Saturday, 16 July 2016

Wheels and Tyres

One of the great things about bikes is that they are very adaptable machines. Swap out a couple of components or add something like bikepacking bags or racks and panniers and you get a "different" bike. Traditionally one of the easiest ways to get a different "feeling" bike was to change the wheels and/or tyres. In fact many quality road bikes come with fairly cheap wheels on the assumption that the purchaser will immediately swap them out for their favourite, a bit like installing a new kitchen when you move into a new house (if you are posh).

In recent years there's been a plethora of new sizes and variations. One of these is 27.5+, AKA 650b+. These "plus" sized tyres are roughly halfway between a traditional trail tyre and fat bike tyres with widths somewhere in the 2.8" - 3.2" region. The idea is to give some of the benefits of a fat tyre without the drawbacks. In order to use these tyres a wider rim is required. As ever with something "new" there isn't a huge choice when it comes to either rims or tyres but this is slowly changing. By a happy coincidence the overall diameter of a 27.5+ wheel and tyre combo is close to that of a normal 29er wheel and tyre which means that many 29er frames can run with the plus sizes, the limiting factor is the width of the tyre since the frames and forks weren't designed with them in mind. Again this is changing, the Mk2 Solaris for example has slightly wider chainstays to allow for the plus tyres though the Mk1 (which I have) is compatible if a little "close".

Until recently if you wanted to go "plus" then the only real option was to build your own wheels using one of the rims available but Alpkit now sell a set of 650b+ wheels called the Rumpus for the bargain sum of £199. Definitely worth a punt.

One of the problems with plus tyres is figuring out if your rim/tyre combination will fit in your frame or forks, some 2.8" tyres come up wider than tyres marked as 3.0" for example, generally unless someone has actually tried the combination you are looking at using and has come up with figures then it's just a guess. After some searching around I settled on a couple of WTB tyres: a Bridger 3.0" for the front and a 2.8" Trailblazer for the rear. I knew that the Trailblazer was likely to fit as it's the tyre that Cy at Cotic used when trying out plus tyres on a similar width rim to the Rumpus (45mm) but the Bridger was a bit of a punt as I hadn't come across anyone using it with my forks.

First impressions of the Rumpus wheels: sturdy but not that heavy given that they've obviously been built to a price. Front and rear were set up for 15mm axles whereas I have a 9mm QR on the rear so had to swap out the provided axle converters which is pretty easy. It's worth noting that the QR converter on the drive side does not have the flats for a cone spanner to work with which may make converting the other way a little tricky as it is a threaded interface.

Running tyres in tubeless mode means using an air-tight rim tape to prevent air loss. Finding 45mm wide tape isn't easy(!) In the end I took the Gorilla Tape option, this is a cheaper method than the branded tapes (which are just generic industry tapes repackaged) but potentially a bit messy as it has contact adhesive on one side but since I've no intent of changing tyres on a regular basis this shouldn't be a problem. The rims are quite shallow so I only needed a single wrap of tape.

The Bridger comes up about 12mm less in diameter than a Bontrager XR4 on a Hope XC rim. The Trailblazer is about 23mm less overall diameter, again on a Hope XC rim. The front weighs 2805g (with disk rotor) compared to the Bontrager XR4/Hope combo weighing 1960g, it does add noticeable weight to the front of the bike. The Trailblazer weighs 2580g (inc rotor but not the cassette). I checked the Bridger in the forks and there's a couple of mm clearance to either side. Something to note is that with the rims being approximately 40mm less in diameter means that the widest part of the wheel may not be at the same point as with a 29er. The widths were as follows:

The XR4 (@ 25psi) measured 59mm at the tread
The XR3 (@ 27psi) measured 56mm at the tread.

Given the quoted sizes this difference isn't too far from what's expected and are spot on (to within 0.5mm) of the stated width.

The Bridger (@12psi) is 74mm at the tread, the sidewall is very roughly the same, possibly slightly less.

