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Recently picked up a used Boardman Hybrid Team and it's my first bike after several years on boris bikes in London.

I was doing great in the summer but recently have slipped/skidded 3 times in last 6 weeks or so and fallen - cutting my knees, once my palm as well. The first was defs my fault (cornering too fast), but the other two I was behaving what I thought to be sensibly and the falls came out of nowhere - though it was wet both times and manhole covers were involved and after searching I'm learning they could be the culprit.

If I want to avoid falling so much I realise I need to change my riding style (keeping an eye out for those manholes to start with, and being more careful with the disc brakes in the wet as they lock up fast).

But beyond changing how I ride, could the tyres the bike has (Schwalbe Stelvio 28mm) also be a contributor? They're pumped up pretty full so I could let some air out, or I could just buy some new (fatter? grippier?) tyres. Would that help with the skidding and falling everywhere? If it would - I'd appreciate any recommendations for tyres to buy as well :) Thank you.

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    I don't know that any tyres can grip on a wet man-hole cover. (They're the culprit in my only tumble in London too.) I think it's just part of urban cycling that you have to avoid man-hole covers when turning. (To those unfamiliar with man-hole covers in the UK they're often polished completely smooth by wear.) – thosphor Oct 20 '20 at 9:56
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    Did you ever remember riding a Boris Bike over a metal plate in the rain while turning/braking ? If so, do you remember how fast you were going ? I expect, "slower than on the new bike" given the weight of boris bikes. – Criggie Oct 20 '20 at 10:30
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    There are definitely differences in grippiness between different tire brands. Reducing tire pressure won't help, grip is determined by force times area, and it's irrelevant whether you put lots of force on a small patch, or low force on a wide patch. However, as @thosphor says: It's your eyes that save you from falling on manhole covers. – cmaster - reinstate monica Oct 20 '20 at 10:31
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    @cmaster-reinstatemonica yes, you integrate the contact force over the contact area, but on real life surfaces the coefficient of friction is non-uniform, and a smaller contact patch samples a smaller area of road - if that patch is unluckily slippery you'll have trouble. Plus too-hard tyres can lose contact more easily due to bumps (e.g. the edges of the covers). – Chris H Oct 20 '20 at 10:52
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    Don’t let out too much air, it’ll mess with the handling, which is bad especially considering how you crash while cornering. I thought Schwalbe was notorious for having high grip and poor durability? At least in the MTB world, Schwalbe tires grip much better than you would expect, but wear out absurdly fast (and are bloody expensive to boot). – MaplePanda Oct 20 '20 at 15:23
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Wet metal plates on the road have an astonishingly low grip, on par with a sheet of ice.

There's very little you can practically change on your bike to improve this - changing to wider tyres at low pressure would help, but the rest of your commute will be like slogging through treacle, and highly unpleasant.

What you can do - change your technique. Never turn or brake while crossing a metal plate. Keep the bars and therefore front wheel straight and roll over it.
If the plate is on a corner (and many are) then try to avoid going over them at all. Take a left or right position and bypass the plate completely. Naturally this requires local knowledge and for you to anticipate what's coming up.

It may be possible to participate in activism - write to the local council or similar roading authority, and request the plate be replaced with a textured one, or surfaced with bitumen. This is a slow process but is not impossible.

Your very last resort is to react quickly should the bike start to slide, and take whatever action helps to restore your balance. That may be a shift in body weight, which could potentially put you into the path of traffic.
The counter here is that when your bike is sliding, it happens really quickly and its hard to react in time.

Or find a route that avoids this corner/plate completely.

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    I had a slide on ice once, with my gopro footage, it was about 3/10 of a second to go from "leaning and cornering normally" to "handlebars strike the road" Given normal human reaction time is roughly 2/10 of a second, the bike was two-thirds of the way down before I could have acted, and that's just too late. – Criggie Oct 20 '20 at 10:33
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    Even lane-marking white/yellow paint has to be treated with caution in the wet. I'm a bit west of the OP but recent weather here has been the sort that leaves the roads really slippery - drizzle after drier weather. – Chris H Oct 20 '20 at 10:40
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    Manhole covers, markings and steel plates covering works are best taken with the bike vertical and going straight ahead, implying some amount of foresight which may be difficult with city traffic. – Carel Oct 20 '20 at 10:44
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    As @Carel says, foresight can be tricky in traffic, but it's much harder to plan ahead if you're too close to the edge of the road to start with. Starting a little further from the kerb gives you more chance to go wide of metalwork rule 67 of the highway code expects you to avoid such hazards – Chris H Oct 20 '20 at 10:57
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    Thanks folks. Goldmine of information here. Just as you mentioned, I barely had time to blink before I'd hit the ground so seems like I just need to retrain my brain to realise that those unassuming little metal squares are way more dangerous than they look - and to avoid them at almost all costs! – Tom H Oct 20 '20 at 12:12
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Those tyres are probably quite old, and rubber perishes over time. They do not appear on the Schwalbe website.

They were racing tyres. https://roadcyclinguk.com/news/event-news/schwalbe-stelvio-evolution.html

They are lightweight racing tyres, and very different from those on a Boris Bike.

I have cycled on tyres between 2"+ and 23mm, and there is an enormous difference in feeling of stability on the former compared to the latter.

