Chinertown
Chinese Carbon MTB => 29+ & 27+ => Topic started by: 3GGG on August 11, 2018, 07:14:40 AM
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Hi All
My last MTB was a new Proflex Beast in the late 90's. I am keen to get back into mountain biking and will be building up a P8 as a 29er.
My build won't be anything over the top but would love some advice on parts selection as I have never built a bike and parts have changed a lot in my 20 year hiatus.
I am looking at this groupsethttps://www.ebay.com.au/i/122225659721?chn=ps&ul_ref=https%253A%252F%252Frover.ebay.com%252Frover%252F1%252F705-139619-5960-0%252F2%253Fmpre%253Dhttps%25253A%25252F%25252Fwww.ebay.com.au%25252Fi%25252F122225659721%25253Fchn%25253Dps%2526itemid%253D122225659721%2526targetid%253D91828837057%2526device%253Dm%2526adtype%253Dpla%2526googleloc%253D9070952%2526poi%253D%2526campaignid%253D184043497%2526adgroupid%253D8467825417%2526rlsatarget%253Dpla-91828837057%2526abcId%253D578876%2526merchantid%253D119060590%2526gclid%253DCjwKCAjwkrrbBRB9EiwAhlN8_EWO1Z_MxVcSz8vL-7bUt3XYkWzWIEo542sGd9QYZp3hA-U8a-rsDBoCiekQAvD_BwE%2526srcrot%253D705-139619-5960-0%2526rvr_id%253D1628415125692%2526rvr_ts%253D28e035241650ac196ab4936afff9da6e but am concerned it won't be compatible with the frame. Any help would be appreciated. Cheers
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Im new to building mountain bikes as well, so hopefully someone else can confirm this. I have a P8 and when I purchased my crank set it was a boost spacing specific. I don't see that mentioned in the ebay add you linked?
Here is the crank set that I ordered:
https://www.jensonusa.com/Shimano-XT-FC-M8000-Boost-Crank-Arms (https://www.jensonusa.com/Shimano-XT-FC-M8000-Boost-Crank-Arms)
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Yeah boost is all new to me.
I assume I will need boost specific hubs and front fork.
The cranks however is it just the bottom bracket or is it a specific crank also?
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Boost rear hub is mandatory, boost front hub/fork is suggested. You could technically do a non-boost fork and front hub, but the axle to crown may not match, you wouldn't have the tire clearance for 27.5+, and then you'd have mismatched front/rear wheels. Short answer, boost front/rear/fork.
The BB is generic BSA. For Shimano, it's the cranks that dictate whether they are boost or non-boost. FYI for Sram, it's just the chainring that dictates boost, at least for the direct mount.
This may help understand crank compatibility: https://www.oneupcomponents.com/pages/understanding-chainline-for-optimal-1x-conversions-boost-and-non-boost
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Excellent thank you for the link. Got it now
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Any thoughts on running the Fox Suspension 32 Float Performance Boost Fork, only 100 mm travel is my concern but nice and light?
Edit : went for a 140 mm fork.
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Good call on the 140mm fork. Ive been running a 140mm Manitou Mattoc fork with a matching Manitou rear shock and its been a blast. I'll be posting my first season review of my P8 build in the next week or so if your looking for parts overiew/review.
-Ryan
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Thanks Ryan, Did you use the Manitou Mcleod and if so did you go the 200 x 50 or 200 x 57 shock?
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Yes I have the McLoed 200x57. It works out to be aproximatly 135mm of travel in the rear.
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Janz, what is your BB height with that setup?
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12.75" unsagged. Its definitly on the low side, after some practice I have gotten used to it though. Ive learned to ratchet over rocky stuff and to time my pedaling. After riding a low BB Im not sure I would want to go back to something much higher. This bike rails corners and hugs the terrain very well.
With that said, if you were concerned, you could always go to a 29x2.4" tire. That would net you another .25-.5" of BB clearance and put this bike inline with most modern geometries.
-Ryan
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Thanks for the reply. What size tyres are you running now?
I assume you have the frame with the original geometry that had the 48mm BB drop, not the newer one with 24mm drop? I really like the frame and the only thing holding me back is the low bb height, I'm trying to work out if the newer version is actually a different front triangle or just a trick on numbers by increasing the drawn axle to crown from 531.9 mm to 551mm.
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Im running 27.5x2.8 nobby nic in the front and a rocket ron in the rear.
FYI, Ican is behind right now on their orders/shipments. I placed an order for a replacement rear carbon wheel that I cracked, due to the typhone that hit them they have been slow to get it out.
Ive been dealing with "Melody" at Ican, she is pretty good to deal with. The language berrior is a bit frustrating at times, but overall shes been great to deal with.
-Ryan
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OK, there is more to that story, how did you crack the rim ? I assume you are happy enough it was your fault that you felt comfortable ordering another one from them?
Is your frame the original geometry?
Thanks
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Yes my frame is the original design, I bought it about a year ago.
Lol, yes it was completely my fault. The rear tire was low from sitting in the cold for a couple weeks, I went for a quick ride around the block knowing it was low (10psi). I went to go bunny hop over a curb and goofed, ended up coming down hard on the edge and nicked the wheel. Its still usable if I have a tub in it, but it seeps now when running it tubeless.
I'll try and fix it to keep it as a backup, but after running tubeless I don't want to go back to running tubes. I have the downhill layup wheels from Ican, and they have been rock solid. I have done a week of riding in the mountains, and a few days in a lift access bike park with zero issues.
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You might be able to "patch" it with some epoxy?
Good luck with it. and thanks for the information.
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I'm about to do a crc order but don't have my rear shock yet. Can anyone confirm what exact size bushes I will need?
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Thanks for the reply. What size tyres are you running now?
I assume you have the frame with the original geometry that had the 48mm BB drop, not the newer one with 24mm drop? I really like the frame and the only thing holding me back is the low bb height, I'm trying to work out if the newer version is actually a different front triangle or just a trick on numbers by increasing the drawn axle to crown from 531.9 mm to 551mm.
As I have it, Its a new rear triangle, not front. I have communication from Melody who initially offered only the updated seatstay and rocker link as an upgrade. They don't do that anymore unfortunately. However, I cant see the BB height increasing and the seat tube getting steeper without the HT getting steeper. The slack seat tube is probably my biggest issue. I've slid my saddle right the way forward after getting a straight mount dropper post(setback didn't help) and it feels pretty good right now, however I couldn't tell if it could be even better with a 70 deg seat angle.
I am quite happy with my P8 now. I have been running 2.3'' 29 er tires and admit the BB height is low. I live in a very rocky area and Its a bit irritating at times, however, not something that cant be avoided.
On the Downhills, the low BB height gives the bike a "planted" feeling. I had mine at a bikepark recently and after some serious cases om big jumps Its developed a creak(It was also an extremely hot day). My first thoughts were oops, something went, but its been 2 months and after inspection I'm most certain its just in need of a grease. I'm looking for a used RS Pike Dual position since I would like to still do longer days in the saddle, but this bike (with 135 mm at the rear) begs for 140-150mm front travel on downhills. So the Pike DPA 120-150mm wil be perfect. I'm currently running a 130mm RS Revelation and its definitely holding the bike back when it comes to downright nasty steep stuff.
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I have a Fox 140mm fork , w/ 29"x 2.4" tires on my P8. Might try a 2.5" or 2.6" tire on front next spring . No real problems with bottoming out with that little extra height from fork and tires. All in all a pretty good trail bike.