemag.com/gear-features/bike-shop/bike-shop-27-5-rear-29-front-the-79er-trail-bike-done-right/ )

If I convert a 29.5 bike, I need to find something with short chainstays, or else (kind of) what's the point? Going this route means finding something with a steeper seat tube and steeper head tube than I want as the end result, is that correct? And something that doesn't have too low BB. Seems like finding these combos in a bike might not be that easy.

 


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