BMW Q6.S XTR rare folding bike

[danson67]

Re:

The bars and stem look fine to me... If it's your back that's causing the problem, I'd go for a shorter stem and some period riser bars to het a higher, shorter grip position.

All the best,

 

[adilmon]

Re: Re:

The bars and stem look fine to me... If it's your back that's causing the problem, I'd go for a shorter stem and some period riser bars to het a higher, shorter grip position.

All the best,

I agree, only the longer stem is helping with the bike reach, with is a bit too close for me. I have bought riser bars though.
These ITM units are 7075 ally, bit stronger than 6061 and a narrow 580mm

Sharing more specs should the internet need it;
Seatpost Diameter 29.8mm
Standard XTR M950 cassette 9 speed 12-34t

in swapping out rear shock for a Fox RP23 I took some measurements of the existing paoili unit.
eye to eye 165mm
standard bolt diameter 6mm (modern is 8mm)
front mount width 31.6mm (23.7mm without spacers)
rear mount width 23.7mm

The mounts on the original shock aren't reusable for the Fox unit. The bushes my Fox Shock came with required too much fettling to make work and for 8mm bolts.
So instead realised the weird 12.7mm eye diameter was 1/2". So bought some 1/2"(12.7) ally tubing from ebay with a 10SWG (3.25mm) thickness.
Bit of quick math means the ID of the tube is (12.7-(3.25x2)) =6.2mm ID. This tolerance works well with the 6mm bolt diameter and I can cut the bush width to size.
Fair bit cheaper than pre-made shock bushes at only £2.99 for 500mm

NB: chose the fox shock as has a max 300psi and rebuildable
NB: be careful opening the folding rear triangle without a wheel installed as chain stay can contact chainset cogs

This really is overly detailed info for a bike most have never heard of, so apologies.

 

[danson67]

overly detailed info for a bike most have never heard o

No problem...fits right in around here ;-)

All the best,

 

[adilmon]

So, hit a little snag. The 6.2mm clearance for the 6mm diameter shock bolts is too much. Considered using nylon/ptfe bushes in the 8mm to take up the slack, but they're good for up to 500psi pressure and a 6mm bolt give much higher pressure. Impossible to find a spacer with a 12.7mm OD and 6mm ID, so will reuse the FOX 8mm ID spacers with a section of 8mm OD 6mm ID ally tube cut to size.
I could widen the mounting holes for the rear shock by 2mm, but someone once told me "a bike is only original once"

Also tracked down some brilliantly weird bars
Bontrager Satellite Elite Carbon Trekking Handlebar
https://www.bikeradar.com/reviews/bikes ... lideshow=1

more pics to follow

 

[adilmon]

Righto, I've picked up some nylon bushes of various diameters to shim up mt 6mm rear shock bolts up to the 8mm diameter needed for the fox rear shock. Really surprised how much lighter the fox RP23 is compared to a coil shock

Also the front coils i had custom made (because HAD to be less than 43mm outer diameter) have arrived. They've been custom designed with 25% 50% and 75% higher spring rates, so i can experiment

Furthermore, learned that the magura louise, despite being hydraulic disc brakes, aren't amazing. They're a single sided piston calipers and their manual says "they are not 100% drag free". No point keeping this original. I picked up a set of M785 shimano saint XT brakes and IS to post mount adapters to address sort it.

Thought about upgrading the rear hub's 18t DT Swiss freehub start ratchet to 54t, but frankly 18t are bulletproof. Also in 2 minds whether to stick to original rims or use the crankbrothers iodine/cobalt combo. The small print apparently says they're designed them for 100kg rider, so will fit when i get fitter (!)

Finally, I treated myself to a 110mm crank brothers iodine 3 stem. It's 7075 aluminium, with a carbon top cap.

Used a cheap luggage scale and weight with my "comfort" saddle is just under 14kg, so about 1kg over what I was expecting stock. Going to throw all this stuff on a see whether any change.

Other bits.
Seat post- thought about changing for carbon, but don't really fancy shimming up to 29.8mm. dropper is probably overkill for x/c duty
1x conversion- Unless i pick up a bargain, I prefer 3x. nowt wrong with a granny gear.
pedals- cheap light flats in favour of SPDs
Forks- refresh lower pivot ball joint pivot boots.

 

[adilmon]

Great, the replacement front springs (25% 50% and 75% higher spring rates) have arrived.
Going to keep it on the original wheels (dt Swiss hugi 240 hubs, Rigida DB Taurus rims) for now as I'm over the crank brothers wheels weight recommendation! So, will upgrade the 18T star ratchet to a 36T and just ride the bloody thing

Also sourced a set of Ashima Disc rotors to try. Read they're noisy and hard on the pads, but I'd like to see for myself

The Selle royal Saddle I use now replaced with a Charge Spoon stealth black, which I'm suprised to say saved around half a kg

The M952 XTR chainset and BB seems really expensive. Had look at upgrading to newer XTR kit, but weight weenies website doesn't show any significant weight advantage in 15ish years of development. Very odd.

Finally, picked up some schwalbe racing ralph tyres to complete the look.
enough text, will post pics next

 

[adilmon]

dusting this topic off (time flies)

In the interim I've been riding another (hybrid) bike with the Bontrager Satellite elite carbon bars (only 229grams) and they're great.
Thinking of turning this into a 29er, but quickly came to my senses. It is what it is. This will be my occasional muddy winter bike, so will fit some Schwalbe cx comps or racing ralphs/rays.

torn between originality and appropriate upgrades, few thoughts;
-ditch the single piston magura brakes for some SLX ones i picked up
-swap saddle/grips for one that suits me (put them somewhere safe)
-use modded springs on front shock
-forget fox air shock and fit retro heavy spring shock with 6mm bolt. (the 6.2mm option mentioned earlier had noticable play)
-the XTR chainsets/cranks in good condition are quite rare, so must add helicopter/gorilla tape to prevent rub
-fit topeak mudguards

pics to follow

 

[Gambitxjs]

Re:

Hi so I got the bug too , never really been into bikes but just loved the design of this beast, so I’ve put gold hollow kmc chain, Ht titanium spindle flat pedals EC90 carbon post , handle bar, stem. Lightweight foam grips , then for ultra weight gone for continental speed king race king tyres with tubolito inner tubes. The weight at the moment is coming in at 12.7kg, just on the hunt for a fox float now which will take final weight to about 12.9kg

 

[Gambitxjs]

Re:

I’m also tempted to go one step further and take it back the metal and give it a full mirror polish , I think it would look sick!

 

[adilmon]

Re:

Great to read I'm not the only one!
The fox 1/2 inch to 8mm standard bushes take a bit of imagination to fit the 6mm bolt hole. The easiest thing would be to drill out the frame hole, but I'm too chicken for that.

Tell you what, it's amazing how light the m952 xtr kit is compared to modern stuff.

I love the lightweight theme. Those tubolitos are a little expensive, but total wheel weight really does make a difference. I read the mavic crossmax xl was a super light wheelset. It was used on the competing audi cross pro bike. I wonder how they compare.

Fyi, i found a few gadgets to make it more practical without a saddlebag;
The rear skewer, I've replaced with Pedro's Tulio (excellent multitool)

Double bottle cage mount by ztto

Topeak Ninja pump, stored in seat post cavity. I taped some glueless patches to the pump body.

Looking forward to seeing the finished project. I saw one in a German ebay site that was powder coated in the xtr metallic grey, which was nice. I particularly like the fluid platinum paint job some boardman hybrids had a few years ago. Almost silver pearlescent.