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NBD (musings on 27.5" wheel full-sus. versus 26" old-school hardtail)

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  • #16
    You'll find the a service manual here https://www.sram.com/en/service/models/sp-rvb-b1 . If you take the saddle off there should be a little valve to screw a shock pump to. Might just be a case of it needs air pressure again. Other then that it's bleeding territory, which needs a kit to do it. Bit of a faff to do it, first time I didnt follow the instructions by the letter and only for me knowing the bike wouldn't fit through the window it would have flown like a bar stool in a western

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    • #17
      Ah thank you Ptank - appreciated

      Yup, there is indeed a little Schrader-valve well hidden in the top of the seat-tube:

      zznombQm.jpg

      A quick check with the shock-pump shows the pressure's not too far off the mark...

      DhZfE3Cm.jpg

      Topped it up to the full 250 (just in case) but hasn't remedied the problem. The post still doesnt extend fully, even with the full psi in it.

      Had a close look at the remote thumb actuator-button on the handlebars, and noticed a bit of black electrical tape round the junction where the oil-line goes into the actuator casting. I'm guessing from that somebody's had problems there before - so I think I'm into bleeding it territory. Played around with it a little, and am pretty sure I can hear some sloshing sounds, like there's air trapped somewhere in the system.

      Looked through the service manual there, and it looks like the things are supposed to be serviced regularly, and rebuilt after the first 200 hours and then again at 400 hours usage.

      I've no idea at all how much it's been used, so just wondering if I should fork out for a bleeder kit and give it a shot - or maybe better to just throw it into the shop and let the pros give me an estimate for the damage they'd inflict on what little's left in the slush fund.

      What d'ye reckon ?

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      • #18
        bear in mind that with a shock or dropper the air volume is quite low so you probably lost a bit of pressure just screwing the pump on.
        anyway reverbs are somewhat known for giving trouble after a few years. Usually they just sag a little, you got unlucky. give the bleeding a go. even a shop shouldn't charge much for it.
        If it needs a rebuild alternatively I did see that wiggle are doing brand x droppers for 80 euro on black friday, that might be cheaper.

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        • #19
          Honestly junk the Reverb, they are very troublesome and expensive to fix, as Phil says BrandX droppers are very, very good for the money, I'm running one for 5 years and zero issues.
          meatballs

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          • #20
            I've never had a Reverb, but agree with the comments on those CRC BrandX droppers. They've been very reliable in my experience too.

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            • #21
              For the price of a bleed kit or someone to look at it you're nearly half way to a brand x. I've had a brand x dropper in my hardtail for 3-4 years no issues. Sticks from non use now but a new cable and housing would sort that. I found on frosty mornings the reverb might not work too. Have had it in the past where I set out from home dropper stopped working (just in time for a climb). Left the bike in the sun while I was waiting on some other lads and hey presto back in action...

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              • #22
                Thanks all - comments on the Reverb / Brand X posts duly noted.

                Left the bike into the pro to see if bleeding will sort it (as I think it may be an issue with the actuator instead of the unit proper) - with instructions not to bother rebuilding it if not.

                He said that won't be a problem, we can't get parts for the Reverb anyway..

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                • #23
                  Update - Nov 27.

                  As you know, left the bike into a local pro on Monday to see what the prognosis was on the seat post. Turns out the bike is actually the X10 model, the mid-range Orbea for that year, and comes equipped with the Reverb Stealth Dropper Post. No word until Thursday - and I was starting to get a bit edgy in case I had to go the Brand X substitute route, and didnt want to miss the Black Friday deals PhilB of this parish had kindly flagged. Got the call from the shop late Thursday to say they'd bled it, and it was back in rude health - €20. The latest bleeder kit and oil for them is somewhere round €60 or so full retail these days, so I'll take that as a result.

                  'Flushed' with that success.. I decided to swop the little flip-chip around at the top shock mount, to see whether it has much effect on the ride and steering. The job takes about 5 minutes with a little hex-key, and is something you could actually do out on the trail.

                  JGKJCEnl.jpg

                  According to the geo chart above, turning the little gubbins round the other way tightens the head angle by a whole 0.5 degree (65.5 to 66 deg) and raises the bottom bracket by the sum total of 7mm. The sum total of bugger all ... or so I thought. Went for a hoon round Ballinastoe today to see how the bike felt with those bits and pieces done to it.

                  So, thoughts from the day:

                  (i) A dropper post which works, and comes back up to full height is a thing of wonder and beauty. I wouldn't wish that experience on me again, or indeed on anybody

                  (ii) That 1/2 degree difference in head angle and 7mm raised bottom bracket height makes a hell of a lot more difference than you'd think. I know some of it probably down to me getting used to the slower steering, but with the sharper geo, the bike definitely felt much more almost like my old hardtail. I could start to look further down the track and pick the lines where I wanted to be rather than looking down near the front tyre to see whether the front wheel was going to behave and get somewhere closer than about +/- a foot of where I'd have liked it to be.