Certainly it's often a good idea to change the tyres on a new bike, as they are a relatively cheap purchase and have the biggest effect on performance, much more so than £500 groupset upgrades or whatever. In your case probably yours are very good for certain purposes, i.e. racing (or at least they were in 2002, or whenever), but they are not really what you are looking for by the sounds of it?

You'd have to check the rims you have (the size will be written on), and the type of brake and fork for clearance before fitting a larger tyre. It might well be that you cannot fit anything larger than 28mm, even though probably you'd be happier with 37mm or something like that.

One thing you could try with your current tyres is less pressure. This will help with grip. Go as low as possible within the manufacturers specs. Lower still is often possible but puncture risk is high.

However it might be best to just replace them. Perhaps you could inspect your frame for clearance for larger tyres.

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    I was just googling about that tyre to write my own answer saying much the same thing. From what i can tell, it's been discontinued for 10 years so the rubber will almost certainly have deteriorated. – Andy P Oct 20 '20 at 10:59
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    Thank you! Hugely valuable. I hadn't realised how old these tyres were! This answer and the other cover everything. I think new tyres + better avoidance of manholes sounds like a great plan. Heading to the LBS now... – Tom H Oct 20 '20 at 12:09
  • I have one stelvio tyre on my folding bike, and its definitely a lightweight racing/training tyre. On par with a Conti GP 4000 or so. – Criggie Oct 21 '20 at 2:32
  • I want to +1 for the sleuthing on the tyre type and advice for replacement but -1 for decreasing pressure. (Still giving +1.) – Jann Poppinga Oct 22 '20 at 11:41
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    I would suggest running a wider tyre at lower pressure - it's not necessarily slower: you lose energy from the greater sidewall deformation, but you also save by transmitting less vertical motion from bumps to the frame - provided you have good quality tyres with supple sidewalls, and put enough air in to avoid pinch punctures. I've found Continental GP4S 28mm, especially, to ride as fast at 2.5 bar as at 6, and far more comfortably. – Andrew Spencer Oct 22 '20 at 13:16
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Braking technique

You seem to have hydraulic brakes and do mention that they tend to lock-up easily. This should not be the case. Hydraulic brakes are known to be more progressive (there are some slight variations due to designs and pads). If you lock up the wheels, it may be because you are braking too hard in the first place. Try to be more gentle in your braking by using less fingers. I only use one finger on my disc road bike and can still lock up the wheel fairly easily.

Anticipation

It is advised to increase spacing with other cars by two when driving in the wet. I would argue that cycling should be more (2 wheels, thin tyres). Anticipating slowdowns and obstacles will be the major reason why you won't crash. Riding in the wet requires focus and attention.

Equipment

Better tyres do help...to some extent. As said, riding over a metal plate with a little angle will make you fall no matter what in the wet, but winter tyres will definitely help while riding on other wet surfaces.

I run slicks on my Brompton and have my front wheel often skidding in these conditions.

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I ride motorcycles, therefore this may not be all that relevant. However, if you want my opinion, in addition to other useful suggestions here, note this: if you can't brake using rear brakes alone, you are going too fast. There is a reason why motorcycles costing €20k and more still have separate brakes, which are not automated. The more unfavourable the conditions, the more you have to resort to your rear brakes. This includes all types of obstacles: metal plates, water and ice, holes, dirt etc. You certainly need to change your tires if they are old. But braking technique is certainly the #1 issue in all braking failures!

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    You got it right: braking is different on a bicycle. Motorcycles have lower center of gravity because they are heavy and have longer wheel base. Because of this the deceleration doesn't move weight to front wheel in the same way, so rear brake works better and you can worry about locking the front wheel, not endo. – ojs Oct 23 '20 at 9:53
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    Additionally two separate independent brake systems are mandated in any modern country as the minimum, regardless of what kind of road vehicle it is, bike/motorbike/car/truck etc. – Criggie Oct 26 '20 at 22:49
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Possibly a wild guess, but based on experience:

Adjust your brakes so that rear brake bites hard and fast, while front brake is slow and not as strong.

Esp. when you need to brake suddenly, I suppose you'd much rather prefer the rear wheel to slip (sideways if you're in a turn), from which you can recover by putting your foot out, as opposed to front wheel slip, which is almost impossible to recover from.

Of course, make sure your brakes are OK too; it may sound silly, but worn pads or loose/stretched cables are often ignored. IMO, you should be able to lock your rear wheel on dry pavement (whether you choose to is up to you), and should not be able to lock your front in mixed conditions (wet, sand on the road). Really strong front brakes, IMO, are only for serious racers, who want to shave every fraction of a second before going into a turn; they also train to modulate braking. There are also brake force limiter devices both for cabled and hydraulic systems.

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    There is a kernel of truth in here - braking more with the rear brake in slippery conditions does help. But derating your brakes is never a good idea; instead work on one's technique for the conditions of each ride. – Criggie Oct 22 '20 at 8:47
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    This is overall bad advice from someone either inexperienced or never ridden a bike. The advice to put your foot out works does not work at all with front wheel slip. – ojs Oct 22 '20 at 9:04
  • @ojs well, except for the fact that sticking out a foot does work and is in fact a pretty good idea in bad grip conditions. – leftaroundabout Oct 22 '20 at 21:47
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    @leftaroundabout yes, if you do it before losing traction. And it works for front wheel too. – ojs Oct 23 '20 at 7:01
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    There is a good additional point at this comment +1 from me – Stefanos Zilellis Oct 23 '20 at 8:53

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