The Trailblazer (@13psi) is 69mm at the sidewall and 58mm at the tread.

So despite being quoted as a 2.8" tyre, the Trailblazer is only 2mm bigger than the XR3 and is narrower at the tread than the XR4! Of course it's a lot bigger in volume.

Bridger 3.0" on left, Bontrager XR4 2.35" on right

The smaller diameters of the wheels has two effects. Firstly the gearing is slightly lower by about 4% which is roughly half of the difference between two gears. Secondly, the bottom bracket is lower: take the average radius difference of the above values: Front radius difference = 12/2 = 6; rear = 23/2 = 11.5. So each axle is lowered by that amount. With the BB being halfway between these it's roughly halfway between the two: (6 + 11.5)/2 = 7.75mm, call it 8mm.

Cost of the whole caboodle:

Rumpus Wheels     £200
650b+ tyres       £ 95
Disk rotors       £ 33
Valves            £  9
Rim tape          £  4
Total             £341

So what difference does it make to the bike? Is it faster, slower, more or less responsive? The only way to find out is to ride it so I came up with a loop with a variety of surfaces and plenty of climbing and descent that should give me an idea of what to expect. First though I needed a baseline so headed round it one afternoon. Whereas many wheel/tyre comparisons concern themselves purely with speed I was more concerned with overall efficiency so wore my HRM and logged that data as well as speed. On subsequent loops I'd try and keep my heart rate similar so that I'd see if the wheels really did make a difference.

So using Strava as the comparison tool and wearing a HRM so that there's a second metric to compare other than just speed this was the ride using the 29er wheels -

There was a strong SouthWesterly and due to recent heavy rain the ground was wet with lying water but underneath the surface dampness it was pretty solid, not muddy at all. I think most of the PRs are due to being on my own rather than in a group and having to wait at gates etc. I didn't really push it - at most times I would have been able to hold a conversation, but equally I wasn't dawdling.

With the new wheels fitted I headed out again. I'd had the bank holiday weekend to get a little familiar with them but I wouldn't say I'm completely up to speed with them, though ... In the intervening eleven days things have dried out completely, now rather than compliant damp turf you had rock hard ridged soil. This time the wind was from the NE so into my face on the early climbs. Again I was keeping things at about the same perceived level of exertion and the HR figures bear this out, some are slightly higher some a little lower. This is the B+ ride

and I'm somewhat shocked to get so many PRs. Remember that the B+ wheels and tyres make the bike over 1.5Kg heavier.

I expected it on one or two segments - "Boss Moor techy climb" for example is ideal for fatter tyres being stony with a few larger loose rocks lying on the surface leading to a rutted section for example. On the Mastiles Lane climb it was just a case of sitting down and spinning your legs, very little back wheel spin/slip. On the descent from Weets Top there is a very short and steep climb up from a beck, slightly loose, I have never managed to get up it. This time it just wasn't a problem (the parade of cows and their calves heading up the track shortly after was a different matter). There is a similar loose section at the start of the last climb which since it got washed out I've never managed but again nearly got it. So the grip is amazing - keep your weight just forward of the back wheel and so long as you can pedal you'll get up things.

The tyres make the bike feel "plush" for want of a better word - on ground where with normal tyres you would get a lot of high frequency chatter it's just all smoothed out. Some of the descents that normally have my eyeballs shaking in their sockets were silky smooth.

So if those are the positives, what are the negatives? Well on the descent from the top of Mastiles I hit a rollercoaster of bumps and hollows and the undamped suspension of the rear tyre set me pogoing and threatened to bounce me over the front. This made me a bit wary on some of the similar stuff later on. The little bit of road on the ride was again hard work - the largest section had the wind on my back and it felt harder than riding in to the wind on the 29er wheels. A few days later Cath and I went out for a bivvy ride, part of the ride out was along a gently rolling road. Whereas normally I'm having to coast a bit to let her keep in touch that night I had to pedal quite hard just to keep up.