                  I found this time, I could place the front tyre pretty much where I wanted, steer round the sneaky little gaps at the edge of the rock steps rather than go over them for example - and even start to pick lines through the rock gardens again, rather than arrive at them out of shape, and have to head for the middle and hope.

                  On the pedal strike front, total count pedal for the day - 1 strike plus 1 half-graze type thing. I put that down to a combination of in part being a bit more familiar with the bike, but also being able to position it more accurately with the revised steering, and the slightly taller bottom bracket. None of them huge factors individually I think, but when you take them all in combination, it has to add up.

                  (iii) One other surprising (to me) thing I found on really slow stuff is that the combination of narrower bar and quicker steering makes it a lot easier to switch direction and balance. Thinking about it, something has to give when you get with relaxed geo and steering set up for downhills, and the trade off must be just that - the loss of manoeuvrability and responsiveness you get from a bike with a steeper front end, and sharper steering.


                  I also found btw doing the 15km / 430m of climb round B'stoe leaves you a lot less b*ll*xed than the full 28km / 750m ascent loop round Rostrevor with the aforementioned bust saddle. I found I could actually keep up with the fit guy on about maybe half of the climbs today. Might also be down in part to the better traction on the long steady grinds I guess, and also perhaps not getting as pounded as much on the downhill sections.

                  Whither next ?

                  The plan now is to sort the suspension, Dial in the right sag heights for my weight, and then set the front fork and rear shock with the manufacturer's recommended starting compression and rebound values. A quick check this afternoon shows the back shock is set up way too soft, and needs more air to firm it up, whereas the front is the opposite, and could do with being softened up just a little. No idea whether any of that will actually result in as noticeable a change as the steering, or indeed anything I;ll be able to notice - but you gotta give these things a go really.

                  Shall report back.
                  Last edited by -alan-; 28-11-2022, 12:55 AM.

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                  • #24
                    That's great stuff Alan. Did you hit the new black trail in bstoe then? Some nice sections on it, it is unusual though. And what did you make of expressway on the new bike? Having done bstoe extensively on the hardtail, there's parts where I'll never go as quick on the full suss, but expressway is quite choppy these days.
                    The berms in bstoe are excellent and are good practice for direction changes on the new rig.
                    Overall with the geo change, probably makes sense.. I don't know that the changes would be massive from half a degree, but if its getting you into your comfort zone where the feel of the bike makes a little more sense, all good. I don't think you are losing out much either in terms of capability on the steeps, so that's good.

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                    • #25
                      The flip chip on my Trance-X steepens/slackens things by 0.7deg and makes a 10mm difference in BB height. Actually very similar front end geo to the Orbea 65.5 - 66.2 deg. TBH I leave it in the low/slack setting 99% of the time unless I'm heading out for a bit of an all-mountain spin. Won't profess to have noticed much of a front-end difference on the few spins I've tried with it in the high position, but what was immediately noticeable was the reduced amount of pedal strikes the addition 10mm BB height gave.

                      The dropper now has you ruined. You will never, ever, ever ride a mtb again without one. In fact riding a mtb down a trail with a post up will strike absolute fear into the core of your soul. Try it the next day

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                      • #26
                        ^ I don't think I've got my head round how to use the dropper post properly yet - tbh I largely forgot about it yesterday. Probably apprehensive that the damn thing would collapse on me again In truth my technique's fairly crap - I don't naturally tend to let the bike move underneath me enough, unless I remember to make a conscious effort. Means you end up with the saddle braced between your legs - which isn't right I know, but I'll try to kick the habit now that I can lower the seat and keep it out of the way.

                        Phil - went down that black trail once on the hardtail, but it was a bit of a handful, especially with the cleats. Need to build up to it and have another go with the Orbea. Wasn't sure which one was Expressway, so had to google it:

                        https://fb.watch/h4oi9iqhfA/

                        Great trail that - it's probably my favourite, as you're usually into your rhythm at that stage. Good test of suspension too - it's the one where I used to struggle most on the hardtail trying to keep up with the other chap, but now find it hell of a lot more fun.

                        Looking at that vid and some of the other clips on it, the quick guys seem to rocket into the rock-beds, and spring the bike over the first half of them altogether. Looks a lot easier, but Im not sure I've the cojones for that just yet

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                        • #27
                          With the dropper - yeah as Desmo says you are ruined now. I ended up buying one for my hardtail as I couldn't do without. One excuse I have is short legs.
                          There's not much to the usage, it can be good to avoid overusing it, I will drop the saddle a little bit on rough pedally trails but try to avoid full drop unless I know I won't be pedalling for a while. In terms of technique yeah need to let go of the bike with legs, whether thats saddle or top tube.
                          You've got me thinking about flipping the chip on the bronson - its high position is the low on yours. Its in low since shortly after I bought it, think that's 64.8.
                          Expressway in my head deserves a lot of respect, you are doing a serious clip down it and a mistake has large consequences. I try to maintain a rhythm down it and do things right rather than fast.

                          That video sets a high bar - Dan Wolfe is a pro.. he's making it look very easy by gapping a lot of the trail - and yep, he has to deal with a lot less rocks as a result. If you watch EWS or DH world cup you'll see that the top riders are only hitting the trail in spots. Slightly galling that in ways it is indeed easier - you are putting the effort into lifting the bike rather than getting battered by the trail.
                          But its very hard getting to that level. Definitely worth trying to unweight the bike over progressively larger sections of trail, on trails that you know well.

                          Complete aside - any interest in a few of us heading on a spin over the Christmas break?

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                          • #28
                            Glad to hear the dude's a pro...don't feel quite so useless now! Yeah Expressway doesn't leave a lot of margin for error - but y'know none of them do really. If you do overcook it even slightly chances are you're into the scenery, and it's in the hands of the downhill Gods whether you end up splattered round a tree or get lucky enough to find a soft landing somewhere.

                            Hey - I'd be up for a festive scoot if there were a few heads thinking of it

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                            • #29
                              Sounds good. Not sure I could commit to a specific date, the wifes shifts are a bit ad-hoc, but if there's a plan for a spin I'll try and get there.

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                              • #30
                                Sunday 11th - B'stoe (again).

                                Looked a bit on the chilly side yesterday, but we decided to go down to Ballinastoe for the hell of it anyway - I had the suspension set up properly for my weight, and was itching to see whether unweighting the bike more over the little steps and rock-gardens would help.

                                My buddy's 2018 Orbea - 29er.

                                SHX4aGAl.jpg

                                Chillier it certainly was down in Wickl'aw..

                                qac27MEl.jpg

                                The place was empty. A couple of runners about, and from the looks of the tracks, clearly a couple of other bikes had been out before us - but that was it.

                                All the Beards with their 'lectric bikes and massive 4x4 pickups were noticeable by their absence. Must have decided doing coffee in Dundrum, waiting for the better halves was challenge aplenty for the new generation of outdoorsmen and their machines on the day that was in it

                                Anyways. First time I've ever really done much in the snow. There was about 4 " or so of fresh powdery stuff in the open areas, dropping back to little or clear under the trees. Pedalling uphill in the snow is hard. There's more drag, and if you're not careful and let the front wheel go more than about 15 degrees left or right, the front wheel slides out. Really bloody hard work actually. My buddy the French guy was in his element, blasting up the hills like yer ones attacking on Alpe-d'Huez in the Tour this year. "Just like ze Biathlon we used to do when I was training in the army". This guy goes cross-country skiing for fun ffs. (Come to think of it, the more he tells me, the more I'm beginning to suspect he might have been in the French equivalent of the SBS Artic and Mountain Warfare cadre )

                                I don't have any pics - largely due to being a tad otherwise occupied - but going down the single-track trails was flippin' excellent.

                                Was like something in Lapland. You got either completely virgin fresh powdery snow, or, mostly that with one or two sets of wheel-marks where a solitary one or two bikes had been out earlier. Hard at times on the former to figure out exactly where the trail went, and not much clue where the rocks are, but with the layer of snow slowing you down a bit, and softening everything underfoot (or under tyre really) it was just bl**dy good fun. The big berms on the lower trails were something else. They always remind me of an Olympic bob-sleigh run anyway, but add in a covering of 3" of snow and heading into a 10ft wall of banked snow - you'd swear you were on the Cresta run.

                                Hard to draw (m)any conclusions on if/whether the changes to the suspension had much of an effect on the day - but I found pushing the bike down onto the side of the tyre in the corners and berms felt good, and seems to get you through all of the nadgery stuff quicker and with more confidence. And yeah, unweighting the front over the little steps and first part of some of the rock gardens seems to keep your momentum up, and make things flow better. One of the side-effects of that tho' is discovering when you do yump some of the rocky bits, you come out of them faster and then have to be careful you don't run out of track and into the scenery when it turns sharp left or right immediately after.

                                Every day's a learning day as they say.
                                Last edited by -alan-; 12-12-2022, 01:58 PM.

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