Another area where they aren't as precise as normal tyres is in mud - you get a weird combination of wallowing and twitchiness, you just have to make sure you are putting pressure on the front of the bike otherwise the front wheel has a mind of its own.

It's early days. I haven't got the pressures dialed in yet, particularly the rear tyre, and when you are running at 12-15psi just one psi up or down can make a big difference. I think that for routes/rides that are predominantly off-road and composed of tracks of packed hardcore or a little rougher then they are well worth considering. For any route with a significant amount of road normal tyres would be preferable.

One thing to watch out for is the new gear "halo effect", basically being ultra keen because you are using new gear. Since I needed to get used to the tyres I ran with them for a few weeks before revisiting the loop. I also needed to get the pressure sorted, at the values in use on these large volume tyres a single PSI change can have a massive impact on handling. The starting point for standard MTB tubeless tyres is (weight in stone x 2) then subtract 1 for the front and add 2 for the rear. For me this is about right, certainly for the back tyre. For plus tyres the advice seems to be "just try pressures until you're happy", but generally start at 15psi and keep dropping 1psi until it feels wrong.

What's important to note about these "results" is that they are specific to me and how I ride that bike so they may not be applicable to anyone else.

Since writing the majority of the above I've fitted rigid carbon forks to the bike. With standard 29er wheels there's quite a bit of chatter but the "plushness" of the plus sized tyres mentioned earlier is a distinct advantage and I've not really noticed the rigid forks on subsequent rides but this might be that I've also adjusted my riding technique to handle the forks better. I used the Plus tyres on the Peak 200 last week and only really had a problem with those sections that had a thin layer of mud overlying harder substrate where you just get a wallowing effect, other than that they were fine.

Tuesday, 12 July 2016

Peak 200

"What the ..." I stare disbelievingly at the seat harness, where there should be a bright yellow dry bag containing my bivy kit there is nothing. At some point in the last couple of Km it has come adrift. It's half past midnight and I've been riding since ten the previous morning. Nothing for it but to hide the bike in the nettles and walk back along the route hoping that I find it.

The Peak 200 ( a slight misnomer since it's actually 230Km) has the dubious honour of having had no finishers from group starts. Just five of us had thrown our hats in to the ring for this year's edition. With heavy rain forecast for Saturday I wasn't even sure about starting but loaded the car up anyway, by Saturday morning the forecast was for rain clearing by midday. Off to Edale it was then.

I turn in Hope towards Edale and the first spots of rain hit the windscreen, by Edale it's heavy.

Javi, myself and Mark. Yep, that's the group start sorted!


There's a van in the car park with a bike leant against it and a large beard sticking out from a hoodie fussing around it. I wander over and introduce myself. The beard hides a big smile. It would turn out that we were the group.

Having seen him ride off in to the mist on Cut Gate whilst I was dealing with a minor mechanical I thought that would be the last I would see of him but he has a bad patch near Hayfield so we end up riding together for most of the first day.

"Have you seen a rider with a big beard on a singlespeed?" I ask two bikers at the top of the descent into Birch Vale. "Ah, yes. He's about ten minutes ahead. We rode with him for a while, could only just keep up, he's a bit determined." Then I notice that they are on e-bikes.

Climbing out of Roych Clough Javi treats me to a masterclass in line choice, ... , well riding a bike really. There's little that stops him.

We have been riding down Long Dale for five minutes followed by a large herd of inquisitive heifers and finally come to the escape gate. As I'm opening it I turn round and see Javi hoist his bike above his head and run towards the cows and shout ... "Boo!"


The rain of recent weeks hasn't been kind to the trails in the southern Peak. My drivetrain is making horrible noises and seems to have picked up a kilo of mud and grass (Gratton Dale). On getting home and getting the bike out of the car it felt very heavy even though I'd removed the front wheel. A good half hour of cleaning and it still felt heavy - the cassette was completely full of clay that wouldn't shift with the hose and so required a full strip down and about an hour's work to get clean.


Surprisingly there aren't a lot of resupply points on the route. I don't know the area well enough that I could nip off-route to get to a tap or spring. Consequently I didn't have enough water, especially come nightfall. Javi did ask about whether the rivers were safe to drink from but a reasonable rule is not to drink from water with habitation upstream and in a densely populated area like the Peak that's not easy. With the heavy rain on Saturday morning all the becks in the Dark Peak were brown with peaty runoff, those dropping off Bleaklow were particularly impressive.

I wander back through the darkness scanning the track from side to side for the bag. I know it can be no further back than Froggatt Pinnacle since that is where I'd originally intended to stop and had taken the bag off but obviously not refastened everything properly. As I get to the moor gate it's there in the middle of the track. Just a long trudge back to the bike and sort myself out for the bivy.

The elastic had finally snapped between Javi and myself, I was always intending to bivy whereas he was aiming to ride through so with a handshake we part on the track above Froggatt and his light disappears in to the distance. Up to that point I'd surprised myself keeping pace with him but then I didn't have 550 miles of the Highland Trail in my legs which has got to take a while to get over. 

Mark heading towards Lockerbrook, rather damp.

After Cut Gate I'd ridden steadily in to the strong head wind, some restocking in Gamesley near Glossop: "Big tyres mate - do you ride on mountains with them?", "Err, yes, that's kind of the point". 

Much of the Western section was the Pennine Bridleway which I'd done once in the opposite direction. I meet up again with Javi at Chinley Head - "had a bad patch a while ago" and we ride together across the transition to The White Peak. I feel cramp coming on as we climb out of one of the small dales but manage to suppress it and I have little problem thereafter. At one point we have to make a detour to avoid a large herd of cows being led in to milk. We miss the correct way out of Chee Dale so end up with some road climbing.

We turn on to The High Peak Trail and suddenly the wind is on our backs: "Hooray! Easy going!". A few Km later and there's a pub, it's 1930 and we need food. With no reservation they make room for two filthy mountain bikers and we tuck in to a mammoth fish pie and chips.

Javi tucking into a well deserved fish pie and chips

More easy riding along the High Peak Trail before we meet the cattle in Long Dale and the mud and rocks of Gratton Dale

The morning's preparations are as much about getting mud and grass out of the drivetrain as anything until the midges win out so it's on with the show. Some nice singletrack, a bit of road, more singletrack until I'm dropping down to Fox House and then the Burbage Valley. Halfway up this I spy a pipe with clean water pouring out of it so take the chance to rehydrate. A minute or two won't make any difference to my time.

I miss the turning for a bridleway and find myself over a kilometre further downhill than I need to be. Even on the climb back up I fail to locate it so go the long way round by road. Stanage Causeway is new to me, on a bike anyway, the last time I was here was walking back to the car after a rock climbing accident that resulted in a broken wrist and a dislocated elbow.

Things begin to go wrong once over the top of Stanage, my GPS has "lost" the map so I've no idea where the route now goes. I cut left and eventually end up on the A57 but not at the point I should be. I know some of the route to the finish but nowhere near all of it so decide to ride what I know. Crossing Ladybower Dam I meet Paul who had seen us off and he turns round to ride back with me at least as far as Hope Cross. Apparently Javi isn't too far ahead though I've cut a couple of loops out by this point so not really a fair indication.

I'm flagging, lack of water and food have had their toll and I'm struggling to walk and push my bike up The Beast. Once at the top I head down the Roman Road while Paul heads more directly to Edale. It's all I can do to keep moving on the road and I eventually roll back to the finish just under 24hrs after setting off.

After a bit of hanging around and consumption of drink and food from the cafe I have to leave so don't get chance to see Javi get back in a time of 25hrs30, the first finisher from a group start.

It's a tough route, I think it would be quite a bit easier after a reasonably long dry spell, it would also be easier earlier in the year when the nettles, thorns and grass aren't so big. Must come back.